U.S. patent application number 15/536886 was filed with the patent office on 2017-11-30 for powder for film formation and material for film formation.
This patent application is currently assigned to NIPPON YTTRIUM CO., LTD.. The applicant listed for this patent is NIPPON YTTRIUM CO., LTD.. Invention is credited to Naoki FUKAGAWA, Kento MATSUKURA, Ryuichi SATO, Yuji SHIGEYOSHI.
Application Number | 20170342539 15/536886 |
Document ID | / |
Family ID | 56614697 |
Filed Date | 2017-11-30 |
United States Patent
Application |
20170342539 |
Kind Code |
A1 |
SATO; Ryuichi ; et
al. |
November 30, 2017 |
POWDER FOR FILM FORMATION AND MATERIAL FOR FILM FORMATION
Abstract
The present invention relates a coating powder comprising a rare
earth oxyfluoride (Ln-O--F) and having: an average particle size
(D.sub.50) of 0.1 to 10 .mu.m, a pore volume of pores having a
diameter of 10 .mu.m or smaller of 0.1 to 0.5 cm.sup.3/g as
measured by mercury intrusion porosimetry, and a ratio of the
maximum peak intensity (S0) assigned to a rare earth oxide
(Ln.sub.xO.sub.y) in the 2.theta. angle range of from 20.degree. to
40.degree. to the maximum peak intensity (S1) assigned to the rare
earth oxyfluoride (Ln-O--F) in the same range, S0/S1, of 1.0 or
smaller in powder X-ray diffractometry using Cu-K.alpha. rays or
Cu-K.alpha..sub.1 rays.
Inventors: |
SATO; Ryuichi; (Omuta-shi,
Fukuoka, JP) ; FUKAGAWA; Naoki; (Omuta-shi, Fukuoka,
JP) ; SHIGEYOSHI; Yuji; (Omuta-shi, Fukuoka, JP)
; MATSUKURA; Kento; (Omuta-shi, Fukuoka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NIPPON YTTRIUM CO., LTD. |
Omuta-shi, Fukuoka |
|
JP |
|
|
Assignee: |
NIPPON YTTRIUM CO., LTD.
Omuta-shi, Fukuoka
JP
|
Family ID: |
56614697 |
Appl. No.: |
15/536886 |
Filed: |
February 2, 2016 |
PCT Filed: |
February 2, 2016 |
PCT NO: |
PCT/JP2016/053064 |
371 Date: |
June 16, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 14/3414 20130101;
C23C 14/35 20130101; C23C 14/06 20130101; C23C 24/082 20130101;
C23C 14/26 20130101; C23C 4/04 20130101; C23C 4/10 20130101; C23C
4/11 20160101; C23C 14/0694 20130101 |
International
Class: |
C23C 4/10 20060101
C23C004/10; C23C 14/26 20060101 C23C014/26; C23C 14/35 20060101
C23C014/35; C23C 24/08 20060101 C23C024/08 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 10, 2015 |
JP |
2015-024627 |
Sep 18, 2015 |
JP |
2015-184844 |
Claims
1. A coating powder comprising a rare earth oxyfluoride (Ln-O--F)
and having: an average particle size (D.sub.50) of 0.1 to 10 .mu.m,
a pore volume of pores having a diameter of 10 .mu.m or smaller of
0.1 to 0.5 cm.sup.3/g as measured by mercury intrusion porosimetry,
and a ratio of the maximum peak intensity (S0) assigned to a rare
earth oxide (Ln.sub.xO.sub.y) in the 2.theta. angle range of from
20.degree. to 40.degree. to the maximum peak intensity (S1)
assigned to the rare earth oxyfluoride (Ln-O--F) in the same range,
S0/S1, of 1.0 or smaller in powder X-ray diffractometry using
Cu-K.alpha. rays or Cu-K.alpha..sub.1 rays.
2. The coating powder according to claim 1, having an average
particle size (D.sub.50) of 0.2 to 5 .mu.m, a dispersion index of
0.7 or smaller, and an aspect ratio of 1.0 to 3.0.
3. The coating powder according to claim 1, having a fluorine
concentration of 30% by mass or lower.
4. The coating powder according to claim 1, showing a pore size
peak in the range of from 0.1 .mu.m to 5 .mu.m in the pore size
distribution of pores having a diameter of 10 .mu.m or smaller
measured by mercury intrusion porosimetry with pore size as
abscissa and log differential pore volume as ordinate.
5. The coating powder according to claim 1, comprising a rare earth
fluoride (LnF.sub.3) in addition to the rare earth oxyfluoride
(Ln-O--F).
6. The coating powder according to claim 1, having a dispersion
index of 0.7 or smaller.
7. The coating powder according to claim 1, having a ratio of the
maximum peak intensity (S0) assigned to a rare earth oxide
(Ln.sub.xO.sub.y) in the 2.theta. angle range of from 20.degree. to
40.degree. to the maximum peak intensity (S1) assigned to the rare
earth oxyfluoride (Ln-O--F) in the same range, S0/S1, of 0.10 or
smaller in powder X-ray diffractometry using Cu-K.alpha. rays or
Cu-K.alpha..sub.1 rays.
8. The coating powder according to claim 1, having a ratio of the
number of moles of oxygen (O) per kg of the powder to the number of
moles of the rare earth (Ln) per kg of the powder, O/Ln by mole, of
0.03 to 1.1.
9. The coating powder according to claim 1, wherein the rare earth
is at least one element selected from yttrium (Y), cerium (Ce),
samarium (Sm), gadolinium (Gd), dysprosium (Dy), erbium (Er), and
ytterbium (Yb).
10. The coating powder according to claim 9, wherein the rare earth
is yttrium (Y).
11. The coating powder according to claim 1, being used to form a
coating by physical vapor deposition, aerosol deposition, or
thermal spraying.
12. The coating powder according to claim 11, wherein the physical
vapor deposition is vacuum evaporation or ion plating.
13. A coating material comprising the coating powder according to
claim 1.
14. The coating material according to claim 13, being in the form
of slurry.
15. The coating material according to claim 14, being used to form
a coating by thermal spraying.
16. A coating material comprising a sintered compact of the coating
powder according to claim 1.
17. The coating material according to claim 16, being used to form
a coating by physical vapor deposition.
18. The coating material according to claim 17, wherein the
physical vapor deposition is vacuum evaporation, ion plating, or
sputtering.
19. A method comprising using a powder comprising a rare earth
oxyfluoride (Ln-O--F) as a raw material for forming a coating, the
powder having: an average particle size (D.sub.50) of 0.1 to 10
.mu.m, a pore volume of pores having a diameter of 10 .mu.m or
smaller of 0.1 to 0.5 cm.sup.3/g as measured by mercury intrusion
porosimetry, and a ratio of the maximum peak intensity (S0)
assigned to a rare earth oxide (Ln.sub.xO.sub.y) in the 2.theta.
angle range of from 20.degree. to 40.degree. to the maximum peak
intensity (S1) assigned to the rare earth oxyfluoride (Ln-O--F) in
the same range, S0/S1, of 1.0 or smaller in powder X-ray
diffractometry using Cu-K.alpha. rays or Cu-K.alpha..sub.1
rays.
20. A method for forming a coating, comprising using a powder
comprising a rare earth oxyfluoride (Ln-O--F), the powder having:
an average particle size (D.sub.50) of 0.1 to 10 .mu.m, a pore
volume of pores having a diameter of 10 .mu.m or smaller of 0.1 to
0.5 cm.sup.3/g as measured by mercury intrusion porosimetry, and a
ratio of the maximum peak intensity (S0) assigned to a rare earth
oxide (Ln.sub.xO.sub.y) in the 2.theta. angle range of from
20.degree. to 40.degree. to the maximum peak intensity (S1)
assigned to the rare earth oxyfluoride (Ln-O--F) in the same range,
S0/S1, of 1.0 or smaller in powder X-ray diffractometry using
Cu-K.alpha. rays or Cu-K.alpha..sub.1 rays.
Description
TECHNICAL FIELD
[0001] This invention relates to a coating powder containing a rare
earth element and a coating material.
BACKGROUND ART
[0002] A halogen gas is used in an etching step in the fabrication
of semiconductor devices. In order to prevent halogen gas corrosion
of an etching apparatus, the inner side of the etching apparatus is
usually coated with a highly anti-corrosive substance by various
coating techniques, such as thermal spraying. Materials containing
a rare earth element as one type of such substances are often
used.
[0003] Coating materials containing a rare earth element are
usually granulated into flowable granules. To use the coating
material in the form of non-granulated powder or slurry containing
non-granulated powder has also been under study.
[0004] Among known coating materials containing a rare earth
element is a thermal spray material comprising a particulate rare
earth oxyfluoride having an aspect ratio of 2 or smaller, an
average particle size of 10 to 100 and a bulk density of 0.8 to 2
g/cm.sup.3 and containing not more than 0.5% by mass of carbon and
3 to 15% by mass of oxygen. It is known that this thermal spray
material can be prepared by granulation (see Patent Literature
1).
[0005] A rare earth-containing compound particles for thermal
spraying, having a polygonal shape with an average particle
diameter of 3 to 100 .mu.m, a dispersion index of up to 0.5, and an
aspect ratio of up to 2 is also known. The particles are not
granulated so that incorporation of impurities, such as iron, is
avoided (see Patent Literature 2).
[0006] Coating techniques other than thermal spraying are also
studied. For example, Patent Literature 3 teaches a method for
producing an anti-corrosive part composed of a substrate made of
ceramics, quartz, or silicon and an anti-corrosive coating of
Y.sub.2O.sub.3. According to the method, a Y.sub.2O.sub.3
anti-corrosive coating having a thickness of 1 to 100 .mu.m is
formed on the substrate by physical vapor deposition (PVD), such as
ion plating.
CITATION LIST
Patent Literature
[0007] Patent Literature 1: US 2014057078A1
[0008] Patent Literature 2: US 2002177014A1
[0009] Patent Literature 3: JP 2005-97685A
SUMMARY OF THE INVENTION
Technical Problem
[0010] The rare earth oxyfluoride thermal spray material of Patent
Literature 1 provides a thermal spray coating exhibiting very good
anti-corrosion properties. However, because the thermal spray
material is prepared by granulation, the resulting thermal spray
coating tends to be less dense.
[0011] The rare earth element-containing compound particles for
thermal spraying of Patent Literature 2 substantially consist of a
rare earth oxide, so that the resulting thermal spray coating,
while satisfactory in resistance to corrosion by a fluorine-based
plasma, tends to have insufficient resistance to corrosion by a
chlorine-based plasma.
[0012] The anti-corrosive coating formed by PVD according to Patent
Literature 3, which is made of yttrium oxide, exhibits high
resistance to corrosion by a fluorine-based plasma but tends to be
unsatisfactory against corrosion by a chlorine-based plasma.
[0013] An object of the invention is to provide a coating powder
that eliminates various disadvantages of the aforementioned
conventional techniques and a coating material containing the
powder.
Means for Solving the Problem
[0014] As a result of extensive studies with a view to solving the
above problem, the inventors have surprisingly found that a coating
powder containing a rare earth oxyfluoride and having a specific
particle size and a specific pore volume measured by mercury
intrusion porosimetry provides a very dense and uniform coating
having high resistance to corrosion by a chlorine-based plasma, and
thus completed the invention.
[0015] The present invention has been completed on the basis of the
above findings and provide a coating powder including a rare earth
oxyfluoride (Ln-O--F) and having: an average particle size
(D.sub.50) of 0.1 to 10 .mu.m; a pore volume of pores having a
diameter of 10 .mu.m or smaller of 0.1 to 0.5 cm.sup.3/g as
measured by mercury intrusion porosimetry; and a ratio of the
maximum peak intensity (S0) assigned to a rare earth oxide
(Ln.sub.xO.sub.y) in the 2.theta. angle range of from 20.degree. to
40.degree. to the maximum peak intensity (S1) assigned to the rare
earth oxyfluoride (Ln-O--F) in the same range, S0/S1, of 1.0 or
smaller in powder X-ray diffractometry using Cu-K.alpha. rays or
Cu-K.alpha..sub.1 rays.
[0016] The invention also provides a coating material comprising
the coating powder.
Advantageous Effects of Invention
[0017] The coating powder and the coating material according to the
invention form a dense and uniform coating having high resistance
to corrosion by not only a fluorine-based plasma but a
chlorine-based plasma and less prone to particle shedding during
plasma etching.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is an X-ray diffraction pattern of the coating powder
of Example 3.
[0019] FIG. 2 is an X-ray diffraction pattern of the coating powder
of Example 10.
[0020] FIG. 3 is an X-ray diffraction pattern of the coating powder
of Example 15.
DESCRIPTION OF EMBODIMENTS
[0021] The invention will be described on the basis of preferred
embodiments.
I. The Coating Powder of the Invention (Hereinafter Also Referred
to as "the Powder of the Invention") Will be Described First.
(1) Rare Earth Oxyfluoride
[0022] The coating powder of the invention is characterized by
containing a rare earth oxyfluoride (hereinafter also referred to
as Ln-O--F). The rare earth oxyfluoride (Ln-O--F) of the invention
is a compound composed of a rare earth element (Ln), oxygen (O),
and fluorine (F). The Ln-O--F includes not only a compound having a
molar ratio between a rare earth element (Ln), oxygen (O), and
fluorine (F), Ln:O:F, of 1:1:1 but a compound having an Ln:O:F
molar ratio other than 1:1:1. For example, when Ln=Y, examples of
the Ln-O--F include Y.sub.5O.sub.4F.sub.7, Y.sub.5O.sub.6F.sub.7,
Y.sub.7O.sub.6F.sub.9, Y.sub.4O.sub.6F.sub.9,
Y.sub.6O.sub.5F.sub.8, Y.sub.17O.sub.14F.sub.23, and
(YO.sub.0.826F.sub.0.17)F.sub.1.174 as well as YOF, and the coating
powder of the invention can contain at least one of these
oxyfluorides. The Ln-O--F is preferably a compound represented by
LnO.sub.xF.sub.y (0.3.ltoreq.x.ltoreq.1.7, 0.1.ltoreq.y.ltoreq.1.9)
in view of ease of preparation of the oxyfluoride and for ensured
effects of the invention, i.e., denseness, uniformity, and high
corrosion resistance of the resulting coating. From the same point
of view, x in the above chemical formula is preferably
0.35.ltoreq.x.ltoreq.1.65, more preferably 0.4.ltoreq.x.ltoreq.1.6;
and y in the formula is preferably 0.2.ltoreq.y.ltoreq.1.8, more
preferably 0.5.ltoreq.y.ltoreq.1.5. The relation between x and y in
the formula is preferably 2.3.ltoreq.2x+y.ltoreq.5.3, more
preferably 2.35.ltoreq.2x+y.ltoreq.5.1, even more preferably
2x+y=3.
[0023] A coating powder having a desired composition of Ln-O--F can
be prepared by adjusting the molar ratio of the rare earth fluoride
(LnF.sub.3) to a rare earth oxide (Ln*) or a rare earth compound
that becomes an oxide on firing (Ln*), i.e., LnF.sub.3/Ln*, used in
step 1 or the conditions of firing in step 2 of a preferred process
of preparation hereinafter described.
[0024] Rare earth elements (Ln) include 16 elements: scandium (Sc),
yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr),
neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd),
terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium
(Tm), ytterbium (Yb), and lutetium (Lu). The coating powder of the
invention contains at least one of the 16 rare earth elements. To
further increase the heat resistance, the wear resistance, and the
corrosion resistance of the coating formed by using the coating
powder or a coating material containing the powder according to the
coating method hereinafter described, it is preferred to use at
least one of yttrium (Y), cerium (Ce), samarium (Sm), gadolinium
(Gd), dysprosium (Dy), erbium (Er), and ytterbium (Yb),
particularly yttrium (Y).
(2) In the Case that Rare Earth Fluoride (LnF.sub.3) is Further
Contained
[0025] The powder of the invention containing Ln-O--F may further
contain a rare earth fluoride (LnF.sub.3). Taking into
consideration ability to form a uniform coating, resistance to
corrosion of a coating to oxygen radicals, and the like, it is
preferred that the Ln-O--F-containing particles of the powder of
the invention be composed solely of Ln-O--F, but the presence of
LnF.sub.3 is acceptable as long as the effects of the invention are
not impaired. The LnF.sub.3 content in the Ln-O--F is adjustable by
the mixing ratio in step 1 in the hereinafter described process for
producing the coating powder of the invention. It is not easy to
accurately determine the fluorine content in the powder of the
invention. Therefore, in the invention, the content of LnF.sub.3 is
estimated from the relative intensity of the main peak assigned to
LnF.sub.3 with respect to the main peak assigned to Ln-O--F in
X-ray diffractometry of the particles of the powder of the
invention. In detail, the particles are analyzed by X-ray
diffractometry using CuK.alpha. or Cu-K.alpha..sub.1 rays, and a
ratio of the maximum peak intensity (S1) assigned to Ln-O--F in the
2.theta. angle range of from 20.degree. to 40.degree. to the
maximum peak intensity (S2) assigned to LnF.sub.3 in the same
range, S1/S2, is obtained. For example, when the ratio, S1/S2, is
0.01 or greater, the resulting coating tends to be denser and more
uniform and be prevented from generating dust particles (particle
shedding) in plasma etching more effectively. From this viewpoint,
the S1/S2 is more preferably 0.02 or greater.
(3) Rare Earth Oxide
[0026] While the powder of the invention may contain LnF.sub.3 in
addition to Ln-O--F as discussed above, it is preferred for the
powder not to contain, or as little as possible, Ln.sub.xO.sub.y,
which is an oxide of a rare earth element alone, in view of
anti-corrosion properties, particularly resistance to a
chlorine-containing gas, of the coating. The Ln.sub.xO.sub.y
content in the coating powder of the invention can be minimized by,
for example, selecting properly the mixing ratio in step 1 and the
firing conditions in step 2 in the hereinafter described process
for producing the coating powder.
[0027] Because it is not easy to quantitatively determine the
Ln.sub.xO.sub.y content in the coating powder of the invention by
chemical analyses, the Ln.sub.xO.sub.y content is estimated from
the intensity of peaks in X-ray diffractometry of the coating
powder in the invention. In detail, the coating powder of the
invention is analyzed by X-ray diffractometry using Cu-K.alpha.
rays or Cu-K.alpha..sub.1 rays, and a ratio of the maximum peak
intensity (S0) assigned to a rare earth oxide in the 2.theta. angle
range of from 20.degree. to 40.degree. to the maximum peak
intensity (S1) assigned to a rare earth oxyfluoride in the same
range, S0/S1, is obtained. X-ray diffractometry adopted in the
invention is powder X-ray diffractometry.
[0028] It is required, in the invention, that the S0/S1 be 1.0 or
smaller. The S0/S1 is preferably 0.20 or smaller, more preferably
0.10 or smaller, even more preferably 0.05 or smaller. The smaller
the S0/S1, the better. The S0/Si is most preferably 0. With the
S0/S1 being as small as 1.0 or less, the coating is highly
resistant to not only corrosion by a fluorine-based plasma but
corrosion by a chlorine-based plasma.
[0029] In powder X-ray diffractometry, the maximum diffraction
peaks assigned to a rare earth oxyfluoride (Ln-O--F), a rare earth
oxide (Ln.sub.xO.sub.y), and a rare earth fluoride (LnF.sub.3)
usually appear at a 2.theta. angle ranging from 20.degree. to
40.degree.. For example, the maximum diffraction peak assigned to
yttrium oxide (Y.sub.2O.sub.3) appears at a 2.theta. angle of
around 29.1.degree..
[0030] In saying that the S0/S1 should be in the range described
above in X-ray diffractometry using Cu-K.alpha. or
Cu-K.alpha..sub.1 rays, it is only necessary that the requirement
be satisfied in X-ray diffractometry using either Cu-K.alpha. rays
or Cu-K.alpha..sub.1 rays. It does not mean that the S0/S1 should
be in that range in both X-ray diffractometry using Cu-K.alpha.
rays and X-ray diffractometry using Cu-K.alpha..sub.1 rays (the
same applies to the S1/S2). Note that, however, because both the
values S0/S1 and S1/S2 do not substantially vary depending on which
of Cu-K.alpha. rays and Cu-K.alpha..sub.1 rays are used, it does
not matter which X-rays are used unless these values are extremely
close to the boundary values of the above ranges. X-ray
diffractometry for obtaining S0, S1, and S2 is carried out under
the conditions described in Examples given later.
[0031] In general, a rare earth oxide (Ln.sub.xO.sub.y), when
produced by firing an oxalate or a carbonate in the air, is a
sesquioxide Ln.sub.2O.sub.3 (x=2 and y=3), except for cerium (Ce),
praseodymium (Pr), terbium (Tb). A cerium oxide is usually obtained
as CeO.sub.2 (x=1 and y=2), a praseodymium oxide is usually
obtained as Pr.sub.6O.sub.11 (x=6 and y=11), and a terbium oxide is
usually obtained as Tb.sub.4O.sub.7 (x=4 and y=7). Oxides of other
forms, such as Ce.sub.2O.sub.3, Pr.sub.2O.sub.3, PrO.sub.2, and
EuO, could be produced under specific conditions but are converted
to the above described usual forms when allowed to stand in the
air. Therefore, the above described usual oxide forms are
preferred.
(4) Average Particle Size (D.sub.50) of Powder
[0032] The Ln-O--F-containing particles in the coating powder of
the invention have an average particle size of 0.1 to 10 .mu.m.
Having an average particle size of 0.1 .mu.m or greater, the powder
is capable of forming a dense and uniform coating. Having an
average particle size of 10 .mu.m or smaller, the powder is capable
of forming a coating dense and less prone to cracking. From these
viewpoints, the average particle size of the Ln-O--F-containing
powder is preferably 0.2 to 8 .mu.m, more preferably 0.5 to 6
.mu.m. As used herein, the term "average particle size" is a
diameter at 50% cumulative volume in the particle size distribution
(hereinafter also simply referred to as D.sub.50).
[0033] D.sub.50 can be determined by laser diffraction/scattering
particle size distribution analysis. Details of the D.sub.50
measurement will be described later. In carrying out laser
diffraction/scattering particle size distribution analysis for the
measurement of D.sub.50, the powder is previously subjected to
ultrasonic dispersion treatment at an ultrasonic power of 300 W for
5 minutes (this also applies to the measurement of D.sub.90 and
D.sub.10 hereinafter described). Powder whose average particle size
is in the range recited can be obtained by properly selecting the
grinding conditions in step 3 of the hereinafter described process
for producing the coating powder of the invention.
(5) Dispersion Index
[0034] It is preferred for the coating powder of the invention to
have a dispersion index of 0.7 or smaller as well as the above
discussed specific D.sub.50. The dispersion index is defined to be
[(D.sub.90-D.sub.10)/(D.sub.90+D.sub.10)], wherein D.sub.90 and
D.sub.10 are diameters at 90% and 10% cumulative volumes,
respectively, counted from the smallest side in the laser
diffraction/scattering particle size distribution. To have a
dispersion index of 0.7 or smaller is preferred in the interests of
obtaining a denser coating that is less prone to particle shedding
in plasma etching. From the same viewpoint, the dispersion index is
preferably 0.6 or smaller, even more preferably 0.5 or smaller.
Although a dispersion index closer to zero is more preferred, the
dispersion index is preferably 0.15 or greater, more preferably or
greater, even more preferably 0.2 or greater, in view of ease of
preparation. Powder of which the dispersion index falls within the
above range can be prepared by carrying out the grinding in step 3
in the hereinafter described process of preparation by at least wet
grinding or in two or more stages.
(6) Volume of Pores Having a Diameter of 10 .mu.m or Smaller
Measured by Mercury Intrusion Porosimetry
[0035] The coating powder of the invention is also characterized by
having a specific volume of pores of 10 .mu.m or smaller diameter
as measured by mercury intrusion porosimetry (hereinafter also
simply referred to as the pore volume). The pore volume is a volume
of spaces between particles of the coating powder with a given
pressure applied thereon. The inventors have extensively
investigated into the relation between the physical properties of
the powder containing a rare earth oxyfluoride and the density of a
coating obtained therefrom and found, as a result, that the pore
volume is an important factor for obtaining a dense coating. The
pore volume depends on not only the particle size and specific
surface area of the coating powder but also the shape and the like
of particles constituting the coating powder. Therefore, powders
having the same particle size and the same BET specific surface
area do not always have the same pore volume. Specifically, it is
important for the coating powder of the invention to have a pore
volume of pores having a diameter of 10 .mu.m or smaller of 0.1 to
0.5 cm.sup.3/g. The inventors have proved that a coating powder
having the pore volume in that range can provide a coating which is
dense and highly resistant to corrosion by a halogen plasma. To
ensure the denseness of the resulting coating, the pore volume of
the coating powder of the invention is preferably 0.12 to 0.48
cm.sup.3/g, more preferably 0.15 to 0.45 cm.sup.3/g.
(7) Peak of Pore Size Distribution (Abscissa: Pore Size; Ordinate:
Log Differential Pore Volume)
[0036] In order to further enhance the effects of the invention, it
is preferred that the pore size distribution of the coating powder
of the invention as measured by mercury intrusion porosimetry (pore
size plotted as abscissa, and log differential pore volume as
ordinate) show a peak in a specific range. Specifically, the
coating powder of the invention preferably shows a peak in the
range of from 0.1 .mu.m to 5 .mu.m in the pore size distribution
measured by mercury intrusion porosimetry. The coating powder of
the invention which shows a pore size peak in that range forms a
coating that is less porous and therefore denser and less liable to
cracking on cooling. To further enhance these effects, the pore
size peak is preferably observed within a range of from 0.3 to 4
.mu.m, more preferably from 0.5 to 3 .mu.m. The results of mercury
intrusion porosimetry are usually plotted with the pore size as
abscissa and the log differential pore volume as the ordinate. In
the invention, too, the results are plotted in that way, and the
peak position is obtained from the plots.
(8) Adjustment of Pore Volume and Pore Size Peak
[0037] The pore volume and pore size peak can be adjusted to fall
within the respective ranges discussed above by properly selecting
various conditions in steps 1 to 3 in the hereinafter described
process for preparing the coating powder of the invention,
particularly the average particle size (D.sub.50) of a rare earth
oxide or a rare earth compound capable of becoming an oxide on
firing and that of a rare earth fluoride that are to be mixed in
step 1, the firing conditions in step 2, and the wet grinding
conditions in step 3. The pore volume and the pore size peak can be
determined by the methods described in Examples hereinafter
given.
(9) BET Specific Surface Area
[0038] The coating powder of the invention has a BET specific
surface area within a specific range. Specifically, the BET
specific surface area of the coating powder of the invention ranges
from 1 to 10 m.sup.2/g. When the coating powder of the invention is
used for forming a coating, the powder containing the rare earth
oxyfluoride moderately melts or vaporizes due to the BET specific
surface area in that range thereby to form a dense coating. To
obtain a denser coating, the BET specific surface area of the
coating powder is preferably 1.2 to 9 m.sup.2/g, more preferably
1.5 to 8 m.sup.2/g. Coating powder whose BET specific surface area
is in that range can be obtained by properly selecting the firing
temperature in step 2 of the hereinafter described process for
preparation. The BET specific surface area can be determined by the
method described in Examples given infra.
(10) O/Ln Molar Ratio
[0039] The coating powder of the invention preferably has a molar
ratio of oxygen element (O) to rare earth element (Ln) per kg, an
O/Ln molar ratio, of 0.03 to 1.1. With the O/Ln molar ratio being
in that range, the resulting coating exhibits further improved
resistance to corrosion by a chlorine-based plasma, and the coating
tends to be denser, more uniform, and less liable to particle
shedding during plasma etching. To ensure these effects, the O/Ln
molar ratio is more preferably 0.04 to 1.08, even more preferably
0.05 to 1.05.
[0040] Examples of typical compositions of coating powders
identified by X-ray diffractometry include: a composition
containing LnF.sub.3 and Ln.sub.7O.sub.6F.sub.9 when
0<O/Ln.ltoreq.0.6; a composition containing
Ln.sub.5O.sub.4F.sub.7 when 0.6<O/Ln.ltoreq.0.83; a composition
containing Ln.sub.7O.sub.6F.sub.9 when 0.83<O/Ln.ltoreq.0.95; a
composition containing LnOF when 0.95<O/Ln.ltoreq.1.05; and a
composition containing LnOF and Ln.sub.2O.sub.3 when
1.05<O/Ln.ltoreq.1.45. The above examples of the compositions of
coating powders are for illustrative purposes only but not for
limitation.
[0041] The O/Ln molar ratio is calculated from the oxygen content
of the coating powder measured by inert gas fusion-IR absorption
spectrometry and the rare earth content of the powder measured by
acid digestion/ICP-AES. The O/Ln molar ratio can be adjusted to be
in the above range by properly selecting the LnF.sub.3/Ln*molar
ratio in step 1, the firing conditions in step 2, and so on in the
hereinafter described preferred process for preparation.
(11) Aspect Ratio
[0042] The coating powder of the invention preferably has an aspect
ratio of 1.0 to 5.0 in view of capability of forming a dense and
uniform coating. From this viewpoint, the aspect ratio is more
preferably 1.0 to 4.0, even more preferably 1.0 to 3.0. The aspect
ratio can be determined by the method described in the Examples
below. Powder having the above aspect ratio can be obtained by
adjusting the size of the grinding medium or the grinding time or
by the use of a grinding machine capable of applying a high energy
in step 3 described below.
II. The Coating Material According to the Invention Will Next be
Described.
[0043] The coating material of the invention contains the coating
powder of the invention. As stated earlier, the coating powder of
the invention can be mixed or shaped with other components to
provide a coating material that is fed to a coating apparatus more
easily.
(1) Coating Material in the Form of Slurry
[0044] The coating material of the invention preferably has the
form of slurry for obtaining a dense coating. The coating material
in the form of slurry will also be called a coating slurry. In the
case where the coating material of the invention has the form of
slurry, the D.sub.50, D.sub.90, D.sub.10, and dispersion index of
the powder particles may be determined as they are suspended in the
form of slurry, but the BET specific surface area, pore volume,
pore size peak, aspect ratio, and fluorine concentration (described
later) of the powder particles are measured after the slurry is
thoroughly dried at 110.degree. C.
[0045] The dispersion medium of the coating slurry may be one of,
or a combination of two or more of, water and various organic
solvents. An organic solvent having a water solubility of 5 mass %
or more or a mixture of such an organic solvent and water is
preferred in terms of forming a denser and more uniform coating.
The organic solvent with a water solubility of 5 mass % or more may
be a freely water-miscible organic solvent. The mixture of the
organic solvent having a water solubility of 5 mass % or more and
water preferably has an organic solvent to water ratio within the
water solubility limit of the organic solvent. In view of the
dispersibility of the particles containing a rare earth oxide, the
proportion of the organic solvent having a water solubility of 5
mass % or more in the dispersion medium is preferably 5 mass % or
more, more preferably 10 mass % or more, even more preferably 12
mass % or more.
[0046] Examples of the organic solvent having a water solubility of
5 mass % or more (including a freely water-miscible one) include
alcohols, ketones, cyclic ethers, formamides, and sulfoxides.
[0047] Examples of the alcohols include monohydric alcohols, such
as methanol (methyl alcohol), ethanol (ethyl alcohol), 1-propanol
(n-propyl alcohol), 2-propanol (isopropyl alcohol, IPA),
2-methyl-1-propanol (isobutyl alcohol), 2-methyl-2-propanol
(tert-butyl alcohol), 1-butanol (n-butyl alcohol), and 2-butanol
(sec-butyl alcohol); and polyhydric alcohols, such as
1,2-ethanediol (ethylene glycol), 1,2-propanediol (propylene
glycol), 1,3-propanediol (trimethylene glycol), and
1,2,3-propanetriol (glycerol).
[0048] Examples of ketones for use in the invention are propanone
(acetone) and 2-butanone (methyl ethyl ketone, MEK). Examples of
the cyclic ethers are tetrahydrofuran (THF) and 1,4-dioxane.
Examples of the formamides include N,N-dimethylformamide (DMF).
Examples of the sulfoxides include dimethyl sulfoxide (DMSO). These
organic solvents may be used either individually or as a mixture
thereof.
[0049] Preferred of the organic solvents having a water solubility
of 5 mass % or more are alcohols. Monohydric alcohols are more
preferred, with at least one of methanol, ethanol, 1-propanol and
2-propanol being particularly preferred.
[0050] In using a water/ethanol mixture as a dispersion medium, the
ethanol concentration is preferably not more than 24 vol % (not
more than 20 mass %) so as to be excluded from the list of
dangerous goods based on United Nations Recommendations on
Transport.
[0051] The concentration of the coating powder in the coating
slurry is preferably 10 to 50 mass %, more preferably 12 to 45 mass
%, even more preferably 15 to 40 mass %. With the powder
concentration being in that range, the formation of a coating from
the slurry can be achieved in a relatively short time with good
coating efficiency, and the resulting coating exhibits good
uniformity.
[0052] The coating material in the form of slurry preferably has a
viscosity of 100 cP (mPas) or less at 25.degree. C. so that it may
be fed stably in thermal spraying to form a uniform coating. From
that viewpoint, the viscosity is more preferably 70 cP (mPas) or
less, even more preferably 50 cP (mPas) or less. The lower limit of
the viscosity of the coating slurry at 25.degree. C. is not
particularly limited but, in view of ease of preparation, is
preferably 0.5 cP or more, more preferably 1.0 cP (mPas) or more,
even more preferably 1.5 cP (mPas) or more. The coating slurry
whose viscosity is in that range may be obtained by properly
selecting the amount of the rare earth oxyfluoride particles to be
used, the type of the dispersion medium, and the like. The
viscosity can be measured by the method described in Examples
below.
[0053] The coating slurry may contain components other than the
rare earth oxyfluoride-containing powder and the dispersion medium,
such as pH adjustors, dispersants, viscosity modifiers, and
bactericides, as long as the effect of the invention is not
impaired. The solid matter of the coating slurry may comprise
particles other than the rare earth oxyfluoride-containing powder
but is preferably composed solely of the rare earth
oxyfluoride-containing powder in terms of forming a dense and
uniform coating.
(2) Coating Material in the Form of Sintered Compact
[0054] The coating material of the invention may include sintered
compact, which is also preferred for obtaining a dense coating. The
coating material in the form of sintered compact is obtained by
firing the coating powder of the invention. A coating material
comprising a sintered compact of the coating powder of the
invention will also be called a coating material in the form of
sintered compact. The coating material in the form of sintered
compact preferably has the same composition as the coating powder
of the invention. Accordingly, the above described preference with
respect to the ranges of S0/S1, S1/S2, and O/Ln molar ratio of the
coating powder equally applies to the powder obtained by grinding
the coating material in the form of sintered compact. When the
fluorine concentration of the powder obtained by grinding the
coating material in the form of sintered compact is determined by
the method described below, a preferred range of the fluorine
concentration is the same as that of the coating powder of the
invention as determined by the same method.
III. Method for Forming Coating
[0055] Coating methods that can be used to form a coating using the
coating powder or coating material of the invention will be
described.
[0056] Coating methods applicable to the invention include thermal
spraying, aerosol deposition (AD), and physical vapor deposition
(PVD).
(1) Thermal Spraying
[0057] Thermal spray techniques that can be applied to the coating
powder of the invention and the coating material in the form of
slurry include flame spraying, high velocity flame spraying (also
called high velocity oxygen fuel spraying), detonation spraying,
laser thermal spraying, plasma thermal spraying, and laser plasma
hybrid spraying.
[0058] The reason why the coating powder of the invention and the
coating material containing the powder form a dense and uniform
thermal spray coating is believed to be because the coating powder
of the invention and the coating material containing the powder are
readily fused uniformly when sprayed.
(2) Aerosol Deposition (AD)
[0059] The coating powder of the invention is also used in the AD
process. The reason why the coating powder of the invention forms a
dense and uniform coating by the AD process is considered to be
because the coating powder of the invention is readily aerosolized
uniformly in the AD process.
[0060] The AD process is a technique in which an aerosol obtained
by mixing the coating powder and a carrier gas at room temperature
is jetted from a nozzle at a high velocity and made to collide with
a substrate to form a coating film on the substrate. Because the
coating powder used in the AD process is especially required to
achieve more uniform and denser film formation, it is required to
be microfine and uniform in shape, being free from acicular or
irregularly shaped particles.
[0061] Specifically, it is preferred for the coating powder of the
invention for use in the AD process to have an average particle
size (D.sub.50) of 0.2 to 5 .mu.m, more preferably 0.5 to 2 .mu.m,
a dispersion index of 0.7 or smaller, more preferably 0.5 or
smaller, and an aspect ratio of 1.0 to 3.0, more preferably 1.0 to
2.0.
(3) Physical Vapor Deposition (PVD)
[0062] PVD is largely classified into sputtering, vacuum
evaporation, and ion plating (see Patent Map: Chemistry 16:
Physical Vapor Deposition, FIG. 4.1.1-3, available on the JPO
website).
[0063] The coating powder of the invention can be used in vacuum
evaporation and ion plating. Vacuum evaporation is a process in
which a coating material is evaporated or sublimated in vacuo, and
the vapor of the material reaches and deposits on a substrate to
form a coating. Electron beam or laser evaporation processes are
preferred because a sufficiently large amount of energy for
vaporizing the powder containing the rare earth oxyfluoride is
provided. The ion plating process is based on almost the same
principle as vacuum evaporation, with the difference being that the
evaporant is passed through a plasma to be positively charged, and
is attracted to a negatively charged substrate, and deposited on
the substrate to form a coating layer.
[0064] The coating material in the form of sintered compact can be
used in vacuum evaporation, sputtering, and ion plating. Sputtering
is a process in which high-energy particles in a plasma, etc. are
bombarded against a target material to eject particles from the
target, and the ejected particles of the target deposit on a
substrate to form a coating layer.
[0065] In the case of the ion plating process, in particular, in
order to enable the application to substrates in various shapes,
the coating powder desirably has a composition with a minimized
fluoride content whether it is used as such or in the form of
sintered compact.
[0066] It is preferred for the powder to have a small fluorine
concentration, specifically not more than 30 mass %, more
preferably not more than 25 mass %. While there is no particular
lower limit to the fluorine concentration, a fluorine concentration
of 5 mass % or more is preferred so as to give a sufficient
oxyfluoride content. The fluorine concentration can be determined
by the method described in the Examples. The coating powder having
the fluorine concentration adjusted within the above range can be
obtained by properly selecting the mixing ratio between the rare
earth oxide (Ln.sub.xO.sub.y) or a rare earth compound capable
becoming an oxide on firing and a rare earth fluoride (LnF.sub.3)
in step 1, the conditions of firing in step 2 of a preferred
process of preparation described below, and the like.
[0067] The reason why the coating powder of the invention or the
coating material in the form of sintered compact provides a dense
and uniform coating when used to form a coating by the PVD
processes is considered to be because they vaporizes uniformly in
the PVD processes.
IV. Process of Preparation
(1) Process for Preparing Coating Powder
[0068] A suitable process for preparing the coating powder of the
invention will then be described. The process includes the
following three essential steps and, as the case may be, an
additional step, which will be described in sequence.
[0069] Step 1: mixing a rare earth oxide (Ln.sub.xO.sub.y) or a
rare earth compound capable of becoming an oxide on firing and a
rare earth fluoride (LnF.sub.3) to prepare a mixture.
[0070] Step 2: firing the mixture obtained in step 1 to form a rare
earth oxyfluoride.
[0071] Step 3: grinding the fired product obtained in step 2.
[0072] Additional step (when the grinding of step 3 is wet
grinding): drying the resulting wet-ground product to give a dry
product.
Step 1:
[0073] The rare earth oxide (Ln.sub.xO.sub.y) or a rare earth
compound capable of becoming an oxide on firing to be subjected to
mixing preferably have an average particle size (D.sub.50) of 0.1
to 10 .mu.m, more preferably 0.15 to 8 .mu.m, even more preferably
0.2 to 7 .mu.m.
[0074] The rare earth fluoride (LnF.sub.3) to be subjected to
mixing preferably has an average particle size (D.sub.50) of
greater than 5 .mu.m and not greater than 500 .mu.m, more
preferably greater than 5 .mu.m and not greater than 100 .mu.m,
even more preferably 5.5 to 50 .mu.m. Measurements of D.sub.50 of
these components are taken after ultrasonication, and specifically,
taken in the same manner as described above with respect to the
D.sub.50 of the coating powder.
[0075] When the average particle sizes (D.sub.50) of the rare earth
oxide (Ln.sub.xO.sub.y) or the rare earth compound capable of
becoming an oxide on firing and the rare earth fluoride (LnF.sub.3)
are in their respective preferred ranges, the grinding labor will
be saved particularly in grinding the rare earth fluoride that
needs much labor to grind while securing the reactivity in the
firing of step 2, and it is easier to control the pore volume and
the peak of the pore size distribution of the finally obtained
coating powder within the respective preferred ranges described
above. Examples of the compound capable of becoming an oxide on
firing include an oxalate and a carbonate of a rare earth
element.
[0076] The mixing ratio is preferably such that the molar ratio of
the rare earth fluoride (LnF.sub.3) to a rare earth oxide (Ln*) or
a rare earth compound that becomes an oxide on firing (Ln*), i.e.,
LnF.sub.3/Ln*molar ratio, is 0.4 to 55, more preferably 0.42 to 40,
even more preferably 0.45 to 30.
Step 2:
[0077] The mixture obtained in step 1 is fired preferably at a
temperature of 750.degree. to 1400.degree. C. When fired at a
temperature within that range, the mixture sufficiently produces an
oxyfluoride of the rare earth element. Although the rare earth
fluoride or a small amount of the rare earth oxide may remain, the
reaction may have been insufficient if both the rare earth fluoride
and the rare earth remain.
[0078] The firing temperature is more preferably 800.degree. to
1300.degree. C., even more preferably 850.degree. to 1200.degree.
C.
[0079] The firing time is preferably 1 to 72 hours, more preferably
2 to 60 hours, even more preferably 3 to 48 hours, provided that
the firing temperature is in the range recited above. Within these
firing time ranges, a rare earth oxyfluoride is sufficiently
produced while holding down the energy consumption.
[0080] The firing may be carried out in an oxygen-containing
atmosphere, such as the air. However, when the firing temperature
is 1100.degree. C. or higher, particularly 1200.degree. C. or
higher, an inert gas atmosphere, such as argon gas, or a vacuum
atmosphere is preferred, because the rare earth oxyfluoride once
formed is liable to decompose to a rare earth oxide in an
oxygen-containing atmosphere.
[0081] It is not impossible to obtain a product equal to that
obtained in step 1 by firing only the rare earth fluoride. However,
in the cases where an O/Ln molar ratio of, e.g., 0.5 or higher is
desired, the firing must be at high temperatures, the resulting
product tends to have a small pore volume, and it would be
difficult to obtain a final product falling within the scope of the
invention.
Step 3:
[0082] The grinding operation may be carried out by any of dry
grinding, wet grinding, and a combination of dry grinding and wet
grinding. In order to produce a coating powder having a dispersion
index of 0.7 or smaller, it is preferred to perform at least wet
grinding. Dry grinding may be carried out using a dry ball mill, a
dry bead mill, a high-speed rotor impact mill, a jet mill, a
grindstone type grinder, a roll mill, or so forth. Wet grinding is
preferably carried out in a wet grinding machine using a spherical,
cylindrical, or other shaped grinding medium, such as a ball mill,
a vibration mill, a bead mill, or Attritor.RTM.. The grinding is
conducted so as to give ground particles having a D.sub.50 of 0.1
to 10 .mu.m, preferably 0.2 to 8 .mu.m, more preferably 0.5 to 6
.mu.m. The D.sub.50 of the ground particles can be controlled by
adjusting the size of the grinding medium used, the grinding time,
the number of times of passages, and the like. Materials of the
grinding media include zirconia, alumina, silicon nitride, silicon
carbide, tungsten carbide, wear resistant steel, and stainless
steel. Zirconia may be metal oxide-stabilized zirconia. The
dispersion medium used in wet grinding may be selected from those
described as the dispersion medium of the coating material in the
form of slurry. The dispersion medium used in step 3 and that of
the slurry obtained in step 3 may be the same or different.
[0083] When a coating powder having a dispersion index of 0.6 or
smaller, particularly 0.5 or smaller is desired, it is preferred to
conduct the grinding by dry grinding followed by wet grinding or to
conduct wet grinding in two or more stages, i.e., a plurality of
stages. When the grinding is conducted in a plurality of states, it
is preferred that the grinding media used in the second and
subsequent stages be smaller in size than those used in the
preceding stage. The number of the grinding stages is preferably
greater, in view of obtaining a powder having the smaller
dispersion index. In view of cost and labor, however, two-stage
grinding is the most preferred.
[0084] In the cases where the grinding is carried out by only dry
grinding, the ground product as obtained in step 3 is supplied as
the coating powder of the invention.
Additional Step:
[0085] When the grinding operation of step 3 involves wet grinding,
it is necessary to dry the slurry after the wet grinding to obtain
the coating powder of the invention. When the slurry after the wet
grinding is dried to obtain a powder, the dispersion medium of the
slurry to be dried may be water. However, it is preferred to
exchange water with an organic solvent before drying because the
powder obtained from a slurry having an organic solvent as a
dispersion medium is less liable to agglomerate. Examples of
suitable organic solvents include alcohols, such as methanol,
ethanol, 1-propanol, and 2-propanol, and acetone. The drying
temperature is preferably 80.degree. to 200.degree. C.
[0086] The dried product may be lightly disintegrated in dry
mode.
[0087] The coating powder of the invention is thus obtained.
(2) Process for Preparing Coating Material
[0088] The coating material in the form of slurry is obtained
through, for example, the following two routes: (1) the coating
powder of the invention is mixed with a dispersion medium and (2)
the slurry obtained by wet grinding in step 3 above is used as such
without drying. In the case of (1), the coating powder to be mixed
with a dispersion medium may be lightly disintegrated.
[0089] The coating material in the form of sintered compact is
prepared through, for example, the following two methods: (a) the
coating powder, either as such or, where needed, after being mixed
with, e.g., an organic binder, such as PVC (polyvinyl alcohol), an
acrylic resin, or methyl cellulose, and/or water, is shaped by
pressing and sintered by firing and (b) the coating powder is
sintered by firing while a pressure is applied thereto using, for
example, a hot press (HP). While it is the most preferred not to
add an organic binder to the powder to be fired, the amount of the
organic binder to be added, if used, is preferably 5 mass % or
less, more preferably 2 mass % or less. In method (a), the pressing
of the powder is achieved by, for example, die pressing, rubber
pressing (cold isotactic pressing), sheet forming, extrusion, or
slip casting. The pressure applied in these pressing processes is
preferably 30 to 500 MPa, more preferably 50 to 300 MPa. In method
(b), the pressure sintering is achieved by, for example, hot press
sintering, pulse current pressure sintering (SPS), or hot isotactic
pressing (HIP) sintering. The pressure applied in these pressing
processes is preferably 30 to 500 MPa, more preferably 50 to 300
MPa. In methods (a) and (b), the firing temperature is preferably
1000.degree. to 1800.degree. C., more preferably 1100.degree. to
1700.degree. C. The firing is preferably conducted in an inert gas
(e.g., argon) atmosphere so as to prevent the rare earth
oxyfluoride from decomposing to a rare earth oxide. Before use as a
coating material, the resulting sintered compact may be subjected
to machining, such as polishing using, e.g., a fixed abrasive
polisher, a silicon carbide slurry, or a diamond slurry, or cutting
to a prescribed size using, e.g., a lathe.
[0090] The thus obtained coating material, including the coating
powder, is suitably used in the aforementioned various coating
techniques. Examples of substrates to be coated include metals such
as aluminum, metal alloys such as aluminum alloys, ceramics such as
alumina, and quartz.
EXAMPLES
[0091] The invention will now be illustrated in greater detail by
way of Examples, but it should be understood that the invention is
not deemed to be limited thereto. Unless otherwise noted, all the
percents are given by mass. The preparation conditions of Examples
1 through 49 and Comparative Examples 1 through 10 are summarized
in Tables 1 and 1A below.
Examples 1 to 15 and Comparative Examples 1 and 2
[0092] A coating powder was prepared in accordance with steps (i)
to (iv) below.
(i) Step 1: Mixing
[0093] Yttrium oxide (Y.sub.2O.sub.3) fine powder available from
Nippon Yttrium Co., Ltd. (D.sub.50: 0.24 .mu.m) and yttrium
fluoride (YF.sub.3) from Nippon Yttrium Co., Ltd. (D.sub.50: 7.4
.mu.m) were mixed at an LnF.sub.3/Ln*molar ratio shown in
Table1.
(ii) Step 2: Firing
[0094] The mixture obtained in step 1 was put in an alumina boat
and fired in an electric oven in the atmosphere at 950.degree. C.
for 8 hours.
(iii) Step 3: Grinding
[0095] The fired product obtained in step 2 was dry ground in an
atomizer (indicated by "A" in Table 1), mixed with an equal mass of
pure water, and wet ground first in a bead mill using 2 mm-diameter
yttria-stabilized zirconia (YSZ) balls for 2 hours and then in a
bead mill using 1.2 mm-diameter YSZ balls for 0.5 hours to make a
slurry.
(iv) Additional Step: Drying
[0096] The slurry obtained in step 3 was dried at 120.degree. C.
for 12 hours to obtain a coating powder of the invention.
[0097] The particle size distribution of the resulting coating
powder was analyzed to determine D.sub.50, D.sub.90, D.sub.10, and
dispersion index by the method below.
[0098] The resulting coating powder was further analyzed for BET
specific surface area by the method below. The pore size
distribution of the coating powder was determined to calculate the
pore volume by the method below.
[0099] The coating powder was analyzed by powder X-ray
diffractometry under the conditions below to obtain the maximum
peak intensities (cps) of LnF.sub.3, Ln-O--F, and Ln.sub.xO.sub.y.
The intensities were expressed relatively taking the highest
intensity as 100. The compound to which the observed maximum
diffraction peak of Ln-O--F was assigned in the X-ray
diffractometry is shown in Table 2B, and the maximum diffraction
peak assigned to Ln.sub.xO.sub.y, when observed, corresponded to
that of the rare earth oxide of the above discussed ordinary form
(these apply equally to Examples 16 to 49 and Comparative Examples
1 to 10; and the compound to which the observed maximum diffraction
peak of Ln-O--F was assigned in Examples 26 to 49 and Comparative
Examples 7 to 10 is shown in Table 2C). As is understood from the
above description, the ordinary form of the oxide of, for example,
yttrium is Y.sub.2O.sub.3. The X-ray diffraction patterns of the
coating powders obtained in Examples 3, 10, and 15 are shown in
FIGS. 1 to 3, respectively.
[0100] The oxygen content and the rare earth content of the
resulting coating powder were determined by the methods below to
obtain the O/Ln molar ratio. The aspect ratio of the coating powder
was measured by the method below.
[Method of X-Ray Diffractometry]
[0101] Apparatus: Ultima IV (from Rigaku Corp.) Source: CuK.alpha.
rays Tube voltage: 40 kV Tube current: 40 mA Scanning speed:
2.degree./min Step size: 0.02.degree. Measurement range:
2.theta.=20.degree. to 40.degree. [Method of Measurement of
D.sub.50, D.sub.90, D.sub.10, and Dispersion Index]
[0102] In a 100 ml glass beaker was put about 0.4 g of the coating
powder, and pure water was added thereto as a dispersion medium to
the scale of 100 ml. The beaker containing the particles and
dispersion medium was set on an ultrasonic homogenizer US-300T
(output power: 300 W) available from Nihonseiki Kaisha Ltd. and
ultrasonicated for 5 minutes to prepare a slurry to be analyzed.
The slurry was dropped into the pure water-containing chamber of
the sample circulator of Microtrac 3300EXII from Nikkiso Co., Ltd.
until the instrument judged the concentration to be adequate, and
D.sub.50, D.sub.90, and D.sub.10 were determined. The dispersion
index was calculated from the measured D.sub.10 and D.sub.90 values
from formula: dispersion
index=(D.sub.90-D.sub.10)/(D.sub.90+D.sub.10).
[Method of Measurement of BET Specific Surface Area]
[0103] The BET specific surface area was determined using an
automatic surface area analyzer Macsorb model-1201 from Mountech
Co., Ltd. according to the single point BET method. A
nitrogen-helium mixed gas (N.sub.2: 30 vol %) was used for the
measurement.
[Method of Measurement of Pore Volume and Pore Size Peak]
[0104] AutoPore IV from Micromeritics was used. A pore size range
of from 0.001 to 100 .mu.m was covered. The cumulative volume of
pores of 10 .mu.m or smaller was taken as the pore volume.
[Method of Measuring O/Ln Molar Ratio]
[0105] The oxygen content (mass %) was measured by inert gas
fusion-IR absorption spectrometry, and the measured value was
converted to the number of moles of oxygen per kg of the powder.
The rare earth content (mass %) was measured by perchloric acid
digestion/ICP-AES, and the measured value was converted to the
number of moles of the rare earth per kg of the powder. The O/Ln
molar ratio was calculated by dividing the number of moles of
oxygen per kg of the powder by the number of moles of the rare
earth element per kg of the powder.
[Method of Measuring Aspect Ratio]
[0106] The aspect ratio was obtained by photographing an SEM
(scanning electron microscope) image of the powder. The
magnifications were 1000/D.sub.50 to 50000/D.sub.50, and SEM images
of at least 20 particles that did not overlap with one another were
photographed, from, where needed, different fields of view. The
micrograph was enlarged if necessary. The length and breadth of the
20 or more particles were measured, from which the aspect ratio,
i.e., the length/the breadth, of the individual particles was
calculated. After calculating the aspect ratio of the individual
particles, the arithmetic mean thereof was obtained, which was
taken as the aspect ratio of the powder.
[0107] A coating was formed using each of the coating powders
obtained in Examples and Comparative Examples by the method
below.
Coating Formation 1: Plasma Thermal Spraying (Coating Powder)
[0108] An 100 mm square aluminum alloy plate was used as a
substrate. A coating was formed on the substrate by plasma thermal
spraying. A powder feeder TPP-5000 available from Kyuyou-Giken Co.,
Ltd. was use for feeding the coating powder (the powder for thermal
spraying). As a plasma thermal spraying apparatus, 100HE available
from Progressive Surface Inc. was used. Plasma thermal spraying was
carried out under the following conditions to form a thermal spray
coating having a thickness of about 150 to 200 .mu.m: argon gas
flow rate, 84.6 L/min; nitrogen gas flow rate, 56.6 L/min; hydrogen
gas flow rate, 56.6 L/min; output power, 105 kW; gun-to-substrate
distance, 70 mm; and powder feed rate, 10 g/min. The plasma thermal
spraying process is abbreviated as "PS" in Table 3 below.
Examples 16 to 21 and Comparative Examples 3 and 4
[0109] A coating powder was prepared in the same manner as in
Example 9, except that the firing temperature was changed as shown
in Table 1 and that, when the firing temperature was 1150.degree.
C. or higher, the firing was performed in an argon gas atmosphere.
The resulting powder was evaluated in the same manner as in Example
9, and a thermal spray coating was formed using the resulting
powder in the same manner as in Example 9.
Examples 22 to 25 and Comparative Examples 5 and 6
[0110] A coating powder was prepared in the same manner as in
Example 9, except for using yttrium fluoride having a D.sub.50 as
shown in Table 1 as the yttrium fluoride to be used in the mixing
step of step 1. Evaluation of the resulting coating powder and
coating formation using the powder were conducted in the same
manner as in Example 9.
[0111] The yttrium fluoride used in step 1, whose D.sub.50 was as
shown in Table 1, was prepared by grinding yttrium fluoride having
a size of several millimeters (coarse particles to be ground to
obtain the aforementioned yttrium fluoride product available from
Nippon Yttrium Co., Ltd.) in a dry ball mill to the D.sub.50 shown
in Table 1 using grinding balls having an adjusted size (3 to 10 mm
in diameter) for an adjusted grinding time.
Example 26
[0112] A coating powder was prepared in the same manner as in
Example 9, except for using yttrium oxide (D.sub.50: 3.1 .mu.m)
available from Nippon Yttrium Co., Ltd. as the yttrium oxide to be
used in the mixing step of step 1. Evaluation of the resulting
coating powder and coating formation using the powder were
conducted in the same manner as in Example 9.
Examples 27 to 29 and Comparative Example 7
[0113] A coating powder was prepared in the same manner as in
Example 9, except for changing the firing temperature in step 2 to
800.degree. C. and changing the wet grinding conditions in step 3
as shown in Table 1A. Evaluation of the resulting coating powder
and coating formation using the powder were conducted in the same
manner as in Example 9.
Example 30 and 31 and Comparative Example 8
[0114] A coating powder was prepared in the same manner as in
Example 9, except that the grinding in step 3 was performed only by
dry grinding in a ball mill. Evaluation of the resulting coating
powder and coating formation using the powder were conducted in the
same manner as in Example 9.
[0115] In Table 1A, "B3", "B5", and "B10" indicate that YSZ balls
having diameters of 3 mm, 5 mm, and 10 mm, respectively, were used.
The grinding time was 6 hours.
Example 32
[0116] A coating powder was prepared in the same manner as in
Example 9, except that the grinding in step 3 was performed only by
dry grinding in Supermasscolloider (indicated by "M" in Table 1A).
Evaluation of the resulting coating powder and coating formation
using the powder were conducted in the same manner as in Example
9.
Example 33
[0117] A coating powder was prepared in the same manner as in
Example 9, except that the grinding in step 3 was performed only by
single-stage wet grinding in a wet ball mill using balls of 3 mm in
diameter for 6 hours (dry grinding was not conducted). Evaluation
of the resulting coating powder and coating formation using the
powder were conducted in the same manner as in Example 9.
Example 34
[0118] A coating powder was prepared in the same manner as in
Example 9, except for replacing the yttrium oxide used in step 1
with yttrium carbonate (Y.sub.2(CO.sub.3).sub.3, D.sub.50: 6.5
.mu.m) as a compound capable of becoming an oxide on firing.
Evaluation of the resulting coating powder and coating formation
using the powder were conducted in the same manner as in Example
9.
Example 35 (Coating Material in the Form of Slurry; Plasma Thermal
Spraying)
[0119] The coating powder obtained in Example 9 was mixed with a
water/ethanol mixture (ethanol 15 vol %) to prepare a coating
material in the form of slurry having the coating powder content of
35 mass %. The viscosity of the resulting slurry at 25.degree. C.
was found to be 4 cp as measured using SV-10 from A & D Co. The
coating slurry was sprayed by plasma spraying to form a thermal
spray coating in the same manner as described supra (Coating
formation 1: plasma thermal spraying), except that the slurry was
fed using a liquid feeder HE from Progressive Surface Inc. at a
rate of 36 ml/min.
Example 36 (Coating Powder of Example 9, High Velocity Oxygen Fuel
Spraying (HVOF))
[0120] A thermal spray coating was formed using the coating powder
of Example 9 by high velocity oxygen fuel spraying (HVOF).
[0121] As a substrate, a 100 mm square aluminum alloy plate was
used. On this substrate, a thermal spray coating was formed by high
velocity oxygen fuel spraying (HVOF). A powder feeder TPP-5000 from
Kyuyou-Giken Co., Ltd. was used for feeding the coating powder (the
powder for thermal spraying). As a high velocity oxygen fuel
spraying (HVOF) apparatus, TopGun from GTV GmbH was used. High
velocity oxygen fuel spraying (HVOF) was conducted under the
following conditions to obtain a thermal spray coating with a
thickness of about 150 to 200 .mu.m: acetylene gas flow rate, 70
L/min; oxygen gas flow rate, 250 L/min; gun-to-substrate distance,
100 mm; and powder feed rate, 10 g/min.
[0122] The high velocity oxygen fuel spraying process is
abbreviated as "HVOF" in Table 3A below.
Example 37 (Coating Powder of Example 9, Electron Beam Vacuum
Evaporation)
[0123] A coating was formed using the coating powder of Example 9
by electron beam vacuum evaporation.
[0124] As a substrate, a 100 mm square aluminum alloy plate was
used. On this substrate, electron beam vacuum evaporation was
carried out. EB-680 from Eiko Engineering Co., Ltd. was used as an
electron beam vacuum evaporation system.
[0125] The deposition chamber pressure was about 1.times.10.sup.-3
Pa and the electron beam output power was 4 kW. A coating with a
deposit thickness of 20 to 30 .mu.m was prepared.
[0126] In Table 3A, "EBVD" indicates electron beam vacuum
evaporation deposition.
Example 38 (Coating Powder of Example 9, Ion Plating)
[0127] A coating was formed using the coating powder of Example 9
by radiofrequency ion plating under the conditions described
below.
[0128] The fluorine concentration of the coating powder was found
to be 19.8 mass % as measured by the method below.
[0129] As a substrate, a 100 mm square aluminum alloy plate was
used. On this substrate, radiofrequency ion plating was carried
out.
[0130] The ion plating conditions were as follows: argon gas
pressure, 0.02 Pa; EB output power, 0.6 kW; RF power, 1 kW; DC
accelerating voltage, 1.5 kV; and source-to-substrate distance, 300
mm. A coating with a thickness of 20 to 30 .mu.m was prepared.
[0131] The ion plating process is abbreviated as "IP" in Table
3A.
Method for Measuring Fluorine Concentration:
[0132] The fluorine concentration was measured by X-ray
fluorescence spectroscopy (XRF) using Rigaku ZSX Primus II.
Example 39 (Coating Powder of Example 28, Aerosol Deposition
(AD))
[0133] A coating was formed by aerosol deposition (AD) using the
coating powder obtained in Example 28. As a substrate, a 100 mm
square aluminum alloy plate was used. On this substrate, aerosol
deposition was carried out.
[0134] Aerosol deposition conditions were as follows: argon gas: 5
L/min; oscillation frequency of oscillator for aerosolization: 30
Hz; oscillation amplitude of oscillator for aerosolization: 1 mm;
aerosolization pressure: 40 kPa; and deposition chamber pressure:
100 Pa. A coating with a thickness of 150 to 200 .mu.m was
prepared.
[0135] The aerosol deposition process is abbreviated as "AD" in
Table 3A.
Example 40 (Preparation Conditions of Example 39, Aerosol
Deposition (AD))
[0136] A coating was formed by aerosol deposition using the coating
powder obtained under the same preparation conditions as in Example
39. The substrate and the coating conditions were the same as in
Example 39.
Comparative Example 9 (Preparation Condition of Dry Grinding of
Example 39, Aerosol Deposition (AD))
[0137] A coating was formed by aerosol deposition using a coating
powder prepared in exactly the same manner as in Example 39 up to
the step of dry grinding, but in this case, the wet grinding was
carried in a single stage in a wet ball mill using 2 mm diameter
balls for 150 hours. The substrate and the coating conditions were
the same as in Example 39.
Example 41 (Coating Material in the Form of Sintered Compact,
Electron Beam Vacuum Evaporation Deposition (EBVD))
(1) Preparation of Sintered Compact
[0138] The coating powder of Example 9 was compacted by die
pressing under a pressure of 49 MPa, followed by isotactic pressing
under a pressure of 294 MPa.
[0139] The resulting green body was fired in an electric oven at
1500.degree. C. for 2 hours in an argon atmosphere and
spontaneously cooled in the oven down to 150.degree. C. to obtain a
sintered compact, which was machined to 150 mm in diameter and 5 mm
in thickness.
(2) Coating
[0140] A coating was formed using the resulting coating material in
the form of sintered compact by electron beam evaporation
deposition.
[0141] As a substrate, a 100 mm square aluminum plate was used. On
this substrate, electron beam vacuum evaporation was carried out.
Remodeled EBAD-1000 from AOV Co., Ltd. was used as an electron beam
vacuum deposition system.
[0142] The deposition chamber pressure was about 1.times.10.sup.-3
Pa and the electron beam output power was 4 kW. A coating with a
thickness of 20 to 30 .mu.m was prepared.
Example 42 (Coating Material in the Form of Sintered Compact, Ion
Plating)
[0143] A coating was formed by radiofrequency ion plating using a
coating material in the form of sintered compact prepared in the
same manner as in Example 41.
[0144] The coating material in the form of sintered compact was
prepared from the coating powder of Example 9. The fluorine
concentration of the coating material was measured again and was
found to be 21.4 mass %.
[0145] Ion plating conditions were as follows: argon gas pressure,
0.02 Pa; EB output power, 0.6 kW; RF output power, 1 kW; DC
accelerating voltage, 1.5 kV; and source-to-substrate distance, 300
mm. A coating with a thickness of 20 to 30 .mu.m was prepared.
Example 43 (Coating Material in the Form of Sintered Compact,
Sputtering)
[0146] The coating material in the form of sintered compact
prepared in the same manner as in Example 40, except for its size.
The sintered body was lathed to a disk of 180 mm in diameter and 5
mm in thickness. A coating was formed on a 100 mm by 100 mm
aluminum alloy plate using the resulting coating material by RF
magnetron sputtering.
[0147] The sputtering conditions were as follows: argon gas
pressure, 5 Pa; RF frequency, 13.56 MHz; plate voltage, 200 V; and
RF power, 200 W. A coating with a thickness of 20 to 30 .mu.m was
prepared.
[0148] The sputtering process is abbreviated as "SP" in Table
3A.
Comparative Example 10 (Coating Material in the Form of Sintered
Compact, Ion Plating)
[0149] A coating material in the form of sintered compact was
prepared from the powder of Comparative Example 1 in the same
manner as in Example 42. A coating was formed using the resulting
coating material by RF ion plating (IP process).
[0150] The fluorine concentration of the coating powder obtained in
Comparative Example 1 was 38.7 mass %. The substrate and the
coating conditions were the same as in Example 42.
Examples 44 to Example 49 (Coating Powder Other than Y, Plasma
Thermal Spraying)
[0151] In these Examples, a rare earth element other than Y was
used as shown in Table 1A (Ce, Sm, Gd, Dy, Er, or Yb).
[0152] A coating material was prepared in the same manner as in
Example 9, except that fine powder of a rare earth oxide
(Ln.sub.xO.sub.y) containing a rare earth element other than Y
(available from Nippon Yttrium Co., Ltd; having the D.sub.50 shown
in Table 1A) and a rare earth fluoride containing a rare earth
element other than Y (LnF.sub.3, available from Nippon Yttrium Co.,
Ltd; having the D.sub.50 shown in Table 1A) were used in step 1.
The resulting coating powder was evaluated in the same manner as in
Example 9, and a thermal spray coating was formed using the
resulting powder in the same manner as in Example 9. When the rare
earth element was Ce, CeO.sub.2 was used as Ln.sub.xO.sub.y, and
when the rare earth element was Sm, Gd, Dy, Er, or Yb, a
sesquioxide (Ln.sub.2O.sub.3) was used as Ln.sub.xO.sub.y.
[0153] The results of evaluation of the coating powders obtained in
Examples 1 to 49 and Comparative Examples 1 to 10 are shown in
Tables 2, 2A, 2B, and 2C.
Evaluation of Coating:
[0154] The coatings obtained in Examples and Comparative Examples
were evaluated for denseness by measuring the number of cracks and
porosity by the methods described below. The coatings were also
evaluated for resistance to corrosion by plasma by the method
below. The surface roughness of the coatings was evaluated by the
method below. The results of evaluation are shown in Tables 3 and
3A.
[Method for Measuring Number of Cracks]
[0155] The coatings formed by various processes were each cut to a
2 cm square with a diamond wet cutter. The cut piece was buried in
an epoxy resin, and a cut surface was abraded using a diamond
slurry. The abraded surface was observed under an FE-SEM at a
magnification of 500. The number of cracks appearing in a 100 .mu.m
square (corresponding to a 50 mm square in magnified view at a
magnification of 500) freely chosen from the observed surface (the
abraded cut surface of the coating) was counted. The coating was
rated according to the following scale on the basis of the number
of cracks.
A: No cracks are observed. B: One to two cracks are observed. C:
Three to five cracks are observed. D: More than five cracks are
observed.
[Method for Measuring Porosity]
[0156] Each coating was cut to a 2 cm square with a diamond wet
cutter and buried in an epoxy resin. A cut surface of the coating
was abraded with a diamond slurry, and the abraded surface was
observed under an optical microscope. The porosity (vol %) was
calculated through image analysis of the optical micrograph. A
smaller porosity indicates higher denseness of the coating.
[Method for Evaluating Resistance to Particle Shedding]
[0157] The each coating formed on the 100 mm square aluminum alloy
plate was subjected to plasma etching. A 3-inch diameter silicon
wafer was placed in the chamber before carrying out plasma etching.
The number of particles having a particle size of about 0.2 .mu.m
or greater out of the particles shed from the coating due to the
etching action and attached to the surface of the silicon wafer was
counted using a magnifier. The plasma etching was conducted using a
fluorine-based plasma under the following conditions:
Atmosphere gas, CHF.sub.3:Ar:O.sub.2=80:160:100 ml/min RF power,
1300 W
Pressure, 4 Pa
Temperature, 60.degree. C.
[0158] Etching time, 50 hours.
[0159] The plasma etching and counting the number of particles were
conducted in the same manner, except for replacing the atmosphere
gas CHF.sub.3 with HCl to create a chlorine-based plasma.
[Method for Measuring Surface Roughness]
[0160] The surface roughness of each coating formed on the 100 mm
square aluminum alloy plate was measured. An arithmetic average
roughness Ra and maximum height roughness Rz (both specified by JIS
B0601:2001) were determined using a stylus profilometer (specified
in JIS B0651:2001).
TABLE-US-00001 TABLE 1 Preparation Conditions Oxide/Compound Wet
Grinding That Becomes 1st Stage 2nd Stage Rare Oxide on Firing
Fluoride Firing Conditions Bead Bead Earth D.sub.50 D.sub.50
LnF.sub.3/Ln* Temp. Time Dry Diameter Time Diameter Time Element
Kind (.mu.m) (.mu.m) Molar Ratio (.degree. C.) (hr) Grinding (mm)
(hr) (mm) (hr) Example 1 Y oxide 0.24 7.4 55 950 8 A 2 2 1.2 0.5
Example 2 30 Example 3 20 Example 4 10 Example 5 5.0 Example 6 3.0
Example 7 1.5 Example 8 1.0 Example 9 0.87 Example 10 0.80 Example
11 0.70 Example 12 0.60 Example 13 0.50 Example 14 0.45 Example 15
0.40 Compara. Example 1 100 Compara. Example 2 0.20 Example 16 Y
oxide 0.24 7.4 0.87 750 8 A 2 2 1.2 0.5 Example 17 850 Example 18
1050 Example 19 1150 Example 20 1250 Example 21 1400 Compara.
Example 3 650 Compara. Example 4 1450 Example 22 Y oxide 0.24 6.0
0.87 950 8 A 2 2 1.2 0.5 Example 23 49 Example 24 96 Example 25 470
Compara. Example 5 3.0 Compara. Example 6 620 *Dry grinding machine
A: atomizer
TABLE-US-00002 TABLE 1A Preparation Conditions Oxide/Compound Wet
Grinding That Becomes 1st Stage 2nd Stage Rare Oxide on Firing
Fluoride Firing Conditions Bead Bead Earth D.sub.50 D.sub.50
LnF.sub.3/Ln* Temp. Time Dry Diameter Time Diameter Time Element
Kind (.mu.m) (.mu.m) Molar Ratio (.degree. C.) (hr) Grinding (mm)
(hr) (mm) (hr) Example 26 Y oxide 3.1 7.4 0.87 950 8 A 2 2 1.2 0.5
Example 27 Y Oxide 0.24 7.4 0.87 800 8 A 0.8 4 0.4 10 Example 28 3
Example 29 2 Compara. Example 7 20 Example 30 Y oxide 0.24 7.4 0.87
950 8 B3 -- -- -- -- Example 31 B5 -- -- -- -- Compara. Example 8
B10 -- -- -- -- Example 32 8 M -- -- -- -- Example 33 8 -- 3 6 --
-- Example 34 Y carbonate 6.5 7.4 0.87 950 8 A 2 2 1.2 0.5 Example
35 Y oxide 0.24 7.4 0.87 950 8 A 2 2 1.2 0.5 Example 36 Example 37
Example 38 Example 39 800 8 A 0.8 4 0.4 3 Example 40 Compara.
Example 9 2 150 -- -- Example 41 950 8 A 2 2 1.2 0.5 Example 42
Example 43 Comp. Example 10 Y oxide 0.24 7.4 100 Example 44 Ce
oxide 0.33 8.5 0.87 950 8 A 2 2 1.2 0.5 Example 45 Sm oxide 0.42
7.2 Example 46 Gd oxide 0.22 6.7 Example 47 Dy oxide 0.27 10.2
Example 48 Er oxide 0.18 8.5 Example 49 Yb oxide 0.29 9.2 Dry
grinding machine: A: atomizer B3: dry ball mill (3 mm diameter
balls) B5: dry ball mill (5 mm diameter balls) B10: dry ball mill
(10 mm diameter balls) M: Supermasscolloider
TABLE-US-00003 TABLE 2 Coating Powder Pore Volume of BET Pores with
Pore Specific XRD Peak Intensity & Peak Particle Size Disper-
Diameter Size Surface Intensity Ratio O/Ln Distribution (.mu.m)
sion of .ltoreq.10 .mu.m Peak Area LnF.sub.3 Ln-O--F
Ln.sub.xO.sub.y Molar Aspect D.sub.50 D.sub.10 D.sub.90 Index
(cm.sup.3/g) (.mu.m) (m.sup.2/g) (S2) (S1) (S0) S0/S1 S1/S2 Ratio
Ratio Example 1 3.3 2.2 4.5 0.34 0.27 2.5 2.2 100 4 0 0 0.04 0.03
1.2 Example 2 3.4 2.2 4.5 0.34 0.30 2.3 1.9 100 7 0 0 0.07 0.05 1.1
Example 3 3.3 2.3 4.4 0.31 0.28 2.2 1.7 100 11 0 0 0.11 0.07 1.4
Example 4 3.2 2.3 4.4 0.31 0.26 2.4 1.6 100 21 0 0 0.21 0.14 1.2
Example 5 3.3 2.2 4.4 0.33 0.32 2.4 2.0 100 45 0 0 0.45 0.26 1.0
Example 6 3.3 2.4 4.5 0.30 0.30 2.3 1.8 100 93 0 0 0.93 0.40 1.0
Example 7 3.2 2.2 4.3 0.32 0.34 2.4 1.8 0 100 0 0 -- 0.63 1.3
Example 8 3.3 2.3 4.3 0.30 0.31 2.2 1.7 0 100 0 0 -- 0.77 1.2
Example 9 3.2 2.4 4.5 0.30 0.33 2.0 1.6 0 100 0 0 -- 0.83 1.2
Example 10 3.1 2.3 4.5 0.32 0.32 2.3 1.7 0 100 0 0 -- 0.86 1.4
Example 11 3.2 2.3 4.4 0.31 0.30 2.1 1.7 0 100 0 0 -- 0.90 1.2
Example 12 3.1 2.2 4.3 0.32 0.34 2.2 1.8 0 100 0 0 -- 0.96 1.3
Example 13 3.3 2.4 4.4 0.29 0.35 2.3 1.9 0 100 0 0 -- 1.02 1.2
Example 14 3.3 2.3 4.4 0.31 0.37 2.1 1.7 0 100 4 0.04 -- 1.05 1.3
Example 15 3.4 2.3 4.5 0.32 0.34 2.1 1.8 0 100 15 0.15 -- 1.10 1.2
Comp. Example 1 3.5 2.3 4.7 0.34 0.25 2.4 2.0 100 0 0 -- 0 0.01 1.0
Comp. Example 2 3.4 2.2 4.7 0.36 0.40 2.8 2.5 0 91 100 1.1 -- 1.3
1.2 Example 16 2.0 1.3 2.7 0.35 0.48 4.2 7.1 0 100 0 0 -- 0.82 1.3
Example 17 2.6 2.0 3.9 0.32 0.41 3.4 4.3 0 100 0 0 -- 0.82 1.2
Example 18 4.2 2.7 5.5 0.34 0.29 1.4 1.5 0 100 0 0 -- 0.84 1.1
Example 19 5.9 3.3 8.9 0.46 0.25 0.73 1.2 0 100 0 0 -- 0.85 1.0
Example 20 7.7 4.0 12 0.50 0.20 0.43 1.1 0 100 0 0 -- 0.83 1.2
Example 21 9.2 4.6 21 0.64 0.10 0.21 0.91 0 100 0 0 -- 0.83 1.3
Comp. Example 3 1.7 1.1 2.6 0.41 0.60 6.1 13 0 100 0 0 -- 0.82 1.1
Comp. Example 4 12.3 5.8 30 0.68 0.04 0.06 0.65 0 100 0 0 -- 0.83
1.4 Example 22 2.8 1.9 4.1 0.37 0.12 0.95 1.5 0 100 0 0 -- 0.83 1.2
Example 23 3.5 2.2 5.0 0.39 0.37 2.5 1.6 0 100 0 0 -- 0.82 1.1
Example 24 4.2 2.7 8.2 0.50 0.41 3.5 1.6 0 100 0 0 -- 0.81 1.3
Example 25 5.7 3.1 12 0.59 0.48 4.7 1.8 0 100 0 0 -- 0.81 1.2 Comp.
Example 5 2.5 1.5 3.8 0.43 0.57 0.15 1.4 0 100 0 0 -- 0.84 1.3
Comp. Example 6 7.1 3.8 25 0.74 0.05 5.8 2.2 0 100 0 0 -- 0.81
1.2
TABLE-US-00004 TABLE 2A Coating Powder Pore Volume of BET Pores
with Pore Specific XRD Peak Intensity & Peak Particle Size
Disper- Diameter Size Surface Intensity Ratio O/Ln Distribution
(.mu.m) sion of .ltoreq.10 .mu.m Peak Area LnF.sub.3 Ln-O--F
Ln.sub.xO.sub.y Molar Aspect D.sub.50 D.sub.10 D.sub.90 Index
(cm.sup.3/g) (.mu.m) (m.sup.2/g) (S2) (S1) (S0) S0/S1 S1/S2 Ratio
Ratio Example 26 3.8 2.7 5.4 0.33 0.30 2.5 1.4 0 100 0 0 -- 0.83
1.2 Example 27 0.12 0.079 0.16 0.34 0.46 0.18 9.5 0 100 0 0 -- 0.82
1.1 Example 28 0.55 0.37 0.76 0.35 0.23 0.55 6.3 0 100 0 0 -- 0.82
1.3 Example 29 1.3 0.82 1.7 0.35 0.11 1.1 2.6 0 100 0 0 -- 0.81 1.2
Comp. Example 7 0.044 0.033 0.064 0.32 0.62 0.04 15 0 100 0 0 --
0.84 1.3 Example 30 7.2 3.1 42 0.86 0.27 2.9 1.5 0 100 0 0 -- 0.83
1.0 Example 31 9.6 5.3 68 0.86 0.24 3.4 1.4 0 100 0 0 -- 0.82 1.1
Comp. Example 8 12.5 6.9 87 0.85 0.20 3.6 1.3 0 100 0 0 -- 0.81 1.1
Example 32 6.2 2.4 54 0.91 0.29 2.7 1.5 0 100 0 0 -- 0.82 1.0
Example 33 4.1 2.1 12 0.70 0.31 2.5 1.5 0 100 0 0 -- 0.82 1.1
Example 34 3.6 2.7 5.1 0.31 0.32 2.2 1.5 0 100 0 0 -- 0.82 1.3
Example 35 3.2 2.4 4.5 0.30 0.33 2.0 1.6 0 100 0 0 -- 0.83 1.3
Example 36 1.0 Example 37 1.1 Example 38 1.2 Example 39 0.55 0.37
0.76 0.35 0.23 0.55 6.3 0 100 0 0 -- 0.82 1.0 Example 40 0.55 0.38
0.85 0.38 0.24 0.55 5.4 0 100 0 0 -- 0.82 1.3 Comp. Example 9 0.55
0.1 4.00 0.95 0.51 0.65 2.1 0 100 0 0 -- 0.82 8.0 Example 41 3.2
2.4 4.5 0.30 0.33 2.0 1.6 0 100 0 0 -- 0.83 1.2 Example 42 1.2
Example 43 3.2 2.4 4.5 0.30 0.33 2.0 1.6 0 100 0 0 -- 0.83 1.3
Comp. Example 10 3.2 2.4 4.5 0.30 0.33 2.0 1.6 100 0 0 -- 0 0.01
1.4 Example 44 3.4 2.5 4.9 0.32 0.35 2.0 1.9 0 100 0 0 -- 0.84 1.2
Example 45 3.3 2.3 4.7 0.34 0.35 1.9 1.7 0 100 0 0 -- 0.82 1.2
Example 46 3.1 2.0 4.2 0.35 0.33 2.1 1.8 0 100 0 0 -- 0.83 1.1
Example 47 3.2 2.3 4.5 0.32 0.33 2.2 1.8 0 100 0 0 -- 0.83 1.4
Example 48 3.1 2.1 4.2 0.33 0.34 2.3 1.6 0 100 0 0 -- 0.82 1.3
Example 49 3.3 2.4 4.5 0.30 0.35 2.2 1.7 0 100 0 0 -- 0.83 1.2
TABLE-US-00005 TABLE 2B Ln-O--F Detected by XRD (assignment of max.
peak of Ln-O--F) Example 1 Y.sub.7O.sub.6F.sub.9 Example 2
Y.sub.7O.sub.6F.sub.9 Example 3 Y.sub.7O.sub.6F.sub.9 Example 4
Y.sub.7O.sub.6F.sub.9 Example 5 Y.sub.7O.sub.6F.sub.9 Example 6
Y.sub.7O.sub.6F.sub.9 Example 7 Y.sub.5O.sub.4F.sub.7 Example 8
Y.sub.5O.sub.4F.sub.7 Example 9 Y.sub.5O.sub.4F.sub.7 Example 10
Y.sub.7O.sub.6F.sub.9 Example 11 Y.sub.7O.sub.6F.sub.9 Example 12
YOF Example 13 YOF Example 14 YOF Example 15 YOF Compara. Example 1
-- Compara. Example 2 YOF Example 16 Y.sub.5O.sub.4F.sub.7 Example
17 Y.sub.5O.sub.4F.sub.7 Example 18 Y.sub.7O.sub.6F.sub.9 Example
19 Y.sub.7O.sub.6F.sub.9 Example 20 Y.sub.5O.sub.4F.sub.7 Example
21 Y.sub.5O.sub.4F.sub.7 Compara. Example 3 Y.sub.5O.sub.4F.sub.7
Compara. Example 4 Y.sub.5O.sub.4F.sub.7 Example 22
Y.sub.5O.sub.4F.sub.7 Example 23 Y.sub.5O.sub.4F.sub.7 Example 24
Y.sub.5O.sub.4F.sub.7 Example 25 Y.sub.5O.sub.4F.sub.7 Compara.
Example 5 Y.sub.7O.sub.6F.sub.9 Compara. Example 6
Y.sub.5O.sub.4F.sub.7
TABLE-US-00006 TABLE 2C Ln-O--F Detected by XRD (assignment of max.
peak of Ln-O--F) Example 26 Y.sub.5O.sub.4F.sub.7 Example 27
Y.sub.5O.sub.4F.sub.7 Example 28 Y.sub.5O.sub.4F.sub.7 Example 29
Y.sub.5O.sub.4F.sub.7 Compara. Example 7 Y.sub.7O.sub.6F.sub.9
Example 30 Y.sub.5O.sub.4F.sub.7 Example 31 Y.sub.5O.sub.4F.sub.7
Compara. Example 8 Y.sub.5O.sub.4F.sub.7 Example 32
Y.sub.5O.sub.4F.sub.7 Example 33 Y.sub.5O.sub.4F.sub.7 Example 34
Y.sub.5O.sub.4F.sub.7 Example 35 Y.sub.5O.sub.4F.sub.7 Example 36
Y.sub.5O.sub.4F.sub.7 Example 37 Y.sub.5O.sub.4F.sub.7 Example 38
Y.sub.5O.sub.4F.sub.7 Example 39 Y.sub.5O.sub.4F.sub.7 Example 40
Y.sub.5O.sub.4F.sub.7 Compara. Example 9 Y.sub.5O.sub.4F.sub.7
Example 41 Y.sub.5O.sub.4F.sub.7 Example 42 Y.sub.5O.sub.4F.sub.7
Example 43 Y.sub.5O.sub.4F.sub.7 Compara. Example 10 -- Example 44
Ce.sub.7O.sub.6F.sub.9 Example 45 Sm.sub.5O.sub.4F.sub.7 Example 46
Gd.sub.5O.sub.4F.sub.7 Example 47 Dy.sub.5O.sub.4F.sub.7 Example 48
Er.sub.5O.sub.4F.sub.7 Example 49 Yb.sub.5O.sub.4F.sub.7
TABLE-US-00007 TABLE 3 Evaluation of Coating Number of Particles
Coating Porosity F-based Cl-based Surface Roughness (.mu.m) Form of
Feed Process Cracking (vol %) Plasma Plasma Ra Rz Example 1 powder
PS B 5 15 20 1.5 1.7 Example 2 A <3 7 9 1.3 1.9 Example 3 A
<3 5 4 1.2 1.6 Example 4 A <3 5 5 1.1 1.6 Example 5 A <3 3
4 1.3 1.7 Example 6 A <3 4 3 1.2 1.8 Example 7 A <3 3 3 1.2
1.9 Example 8 A <3 1 2 1.3 1.8 Example 9 A <3 0 1 1.2 1.7
Example 10 A <3 3 1 1.3 1.9 Example 11 A <3 2 3 1.4 1.6
Example 12 A <3 3 5 1.2 1.5 Example 13 A <3 4 7 1.4 1.9
Example 14 A <3 7 10 1.2 1.5 Example 15 B 5 9 20 1.2 1.9
Compara. Example 1 C 7 25 29 1.1 1.5 Compara. Example 2 D 21 35 97
1.2 1.6 Example 16 powder PS A <3 17 19 1.1 1.9 Example 17 A 9 9
10 1.4 1.8 Example 18 A <3 4 5 1.1 1.6 Example 19 A 5 4 4 1.4
1.8 Example 20 A 9 6 5 1.4 1.9 Example 21 A <3 4 5 1.1 1.5
Compara. Example 3 B 12 32 38 5.4 8.5 Compara. Example 4 D 42 38 44
2.1 5.6 Example 22 powder PS A 5 1 2 1.1 1.9 Example 23 A <3 3 5
1.4 1.8 Example 24 A <3 10 13 1.2 1.9 Example 25 A <3 15 20
1.4 1.6 Compara. Example 5 C 23 21 25 1.1 1.6 Compara. Example 6 C
27 28 35 5.4 9.5 *Coating process PS: plasma thermal spraying
TABLE-US-00008 TABLE 3A Evaluation of Coating Number of Particles
Coating Porosity F-based Cl-based Surface Roughness (.mu.m) Form of
Feed Process Cracking (vol % 5) Plasma Plasma Ra Rz Example 26
powder PS A 5 5 4 1.4 1.9 Example 27 powder PS A 4 16 18 1.2 1.8
Example 28 A 10 10 9 1.2 1.5 Example 29 A 5 5 5 1.2 1.9 Compara.
Example 7 A 20 38 42 1.4 1.9 Example 30 B <3 13 11 1.1 1.9
Example 31 B 6 16 18 1.4 1.8 Compara. Example 8 D 12 35 47 4.5 12.0
Example 32 B <3 15 17 1.1 1.9 Example 33 A <3 9 10 1.4 1.9
Example 34 A <3 3 3 1.5 1.2 Example 35 slurry A <3 1 1 1.0
1.8 Example 36 powder HVOF A 9 5 7 1.2 1.9 Example 37 EBVD A <3
13 12 1.1 1.9 Example 38 IP A <3 2 3 1.1 1.8 Example 39 AD A
<3 0 0 1.0 1.5 Example 40 A <3 0 0 1.0 1.5 Compara. Example 9
A 12 45 34 1.5 3.0 Example 41 Sintered EBVD A 10 7 8 1.4 1.3
Example 42 compact IP A <3 2 1 1.5 1.2 Example 43 SP A 5 3 5 1.0
1.7 Compara. Example 10 Sintered IP A <3 21 21 1.4 1.7 compact
Example 44 powder PS A <3 2 2 1.1 1.5 Example 45 A <3 1 2 1.2
1.6 Example 46 A <3 2 1 1.0 1.5 Example 47 A <3 2 2 1.1 1.8
Example 48 A <3 1 2 1.4 1.5 Example 49 A <3 1 0 1.2 1.4
*Coating process: PS: plasma thermal spraying HVOF: high velocity
oxygen fuel spraying EBVD: electron beam vacuum evaporation
deposition IP: ion plating SP: sputtering AD: aerosol
deposition
[0161] As is apparent from the results shown in Tables 3 and 3A,
all the coatings formed by using the coating powders and coating
materials prepared in Examples exhibit no or little cracking, low
porosity, small surface roughness, and low particle shedding when
exposed to each of fluorine-based plasma and chlorine-based plasma.
In contrast, the coatings of Comparative Examples show considerable
cracking and/or high porosity, indicating poor denseness, and/or
exhibit high particle shedding. As can be seen from the results of
Comparative Examples 3, 4, 6, 8, and 9, coatings of many of
Comparative Examples, in which the pore volume and the average
particle size are out of the scope of the invention, revealed to be
inferior in denseness in terms of surface roughness. In particular,
when comparison is made between Examples 39 and 40 and Comparative
Example 9, in which the coating was formed by the AD process, the
coating of Examples 39 and 40 is inferior to that of Comparative
Example 9 in surface roughness.
* * * * *