U.S. patent application number 12/409692 was filed with the patent office on 2009-10-01 for coating method and electrolyzing apparatus used therefor.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Kazuhiro Kitayama, Hiroaki Okamoto, Masahiro Saito, Yoshiaki Sakai, Yomei Yoshioka.
Application Number | 20090242418 12/409692 |
Document ID | / |
Family ID | 40846050 |
Filed Date | 2009-10-01 |
United States Patent
Application |
20090242418 |
Kind Code |
A1 |
Saito; Masahiro ; et
al. |
October 1, 2009 |
COATING METHOD AND ELECTROLYZING APPARATUS USED THEREFOR
Abstract
The present invention provides a coating method, in which a
composite coating layer is formed on a surface of an alloy base
member by utilizing a rotary electrode device. The coating method
includes the steps of: preparing an electrolytic solution
containing A ion wherein A is Co or Ni; preparing a MCrAlY powder
wherein M denotes at least one element selected from the group
consisting of Ni and Co, and the MCrAlY powder contains at least Ni
when A is Co or the MCrAlY powder contains at least Co when A is
Ni; preparing a dispersion liquid by dispersing the MCrAlY powder
into the electrolytic solution; immerging the cylindrical rotary
electrode and the alloy base member into the dispersion liquid; and
electrolyzing the surface of the alloy base member while the
cylindrical rotary electrode covered with the nonwoven fabric layer
is rolled on the on the surface of the alloy base member thereby to
form the composite coating layer onto the surface of the alloy base
member.
Inventors: |
Saito; Masahiro;
(Yokohama-Shi, JP) ; Yoshioka; Yomei;
(Yokohama-Shi, JP) ; Kitayama; Kazuhiro;
(Yokohama-Shi, JP) ; Okamoto; Hiroaki;
(Yokohama-Shi, JP) ; Sakai; Yoshiaki;
(Yokohama-Shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
|
Family ID: |
40846050 |
Appl. No.: |
12/409692 |
Filed: |
March 24, 2009 |
Current U.S.
Class: |
205/269 ;
204/212; 205/271; 205/273 |
Current CPC
Class: |
Y02T 50/672 20130101;
C25D 5/08 20130101; F05D 2230/90 20130101; F01D 5/288 20130101;
C25D 5/50 20130101; Y02T 50/60 20130101; C25D 15/02 20130101; C25D
17/18 20130101; C25D 17/14 20130101; C25D 5/06 20130101; F05B
2230/90 20130101 |
Class at
Publication: |
205/269 ;
205/271; 205/273; 204/212 |
International
Class: |
C25D 3/12 20060101
C25D003/12; C25D 17/12 20060101 C25D017/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 25, 2008 |
JP |
2008-078832 |
Claims
1. A coating method in which a composite coating layer is formed on
a surface of an alloy base member by utilizing an electrolyzing
apparatus provided with a rotary electrode device which includes a
cylindrical rotary electrode capable of rolling on a surface of the
alloy base member and a non-woven fabric layer covering a surface
of the cylindrical rotary electrode, the coating method comprising
the steps of: preparing an electrolytic solution containing A ion
wherein A is Co or Ni; preparing a MCrAlY powder wherein M denotes
at least one element selected from the group consisting of Ni and
Co, and the MCrAlY powder contains at least Ni when A is Co or the
MCrAlY powder contains at least Co when A is Ni; preparing a
dispersion liquid by dispersing the MCrAlY powder into the
electrolytic solution; immerging the cylindrical rotary electrode
and the alloy base member into the dispersion liquid; and
electrolyzing the surface of the alloy base member while rolling
the cylindrical rotary electrode covered with the nonwoven fabric
layer on the surface of the alloy base member to thereby form a
composite coating layer on the surface of the alloy base
member.
2. The coating method according to claim 1, wherein the composite
coating layer comprises a matrix phase composed of the A and the
MCrAlY powder dispersed in the matrix phase.
3. The coating method according to claim 1, wherein the MCrAlY
powder contained in the dispersion liquid has a grain size
exceeding 10 .mu.m and 30 .mu.m or less.
4. The coating method according to claim 1, wherein the dispersion
liquid contains the MCrAlY powder at a mixing rate of 10 g/l to 30
g/1.
5. The coating method according to claim 1, wherein the current
density at the time of electrolyzing is set to 10 A/dm.sup.2 to 30
A/dm.sup.2.
6. The coating method according to claim 1, wherein the dispersion
liquid has a temperature set to 40.degree. C. to 60.degree. C. at
the time of electrolyzing process.
7. The coating method according to claim 1, wherein the
electrolytic solution of the dispersion liquid is a nickel
sulfamate aqueous solution, and the MCrAlY powder is CoCrAlY
powder.
8. The coating method according to claim 1, wherein the
electrolytic solution of the dispersion liquid is a cobalt
sulfamate aqueous solution, and the MCrAlY powder is NiCrAlY
powder.
9. The coating method according to claim 1, wherein the alloy base
member is composed of super alloy containing at least one element
selected from a group consisting of Ni, Cr and Fe as main
component.
10. The coating method according to claim 1, further comprising the
step of heating the alloy base member and the composite coating
layer at temperature of 800.degree. C. to 1200.degree. C. for
60-300 minutes.
11. The coating method according to claim 1, wherein the alloy base
member is a part for a gas turbine.
12. The coating method according to claim 11, wherein the gas
turbine part is a turbine blade.
13. An electrolyzing apparatus used for a coating method of claim
1, comprising: an electrolytic bath filled with dispersion liquid;
a rotary electrode device in which a rotary drum unit having a
cylindrical rotary electrode is immerged into the dispersion
liquid; a robot arm having a top end portion attached to the rotary
drum unit; a control unit for controlling a movement of the robot
arm; a dispersion liquid supply pump connected to the rotary
electrode device so as to eject the dispersion liquid from the
rotary drum unit; and an agitator for agitating the dispersion
liquid.
14. The electrolyzing apparatus according to claim 13, wherein the
rotary electrode device includes a rotary drum unit including the
cylindrical rotary electrode and side members for closing both end
portions in an axial direction of the cylindrical rotary electrode,
a supporting member for rotatably supporting the rotary drum unit,
a drum operating member connected to the supporting member, and a
nonwoven fabric layer covering the surface of the cylindrical
rotary electrode.
15. The electrolyzing apparatus according to claim 14, wherein the
rotary drum unit is formed with a hollow portion therein, the
cylindrical rotary electrode is provided with a plurality of first
liquid ejection holes that are communicated with the hollow
portion, and each of the supporting member and the drum operating
member is formed with hollow portions that are connected to each
other.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method of coating a
composite coating layer onto a surface of a heat resistant part
which is used in a high-temperature oxidizing atmosphere or a
corrosive atmosphere or the like and also relates to an
electrolyzing apparatus used for the coating method. More
particularly, relates to a coating method for the heat resistant
parts constituting a gas turbine, a jet engine or the like and an
electrolyzing apparatus used for performing the coating method.
[0003] 2. Description of Related Art
[0004] In recent years, a power generation using a gas turbine has
been paid attention from a viewpoint of effectively utilizing an
energy resource. In a power generating system using the gas
turbine, a combustion gas discharged from a combustion chamber and
having a high temperature and a high pressure is introduced into a
turbine body. Then, the combustion gas rotates rotor vanes (moving
blades) provided to a turbine shaft, so that a shaft of a generator
directly connected to the turbine shaft is rotated to thereby
generate electric power.
[0005] Generally, in a gas turbine generating system, higher heat
efficiency can be obtained as the temperature of the combustion gas
at an inlet of the gas turbine is increased, and therefore, stator
vanes and rotor vanes of the gas turbine are exposed to high
temperature and high pressure atmosphere, so that it has been
required for these vanes to provide higher heat resisting
property.
[0006] Further, when the combustion gas having a high temperature
is utilized, corrosive substances such as sulfuric acid and marine
salt or the like generated from a fuel are liable to be contained
in the combustion gas, and accordingly, high-temperature corrosion
and high-temperature oxidation would occur. Therefore, the gas
turbine parts are required to have not only a heat resistance but
also a corrosion resistance.
[0007] Conventionally, there have been proposed many techniques to
form a corrosion resistant film (coated film layer) having high
heat resistance and corrosion resistance onto a surface of a metal
base member such as stator vane or rotor vane or the like of the
gas turbine. For example, Japanese Patent Publication No. SHO
60-13056 (Patent Document 1) discloses a technique in which a
CoCrAlY coating layer deposited by plasma spraying (flaming) method
is formed onto a surface of an Ni-based alloy to thereby obtain a
coated Ni-based alloy product having a predetermined thermal
expansion coefficient. The coated Ni-based alloy product disclosed
in the Patent Document 1 is excellent in oxidation resistance and
corrosion resistance at a high temperature.
[0008] However, since the plasma spraying is a method in which
material powder is heated and molten to obtain a high temperature,
and the molten material is sprayed onto a base member or the like,
there have been posed many inconveniences such that an entire base
member is deformed due to the high temperature, structure of the
base member causes breakage or deformation. When a heat treatment
is conducted to repair the damaged structure, life duration of the
base member is disadvantageously shortened, or a manufacturing cost
is significantly increased. Furthermore, there has been also posed
a problem such that the plasma spraying method requires much time
to form the coating layer.
[0009] On the other hand, prior art has also proposed techniques to
form the corrosion resistant film having high heat resistance and
corrosion resistance by utilizing a method other than the plasma
spraying method mentioned above. For example, U.S. Pat. No.
4,789,441 (Patent Document 2) discloses a technique in which the
corrosion resistant film is formed by electroplating, and the
coated base member has a coating layer comprising a matrix phase M1
containing CrAlY particles wherein M1 is at least one element
selected from the group consisting of Ni, Co and Fe. The coated
base member disclosed in the Patent Document 2 is excellent in
oxidation resistance and corrosion resistance at a high
temperature.
[0010] Since the coated base member disclosed in the Patent
Document 2 is manufactured by using the electrolytic plating
method, when the base member has a complicated shape like a gas
turbine rotor vane or the like, there has been posed a problem such
that it is difficult to form the coating layer having a uniform
thickness onto a surface of the base member.
SUMMARY OF THE INVENTION
[0011] The present invention was conceived in consideration of the
circumstances encountered in the prior art mentioned above and an
object of the present invention is to provide a coating method
capable of forming a coating layer excellent in oxidation
resistance and corrosion resistance at a high temperature without
causing any deformation or structure change in a base member and
capable of manufacturing the coating layer in a short manufacturing
time through a simple manufacturing process, resulting in a low
manufacturing cost and also provide an electrolyzing apparatus used
for performing the coating method.
[0012] The above and other objects can be achieved according to the
present invention by providing, in one aspect, a coating method in
which a composite coating layer is formed on a surface of an alloy
base member by utilizing an electrolyzing apparatus provided with a
rotary electrode device which includes a cylindrical rotary
electrode capable of rolling on a surface of the alloy base member
and a non-woven fabric layer covering a surface of the cylindrical
rotary electrode, the coating method comprising the steps of:
[0013] preparing an electrolytic solution containing A ion wherein
A is Co or Ni;
[0014] preparing a MCrAlY powder wherein M denotes at least one
element selected from the group consisting of Ni and Co, and the
MCrAlY powder contains at least Ni when A is Co or the MCrAlY
powder contains at least Co when A is Ni;
[0015] preparing a dispersion liquid by dispersing the MCrAlY
powder into the electrolytic solution;
[0016] immerging the cylindrical rotary electrode and the alloy
base member into the dispersion liquid; and
[0017] electrolyzing the surface of the alloy base member while
rolling the cylindrical rotary electrode covered with the nonwoven
fabric layer on the surface of the alloy base member to thereby
form a composite coating layer on the surface of the alloy base
member.
[0018] In preferred embodiments, the composite coating layer may
include a matrix phase composed of the A and the MCrAlY powder
dispersed in the matrix phase.
[0019] The MCrAlY powder contained in the dispersion liquid may
have a grain size exceeding 10 .mu.m and 30 .mu.m or less.
[0020] The dispersion liquid may contain the MCrAlY powder at a
mixing rate of 10 g/l to 30 g/l.
[0021] It may be desired that the current density at the time of
electrolyzing is set to 10 A/dm.sup.2 to 30 A/dm.sup.2.
[0022] The dispersion liquid may have a temperature set to
40.degree. C. to 60.degree. C. at the time of electrolyzing
process.
[0023] It may be desired that the electrolytic solution of the
dispersion liquid is a nickel sulfamate aqueous solution, and the
MCrAlY powder is CoCrAlY powder, or the electrolytic solution of
the dispersion liquid is a cobalt sulfamate aqueous solution, and
the MCrAlY powder is NiCrAlY powder.
[0024] The alloy base member may be composed of super alloy
containing at least one element selected from a group consisting of
Ni, Cr and Fe as main component.
[0025] The coating method may further comprise the step of heating
the alloy base member and the composite coating layer at
temperature of 800.degree. C. to 1200.degree. C. for 60-300
minutes.
[0026] The alloy base member is a turbine blade.
[0027] In another aspect of the present invention, there is also
provided an electrolyzing apparatus used for performing a coating
method of claim 1, comprising: an electrolytic bath filled with
dispersion liquid; a rotary electrode device in which a rotary drum
unit having a cylindrical rotary electrode is immerged into the
dispersion liquid; a robot arm having a top end portion attached to
the rotary drum unit; a control unit for controlling a movement of
the robot arm; a dispersion liquid supply pump connected to the
rotary electrode device so as to eject the dispersion liquid from
the rotary drum unit; and an agitator for agitating the dispersion
liquid.
[0028] In this aspect, the rotary electrode device may include a
rotary drum unit including the cylindrical rotary electrode and
side members for closing both end portions in an axial direction of
the cylindrical rotary electrode, a supporting member for rotatably
supporting the rotary drum unit, a drum operating member connected
to the supporting member, and a nonwoven fabric layer covering the
surface of the cylindrical rotary electrode.
[0029] The rotary drum unit may be formed with a hollow portion
therein, the cylindrical rotary electrode is provided with a
plurality of first liquid ejection holes that are communicated with
the hollow portion, and each of the supporting member and the drum
operating member is formed with hollow portions that are connected
to each other.
[0030] According to the coating method of the present invention,
there can be formed a coating layer excellent in oxidation
resistance and corrosion resistance at a high temperature without
causing any deformation or structure change in the base member, and
the coating layer can be manufactured in a short time through a
simple manufacturing process resulting in a low manufacturing
cost.
[0031] The nature and further characteristic features of the
present invention will be made clearer from the following
descriptions made with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] In the accompanying drawings:
[0033] FIG. 1 is a view showing an illustration of an overall
structure of an electrolyzing device used in a coating method
according to the present invention;
[0034] FIG. 2 is a perspective view showing a rotary electrode
device constituting the electrolyzing device;
[0035] FIG. 3 is a partial cross sectional view, in an enlarged
scale, taken along the line III-III in FIG. 2;
[0036] FIG. 4 is a cross sectional view, in an enlarged scale,
taken along the line IV-IV in FIG. 2;
[0037] FIG. 5 is an illustrated perspective view showing an outer
configuration of an alloy base member according to one embodiment
used in the present invention;
[0038] FIG. 6 is a cross sectional view, in an enlarged scale,
taken along the line VI-VI shown in FIG. 5;
[0039] FIG. 7 is an illustrated perspective showing an outer
configuration of an alloy base member (coating layer formed
product) formed with a composite coating layer;
[0040] FIG. 8 is a cross sectional view, in an enlarged scale,
taken along the line VIII-VIII shown in FIG. 7;
[0041] FIG. 9 is an illustrated sectional view, in an enlarged
scale, of a portion IX shown in FIG. 8;
[0042] FIG. 10 is a cross sectional view, in an enlarged scale,
taken along the line IV-IV in FIG. 2 concerning another rotary
electrode device;
[0043] FIG. 11 is a view showing an illustration of an overall
structure of another electrolyzing device used in a coating method
according to the present invention;
[0044] FIG. 12 is a perspective view showing another rotary
electrode device constituting the electrolyzing device of FIG. 11;
and
[0045] FIG. 13 is a partial cross sectional view, in an enlarged
scale, taken along the line XIII-XIII in FIG. 12.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0046] Preferred embodiments of the present invention will be
described hereunder with reference to the accompanying drawings,
and it is first to be noted that the coating method according to
the present invention is a method in which the alloy base member is
immersed into a specified dispersion liquid, and an electrolyzing
operation (hereinafter, referred to as "electrolyzation" or
"electrolyzing") is performed by using a specified rotary electrode
device to thereby form a specified composite coating layer onto a
surface of the alloy base member.
First Embodiment
[0047] Hereunder, a first embodiment of an electrolyzing device
used in the present invention will be explained with reference to
the accompanying drawings.
[0048] As shown in FIGS. 1 and 2, an electrolyzing device 1
comprises: an electrolytic bath 70 filled with dispersion liquid
97; a rotary electrode device 10 in which a rotary drum unit 11
having a cylindrical rotary electrode 21 is immerged into the
dispersion liquid 97; a robot arm 50 having a top end portion
attached to the rotary drum unit 11 of the rotary electrode device
10 so that the rotary drum unit 11 is transferred in the dispersion
liquid 97; a control unit 60 for controlling a movement of the
robot arm 50; a dispersion liquid supply pump 45 connected to the
rotary electrode device 10 so as to eject the dispersion liquid
from the rotary drum unit 11; and an agitator 75 for agitating the
dispersion liquid 97.
[0049] The above structural elements will be explained in detail
hereunder, respectively.
[0050] The rotary electrode device 10 is provided with a
cylindrical rotary electrode 21 mounted to the rotary drum unit 11.
When DC voltage is applied to a portion between the cylindrical
rotary electrode 21 and an alloy base member 80 such as turbine
rotor vane or the like that are immersed in the dispersion liquid
97 stored in the electrolytic bath 70, a composite coating layer is
formed on a surface of the alloy base member.
[0051] A DC power source 40 supplies DC current to the rotary
electrode device 10 and the alloy base member 80 through conducting
wires 41 and 42.
[0052] The dispersion liquid supply pump 45 supplies the dispersion
liquid 97 to the rotary electrode device 10. A suction side hose 46
connected, at its one end, to a suction port of the dispersion
liquid supply pump 45 is immerged into the dispersion liquid 97 in
the electrolytic bath 70.
[0053] On the other hand, a discharge side hose 47 connected, at
its one end, to a discharge port of the dispersion liquid supply
pump 45 is connected to a hollow portion of the drum operating
member 13 of the rotary electrode device 10, so that the dispersion
liquid 97 is supplied to the drum operating member 13 of the rotary
electrode device 10. The dispersion liquid 97 in the drum operating
member 13 is supplied to a hollow portion, not shown, of the rotary
drum unit 11 through a hollow portion, not shown, of the supporting
member 12.
[0054] The robot arm 50 is composed of: a base portion 51; a base
portion arm 53; an intermediate arm 55; a tip end arm 57; an
articulated (joint) portion 52 for connecting the base portion 51
and the base portion arm 53; an articulated (joint) portion 54 for
connecting the base portion arm 53 and the intermediate arm 55; and
an articulated (joint) portion 56 for connecting the intermediate
arm 55 and the tip end arm 57.
[0055] The tip end arm 57 is connected to the drum operating member
13 of the rotary electrode device 10 so as to move and transfer the
rotary electrode device 10.
[0056] The control unit 60 is electrically connected to the robot
arm 50 to control the movement of the robot arm 50 on the basis of
three-dimensional shape data of the alloy base member, and the
three-dimensional shape data has been inputted in advance in the
control unit 60.
[0057] When the rotary drum unit 11 of the rotary electrode device
10 is moved along a surface shape of the alloy base member 80 by
operating the control unit 60, a composite coating layer having a
uniform thickness is formed on the surface of the alloy base member
80.
[0058] The electrolytic bath 70 is configured such that the rotary
electrode device 10 and the alloy base member 80 can be immerged
into the dispersion liquid 97. An agitator 75 for agitating the
dispersion liquid 97 is provided in the electrolytic bath 70 and
MCrAlY powder 94 (refer to FIG. 9) can be dispersed into the
dispersion liquid 97.
[0059] (Rotary Electrode Device 10)
[0060] Next, the rotary electrode device will be explained with
reference to the FIGS. 2 to 4 of the accompanying drawings.
[0061] As shown in FIG. 2, the rotary electrode device 10
comprises: a rotary drum unit 11 including a cylindrical rotary
electrode 21; a supporting member 12 supporting side members 22, 22
disposed both side portions of the cylindrical rotary electrode 21,
the side members being provided with axial bores; a drum operating
member 13 connected to the supporting member 12; and a nonwoven
fabric layer 31 covering the surface of the cylindrical rotary
electrode 21.
[0062] (Rotary Drum Unit 11)
[0063] As mentioned above, the rotary drum unit 11 comprises the
cylindrical rotary electrode 21 and circular-disc-shaped side
members 22, 22 for closing both end portions, in an axial
direction, of the cylindrical rotary electrode 21 so as to provide
a columnar shape of the rotary drum unit 11. Center portions of the
side members 22, 22 are provided with axial bores 23, 23 into which
the support member 12 can be inserted.
[0064] As shown in FIGS. 3 and 4, the cylindrical rotary electrode
21 of the rotary drum unit 11 has an inner hollow portion 27, and
the rotary drum unit 11 is formed to provide a cylindrical
shape.
[0065] As the cylindrical rotary electrode 21, the following
composite electrode may be also used. For example, a composite
electrode which is manufactured by plating gold and platinum in
turn onto a surface of a lead electrode body or a lead base member,
or a composite electrode which is manufactured by plating platinum
onto a surface of a titanium electrode or a titanium base member
may be used. Among these composite electrodes, the composite
electrode which is manufactured by plating gold and platinum in
turn onto the surface of the lead base member and the composite
electrode which is manufactured by plating platinum onto the
surface of the titanium base member have a high corrosion
resistance, thus being preferable.
[0066] The cylindrical rotary electrode 21 is provided with a lot
of first liquid ejection holes 25. The first liquid ejection holes
25 have a function of blowing out the dispersion liquid 97 in the
hollow portion 27 toward the outside of the cylindrical rotary
electrode 21 by discharge pressure of the dispersion liquid supply
pump 45.
[0067] It is preferable that each the first liquid ejection holes
25 normally has a diameter within a range of 0.1 mm to 0.5 mm, more
preferably 0.2 mm to 0.4 mm. When the diameter of the first liquid
ejection holes 25 is set within this range, the MCrAlY powder 94
contained in the dispersion liquid 97 can smoothly pass through the
first liquid ejection holes 25, thus being preferable.
[0068] (Support Member 12)
[0069] As shown in FIG. 2, the support member 12 includes: a
rod-shaped base portion 12c; intermediate portions 12b, 12d formed
so as to be bent at right angle from both ends of the base portion
12c; tip end portions 12a, 12e formed so as to be bent at right
angle from ends of the intermediate portions 12b, 12d, so that the
support member 12 provides an outer configuration of C-shape.
[0070] As shown in FIG. 3, the tip end portions 12a, 12e of the
support member 12 are inserted into the axial bores (holes) 23, 23
of the rotary drum unit 11 through a ball bearing 17, so that the
rotary drum unit 11 is rotatably supported by the support member
12.
[0071] The support member 12 is formed with a hollow portion 28
therein. The end portions of the tip portions 12a, 12e of the
support member 12 are opened, and the hollow portion 28 is
communicated with the hollow portion 27 of the rotary drum unit
11.
[0072] (Drum Operating Member 13)
[0073] As shown in FIG. 2, the drum operating member 13 is
connected to a base portion 12c of the support member 12. The drum
operating member 13 is formed with a hollow portion, not shown,
therein, and this hollow portion is communicated with the hollow
portion 28 of the support member 12.
[0074] (Nonwoven Fabric Layer 31)
[0075] As shown in FIG. 2, the nonwoven fabric layer 31 covers a
surface of the cylindrical rotary electrode 21. As a material
constituting the nonwoven fabric layer 31, a nonwoven fabric having
an opening through which the electrolytic solution in the
dispersion liquid can pass and the MCrAlY powder contained in the
dispersion liquid 97 can be trapped is effectively used.
[0076] The nonwoven fabric layer 31 has a function of insulating an
electrical conduction between the alloy base member and the
cylindrical rotary electrode 21. Therefore, as a material for
constituting the nonwoven fabric layer 31, a material having an
electrically insulating property may be preferably used. Examples
of the material constituting the nonwoven fabric layer 31 may
include, for example, nonwoven fabric composed of synthetic fiber,
glass fiber or the like.
[0077] The nonwoven fabric layer 31 normally has a thickness within
a range of 500 .mu.m to 5000 .mu.m. When the thickness of the
nonwoven fabric layer 31 is set within this range, a preferred
passing-through property of the electrolytic solution and the
MCrAlY powder 94 will be provided while maintaining good insulating
performance.
[0078] As shown in FIGS. 3 and 4, the nonwoven fabric layer 31 is
formed with a lot of second ejection holes 35. As explained
hereinbefore, the second ejection holes 35 means a hole having a
diameter through which the MCrAlY powder 94 contained in the
dispersion liquid 97 can pass.
[0079] Namely, the nonwoven fabric layer 31 is configured such that
an entire dispersion liquid 97 containing the MCrAlY powder 94 can
pass through at the second ejection holes 35 of the nonwoven fabric
layer 31, while the MCrAlY powder 94 contained in the dispersion
liquid 97 cannot pass through a portion other than the second
ejection holes 35 of the nonwoven fabric layer 31.
[0080] It is preferable that the second ejection hole 35 has a
diameter within a range of 0.1 mm to 0.5 mm, more preferably 0.2 mm
to 0.4 mm. When the diameter of the second ejection hole 35 is set
within this range, the MCrAlY powder 94 can smoothly pass through
the second ejection holes 35, thus being preferable.
[0081] Further, it is preferable that the second ejection holes 35
of the nonwoven fabric layer 31 are formed so as to overlap with
the first ejection holes 25 of the cylindrical rotary electrode 21
at a wide range thereof.
[0082] The coating method according to the present invention is a
method in which the alloy base member 80 is immersed into a
specified dispersion liquid 97, and an electrolyzing operation is
performed by using a specified electrode device 1 including the
rotary electrode device 10 of the structure mentioned above to
thereby form a specified composite coating layer onto a surface of
the alloy base member 80.
[0083] (Alloy Base Member 80)
[0084] It is preferable that the alloy base member 80 is composed
of super alloy containing at least one element selected from a
group consisting of Ni, Co and Fe as main component. In this
regard, the super alloy means an alloy having at least heat
resistance, and having oxidation resistance and corrosion
resistance at high temperature.
[0085] In this connection, the term "main component" means a
component having the largest molar quantity of the element selected
from Ni, Co and Fe among total molar quantity of metal elements
constituting the alloy base member 80. For example, in a case where
the alloy base member 80 is composed of Ni, Co, Fe and other metal
elements, a total molar quantity of Ni and Co is largest among the
total molar quantity of the metal elements constituting the alloy
base member 80.
[0086] As a composition of the super alloy constituting the alloy
base member 80, for example, an alloy having a composition of 60 wt
% Ni-16 wt % Cr-8.5 wt % Co-1.7 wt % Mo is preferably usable.
[0087] As far as the alloy base member 80 is composed of the super
alloy having the above composition, a shape of the alloy base
member 80 is not particularly limited. However, the present
invention can effectively applied to a base member having a
complicated surface shape. Examples of the base members may include
gas turbine parts such as rotor vane and stator vane of turbine
blade, shroud, combustor or the like.
[0088] In a case where the alloy base member 80 has the complicated
surface shape, it is difficult to form a composite coating layer
having a uniform thickness by using conventional dispersion plating
methods. However, according to the coating method of the present
invention, it is easy to form a composite coating layer having a
uniform thickness by using the rotary electrode device 10, thus
providing significant effects according to the present
invention.
[0089] The alloy base member 80 will be explained with reference to
the accompanying drawings. FIG. 5 is a perspective view
schematically showing the outer configuration of the rotor vane as
the alloy base member 80 of a turbine blade. FIG. 6 is a cross
sectional view showing a cross section taken along the line VI-VI
shown in FIG. 5.
[0090] As shown in FIG. 5, the rotor vane of the turbine blade
(alloy base member) 80 includes a base portion 81 and a vane
portion 82 upwardly extending from the base portion 81.
[0091] The vane portion 82 is provided with air-cooling holes 85
penetrating through the vane portion 82 in a longitudinal
direction, and one end of the air-cooling hole 85 is opened at a
tip end portion 83 thereof. Another end of the air-cooling hole 85
is communicated with the base portion 81, and cooling air is
supplied to the air-cooling hole 85 from an air-supply device, not
shown, provided on the side of the base portion 81. The cooling air
flows in the air-cooling hole 85 and is then discharged to a
direction shown by an arrow G.
[0092] As shown in FIG. 6, the vane portion 82 is composed of super
alloy and has a sublunate shaped cross sectional surface. The
air-cooling holes 85 are formed in the sublunate-shaped alloy
member phase 91.
[0093] Next, a dispersion liquid used in the present invention will
be explained. The dispersion liquid used in the present invention
is prepared by dispersing the MCrAlY powder into a specified
electrolytic solution. (Electrolytic Solution)
[0094] The electrolytic solution used in the present invention
contains an ion of specified metal A. As the metal A used in the
present invention, Co or Ni is suitably used. Normally, the
electrolytic solution contains only Co ion or Ni ion as metal A
ion. Concrete examples of the electrolytic solution may include
nickel sulfamate aqueous solution, cobalt sulfamate aqueous
solution or the like.
[0095] When an electroplating is performed using the rotary drum
unit 11 of the rotary electrode device 10 as a positive electrode
while the alloy base member 80 is used as a negative electrode, the
metal A ion forms a matrix phase of metal A onto a surface of the
alloy base member 80. The matrix phase of metal A is substantially
composed of either Co or Ni.
[0096] (MCrAlY Powder)
[0097] The MCrAlY powder used in the present invention may be an
alloy powder composed of metal M, Cr, Al and Y. A composition ratio
of metal M, Cr, Al and Y is not particularly limited in the present
invention.
[0098] When the dispersion plating is performed, the MCrAlY powder
is dispersed and entrained in the matrix of metal A formed on the
surface of the alloy base member 80, whereby the matrix of metal A
and the MCrAlY powder would form a composite coating layer.
[0099] As the metal M constituting the MCrAlY powder, at least one
metal element selected from the group consisting of Ni and Co can
be used. The metal M of the MCrAlY powder contains at least Ni when
metal A ion in the electrolytic solution is Co. Further, the MCrAlY
powder contains at least Co when metal A ion in the electrolytic
solution is Ni.
[0100] For example, when the electrolytic solution contains Co ion,
NiCrAlY powder or the like is selected as the MCrAlY powder.
[0101] Further, when the electrolytic solution contains Ni ion,
CoCrAlY powder or the like may be selected as the MCrAlY
powder.
[0102] When the MCrAlY powder is selected in accordance with kind
of the metal A ion contained in the electrolytic solution, an
intermetallic compound of Ni and Co is liable to be formed at
boundary between the matrix phase of metal A and the MCrAlY powder
in the composite coating layer, so that a bonding property
(adhesion property) between the matrix phase and the MCrAlY powder
can be easily increased, thus being preferable. The intermetallic
compound of Ni and Co is formed, for example, by conducting a heat
treatment to the composite coating layer.
[0103] Further, it is preferable that the MCrAlY powder has a grain
size exceeding 10 .mu.m and 30 .mu.m or less, more preferably has a
grain size exceeding 10 .mu.m and 25 .mu.m or less. When the grain
size of the MCrAlY powder is set within the above range and a
composite coating layer having a sufficient thickness for
protecting the surface of the alloy base member 80, it becomes
possible to form the composite coating layer having a small
porosity in a short time, thus being effective and
advantageous.
[0104] In this connection, "porosity" is an index showing a ratio
of void volume with respect to an entire volume of the composite
coating layer. The porosity can be calculated, for example, through
the following method. Namely, a photograph of the cross sectional
structure is taken, then a total void area is measured on the
photograph. Finally, the porosity can be calculated as a ratio of
void area with respect to an entire cross sectional area of the
composite coating layer.
[0105] When the grain size of the MCrAlY powder is 10 .mu.m or
less, there may be posed fears such that it takes a long time to
prepare a composite coating layer having a sufficient thickness for
effectively protecting the surface of the alloy base member 80,
wettability is deteriorated, and the MCrAlY powder is easily
aggregated to each other to thereby increase the porosity of the
composite coating layer.
[0106] On the other hand, when the grain size of the MCrAlY powder
exceeds 30 .mu.m and the composite coating layer having a
sufficient thickness for effectively protecting the surface of the
alloy base member 80 is formed, there may be posed a fear that the
porosity of the composite coating layer is disadvantageously
increased.
[0107] Furthermore, when a classification using a sieve having an
opening corresponding to an upper limit of the grain size range and
another sieve having an opening corresponding to a lower limit of
the grain size range is performed, or when a classification using a
cyclone-type classifier is performed, the grain size of the MCrAlY
powder can be set within the above range.
[0108] (Dispersion Liquid)
[0109] The dispersion liquid used in the present invention can be
obtained by dispersing the above MCrAlY powder into the
electrolytic solution. As a method of dispersing the MCrAlY powder
into the electrolytic solution, there may be used a method in which
the MCrAlY powder is added into the electrolytic solution, which is
then agitated.
[0110] Further, it is preferable that the dispersion liquid
normally contains the above-mentioned MCrAlY powder at a mixing
rate of 10 g/l to 30 g/l, more preferably 10 g/l to 25 g/l. When
the content of the MCrAlY powder in the dispersion liquid is set to
within the above range and a composite coating layer having a
sufficient thickness for protecting the surface of the alloy base
member 80 is formed, a composite coating layer having a small
porosity can be manufactured in a short processing time, thus being
advantageous.
[0111] In contrast, when the content of the MCrAlY powder in the
dispersion liquid is less than 10 g/l, there may cause a fear that
a time required for forming the composite coating layer having a
sufficient thickness for protecting the surface of the alloy base
member 80 is disadvantageously prolonged.
[0112] On the other hand, when the content of the MCrAlY powder in
the dispersion liquid exceeds 30 g/l and a composite coating layer
having a sufficient thickness for protecting the surface of the
alloy base member 80 is formed, there may cause a fear that the
porosity of the composite coating layer is increased.
[0113] Furthermore, it is preferable that a temperature of the
dispersion liquid at the time of electrolyzing is set to 40.degree.
C. to 60.degree. C., preferably 45.degree. C. to 55.degree. C. When
the temperature of the dispersion liquid at the time of
electrolyzing is set within the above range, a precipitation of
metal ion contained in the electrolytic solution is effectively
activated, so that the coating layer can be formed in a short time.
Furthermore, the porosity of the composite coating layer formed on
surface of the alloy base member can be decreased, thus being very
effective.
[0114] (Electrolyzation)
[0115] In the coating method according to the present invention,
electrolyzing operation is performed in the dispersion liquid by
using the electrode device 1 containing the above rotary electrode
device 10, whereby a specified composite coating layer is formed
onto the surface of the alloy base member 80.
[0116] The electrode device 1 will operate or function as
follows.
[0117] (Roughening Treatment and Scrubbing (Washing) Treatment)
[0118] At first, as occasion demands, the alloy base member 80 is
subjected to a roughening treatment such as blasting treatment or
the like, or washing treatment such as acid pickling or alkaline
washing. When the roughening treatment and the washing treatment
are performed, adhesion property (close-contacting property) of the
composite coating layer with respect to the alloy base member 80 is
enhanced, thus being preferable.
[0119] (Agitating Process for Dispersion Liquid)
[0120] On the other hand, as shown in FIG. 1, after the dispersion
liquid 97 is retained in the electrolytic bath 70 of the electrode
device 1, the alloy base member 80 is immersed into the dispersion
liquid 97. Thereafter, the dispersion liquid 97 is kept to being
agitated by the agitator 75.
[0121] By agitating the dispersion liquid 97, it becomes possible
to perform the dispersion plating in which the MCrAlY powder 94
contained in the dispersion liquid 97 is uniformly involved into
the composite coating layer. In this regard, "dispersion plating"
means a plating method in which the MCrAlY powder 94 contained in
the dispersion liquid 97 is involved into the matrix phase composed
of metal A when the matrix phase composed of metal A is formed by
reducing (deoxidizing) A ion contained in the electrolytic solution
in the dispersion liquid 97.
[0122] Further, at the time of electrolyzation, it is preferable
that the alloy base member 80 immersed into the dispersion liquid
97 is kept to have substantially the same temperature as that of
the dispersion liquid 97. When the alloy base member 80 and the
dispersion liquid 97 have substantially the same temperature, a
temperature-lowering or change of the electrolytic solution can be
prevented, so that it becomes possible to form a uniform coating
layer having high quality onto the alloy base member 80 throughout
the formation of an initial coating layer to a final coating
layer.
[0123] (Process for Supplying Dispersion Liquid)
[0124] Next, as a process for supplying dispersion liquid, a
dispersion liquid supply pump 45 is driven so as to supply the
dispersion liquid 97 retained in the electrolytic bath 97 to the
hollow portion 27 of the rotary drum unit 11 provided to the rotary
electrode device 10.
[0125] The dispersion liquid 97 supplied to the hollow portion 27
of rotary drum unit 11 passes through the first liquid ejection
holes 25 of the rotary drum unit 11 by the action of the discharge
pressure of the dispersion liquid supply pump 45. Then, the
dispersion liquid 97 is spouted out and ejected through the second
liquid ejection holes 35 of the nonwoven fabric layer 31.
[0126] (Dispersion Plating Process)
[0127] Further, a dispersion plating process is performed. That is,
under a condition that the cylindrical rotary electrode 21 covered
with the nonwoven fabric layer 31 is rolled on the surface of the
alloy base member 80, an electrolyzing operation is performed at a
constant current by using direct current power source 40, thereby
to conduct the dispersion plating.
[0128] The electrolyzing operation is performed by using the
cylindrical rotary electrode 21 of the rotary electrode device as a
positive electrode while using the alloy base member 80 as a
negative electrode.
[0129] In the dispersion plating operation, the dispersion liquid
97 existing at a portion between the nonwoven fabric layer 31 of
the rotary electrode device 10 and the alloy base member 80, and
the dispersion liquid 97 spouted out from the second ejection hole
35 of the nonwoven fabric layer 31, are used as supply source of A
ion and the MCrAlY powder 94.
[0130] Due to above dispersion plating operation, a composite
coating layer 92 is formed onto the surface of the alloy base
member 80 to thereby manufacture a coating layer formed product 80A
which includes the alloy base member 80 and the composite coating
layer 92.
[0131] The rotary electrode device 10 having the cylindrical rotary
electrode 21 is configured such that the cylindrical rotary
electrode 21 rolls on the surface of the alloy base member 80 by
moving, in forward/rearward direction and lateral direction of the
drum operating member 13 which is driven by the robot arm 50
connected to the drum operating member 13.
[0132] The movement of the robot arm 50 is controlled by the
control unit 60 on the basis of three-dimensional shape data of the
alloy base member 80 such as rotor vane of the turbine blade or the
like, the three-dimensional shape data having been inputted in
advance in the control unit 60.
[0133] It is preferable that the current density at the time of
electrolyzing is set within a range of 10 A/dm.sup.2 to 30
A/dm.sup.2, more preferably within a range of 10 A/dm.sup.2 to 25
A/dm.sup.2. In the case when the current density at the time of
electrolyzing is set within the above range, if a composite coating
layer has a sufficient thickness for protecting the surface of the
alloy base member 80, it becomes possible to form the composite
coating layer having a small porosity in a short time, thus being
effective and advantageous.
[0134] When the current density at the time of electrolyzing is
less than 10 A/dm.sup.2, there may cause a fear that it takes a
long time to form a composite coating layer having a sufficient
thickness for effectively protecting the surface of the alloy base
member 80.
[0135] On the other hand, when the current density at the time of
electrolyzing exceeds 30 A/dm.sup.2 and the composite coating layer
having a sufficient thickness for effectively protecting the
surface of the alloy base member 80 is formed, there may also cause
a fear that the porosity of the composite coating layer is
disadvantageously increased.
[0136] The coating-layer formed product 80A will be explained
hereunder with reference to the accompanying drawings. FIG. 7 is a
perspective view schematically showing an outer configuration of
the coating-layer formed product 80A formed with a composite
coating layer. FIG. 8 is a cross sectional view taken along the
line VIII-VIII shown in FIG. 7.
[0137] As shown in FIG. 7, the rotor vane of the turbine blade
(coating layer formed product) 80A formed with a composite coating
layer on the surface of the alloy base member 80 is provided with a
base portion 81A and a vane portion 82A upwardly extending from the
base portion 81A.
[0138] The base portion 81A is formed in such a manner that the
composite coating layer 92 is formed on an entire surface of the
base portion 81 of the alloy base member 80 shown in FIG. 5 through
the dispersion plating process. The vane portion 82A is formed in
such a manner that the composite coating layer 92 is formed on a
surface other than the tip end portion 83 among the surface of the
vane portion 82.
[0139] As shown in FIG. 8, the vane portion 82A has a sublunate
(crescent) shaped alloy member phase 91 on which a composite
coating layer 92 is formed. Since an electrical current hardly
conduct at an inner wall of the air-cooling holes 85 formed in the
alloy base material phase 91, the composite coating layer 92 is not
formed under a normal condition. However, the composite coating
layer 92 may be also formed to the inner wall of the air-cooling
holes 85.
[0140] The composite coating layer 92 will be further explained
with reference to the accompanying drawings. FIG. 9 is an enlarged
cross sectional view partially showing a cross section of a portion
IX shown in FIG. 8.
[0141] As shown in FIG. 9, the composite coating layer 92 formed on
the surface of the alloy base member phase 91 is configured so as
to uniformly disperse the MCrAlY powder 94 in the matrix phase 93
composed of metal A.
[0142] As occasion demands, a heat treatment may be conducted to
the rotor vane (coating layer formed product) 80A of the turbine
blade which is formed with the composite coating layer 92.
Conditions of the heat treatment may vary in accordance with kinds
of the super alloy constituting the base members. The heat
treatment is preferably conducted under a temperature condition of
solution treatment or aging treatment for the super alloy. The heat
treatment may be conducted, for example, at a temperature of
800.degree. C. to 1200.degree. C. for 60 to 300 minutes.
[0143] When the above heat treatment is conducted, the matrix phase
93 composed of metal A and the MCrAlY powder 94 in the composite
coating layer 92 cause an alloying reaction, thus forming an
intermetallic compound, thus being preferable.
[0144] When the metal A and M component of the MCrAlY powder 94 are
mutually diffused to thereby generate the intermetallic compounds
such as Ni--Al, Co--Al, a bonding strength between the matrix phase
93 composed of metal A and the MCrAlY powder 94 is increased.
[0145] Further, when M component of the MCrAlY powder 94 and Ni,
Co, Cr component mutually cause elemental migrations to thereby
generate the intermetallic compounds, a bonding strength between
the composite coating layer 92 and the alloy base member 80 is also
increased.
[0146] According to the coating method using the electrolyzing
device 1, the movement of the rotary electrode device 10 is
controlled by the robot arm 50 at the time of plating operation,
the composite coating layer 92 having a uniform thickness and small
amount of void can be formed onto the surface of the alloy base
member 80.
Second Embodiment
[0147] Next, a second embodiment of an electrolyzing device 1A used
in the present invention will be explained with reference to the
accompanying drawings.
[0148] The second embodiment of the electrolyzing device 1A is
configured such that a rotary electrode device 10A is used in place
of the rotary electrode device 10 shown in the electrolyzing device
1 according to the first embodiment, and a filter, not shown, for
trapping the MCrAlY powder 94 is provided to a suction port 46a of
the suction side hose 46.
[0149] Further, the rotary electrode device 10A has a structure in
which a nonwoven fabric layer 31A is used in place of the nonwoven
fabric layer 31 used in the rotary electrode device 10 explained
hereinbefore in connection with the first embodiment. The rotary
electrode device 10A and the rotary electrode device 10 have
substantially the same structure except a difference between the
nonwoven fabric layer 31 and the nonwoven fabric layer 31A.
Therefore, the same reference numerals are used to denote the same
elements, members or parts, and the explanations for the structure
and operation of the same elements or the like are omitted or
simplified herein.
[0150] Outer configuration of the electrolyzing device 1A is the
same as that of the electrolyzing device 1 and has substantially
the same outer configuration. In addition, an outer configuration
of the rotary electrode device 10A also has substantially the same
outer configuration as that of the rotary electrode device 10 shown
in FIG. 2.
[0151] The rotary electrode device 10A is configured such that the
nonwoven fabric layer 31A shown in FIG. 10 is used in place of the
nonwoven fabric layer 31 in the rotary electrode device 10 shown in
FIGS. 1 and 2 as mentioned above.
[0152] FIG. 10 is a cross sectional view taken along the line IV-IV
shown in FIG. 2 showing the rotary electrode device 10A.
[0153] As shown in FIG. 10, unlike the nonwoven fabric layer 31,
the nonwoven fabric layer 31A is not provided with the second
liquid ejection holes 35. Therefore, the nonwoven fabric layer 31A
is configured so that only the electrolytic solution contained in
the dispersion liquid 97 can pass through the nonwoven fabric layer
31A, while the MCrAlY powder 94 cannot pass through the nonwoven
fabric layer 31A.
[0154] A filter, not shown, for trapping the MCrAlY powder 94 is
provided at the suction port 46a of the suction side hose 46 in the
electrolyzing device 1A. As the filter for trapping the MCrAlY
powder 94, a nonwoven fabric composed of the same material as that
of the nonwoven fabric layer 31A is used, for example. Due to the
above structure, the dispersion liquid supply pump 45 supplies only
the electrolytic solution of the rotary electrode device 10A.
[0155] Next, the electrolyzing device 1A will function in the
manner described hereunder.
[0156] The function of the electrolyzing device 1A is substantially
the same as that of the electrolyzing device 1 except that
supplying process for supplying the electrolytic solution in place
of dispersion liquid is performed, and a dispersion plating process
including a different content is performed. Therefore, only the
supplying process for supplying the electrolytic solution and the
dispersion plating process will be explained and explanations of
the other processes are omitted hereunder.
[0157] (Process of Supplying Electrolytic Solution)
[0158] In the coating method using the electrolyzing device 1A, the
process of supplying the electrolytic solution is performed after
completion of an agitating process for agitating the dispersion
liquid. The process of supplying the electrolytic solution is
performed in a manner of driving the dispersion liquid supplying
pump 45 provided with the filter for trapping the MCrAlY powder 94
to the suction port 46a of the suction side hose 46, and only the
electrolytic solution contained in the dispersion liquid 97
retained in the electrolyzing bath 70 is supplied to the hollow
portion 27 of the rotary drum unit 11 of the rotary electrode
device 10A.
[0159] The electrolytic solution supplied to the hollow portion 27
of the rotary drum unit 11 passes through the first liquid ejection
hole 25 of the rotary drum unit 11 by the action of a discharge
pressure of the dispersion liquid supply pump 45, and then, the
electrolytic solution is leached out from the nonwoven fabric layer
31A.
[0160] (Dispersion Plating Process)
[0161] After the completion of the electrolytic solution supplying
process, there is performed the dispersion plating process in which
the cylindrical rotary electrode 21 covered with the nonwoven
fabric layer 31A is rolled on a surface of the alloy base member
80, and an electrolyzation is performed at a constant current by
using a direct current power source 40, thereby conducting the
dispersion plating on the surface of the alloy base member 80.
[0162] In this connection, the electrolyzation is performed under
the condition that the cylindrical rotary electrode 21 of the
rotary electrode device 10A is used as a positive electrode while
the alloy base member 80 is used as a negative electrode. In the
dispersion plating operation, i) the dispersion liquid 97 existing
at a portion between the nonwoven fabric layer 31A of the rotary
electrode device 10A and the alloy base member 80; and ii) the
electrolytic solution leached out from an entire nonwoven fabric
layer 31A; are used as a supplying source of the A ion and the
MCrAlY powder 94.
[0163] Due to the above dispersion plating, the composite coating
layer 92 is formed on the surface of the alloy base member 80 so as
to manufacture a coating-layer formed product 80A composed of the
alloy base member 80 and the composite coating layer 92. The
current density applied during the electrolyzing operation is the
same as that of the case where the electrolyzing device of the
first embodiment is used for the electrolyzing operation.
[0164] According to the coating method using the electrolyzing
device 1A, the movement of the rotary electrode device 10A is
controlled by the robot arm 50 during the plating operation, and a
composite coating layer 92 having a uniform thickness and small
amount of void can be formed onto the surface of the alloy base
member 80.
[0165] Further, according to the coating method using the
electrolyzing device 1A, since it is not necessary to perforate
holes (ejection holes) to the nonwoven fabric layer 31A, lowering a
manufacturing cost of the rotary electrode device 10A.
[0166] In addition, according to the coating method using the
electrolyzing device 1A, the MCrAlY powder 94 would not be clogged
at portions such as inside of the hollow portion 27 of the rotary
drum unit 11 and the first liquid ejection holes 25. Therefore, the
maintenance property of the electrolyzing device 1A is more
improved than that of the electrolyzing device 1 of the first
embodiment.
Third Embodiment
[0167] Next, a third embodiment of an electrolyzing device used in
the present invention will be explained hereunder with reference to
the accompanying drawings.
[0168] In the third embodiment of the electrolyzing device 1B, a
rotary electrode device 10B is used in place of the rotary
electrode device 10 in the electrolyzing device 1 according to the
first embodiment, and the dispersion liquid supply pump 45 is not
provided.
[0169] Further, the rotary electrode device 10B is configured such
that a rotary drum unit 11A shown in FIG. 11 is used in place of
the rotary drum unit 11 and a nonwoven fabric layer 31A adopted in
the second embodiment is used in place of the nonwoven fabric layer
31 used in the rotary electrode device 10.
[0170] The rotary electrode device 10B and the rotary electrode
device 10 have substantially the same structure except a difference
between the rotary drum unit 11 and the rotary drum unit 11A and a
difference between the nonwoven fabric layer 31 and the nonwoven
fabric layer 31A. Therefore, the same reference numerals are used
to denote the same elements, members or parts, and the explanations
for the structure and operation of the same elements or the like
are omitted or simplified herein.
[0171] FIG. 11 is a view showing an overall structure of an
electrolyzing device 1B. FIG. 12 is a perspective view showing a
rotary electrode device 10B. FIG. 13 is a cross sectional view
taken along the line XIII-XIII shown in FIG. 12.
[0172] As shown in FIG. 11, the electrolyzing device 1B comprises a
rotary electrode device 10B, a direct current power source 40, a
robot arm 50, a control unit 60, an electrolyzing bath 70, and an
agitator 75.
[0173] As shown in FIG. 12, the rotary electrode device 10B
comprises: a rotary drum unit 11A including a cylindrical rotary
electrode 21A; a supporting member 12 for rotatably supporting side
members 22, 22 of the rotary drum unit 11A; a drum operating member
13 connected to the supporting member 12; and the nonwoven fabric
layer 31A covering the surface of the cylindrical rotary electrode
21A. The side members 22, 22 is for closing both end portions in an
axial direction of the cylindrical rotary electrode 21A.
[0174] The rotary electrode device 10B does not include the
dispersion liquid supply pump 45, the suction side hose 46, and the
discharge side hose 47 that are used in the first embodiment shown
in FIG. 1. Therefore, the discharge side hose 47 is not connected
to the drum operating member 13.
[0175] As shown in FIGS. 12 and 13, the cylindrical rotary
electrode 21A of the rotary drum unit 11A is not provided with the
liquid ejection holes 25, so that the hollow portion 27 is not
communicated with an outside of the cylindrical rotary electrode
21A. Therefore, the dispersion liquid 97 or the electrolytic
solution is not ejected from the surface of the cylindrical rotary
electrode 21A.
[0176] Further, the hollow portion 27 is communicated with the
support member 12 and the drum operation member 13. However, the
discharge side hose 47 is not connected to the drum operating
member 13, so that the dispersion liquid 97 and the electrolytic
solution are not retained therein.
[0177] Next, an operation of the electrolyzing device 1B will be
explained hereunder. The operation of the electrolyzing device 1B
is substantially the same as that of the electrolyzing device 1
shown in FIG. 1 except that the supplying process for supplying the
dispersion liquid is not performed and the contents of the
dispersion plating process are different. Therefore, only the
dispersion plating process is explained hereunder and explanations
of the other processes are omitted.
[0178] (Dispersion Plating Process)
[0179] After the completion of the electrolytic solution agitating
process, the dispersion plating process is then performed without
carrying out the supplying process for supplying the dispersion
liquid or the electrolytic solution. The dispersion plating process
is performed so that the cylindrical rotary electrode 21A covered
with the nonwoven fabric layer 31A is rolled on a surface of the
alloy base member 80, and an electrolyzation at a constant current
is performed by using a direct current power source 40, to thereby
conduct the dispersion plating to the surface of the alloy base
member 80.
[0180] In this connection, the electrolyzation is performed under
the condition that the cylindrical rotary electrode 21A of the
rotary electrode device 10B is used as a positive electrode while
the alloy base member 80 is used as a negative electrode. In the
dispersion plating operation, only the dispersion liquid 97
existing at a portion between the nonwoven fabric layer 31A of the
rotary electrode device 10B and the alloy base member 80 is used as
a supplying source of the A ion and the MCrAlY powder 94.
[0181] Due to the above dispersion plating, the composite coating
layer 92 is formed on the surface of the alloy base member 80 to
manufacture a coating-layer formed product 80A composed of the
alloy base member 80 and the composite coating layer 92. The
current density applied during the electrolyzing operation is the
same as that of the case where the electrolyzing device 1 of the
first embodiment is used for the electrolyzing operation.
[0182] According to the coating method using the electrolyzing
device 1B, the movement of the rotary electrode device 10 is
controlled by the robot arm 50 at the time of plating operation,
the composite coating layer 92 having a uniform thickness and small
amount of void can be formed onto the surface of the alloy base
member 80.
[0183] Furthermore, according to the coating method using the
electrolyzing device 1B, since it is not necessary to perforate
holes (ejection holes) to the cylindrical rotary electrode 21A and
the nonwoven fabric layer 31A, thus lowering a manufacturing cost
of the rotary electrode device 10B.
[0184] In addition, according to the coating method using the
electrolyzing device 1B, the MCrAlY powder 94 would not be clogged
at portions such as inside of the hollow portion 27 of the rotary
drum unit 11, and the first liquid ejection hole 25. Therefore, a
maintenance property of the electrolyzing device 1B is further
improved than that of the electrolyzing device 1 of the first
embodiment as previously explained.
[0185] In the respective embodiments of the electrolyzing devices 1
to 1B, each of the rotary drum unit 11 and the rotary drum unit 11A
are constituted by one cylindrical member extending in an axial
direction. However, the rotary drum unit may be also formed by
connecting a plurality of flat columnar members in an axial
direction, each of the flat columnar members having a short length
in the axial direction and having a axial bore. That is, a
plurality of flat columnar members are arranged in an axial
direction so that the axial directions of the flat columnar members
are coincide with each other, and the axial bores of adjacent flat
columnar members are connected by means of a flexible tube, not
shown, such as rubber hose or the like.
[0186] According to the above structure, a follow-up property of
the rotary drum unit onto the surface of the alloy base member 80
having a complicated surface shape is improved. Therefore, even in
a case where it is required for the rotary drum unit 11 or the
rotary drum unit 11A to change its tilt angle and roll on the alloy
base member 80 at several times, the composite coating layer 92
having a uniform thickness can be formed only by rolling the rotary
drum unit at a few rolling times.
EXAMPLES
[0187] Hereunder, although more concrete Examples according to the
present invention will be explained, the present invention should
not be limited to the Examples.
Example 1
[0188] A dispersion liquid 97 described later was stored in the
electrolyzing bath 70 of the electrolyzing device 1 shown in FIG.
1, and the dispersion liquid 97 was then agitated by the agitator
75. In this condition, a rotor vane 80 of a turbine blade having a
composition of 61 wt % Ni-16 Cr-8.5 Co-1.7 Mo-2.6 W-balance other
metal components and having a shape shown in FIG. 5 was immersed
into the dispersion liquid 97.
[0189] Then, the electrolyzing operation was performed under the
following conditions while the cylindrical rotary electrode 21
covered with the nonwoven fabric layer 31 was rolled onto the
surface of the rotor vane 80 as the alloy base member. The
electrolyzing operation was performed such that an electric
quantity to be supplied to the surface of the rotor vane 80 is
uniformly supplied to any portions of the rotor vane 80 by
controlling a rolling state of the cylindrical rotary electrode 21
by means of the robot arm 50, thus forming the uniform composite
coating layer 92.
[0190] With the thus formed composite coating layer 92, coating
thickness and porosity were measured. The coating thickness was
indicated as an average value, while the porosity was measured by a
method described later.
[0191] Further, on the basis of the thus measured coating thickness
and the porosity, an overall evaluation was conducted to the
respective composite coating layers 92. The following evaluation
criteria were adopted. Namely, in a case where the composite
coating layer 92 formed in an electrolyzing time of 30 minutes had
a thickness of 300 .mu.m or more and a porosity of 2.0 or less, the
composite coating layer 92 was judged to be acceptable. On the
other hand, the thickness and the porosity did not satisfy the
above ranges, the composite coating layer 92 was judged to be not
acceptable.
[0192] The above evaluation criteria were derived from acceptable
criteria for the conventional coating layers. That is, when a
CoCrAlY coating layer is deposited onto a Ni-based alloy at a
thickness of about 300 .mu.m by a plasma spraying method and the
CoCrAlY coating layer has a porosity of 2.0% or less, the CoCrAlY
coating layer is generally judged to be acceptable. In this
connection, in order to deposit the CoCrAlY coating layer having
the thickness of about 300 .mu.m by the plasma spraying method, it
takes a long time of about 60 minutes.
[0193] The results of the evaluation are shown in Table 2.
(Dispersion Liquid)
[0194] As a dispersion liquid, a dispersion liquid prepared by
dispersing a MCrAlY powder described later into an electrolytic
solution described later at a mixing rate of 20 g/l was used.
(Electrolytic Solution)
[0195] Compositional condition and property of the electrolytic
solution (sulfamic acid aqueous solution) are as follows.
Ni(NH.sub.2SO.sub.3).sub.2.4H.sub.2O: 450 g/l
NiCl.sub.2.6H.sub.2O: 10 g/l
H.sub.3BO.sub.3: 40 g/l
H.sub.3PO.sub.3: 20 g/l
[0196] pH: 1.4
(MCrAlY Powder)
[0197] A composition of the MCrAlY powder is shown in Table 1. In
the Table 1, the term "Bal." means balance component.
[0198] As a MCrAlY powder, a MCrAlY powder having an average grain
size D50 of over 10 .mu.m and less than 15 .mu.m was used. A grain
size distribution of the MCrAlY powder was measured by means of a
laser-diffraction type grain size distribution measuring device
(SALD-200A, manufactured by Shimazu Corporation). The average grain
size D50 is defined as a grain size corresponding to an accumulated
weight of 50%.
(Electrolyzing Conditions)
[0199] Temperature of Dispersion Liquid: 50.degree. C.
[0200] Current Density: 20 A/dm.sup.2
[0201] Electrolyzing Time: 30 minutes
(Method of Measuring Porosity)
[0202] A photograph of a sectional area of the composite coating
layer 92 was taken, and the porosity was defined as an area ratio
(%) of a void area with respect to an entire sectional area of the
composite coating layer observed in the photograph.
Examples 2-4 and Comparative Examples 1-9
[0203] The same procedures as in Example 1 were repeated except
that the average grain size of the MCrAlY powders were changed as
indicated in Table 2 to form the respective composite coating
layers 92 for the rotor vanes 80 of Examples 2-4 and Comparative
Examples 1-9. Evaluation was made to the respective rotor vanes 80.
The evaluation results are shown in Table 2.
Example 5
[0204] The same procedures as in Example 1 were repeated except
that the average grain size of the MCrAlY powder was set to 20
.mu.m and the current density was changed to 10 A/dm.sup.2 to form
a composite coating layer 92 for the rotor vane 80 of Example 5.
Evaluation was made to the rotor vane 80. The evaluation result is
shown in Table 3.
Examples 6-9 and Comparative Examples 10-17
[0205] The same procedures as in Example 5 were repeated except
that the current densities were changed as indicated in Table 3 to
form the respective composite coating layers 92 for the rotor vanes
80 of Examples 6-9 and Comparative Examples 10-17. Evaluation was
made to the respective rotor vanes 80. The evaluation results are
shown in Table 3.
Example 10
[0206] The same procedures as in Example 7 were repeated except
that the mixing rate of the MCrAlY powder in the dispersion liquid
was set to 10 g/l to form a composite coating layer 92 for the
rotor vane 80 of Example 10. Evaluation was made to the rotor vane
80. The evaluation result is shown in Table 4.
Examples 11-13 and Comparative Examples 18-25
[0207] The same procedures as in Example 10 were repeated except
that the mixing rate of the MCrAlY powder in the dispersion liquid
was set to values as indicated in Table 4 to form composite coating
layers 92 for the rotor vanes 80 of Example 11-13 and Comparative
Examples 18-25. Evaluations were made to the rotor vanes 80. The
evaluation results are shown in Table 4.
TABLE-US-00001 TABLE 1 Cr Al Y Co Ni (wt %) (wt %) (wt %) (wt %)
(wt %) CoCrAlY 28.8 6.25 0.35 Bal. -- NiCrAlY 31.45 11.55 0.83 --
Bal.
TABLE-US-00002 TABLE 2 Powder Current Coating Admission Decision of
Powder Grain Mixing Rate Density Thickness Porosity Composite
Coating Sample No. (.mu.m) (g/l) (A/dm.sup.2) (.mu.m) (%) Layer
Comparative 1 .mu.m over 20 20 20 0.1 X Example 1 5 .mu.m or less
Comparative 5 .mu.m over 20 20 70 0.3 X Example 2 10 .mu.m or less
Example 1 10 .mu.m over 20 20 300 0.8 .largecircle. 15 .mu.m or
less Example 2 15 .mu.m over 20 20 300 1.0 .largecircle. 20 .mu.m
oe less Example 3 20 .mu.m over 20 20 320 1.2 .largecircle. 25
.mu.m or less Example 4 25 .mu.m over 20 20 330 1.6 .largecircle.
30 .mu.m or less Comparative 30 .mu.m over 20 20 360 2.1 X Example
3 35 .mu.m or less Comparative 35 .mu.m over 20 20 400 2.5 X
Example 4 40 .mu.m or less Comparative 40 .mu.m over 20 20 410 2.7
X Example 5 45 .mu.m or less Comparative 45 .mu.m over 20 20 420
2.7 X Example 6 50 .mu.m or less Comparative 50 .mu.m over 20 20
430 3.0 X Example 7 55 .mu.m or less Comparative 55 .mu.m over 20
20 460 4.4 X Example 8 60 .mu.m or less Comparative 60 .mu.m over
20 20 470 4.8 X Example 9 65 .mu.m or less
TABLE-US-00003 TABLE 3 Powder Powder Current Coating Admission
Decision of Grain Size Mixing Rate Density Thickness Porosity
Composite Coating Sample No. (.mu.m) (g/l) (A/dm.sup.2) (.mu.m) (%)
Layer Comparative Example 10 20 20 1 20 0.3 X Comparative Example
11 20 20 2 70 0.4 X Comparative Example 12 20 20 5 100 0.5 X
Comparative Example 13 20 20 8 200 0.8 X Example 5 20 20 10 300 1.0
.largecircle. Example 6 20 20 15 300 1.2 .largecircle. Example 7 20
20 20 310 1.2 .largecircle. Example 8 20 20 25 310 1.5
.largecircle. Example 9 20 20 30 320 1.7 .largecircle. Comparative
Example 14 20 20 35 350 2.0 X Comparative Example 15 20 20 40 390
3.0 X Comparative Example 16 20 20 45 420 4.2 X Comparative Example
17 20 20 50 460 4.8 X
TABLE-US-00004 TABLE 4 Powder Powder Current Coating Grain Size
Mixing Rate Density thickness Porosity Admission Decision of Sample
No. (.mu.m) (g/l) (A/dm.sup.2) (.mu.m) (%) Composite Coating Layer
Comparative Example 18 20 1 20 20 0.3 X Comparative Example 19 20 2
20 70 0.4 X Comparative Example 20 20 5 20 100 0.5 X Comparative
Example 21 20 8 20 200 0.8 X Example 10 20 10 20 300 1.0
.largecircle. Example 11 20 15 20 300 1.2 .largecircle. Example 7
20 20 20 310 1.2 .largecircle. Example 12 20 25 20 310 1.5
.largecircle. Example 13 20 30 20 320 1.7 .largecircle. Comparative
Example 22 20 35 20 350 2.2 X Comparative Example 23 20 40 20 390
3.0 X Comparative Example 24 20 45 20 420 4.2 X Comparative Example
25 20 50 20 460 4.8 X
* * * * *