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.

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 μm and 30 μm 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 2  to 30 A/dm 2 . 
   
   
       6 . The coating method according to  claim 1 , wherein the dispersion liquid has a temperature set to 40° C. to 60° 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° C. to 1200° 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.