U.S. patent application number 14/385644 was filed with the patent office on 2015-03-05 for method for forming fluoride spray coating, and fluoride spray coating covered member.
The applicant listed for this patent is TOCALO CO., LTD.. Invention is credited to Yoshio Harada, Kenichiro Togoe.
Application Number | 20150064406 14/385644 |
Document ID | / |
Family ID | 49222156 |
Filed Date | 2015-03-05 |
United States Patent
Application |
20150064406 |
Kind Code |
A1 |
Harada; Yoshio ; et
al. |
March 5, 2015 |
METHOD FOR FORMING FLUORIDE SPRAY COATING, AND FLUORIDE SPRAY
COATING COVERED MEMBER
Abstract
[Problem] To provide a fluoride spray coating covered member in
which a fluoride spray coating firmly adheres by coating carbide
cermet to a surface of a substrate and interposing it, and to
propose a method therefor. [Solution] A fluoride spray coating is
formed in such a manner that an undercoat layer of carbide cermet,
which covers a substrate in a film-shaped manner while a tip
portion of carbide cermet particles is embedded in the substrate,
or a primer part of carbide cermet, is formed by blowing a carbide
cermet material at a high velocity by using a spray gun to a
surface of the substrate, and after that, a fluoride particle is
sprayed thereon.
Inventors: |
Harada; Yoshio; (Hyogo,
JP) ; Togoe; Kenichiro; (Hyogo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOCALO CO., LTD. |
Kobe-shi, Hyogo |
|
JP |
|
|
Family ID: |
49222156 |
Appl. No.: |
14/385644 |
Filed: |
November 28, 2012 |
PCT Filed: |
November 28, 2012 |
PCT NO: |
PCT/JP2012/080687 |
371 Date: |
September 16, 2014 |
Current U.S.
Class: |
428/148 ;
427/314; 427/402; 427/419.7; 427/450 |
Current CPC
Class: |
C23C 4/10 20130101; Y10T
428/24413 20150115; C23C 4/02 20130101; C23C 4/04 20130101; C23C
4/129 20160101; C23C 4/134 20160101 |
Class at
Publication: |
428/148 ;
427/402; 427/419.7; 427/314; 427/450 |
International
Class: |
C23C 4/10 20060101
C23C004/10; C23C 4/12 20060101 C23C004/12; C23C 4/02 20060101
C23C004/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 22, 2012 |
JP |
2012-064797 |
Mar 22, 2012 |
JP |
2012-064799 |
Claims
1. A method for forming a fluoride spray coating characterized in
that an undercoat layer of carbide cermet, which covers a substrate
in a film-shaped manner while a tip portion of carbide cermet
particles is embedded in the substrate, or a non-film shaped primer
part of carbide cermet, is formed by blowing a carbide cermet
material by using a spray gun for a high velocity spraying to the
roughened substrate surface and after that, a fluoride spray
material is sprayed onto the undercoat layer or the primer
part.
2. A method for forming a fluoride spray coating according to claim
1, wherein the undercoat layer of carbide cermet is a layer with a
film-shaped structure having a layer thickness of 10 .mu.m-150
.mu.m, in which, at a side of a substrate surface, a tip portion of
a part of the carbide cermet particles is embedded in the substrate
and a thickness is made thicker by increasing a spraying
number.
3. A method for forming a fluoride spray coating according to claim
1, wherein the primer part of carbide cermet is made by a non
film-shaped structure having such a state that a tip portion of
spray particles is stuck as piles and is sparsely upstanding, at a
portion of area ratio 8-50% with respect to a substrate
surface.
4. A method for forming a fluoride spray coating according to claim
1, wherein the undercoat layer of carbide cermet and the primer
part of carbide cermet are formed in such a manner that a spray
treatment, in which particles having a particle size of 5-80 .mu.m
which is made of one or more metal carbides selected from Ti, Zr,
Hf, V, Nb, Ta, Cr, Mo, W and Si and 5-40 mass % of one or more
metals or their alloys selected from Co, Ni, Cr, Al and Mo are
blown by using the spray gun for a high velocity blowing which can
blow at a flying velocity of 150-600 m/sec., is repeated at 6 times
or more in case of the undercoat layer and at 5 times or less in
case of the primer part.
5. A method for forming a fluoride spray coating according to claim
1, wherein the substrate is preheated to 80-700.degree. C. prior to
a spraying fluoride particles.
6. A method for forming a fluoride spray coating according to claim
1, wherein a spraying method of fluoride is any one spraying method
selected from atmospheric plasma spraying method, reduced-pressure
plasma spraying method and high-velocity flame spraying method.
7. A method for forming a fluoride spray coating according to claim
1, wherein any of Al and its alloy, Ti and its alloy, carbon steel,
stainless steel, Ni and its alloy, oxide, nitride, carbide,
silicide, carbon sintered materials and plastics, a surface
roughness of which is controlled to be Ra: 0.05-0.74 .mu.m and Rz:
0.09-2.0 .mu.m by blowing abrasives such as Al.sub.2O.sub.3 and SiC
with a blast roughening treatment, is used as the substrate.
8. A method for forming a fluoride spray coating according to claim
1, wherein the fluoride spray coating is a coating by blowing
fluoride particles having a particle size of 5 .mu.m-80 .mu.m made
of one or more selected from fluorides of: Mg in Group IIa of the
Periodic Table; Al in Group IIIb of the Periodic Table; Y in Group
IIa of the Periodic Table; and lanthanide series metals of Atomic
Numbers 57-71 of the Periodic Table such as La, Ce, Pr, Nd, Pm, Sm,
Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu onto the substrate surface at
thickness of 20 .mu.m-500 .mu.m.
9. A fluoride spray coating covered member comprising: a substrate,
a surface of which is subjected to a roughening treatment; a
carbide cermet layer coated to a surface of the substrate; and a
fluoride spray coating formed thereon, characterized in that the
carbide cermet layer is a film-shaped undercoat layer wherein a
part of carbide cermet particles is embedded in the substrate to
make a thickness thicker or a primer part of non-film shaped
structure having a construction that a tip portion of spray
particles is stuck as piles and is sparsely upstanding, by blowing
carbide cermet particles having a particle size of 5-80 .mu.m which
is made of one or more metal carbides selected from Ti, Zr, Hf, V,
Nb, Cr, Mn, W and Si and 5-40 mass % of one or more metals or their
alloys selected from Co, Ni, Cr, Al and Mo by using the spray gun
for a high velocity blowing.
10. A fluoride spray coating covered member according to claim 9,
wherein the undercoat layer of carbide cermet is a layer with a
film-shaped structure having a layer thickness of 10 .mu.m-150
.mu.m, in which, at a side of a substrate surface, a tip portion of
a part of the carbide cermet particles is embedded in the substrate
and a thickness is made thicker by increasing a spraying
number.
11. A fluoride spray coating covered member according to claim 9,
wherein the primer part of carbide cermet is made by a non-film
shaped structure having such a state that a tip portion of spray
particles is stuck as piles and is sparsely upstanding, at an area
ratio 8-50% with respect to the substrate surface.
12. A fluoride spray coating covered member according to claim 9,
wherein any of Al and its alloy, Ti and its alloy, carbon steel,
stainless steel, Ni and its alloy, oxide, nitride, carbide,
silicide, carbon sintered materials and plastics, a surface
roughness of which is controlled to be Ra: 0.05-0.74 .mu.m and Rz:
0.09-2.0 .mu.m by a roughening treatment in which abrasives such as
Al.sub.2O.sub.3 and SiC are blown, is used as the substrate.
13. A fluoride spray coating covered member according to claim 9,
wherein the fluoride spray coating has a thickness of 20-500
.mu.m.
14. A fluoride spray coating covered member according to claim 9,
wherein the fluoride spray coating is formed in such a manner that
fluoride particles having a particle size of 5 .mu.m-80 .mu.m made
of a fluoride of one or more materials selected from a group of Mg
in Group IIa of the Periodic Table; Al in Group IIIb of the
Periodic Table; Y in Group IIIa of the Periodic Table; and
lanthanide metals in Atomic Numbers 57-71 of the Periodic Table
such as La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and
Lu are blown to the substrate surface to be a coating thickness of
20 .mu.m-500 .mu.m.
Description
TECHNICAL FIELD
[0001] This invention relates to a method for forming fluoride
spray coating and a fluoride spray coating covered member. More
particularly, the invention relates to a method for forming a
fluoride spray coating on a surface of a member for semiconductor
working device and the like subjected to a plasma etching process
under highly corrosive gas environment through carbide cermet, and
also relates to a fluoride spray coating covered member provided by
performing this method.
RELATED ART
[0002] As a coating with corrosion resistance formed on a surface
of the member for semiconductor working device, a spray coating is
useful. For example, in case that the member is subjected to a
plasma treatment under an existence of halogen or halogen compound,
or in case that the member is used in a field of semiconductor
working device wherein fine particles generated by the plasma
treatment are required to be cleaned and removed, it is necessary
to apply a further surface treatment, and thus there are proposed
several conventional techniques.
[0003] In a working environment of the devices such as dry etcher,
CVD and PVD used in the semiconductor working process and the
production process of liquid crystal, a higher cleanliness is
demanded so as to improve an accuracy of micro-fabrication
associated with high circuit integration of a substrate such as
silicon and glass. However, since gas or aqueous solution having a
strong corrosive nature such as fluoride and chloride is used in
various processes for micro-fabrication, the members provided in
these devices are fast in corrosive wearing, and as a results,
there is a fear of secondary contamination of environment based on
the generation of corrosion products.
[0004] The manufacturing and working process of the semiconductor
device is a so-called dry process in which a compound semiconductor
made Si, Ga, As, P and so on is mainly used and treated in vacuum
or in an atmosphere under a reduced pressure. As an apparatus and a
member used in the dry process are included an oxidation furnace,
CVD apparatus, PVD apparatus, an epitaxial growing apparatus, an
ion implantation apparatus, a diffusion furnace, a reactive ion
etching apparatus as well as members and parts accompanied with
these apparatuses such as pipes, intake and exhaust fans, vacuum
pump, valves and the like. In addition, it is known that the
apparatus uses fluorides such as BF.sub.3, PF.sub.3, PF.sub.6,
NF.sub.3, WF.sub.3, HF, chlorides such as BCl.sub.3, PCl.sub.3,
PCl.sub.5, POCl.sub.3, AsCl.sub.3, SnCl.sub.4, TiCl.sub.4,
SiH.sub.2Cl.sub.2, SiCl.sub.4, HCl, Cl.sub.2, bromides such as HBr,
and further strong corrosive reagents and gases such as NH.sub.3,
CH.sub.3F or the like.
[0005] In the dry process using these halides, plasma
(low-temperature plasma) is frequently used for activation of
reaction and the improvement of working accuracy. Under an
environment using such plasma, various halides are converted into
strong corrosive atomic or ionized F, Cl, Br, l, and provide a
large effect to micro-fabrication of semiconductor material. On the
other hand, there is a problem that fine particles of SiO.sub.2,
Si.sub.3N.sub.4, Si, W and the like, which are removed from the
surface of the plasma-treated semiconductor material (especially a
plasma etching treatment) through the etching treatment are floated
in the treating environment and adhered to the surface of the
device during or after the working to considerably deteriorate the
quality thereof.
[0006] As one of these countermeasures for these problems, there is
a method wherein the surface of the member for semiconductor
manufacturing and working apparatus is subjected to a surface
treatment with an anode oxide of aluminum (alumite). And also,
there is known a technique wherein an oxide such as
Al.sub.2O.sub.3, Al.sub.2O.sub.3.Ti.sub.2O.sub.3, Y.sub.2O.sub.3 or
an oxide in Group IIIa metal of the Periodic Table is applied onto
a surface of the member by a spraying method or an evaporation
method (CVD method, PVD method), or utilized as a sintered body
(Patent Documents 1-5).
[0007] In recent years, there is known a technique wherein the
resistance to plasma erosion is improved by irradiating a laser
beam or an electron beam onto a surface of Y.sub.2O.sub.3 or
Y.sub.2O.sub.3--Al.sub.2O.sub.3 spray coating to remelt the surface
of the spray coating (Patent Documents 6-9).
[0008] Moreover, in a field of high-performance semiconductor
processing, there is a proposal that YF.sub.3 (yttrium fluoride) is
used in a coating-formation condition as a means for improving a
cleanness of working environment as well as a material for
surpassing plasma erosion resistance of Y.sub.2O.sub.3 spray
coating. For example, there are proposed a method of covering a
surface of a sintered body of YAG or the like or an oxide in Group
IIIa element of the Periodic Table with YF.sub.3 coating (Patent
Documents 10.about.11), a method wherein a mixture of
Y.sub.2O.sub.3 or Yb.sub.2O.sub.3 and YF.sub.3 and the like is used
as a coating material (Patent Documents 12-13), a method in which
YF.sub.3 itself is coated as a coating material by a spraying
method (Patent Documents 14-15).
PRIOR ART DOCUMENTS
Patent Documents
[0009] Patent Document 1: JP-A-H06-36583 [0010] Patent Document 2:
JP-A-H09-69554 [0011] Patent Document 3: JP-A-2001-164354 [0012]
Patent Document 4: JP-A-H11-80925 [0013] Patent Document 5:
JP-A-2007-107100 [0014] Patent Document 6: JP-A-2005-256093 [0015]
Patent Document 7: JP-A-2005-256098 [0016] Patent Document 8:
JP-A-2006-118053 [0017] Patent Document 9: JP-A-2007-217779 [0018]
Patent Document 10: JP-A-2002-293630 [0019] Patent Document 11:
JP-A-2002-252209 [0020] Patent Document 12: JP-A-2008-98660 [0021]
Patent Document 13: JP-A-2005-243988 [0022] Patent Document 14:
JP-A-2004-197181 [0023] Patent Document 15: JP-A-2002-037683 [0024]
Patent Document 16: JP-A-2007-115973 [0025] Patent Document 17:
JP-A-2007-138288 [0026] Patent Document 18: JP-A-2007-308794
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0027] A fluoride spray coating has an excellent halogen resistance
but has a drawback that an adhesion with substrate is worse. From
an experience of the inventors, since a fluoride spray coating
covered to a substrate surface has a less ductility and a small
surface energy, there is a phenomenon that a crack is generated and
a local peeling-off occurs. However, a countermeasure for
eliminating the above drawback is not referred in any of the above
Patent Documents. This cause is assumed to be the followings. That
is, since fluoride (YF.sub.3, AlF.sub.3 and the like) is not
thought to be adapted to Japanese Industrial Standards (JIS) and
International Organization for Standardization (ISO) that are a
basis of a spray and working technique, a working standard method
for a fluoride spray coating is not defined, and thus a spraying is
performed on the basis of the same standard as that of metal
(alloy), ceramics and cermet material and the like.
[0028] In the spray working, a substrate surface is generally
subjected to a roughening before the spray working. In the Japanese
Industrial Standards (JIS), the following blast roughening
treatment methods are defined for each of coating materials.
[0029] (1) Metal coating: In JIS H8300 "Thermal spraying of zinc,
aluminum and alloy thereof--Thermal spray working standard", oxide
is removed from a steel substrate by using blast-furnace slag,
steel slag and the like defined by JIS Z0312 for oxide (scale)
removal, and then the oxide removed surface is subjected to a
roughening treatment by using a cast-iron grid defined by JIS Z0311
or a fused alumina (Al.sub.2O.sub.3) grid defined by JIS Z0312.
[0030] (2) Ceramic coating: In JIS H9302 "Ceramic thermal spray
working standard", after the blast treatment for removing the oxide
is performed, the treated surface is subjected to a roughening
treatment by artificial abrasives (Al.sub.2O.sub.3, SiC) defined by
JIS R6111.
[0031] (3) Cermet coating: In JIS H8306 "Cermet thermal spraying",
it is defined that a roughening treatment is conducted by using the
cast-iron grid manufactured in accordance with JIS G5903 or the
artificial abrasives manufactured in accordance with JIS R6111.
[0032] As mentioned above, in the thermal spraying field, the blast
materials used for the blast roughening treatment to the substrate
surface and its roughened condition are severely defined for each
of the coating materials. Moreover, as for the substrate roughening
treatment disclosed in each of the Patent Documents relating to the
fluoride spray coating, a treatment condition and an extent of
roughening are not disclosed. Even if it is disclosed, only the
blast material is disclosed, and it is not a disclosure of a method
for improving an adhesion of the fluoride spray coating (Patent
Documents 14, 16). In Patent Documents 17, 18, a roughening by
corundum (Al.sub.2O.sub.3) is only disclosed. In fact, in these
Patent Documents and known documents relating to the fluoride spray
coating, there is no disclosure about a roughening treatment as a
countermeasure for improving an adhesion of the coating and a
formation of an intermediate layer such as an undercoat layer, and
also there is no disclosure about a surface roughness.
[0033] Further, in these Patent Documents, a process for forming
the fluoride spray coating directly onto the substrate surface is
employed, and there is no ingenuity for an adhesion of the fluoride
spray coating, for example, there is no intermediate layer such as
the undercoat layer formed prior to a formation of the fluoride
spray coating. This is assumed as a cause for frequently generating
a peel-off of the coating under an actual use environment.
[0034] An object of this invention is to provide a fluoride spray
coating covered member which a firm adhesion of a fluoride spray
coating is performed by interposing carbide cermet on a substrate
surface, and its advantageous manufacturing method.
Solution for Problems
[0035] This invention found out that an employ of new spray coating
formation techniques from the following viewpoints is advantageous
so as to overcome the above problems that the conventional
technique has.
(1) In order to improve an adhesion property of a fluoride spray
coating, a preliminary treatment technique of a substrate surface
is important. Particularly, prior to forming a fluoride spray
coating onto the substrate surface, it is effective to form an
intermediate layer (preliminary treatment) such as an undercoat
layer of carbide cermet or a primer part in which carbide cermet
particle is stuck as piles and is sparsely scattered on the
substrate surface. Since the intermediate layer of carbide cermet
formed by this preliminary treatment has a good match with a
fluoride (between fluorine and carbon), it is beneficial for
increasing adhesion strength of a fluoride spray coating as a
topcoat.
[0036] (2) As one of the above preliminary treatments, an undercoat
layer is formed onto the roughened substrate surface after a blast
treatment by a high velocity spraying of carbide cermet. In this
case, after forming a state such that a part of primary particles
blown to the substrate surface is stuck as piles to the substrate
surface and is upstanding, a coating-formation is performed by
repeating the blowing treatment successively. After that, it is
advantageous to form a fluoride spray coating according to a
conventional means on the undercoat layer formed in a film-shaped
manner.
[0037] (3) Moreover, as another preliminary treatment, after
forming a non-film shaped primer part (adhesion area ratio: about
8-50%) wherein a carbide cermet particle is stuck as piles and is
sparsely upstanding to the substrate surface by blowing a carbide
cermet material at high velocity (150-600 m/sec.) in addition to a
roughening of the substrate surface by a blast treatment, it is
advantageous to improve an adhesion property of a fluoride spray
coating by forming a fluoride spray coating through a primer
part.
[0038] (4) In this case, prior to a formation of the undercoat
layer or the primer part of carbide cermet, it is advantageous to
perform a blast roughening treatment using particles such as
Al.sub.2O.sub.3 and SiC to the substrate surface, which is
compliant with a ceramic spray coating working standard defined by
JIS H9302.
[0039] (5) Basically, after roughening the substrate surface by a
blast treatment, the non-film shaped primer part having a structure
that at least a part of the tip portion of carbide cermet spray
particles flying at a high velocity is stuck as piles and is
sparsely upstanding to the substrate surface, is formed by blowing
a carbide cermet material such as WC--Co and WC--Ni--Cr at a high
velocity (spraying number: not more than 5 times) by means of a
spray gun used in a high-velocity flame spraying method or a
low-temperature thermal spraying method. Then, it is preferable to
form the film-shaped undercoat layer wherein carbide cermet spray
particles are deposited by repeating this state successively
(spraying number: not less than 6 times). Then, a fluoride spray
coating is formed by a conventional spraying method using a plasma
flame or a combustion flame of fossil fuel as a heat source through
such an intermediate layer (primer part or undercoat layer).
[0040] (6) After forming the intermediate layer (primer part and
undercoat layer) by spraying successively a carbide cermet material
at a high velocity to the substrate surface to which a roughening
treatment is performed, it is preferable to preheat the substrate
at a temperature of 80.degree. C.-700.degree. C. and then to
perform a spraying of a fluoride spray material by means of methods
such as atmospheric plasma spraying method, reduced-pressure plasma
spraying method and high-velocity flame spraying method.
[0041] The invention developed according to the above viewpoints is
a method for forming a fluoride spray coating characterized in that
an undercoat layer of carbide cermet, which covers a substrate in a
film-shaped manner while a tip portion of carbide cermet particles
is embedded in the substrate, or a non-film shaped primer part of
carbide cermet, is formed by spraying a carbide cermet material by
using a spray gun for a high velocity spraying to a surface of the
substrate to which a roughening treatment is performed, and after
that, a fluoride spray coating material is sprayed onto the
undercoat layer or the primer part.
[0042] Moreover, the invention proposes a fluoride spray coating
covered member comprising: a substrate, a surface of which is
subjected to a roughening treatment; a carbide cermet layer coated
to a surface of the substrate; and a fluoride spray coating formed
thereon, characterized in that the carbide cermet layer is a
film-shaped undercoat layer wherein a part of carbide cermet
particles is embedded in the substrate to make a thickness thicker
or a primer part of non-film shaped structure having a construction
that a tip portion of spray particles is stuck as piles and is
sparsely upstanding, by blowing carbide cermet particles having a
particle size of 5-80 .mu.m which is made of one or more metal
carbides selected from Ti, Zr, Hf, V, Nb, Cr, Mn, W and Si and 5-40
mass % of one or more metals or alloys thereof selected from Co,
Ni, Cr, Al and Mo by using the spray gun for a high velocity
spraying.
[0043] In addition, in the invention the following constructions
are preferable solution means:
(1) The undercoat layer of carbide cermet is a layer with a
film-shaped structure having a layer thickness of 10 .mu.m-150
.mu.m, in which, at a side of a substrate surface, a tip portion of
a part of the carbide cermet particles is embedded in the substrate
and a thickness is made thicker by increasing a spraying number;
(2) The primer part of carbide cermet is made by a non-film shaped
structure having such a state that a tip portion of spray particles
is stuck as piles and is sparsely upstanding, at a portion of area
ratio 8-50% with respect to a substrate surface; (3) The undercoat
layer and the primer part of carbide cermet are formed in such a
manner that a spray treatment, in which particles having a particle
size of 5-80 .mu.m which is made of one or more metal carbides
selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si and 5-40 mass
% of one or more metals or its alloys selected from Co, Ni, Cr, Al
and Mo are sprayed by using the spray gun for a high velocity
spraying at a flying velocity of 150-600 m/sec., is repeated at 6
times or more in case of the undercoat layer and at 5 times or less
in case of the primer part; (4) The substrate is preheated to
80-700.degree. C. prior to a spraying of fluoride particles; (5) A
spray method of fluoride is any one spray method selected from
atmospheric plasma spraying method, reduced-pressure plasma
spraying method and high-velocity flame spraying method; (6) Any of
Al and its alloy, Ti and its alloy, carbon steel, stainless steel,
Ni and its alloy, oxide, nitride, carbide, silicide, carbon
sintered body and plastics, a surface roughness of which is
controlled to be Ra: 0.05-0.74 .mu.m and Rz: 0.09-2.0 .mu.m by a
blast roughening treatment in which abrasives such as
Al.sub.2O.sub.3 and SiC are blown, is used as the substrate; (7)
The fluoride spray coating is formed in such a manner that fluoride
particles having a particle size of 5 .mu.m-80 .mu.m made of a
fluoride of one or more materials selected from a group of: Mg in
Group IIa of the Periodic Table; Al in Group IIIb of the Periodic
Table; Y in Group IIIa of the Periodic Table; and lanthanide metals
of Atomic Numbers 57-71 in the Periodic Table such as La, Ce, Pr,
Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu are blown to the
substrate surface to be a coating thickness of 20 .mu.m-500 .mu.m;
and (8) The fluoride spray coating has a thickness of 20-500
.mu.m.
Effect of the Invention
[0044] According to the invention having the above constructions,
the following effects will be expected.
(1) If a hard carbide cermet material is blown to a substrate
surface at a high velocity, at least a part of primary carbide
cermet spray particles is stuck to the substrate surface, and then
a thickness becomes gradually thicker by a repetition of sprayings
to form an undercoat layer or the primer part. If fluoride
particles are sprayed to the thus formed undercoat layer or primer
part, the fluoride spray particles adhere onto the undercoat layer
of carbide cermet with a high adhesion. (2) Particularly, a
fluoride has a weak chemical wettability and less joining property
with a metal (aluminum, titanium, cast iron and the like) but has a
large chemical affinity with carbide cermet (carbon is an main
ingredient). Therefore, a fluoride spray coating having an
excellent adhesion can be formed to a surface of the undercoat
layer or the primer part having a deposited layer of carbide cermet
spray particles as a main ingredient due to a physical function
itself or a physical function combined with a chemical affinity
function. (3) Since, in the undercoat layer and the primer part of
carbide cermet, a part of primary spray particles is first stuck or
embedded to the substrate surface and then they become gradually a
film-shaped state, a strong compressive residual stress occurs in
these substrates, and thus the substrate exhibits a strong
resistance to a deformation and a strain. In a member to which the
treatment mentioned above is performed, a peeling-off of fluoride
spray coating due to mechanical load and vibration of a member
covered with a fluoride coating is suppressed during an actual
using environment. (4) In addition to the function and effect of
the undercoat layer and the primer part of carbide cermet, it is
possible to obtain a member having a strong adhesion of respective
coatings mutually by forming a fluoride spray coating under a
condition that an overall substrate is preheated. (5) Since, in the
fluoride spray coating covered member according to the invention, a
firm adhesion between the substrate and the fluoride spray coating
through carbide cermet can be performed, the fluoride spray coating
body exhibits an excellent corrosion resistance (halogen gas
resistance) and halogen gas plasma erosion resistance, and it is
possible to obtain a member which endures for a long time of use if
applied to a semiconductor working member and the like. (6) Since
the fluoride spray coating covered member according to the
invention has an undercoat layer and a primer part in which a tip
portion of spraying particles is embedded in a substrate by
strongly spraying a hard carbide cermet particle such as WC--Ni--Cr
and Cr.sub.3C.sub.2--Ni--Cr into a substrate surface with a
high-velocity flame spaying method, it is possible to form a
fluoride spray coating having a further strong adhesion on the
substrate.
[0045] That is, since a fluoride itself has a small surface energy
(Al, Ti, Fe and the like) and a weak chemical wettability, a mutual
bonding force between fluoride particles or an adhesion between the
substrate and the fluoride particle is small, and thus there is a
nature that it is sometimes peeled-off. In this point, according to
the invention, since a fluoride and a carbide cermet (carbon is a
main ingredient) has a strong chemical affinity and a good
wettability between them, it is possible to improve a coating
adhesion by utilizing their chemical affinity as well as a physical
adhesion mechanism of the fluoride spray particles if interposing
the undercoat layer and the primer part of carbide cermet.
(7) Further, since the undercoat layer of carbide cermet is dense
(porosity: 0.1-0.6%) and the primer part of carbide cermet has a
structure that a spray particle of carbide cermet is stuck as poles
and is sparsely upstanding, there is a function for strongly
suppressing a strain and a deformation of the substrate. Therefore,
a peeling-off phenomenon of the fluoride spray coating which is
liable to occur by a deformation or a vibration of the substrate
can be prevented effectively. (8) As explained above, the fluoride
spray coating formed by a technique according to the invention can
endure a thermal shock due to a repetition of an abrupt temperature
variation as well as a physical variation such as a load of
micro-vibration and bending stress, and can exhibit an excellent
chemical property of primary fluoride spray coating for a long
time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 is a flowchart showing a process sequence for
carrying out the method according to the invention.
[0047] FIG. 2 illustrates an initial layer of a substrate surface
to which WC-12 mass % Co cermet particles are sprayed sparsely by a
high-velocity flame spraying method and a cross sectional SEM image
of the same portion: (a) is a view of surface sparsely sprayed with
the carbide cermet particles; (b) is an enlarged view of the
surface; and (c) is a cross sectional view of a substrate condition
prior to forming an undercoat layer sprayed with carbide cermet
particles.
EMBODIMENTS FOR CARRYING OUT THE INVENTION
[0048] An embodiment of the invention will be explained below with
reference to the accompanying drawings. FIG. 1 is a flowchart
showing process sequence for carrying out the method according to
the invention. Hereinafter, the invention will be explained
according to this process sequence.
(1) Substrate
[0049] As a substrate usable in the invention is Al and its alloy,
Ti and its alloy, various alloy steels including stainless steel,
carbon steel, Ni and its alloy and so on. In addition, ceramic
sintered materials such as oxide, nitride, carbide and silicide,
sintered carbon, and organic polymer materials such as plastics can
be used.
(2) Pretreatment
[0050] The surface of the substrate is preferable to be pretreated
according to operation standard of ceramic sprayed coatings defined
in JIS H9302. For example, after removing rusts and fats on the
substrate surface, a blast treatment for roughening is performed
concurrently with a descale and the like by blowing abrasive
particles such as Al.sub.2O.sub.3 and SiC. The roughness after the
blast roughening treatment is preferable to be about Ra: 0.05-0.74
.mu.m and Rz: 0.09-2.0 .mu.m.
(3) Formation of a Film-Shaped Undercoat Layer or a Non-Film Shaped
Primer Part of Carbide Cermet
[0051] a. Film-Shaped Undercoat Layer of Carbide Cermet
[0052] Carbide cermet material having a particle size of 5-80 .mu.m
is sprayed at a high velocity to a roughened substrate surface
after a blast process with a spray gun by means of a high-velocity
flame spraying method or an inert gas spraying method. Accordingly,
an operation, which forms a state such that at least a part of tip
portions of spray particles is stuck and is embedded to the
substrate surface and also a state such that another part of tip
portions adheres and is deposited, is performed at plural times
(not less than 6 times). In this manner, an undercoat layer,
wherein the carbide cermet is gradually made thicker and adheres in
a film-shaped manner, is formed. This undercoat layer is formed in
a film-shaped state by spraying the carbide cermet material
(particle size: 5 .mu.m-80 .mu.m) at a spraying number of about not
less than 6 times and not more than 10 times by means of a spray
gun for high velocity spraying with a flying velocity of 150-600
m/sec. and preferably 300-600 m/sec. It should be noted that, if a
flying velocity of the spraying particles is less than 150 .mu.m, a
bitten depth of the particles into the substrate surface is not
sufficient and adhesion strength is decreased. On the other hand,
when the flying velocity exceeds 600 m/sec., an effect is saturated
in the case of using the carbide cermet particles. Moreover, if the
spraying number is not more than 5 times, it is difficult to form a
uniform film-shaped spray coating.
[0053] FIG. 2 shows forms of a substrate surface and a section
thereof at an initial state in the formation of the undercoat layer
of carbide cermet materials i.e. just after the carbide cermet
particles are sprayed at a flying velocity of 550 m/sec. by a
high-velocity flame spraying method. FIG. 2(b) shows a state that a
part of sprayed WC--Co cermet particles adhere to a substrate
surface so as to dig thereinto, while the other WC--Co cermet
particles are scattered in the substrate at a partially crushed
state by collision energy and attached thereto. FIG. 2(c) shows a
cross-sectional state when observing a distribution condition of
WC--Co cermet particles sprayed to a surface layer portion of the
substrate surface at an initial stage before the coating formation.
As seen from this photograph, tip portions of part of WC--Co cermet
particles are stuck and buried into the substrate surface at the
initial stage while the other part becomes simply adhered or buried
state. In this manner, more uniform coating is obtained as the
spraying number is increased.
[0054] That is, when the WC--Co spraying material is sprayed
further repeatedly (.gtoreq.6 times) to the substrate surface
adhered with WC--Co cermet spraying particles by a high-velocity
flame spraying method, WC--Co particles are gradually deposited
even onto a non-adhered parts of the substrate surface (black parts
of FIG. 2(a)), to form a film-shaped undercoat layer of WC--Co
cermet particles applied over the whole surface in due course. On
the contrary, in the case of general metallic undercoat of Ni--Cr,
Ni--Al, or the like widely used in the formation of an oxide
ceramic spray coating, particles buried in the substrate as shown
in FIG. 2 are not observed.
[0055] In the invention, when the undercoat layer of carbide cermet
is formed in the substrate surface, the adhesion between the
undercoat and the substrate is enhanced by the behavior of hard
carbide cermet, while the improvement of the adhesion of undercoat
layer/topcoat (fluoride spray coating) i.e. adhesion of the
fluoride spray coating is attained by a synergistic effect of a
surface roughness of the undercoat layer and a chemical affinity
between carbon and fluoride (top coat).
[0056] Carbide cermet spraying particles being at a state that the
particles existing in a lowermost layer of the undercoat layer are
stuck into the substrate surface are firmly bonded to the substrate
while a large compression strain is applied to the substrate
surface, which not only gives a large resistance to mechanical
deformation of the substrate but also improves the adhesion between
the substrate and the undercoat layer of carbide cermet itself to
improve the adhesion to the fluoride spray coating covered
thereon.
[0057] In the invention, the undercoat layer of carbide cermet
adhered and deposited onto the substrate surface at a state of
burying a part of the spraying particles is particularly effective
for the substrate being soft and susceptive to deformation or
strain under a load in a use environment such as Al and its alloy,
Ti and its alloy, mild steel, various stainless steels and so on,
and guarantees the formation of fluoride spray coating having
always a stable and high adhesion regardless of kind of substrate
material.
[0058] That is, a fluoride coating is originally poor in the
ductility and small in the surface energy and hardly joins to a
metal series substrate, so that the peel-off of the coating is
easily caused by the generation of a little deformation or strain
of the substrate. However, it is possible to suppress external
stress or a strain applied to the fluoride coating by the
suppression of the substrate deformability due to the burying of
carbide cermet particles into the substrate surface and the
formation of the undercoat layer of carbide cermet formed
thereon.
[0059] The thickness of the undercoat layer of carbide cermet
formed on the substrate surface is preferable within a range of
30-200 .mu.m, particularly preferable within a range of 80-150
.mu.m. When the thickness of the undercoat layer is less than 30
.mu.m, the coating thickness becomes easily uneven, while when it
exceeds 200 .mu.m, an effect as the undercoat layer is saturated
and is uneconomic.
[0060] b. Formation of Non-Film Shaped Primer Part by Carbide
Cermet
[0061] Carbide cermet particles having a particle size of 5-80
.mu.m are sprayed onto the substrate surface which is roughened
through blasting at a high velocity by a spray gun for
high-velocity spraying used in a high-velocity flame spraying
method or an inert gas spraying method, whereby tip portions of at
least a part of the sprayed hard carbide cermet particles are
independently skewed and stuck as piles into the substrate surface.
Moreover, according to this method, a portion (primer part), in
which the carbide cermet particles adhering to the substrate
surface in a sparse pattern are dotted and adhere, is formed. In
this case, if the particle size of the carbide cermet particles is
less than 5 .mu.m, the amount supplied to a spray gun becomes
uneven and the uniform spraying can not be performed. In addition,
the amount of skewed particles becomes small and it is impossible
to form effective primer part wherein spray particles are
effectively dotted and adhered. On the other hand, if the particle
size exceeds 80 .mu.m, the skewing effect becomes weakened.
[0062] Moreover, as is the same as the undercoat layer, the primer
part is a part that the carbide cermet material (particle size 5-80
.mu.m) is sprayed to the substrate surface at an area ratio of
8-50% with a spray gun at a flying velocity of 150-600 m/sec,
preferably 300-600 m/sec in the spraying number of not more than 5
times, preferably not more than 3 times to adhere the sprayed
particles at a state of sparsely sticking as piles.
[0063] The primer part, wherein carbide cermet spray particles
dispersed sparsely in this treating step is dotted, is not
completely film-shaped and forms the following structure. That is,
as seen from FIGS. 2(a) and 2(b) showing an appearance state when
particles of WC-12 mass % Co carbide cermet material are sprayed to
a surface of SUS310 steel substrate, a part of the sprayed WC--Co
cermet particles is at a state of adhering to 8-50% portions of the
substrate surface so as to dig thereinto. Moreover, the other
WC--Co cermet particles are dispersedly adhered to the substrate
surface at a state of being partially crushed by collision energy,
and further a part of the other is at a state of completely burying
in the substrate to form a reinforcing layer of carbide cermet in
the surface layer of the spray coating.
[0064] FIG. 2(c) is a view observing a distribution state of the
sprayed WC--Co cermet particles existing in the surface layer
portion of the substrate at section. As seen from this photograph,
WC--Co cermet particles are existent at a state of foresting small
piles sparsely stuck in the substrate surface and another part
thereof is simply adhered or buried. In the invention, when the
fluoride particles are sprayed onto the substrate surface at such a
state, i.e. onto the primer part (this part does not form a
complete layer) of the carbide cermet particles adhered at such
state, the fluoride spray coating having high adhesion will be
formed by utilizing a mutual interlocking effect i.e. anchoring
effect (JIS H8200 Thermal spraying terms) with hard WC--Co cermet
particles stuck as piles (fluoride spray particles) or a skewing
phenomenon (fluoride particles are skewed and adhere to a tip
portion of hard WC--Co cermet particle stuck as piles).
[0065] In this invention, as for a construction of the primer part
of the carbide cermet, an area ratio (area occupying ratio) of
carbide cermet particles is shown by means of an image analyzing
device using SEM photograph of FIG. 2(a) or FIG. 2(b) when white
parts are carbide cermet particles and black parts are an exposed
surface of the substrate. That is, in the primer part, a ratio
occupied by the spray particles with respect to the surface area of
the substrate i.e. an area ratio is to be controlled within a range
of 8-50% preferably. This is because, when it is less than 8%, the
wedging effect of carbide cermet particles is weak, while when it
exceeds 50%, the action mechanism is the same as in an undercoat
layer of carbide cermet mentioned later and the wedging effect of
the fluoride particles becomes small. In this invention, a state of
the substrate surface in which the carbide cermet particles are
sprayed at an area ratio of 8-50% to the substrate surface is
called as "primer part".
[0066] As the carbide cermet spraying material usable in this
invention can be used of WC--Co, WC--Ni--Cr, WC--Co--Cr,
Cr.sub.3C.sub.2--Ni--Cr and the like. Moreover, a percentage of
metal ingredient occupied in this carbide cermet is preferably
within a range of 5-40 mass %, particularly preferable within a
range of 10-30 mass %. The reason is that if a metal ingredient is
less than 5 mass %, the hard carbide is made to a small powder and
a ratio remaining on the substrate surface becomes small when
spraying to the substrate surface strongly. On the other hand, when
the metal ingredient exceeds 40 mass %, the hardness and corrosion
resistance are deteriorated and the entangling effect with the
fluoride particle is decreased, and the substrate is liable to be
corroded by a corrosive gas penetrated from through-holes of the
fluoride spray coating and also the bonding force of the fluoride
spray coating is vanished to induce the peeling-off.
[0067] The sprayed carbide cermet material is preferred to have a
particle size of 5-80 .mu.m, particularly 10-45 When the particle
size is less than 5 .mu.m, the supply to the spray gun becomes
discontinuous, and the formation of uniform coating is difficult,
and the particles are finely crushed and scattered in the collision
with the substrate and hardly retains on the substrate surface.
While, when the particle size exceeds 80 .mu.m, an effect is
saturated and it is difficult to obtain commercially available
products.
(4) Preheating of Substrate
[0068] The substrate after the roughening and the substrate after
the formation of the undercoat layer of carbide cermet and a primer
part wherein spray particles are dotted are subjected to a
preheating prior to the fluoride spraying treatment. The preheating
temperature is preferable to be controlled in accordance with the
nature of the substrate and is recommended to be the following
temperature. Moreover, the preheating may be performed as one of
pretreatments.
(i) Al, Ti and alloys thereof: 80.degree. C.-250.degree. C. (ii)
Iron steel (low alloy steel): 80.degree. C.-250.degree. C. (iii)
Stainless steels: 80.degree. C.-250.degree. C. (iv) Ceramic
sintered material of oxides, carbides and the like: 120.degree.
C.-500.degree. C. (v) Sintered carbon: 200.degree. C.-700.degree.
C.
[0069] Moreover, the preheating may be conducted in air or under
vacuum or in an inert gas, but an atmosphere of oxidizing the
substrate material by preheating to produce an oxide film on the
surface should be avoided.
[0070] As a method for forming a fluoride spray coating,
atmospheric plasma spraying method, reduced-pressure plasma
spraying method, high-velocity flame spraying method and the like
are preferably used.
(5) Formation of Fluoride Spray Coating (Topcoat)
[0071] a. Fluoride Spraying Material
[0072] As a fluoride spraying material used in the invention are
included fluorides of Mg in Group Ha of the Periodic Table, Al in
Group IIIb of the Periodic Table, Y in Group IIIa of the Periodic
Table, and lanthanide metals belonging to Atomic Number 5771 in the
Periodic Table. The metal elements of Atomic Number 5771 are 15
sorts of lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium
(Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium
(Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er),
thulium (Tm), ytterbium (Yb) and lutetium (Lu).
[0073] As the fluoride spraying material are used fluoride
particles of the above metal adjusted to be a particle size of 5-80
.mu.m. When the spraying material is a fine particles having a
particle size of less than 5 .mu.m, there is a drawback that the
particles are frequently flied apart without forming the coating in
the collision with the substrate surface while when the particle
size exceeds 80 .mu.m, the rate supplied to a spraying gun is
hardly equalized and the tendency of increasing the pore size of
the formed coating becomes remarkable.
[0074] The spray coating by spraying fluoride spray materials
formed on the surface of the substrate or the like after the
roughening or after the formation of the undercoat layer or primer
part of carbide cermet or further the preheating is sufficient to
have a thickness of 20-500 .mu.m, particularly 50-200 .mu.m is
preferable. When the coating is thinner than 20 .mu.M, uniform
thickness is not obtained, while when the thickness exceeds 500
.mu.m, residual stress in the formation of the fluoride coating
becomes large to bring about the decrease of the adhesion force to
the substrate and the peeling is liable to be easily caused.
[0075] b. Characteristics of Fluoride Spray Coating
[0076] As physicochemical properties of the fluoride itself can be
pointed out the followings. That is, the fluoride coating has a
chemical stability to a halogen-based gas as compared with a metal
coating or a ceramic coating but is weak in the mutual bonding
force of fluoride particles constituting the coating and adhesion
strength to the substrate because the surface energy is small.
Also, since a large residual stress is liable to be generated when
forming a coating, a peeling-off of the coating is liable to occur
easily and frequently due to a slight deformation of substrate
after coating-formation. In addition, since the fluoride is poor in
ductility, the coating is "cracked" easily and causes corrosion of
the substrate due to internal penetration of an acid or alkali
cleaning liquid together with porous portions produced in the above
coating formation. Therefore, the fluoride is good in the corrosion
resistance but has a problem that the property cannot be utilized
as a corrosion resistance coating.
[0077] In this regard, if the aforementioned of the invention is
applied, since the undercoat layer or the primer part of carbide
cermet is formed to the substrate surface, adhesion of the coating
is further improved, whereby the above problems of the fluoride
spray coating can be solved. That is, the effect of preventing the
corrosion of the substrate can be seen by the prevention from
peeling or cracking of the coating and the prevention from
penetration of the cleaning fluid accompanied therewith.
[0078] Moreover, the fluoride spray coating formed according to the
invention can be used as is in a coating-forming state, but is
subject to a heat treatment at 250.degree. C.-500.degree. C. after
the coating formation, if necessary, whereby the residual stress
can be released easily or an amorphous phase can be easily
crystallized (orthorhombic crystal phase). In the invention,
therefore, the use of these treatments is not particularly limited.
The reason why the temperature of the heat treatment is limited to
the above range is due to the fact that when it is lower than
250.degree. C., a long time is taken for releasing the residual
stress of the coating and the crystallization is also insufficient,
while when it exceeds 500.degree. C., there is a possibility for
promoting a physicochemical change of the fluoride spray
coating.
EXAMPLES
Example 1
[0079] In this example, an influence of pretreatment of a substrate
surface affected to an adhesion of fluoride spray coating is
investigated.
(1) Kind of Pretreatment
[0080] The following pretreatments are performed to one surface of
Al3003 alloy ("JIS M 4000", size: diameter 25 mm.times.thickness 5
mm) as the substrate.
(i) After degreasing, the surface is polished by a wire brush
lightly. (ii) After degreasing, a metal undercoat layer of Ni-20
mass % Cr having a thickness of 50 .mu.m is formed by an
atmospheric plasma spraying method (flying velocity: 250 m/sec.).
(iii) After degreasing, a primer part is formed by blowing WC-12
mass % Co in a sparse pattern (area ratio: 22%) by a high-velocity
flame spraying method (flying velocity: 580 m/sec., spraying
number: 3 times). (iv) After degreasing, an undercoat layer of
carbide cermet of Cr.sub.3C.sub.2-18 mass % Ni-7 mass % Cr having a
thickness of 30 .mu.m is formed by a high-velocity flame spraying
method (flying velocity: 560 m/sec., spraying number: 6 times). (v)
After degreasing, a blast roughening treatment is performed to a
substrate surface by using Al.sub.2O.sub.3 abrasive. (vi) After the
above blast roughening treatment, a metal undercoat layer made of
Ni-20 mass % Cr film having a thickness of 50 .mu.m is further
formed by atmospheric plasma spraying method (same as (ii)). (vii)
After the above blast roughening treatment, a primer part is
further formed by blowing WC-12 mass % Co in a sparse pattern (area
ratio: 18%) by a high-velocity flame spraying method (same as
(iii)). (viii) After the above blast roughening treatment, an
undercoat layer of carbide cermet having a thickness of 30 .mu.m is
further formed by blowing Cr.sub.3C.sub.2-18 mass % Ni-7 mass % Cr
by a high-velocity flame spraying method (same as (iv)).
[0081] (2) Formation of Fluoride Spray Coating
[0082] With respect to the substrate surface after the above
pretreatments, YF.sub.3 spray coating having a thickness of 100
.mu.m is formed by an atmospheric plasma spraying method.
[0083] (3) Test Method of Coating Adhesion
[0084] An adhesion of a coating is measured by a test method of
adhesion strength defined in Test method of ceramic spray coating
of JIS H8666.
[0085] (4) Test Results
[0086] Test results are shown in Table 1. As is clear from these
results, the sample piece (No. 1), in which a fluoride spray
coating is formed after degreasing the substrate surface only,
seldom indicates adhesion force, and the coating is peeled-off at
0.5-1.2 MPa. Moreover, the coating (No. 2) formed on the metal
undercoat layer indicates an adhesion force of about 4-5 MPa.
However, since a blast roughening treatment is not performed to the
substrate surface, some sample pieces show a peeling-off from a
boundary between the metal undercoat layer and the substrate. On
the other hand, the sample piece (No. 3), in which the primer part
of carbide cermet particle is formed, and the sample piece (No. 4),
in which the undercoat layer is formed, exhibit a high adhesion
force. Therefore, it is confirmed that, even if a blast roughening
treatment is omitted, adhesion force required for an actual use can
be obtained.
[0087] Then, since YF.sub.3 coating (No. 5) formed on the blast
roughened substrate surface indicates an adhesion force of 4-6 MPa
and has a high bonding force as compared with the coating of No. 1,
it is confirmed that a blast roughening treatment is effective for
a formation of fluoride spray coating. Moreover, an adhesion of the
test pieces (Nos. 7 and 8), wherein a primer part or an undercoat
layer is formed by spraying carbide cermet particles to a substrate
surface, to which a blast roughening treatment is performed, and
then a fluoride spray coating is formed thereon, is further
increased. Therefore, it is confirmed that these treatments are
suitable for the pretreatment method for forming a fluoride spray
coating.
TABLE-US-00001 TABLE 1 Coating Structure Adhesion No. Substrate
Pretreatment Undercoat Topcoat MPa Remarks 1 Al3003 Degreasing None
YF.sub.3 0.5~1.2 Comparative 2 (Al Only Ni--Cr 4~5 example alloy)
(Light wire (50 .mu.m) 3 brushing) WC--12Co 13~16 Invention Blowing
example (Primer part) 4 Cr.sub.3C.sub.2--Ni.cndot.Cr 14~19
Invention (Undercoat example layer) (30 .mu.m) 5 Blast treatment
None 4~6 Comparative 6 after Ni--Cr 7~8 example degreasing (50
.mu.m) 7 WC--12Co 13~15 Invention Blowing example (Primer part) 8
Cr.sub.3C.sub.2--Ni.cndot.Cr 14~18 Invention (Undercoat example
layer) (30 .mu.m) (Remarks) (1) The coating to be tested is formed
by an atmospheric plasma spraying method and has a thickness of 100
.mu.m. (2) Three samples are tested per one condition and an
adhesion force of coating is indicated by maximum value to minimum
value. (3) The adhesion strength of the coating is measured by a
test method defined at JIS H8666 Test method of ceramic sprayed
coating.
Example 2
[0088] In this example, an adhesion of the spray coating is
examined when YF.sub.3 spray coating having a thickness of 100
.mu.m is formed to SS400 steel substrate by a reduced-pressure
plasma spraying method.
(1) Kind of Pretreatment (Roughening, Formation of Intermediate
Layer)
[0089] Pretreatments, that are the same kinds as those of Example
1, are performed.
[0090] (2) Formation of Fluoride Spray Coating
[0091] A fluoride spray coating having a thickness of 100 .mu.m is
formed by a plasma spraying method (a reduced-pressure plasma
spraying method) using YF.sub.3 under reduced pressure environment
of Ar gas at 100-200 hPa.
[0092] (3) Test Method of Coating Adhesion
[0093] The same test method as that of Example 1 is performed.
[0094] (4) Test Results
[0095] Test results are shown in Table 2. As seen from the results,
an adhesion of the coating after blast treatment is higher as
compared with the case (No. 1) in which YF.sub.3 spray coating is
directly formed to the substrate surface, and it is confirmed that
an excellent adhesion can be obtained as compared with Al alloy
substrate of Example 1. However, even if SS400 steel substrate is
used, the cases (Nos. 3 and 7) wherein the primer part is formed by
spraying carbide cermet particles and the cases (Nos. 4 and 8)
wherein the undercoat layer is formed exhibit further higher
adhesion. That is, it is confirmed that the pretreatment method in
which the undercoat layer and the primer part are formed by carbide
cermet can always form the coating having a high adhesion
regardless of effects of substrate kinds.
TABLE-US-00002 TABLE 2 Coating Structure Adhesion No. Substrate
Pretreatment Undercoat Topcoat MPa Remarks 1 SS400 Degreasing None
CeF.sub.3 0.7~1.3 Comparative 2 steel Only Ni--Cr 4~5 example
(Light wire (50 .mu.m) 3 brushing) WC--12Co 15~18 Invention Blowing
example (Primer part) 4 Cr.sub.3C.sub.2--Ni.cndot.Cr 16~19
Invention (Undercoat example layer) (30 .mu.m) 5 Blast treatment
None 5~8 Comparative 6 after Ni--Cr 10~12 example degreasing (50
.mu.m) 7 WC--12Co 15~18 Invention Blowing example (Primer part) 8
Cr.sub.3C.sub.2--Ni.cndot.Cr 17~20 Invention (Undercoat example
layer) (30 .mu.m) (Remarks) (1) The coating to be tested is formed
by a reduced-pressure plasma spraying method and has a thickness of
100 .mu.m. (2) Three sample pieces are tested per one condition and
an adhesion of coating is indicated by maximum value to minimum
value. (3) The adhesion strength of the coating is measured by a
test method defined at JIS H8666 Test methods for ceramic sprayed
coatings.
Example 3
[0096] In this example, an adhesion of YF.sub.3 spray coating
formed to SS400 steel substrate by a high-velocity flame spraying
method is examined.
(1) Kind of Pretreatment (Roughening, Formation of Intermediate
Layer)
[0097] Pretreatments, that are the same as those of Example 1, are
performed.
[0098] (2) Formation of Fluoride Spray Coating
[0099] A fluoride spray coating having a thickness of 100 .mu.m is
formed by a high-velocity flame spraying method using YF.sub.3.
[0100] (3) Test Method of Coating Adhesion
[0101] The same test method as that of Example 1 is performed.
[0102] (4) Test Results
[0103] Test results are shown in Table 3. As seen from the results
of this table, as is the same results as those of Examples 1 and 2,
in the cases (Nos. 3, 4, 7, 8) wherein the undercoat layer and the
primer part of carbide cermet are formed according to the
invention, it is confirmed that it is always possible to form a
fluoride spray coating having a high adhesion regardless of
presence or absence of a blast roughening treatment of the
substrate.
TABLE-US-00003 TABLE 3 Coating structure Adhesion No. Substrate
pretreatment Undercoat Topcoat MPa Remarks 1 SS400 Degreasing None
YF.sub.3 0.6~1.3 Comparative 2 steel Only Ni--Cr 3~4 example (Light
wire (50 .mu.m) 3 brushing) WC--12Co 10~12 Invention Blowing
example (Primer part) 4 Cr.sub.3C.sub.2--Ni.cndot.Cr 12~13
Invention (Undercoat example layer) (30 .mu.m) 5 Blast treatment
None 2~4 Comparative 6 after Ni--Cr 4~5 example degreasing (50
.mu.m) 7 WC--12Co 11~14 Invention Blowing example (Primer part) 8
Cr.sub.3C.sub.2--Ni.cndot.Cr 14~16 Invention (Undercoat example
layer) (30 .mu.m) (Remarks) (1) The coating to be tested is formed
by a high-velocity flame spraying method and has a thickness of 100
.mu.m. (2) Three sample pieces are tested per one condition and an
adhesion of coating is indicated by maximum value to minimum value.
(3) The adhesion strength of the coating is measured by a test
method defined at JIS H8666 Test methods of ceramic spray
coatings.
Example 4
[0104] In this example, SUS304 steel is used as a substrate, and an
adhesion of three kinds of fluoride spray coatings formed by an
atmospheric plasma spraying method is examined.
(1) Kind of Pretreatment
[0105] After a substrate is subjected to a blast roughening
treatment by SiC abrasives, WC-12 mass % Co-5 mass % Cr or
Cr.sub.3C.sub.2-17 mass % Ni-7 mass % Cr is brown onto the
roughened surface at a high-velocity as is the same conditions of
Example 1 so as to obtain a blowing thickness of 80 .mu.m.
[0106] (2) Formation of Fluoride Spray Coating
[0107] A fluoride spray coating having a thickness of 120 .mu.m is
formed by an atmospheric plasma spraying method using CeF.sub.3,
DyF.sub.3 and EuF.sub.3.
[0108] (3) Test Method of Coating Adhesion
[0109] The same test method as that of Example 1 is performed.
[0110] (4) Test Results
[0111] Test results are shown in Table 4. As seen from the results
of this table, it is confirmed that the coating to which the
undercoat layer of carbide cermet is formed has an effect for
improving an adhesion to the fluoride spray coating such as
CeF.sub.3, DyF.sub.3 and EuF.sub.3.
TABLE-US-00004 TABLE 4 Adhesion according to pretreatment kind
Blast WC--12Co Cr.sub.3C.sub.2--Ni.cndot.Cr Coating roughening
(Primer (Undercoat No. Substrate material treatment None part)
layer) 1 SUS304 CeF.sub.3 perform 4~7 11~12 11~14 2 steel DyF.sub.3
5~8 10~14 12~15 3 EuF.sub.3 4~6 11~13 12~14 (Remarks) (1) The
coating to be tested is formed by an atmospheric plasma spraying
method and has a thickness of 120 .mu.m. (2) Three sample pieces
are tested per one condition and an adhesion of coating is
indicated by maximum value to minimum value. (3) The adhesion
strength of the coating is measured by a method defined at JIS
H8666 Test methods of ceramic spraying coatings.
Example 5
[0112] In this example, a primer part of carbide cermet and a
fluoride spray coating thereon are formed to a surface of Al alloy
substrate (size: width 30 mm.times.longitudinal 50
mm.times.thickness 3 mm) by the method adapted to the invention to
evaluate a resistance to plasma etching of the spray coating.
(1) Substrate: A fluoride spray coating is prepared by: subjecting
a surface of Al alloy (A3003 defined by JIS H4000) to a blast
roughening treatment; performing a pretreatment for forming a
primer part having a sparse pattern (area ratio of 12%) by blowing
carbide cermet materials (spraying number: 2 times) at a high
velocity (550 m/sec.) according to the invention; and preheating at
a temperature of 180.degree. C.
[0113] (2) Fluoride for coating-formation: YF.sub.3, DyF.sub.3 and
CeF.sub.3 (particle size 5-45 .mu.m) are sprayed to form a coating
having a coating thickness of 180 .mu.m by an atmospheric plasma
spraying method. Moreover, as a coating of a comparative example,
oxide coatings having a thickness of 180 .mu.m respectively, which
are formed by the atmospheric plasma spraying method of
Y.sub.2O.sub.3, Dy.sub.2O.sub.3 and CeO.sub.2, are tested.
[0114] (3) Gas Composition of Plasma Etching Atmosphere and Plasma
Output
(i) Conditions of atmospheric gas and flow rate (a) F-containing
gas: CHF.sub.3/O.sub.2/Ar=80/100/160 (flow rate per 1 minute
cm.sup.3) (b) CH-containing gas: C.sub.2H.sub.2/Ar=80/100 (flow
rate per 1 minute cm.sup.3) (ii) Plasma irradiation output
High-frequency power: 1300 W
Pressure: 4 Pa
Temperature: 60.degree. C.
[0115] (iii) Atmosphere of plasma etching test (a) Performed in a
F-containing gas atmosphere (b) Performed in a CH-containing gas
atmosphere (c) Performed in an alternately repeated atmosphere of
F-containing gas atmosphere for 1 hourCH-containing gas atmosphere
for 1 hour
[0116] (4) Evaluation Method
[0117] In an evaluation of the test of plasma erosion resistance,
the plasma erosion resistance and environmental pollution
resistance are investigated by measuring the number of particles of
coating ingredients flied from the coating to be tested by etching
treatment. The number of particles is evaluated by measuring time
duration until the number of particles having a particle size of
not less than 0.2 .mu.m adhered to a surface of silicon wafer
having a diameter of 8 inch disposed in a test container reached to
30.
[0118] (5) Test Results
[0119] Test results are shown in Table 5. As seen from the results,
the oxide based spray coatings (No. 1, 3, 5) of the comparative
examples indicate such a situation that the generation of particles
is smallest in the CH-containing gas and becomes somewhat large in
the F-containing gas, and the time reaching to an acceptable value
becomes short. However, it is proved that the number of particles
generated becomes further large in the alternately repeated
atmosphere of the F-containing gas and the CH-containing gas and
the time reaching to an acceptable value becomes very short. This
cause is considered due to the fact that the oxide film in the
surface of the oxide ceramic coating becomes always unstable and is
scattered by a repetition of oxidation function of fluoride gas in
the F-containing gas and a reduction function of CH gas. On the
other hand, it is considered that the fluoride spray coatings of
No. 2, 4 and 6 are maintained in a chemically stable state even in
the F-containing gas, in the CH-containing gas and the alternately
repeated atmosphere of these gasses, which is considered to
suppress the generation of particles.
TABLE-US-00005 TABLE 5 Time until particle generation amount
exceeds acceptable value Mutual repetition of Coating F CH gas
containing to containing containing F and gas No. be tested gas gas
containing CH Remarks 1 Y.sub.2O.sub.3 70 120 35 Comparative
example 2 YF.sub.3 108 220 82 Invention example 3 Dy.sub.2O.sub.3
70 120 30 Comparative example 4 DyF.sub.3 98 210 77 Invention
example 5 CeO.sub.2 80 78 30 Comparative example 6 CeF.sub.2 101
240 78 Invention example (Remarks) (1) Coating thickness of the
coating to be tested is 180 .mu.m. (2) Surface roughness of
substrate after blast roughening treatment: Ra 0.4-0.5 .mu.m, Rz
0.7-1.0 .mu.m. (3) Formation of coating is performed by an
atmospheric plasma spraying method.
Example 6
[0120] In this example is examined a corrosion resistance to a
vapor of a halogen based acid in a fluoride spray coating formed on
a substrate surface by a method adapted to the invention.
(1) Substrate: A substrate of SS400 steel (size: width 30
mm.times.longitudinal 50 mm.times.thickness 3.2 mm) is used, and a
coating-formation is performed by: subjecting a substrate surface
to a blast roughening treatment; forming a primer part having a
sparse pattern (area ratio of 28%) of carbide cermet particles on
the substrate surface by blowing carbide cermet particles of
Cr.sub.2C.sub.3-18 mass % Ni-8 mass % Cr at a high velocity by a
high-velocity flame spraying method (560 m/sec., spraying number: 3
times); and preheating the substrate to a temperature of
200.degree. C.
[0121] (2) Fluoride for coating-formation: MgF.sub.2, YF.sub.3
(particle size: 10-60 .mu.m) are used, and a sample having a
fluoride coating with a coating thickness of 250 .mu.m is prepared
by a reduced-pressure plasma spraying method. Moreover, as a
coating of a comparative example, coatings having a thickness of
250 .mu.m respectively formed by a reduced-pressure plasma spraying
method of MgO, Y.sub.2O.sub.3, are tested under the same
conditions.
[0122] (3) Corrosion Test
(a) A corrosion test by HCl vapor is adopted a method wherein 100
ml of an aqueous solution of 30% HCl is placed in a bottom portion
of desiccator for chemical experiment and a sample is suspended in
a top portion thereof and exposed to HCl vapor generated from the
aqueous HCl solution. A temperature of the corrosion test is
30.degree. C.-50.degree. C., and a time thereof is 96 hours. (b) A
corrosion test by HF vapor is conducted by placing 100 ml of HF
aqueous solution in a bottom portion of autoclave made of SUS316
and suspending a sample in a top portion thereof. A temperature of
the corrosion test is 30.degree. C.-50.degree. C., and an exposing
time thereof is 96 hours.
[0123] (4) Test Results
[0124] Test results are shown in Table 6. As seen from the results,
a large amount of red rust reached to the surface of the coatings
in the oxide based coating of the comparative examples (No. 2, 4).
That is, it is considered that, since many through-holes are
existent in the oxide coating, a vapor of HCl, HF and the like
reaches to an interior of the coating via the through-holes to
corrode the SS400 steel substrate, and an iron component as a
corroded product reaches to the coating surface via the
through-holes to present red rust state. On the other hand, in the
fluoride coatings (No. 1, 3) formed according to the invention, a
generation of red rust is recognized, but its extent remained to
about 30-40% of the comparative example. From the results, it is
found that there are through-holes in the fluoride spray coating
but they are little as compared with those of the oxide spray
coating, and further since the fluoride coating itself has an
excellent corrosion resistance, the good corrosion resistance is
developed to vapors of comprehensive halogen based acids.
TABLE-US-00006 TABLE 6 Corrosion test results Coating HCl No.
Substrate material vapor HF vapor Remarks 1 SS400 MgF.sub.2 .DELTA.
.DELTA. Invention example 2 steel MgO x x Comparative example 3
YF.sub.3 .DELTA. .DELTA. Invention example 4 Y.sub.2O.sub.3 x x
Comparative example (Remarks) (1) The coating to be tested is
formed to be a thickness of 250 .mu.m by a reduced-pressure plasma
spraying method. (2) An area ratio of a sparse pattern by means of
Cr.sub.3C.sub.2--Ni--Cr carbide particles is 28%. (3) Symbols of
corrosion test results: x: large generation of red rust .DELTA.:
small generation of red rust.
INDUSTRIAL APPLICABILITY
[0125] The technique according to the invention can be applied to a
surface treatment of members for precise working apparatus for
semiconductors requiring a high resistance to halogen corrosion and
plasma erosion. For example, they can be utilized as a corrosion
resistant coating such as deposit shield, baffle plate, focus ring,
insulator ring, shield ring, bellows cover, electrode and the like
disposed in a plasma treating apparatus with a treating gas
including halogen and a compound thereof as well as members for
chemical plant apparatus in similar gas atmosphere.
[0126] Moreover, a technique for forming an undercoat layer of
carbide cermet to a substrate according to the invention can be
applied to a technique for processing a topcoat for metal (alloy)
coating, oxide ceramics, plastics and the like.
* * * * *