Method of coating a surface

Abstract

A method is proposed of coating a surface of a body which has at least one throughgoing bore having an inlet and having an outlet, wherein the outlet is provided in the surface to be coated, in which method the coating takes place by means of thermal spraying, wherein, during the thermal spraying, the bore is flowed through by a fluid which flows out through the outlet of the bore and substantially prevents a constriction of the bore caused by the coating.

1 . A method of coating a surface of a body which has at least one throughgoing bore having an inlet and having an outlet, wherein the outlet is provided in the surface to be coated, in which method the coating takes place by means of thermal spraying, characterized in that, during the thermal spraying, the bore is flowed through by a fluid which flows out through the outlet of the bore and substantially prevents a constriction of the bore caused by the coating. 
     
     
         2 . A method in accordance with  claim 1 , wherein the fluid is a gas. 
     
     
         3 . A method in accordance with  claim 1 , wherein the flow rate of the fluid amounts at most to 5 SLPM. 
     
     
         4 . A method in accordance with  claim 1 , wherein the thermal spraying is a plasma spray process. 
     
     
         5 . A method in accordance with  claim 1 , wherein the thermal spraying is a plasma spray process which is carried out at a process pressure which amounts to less than 10,000 Pa. 
     
     
         6 . A method in accordance with  claim 5 , wherein a value between 50 and 2000 Pa is selected for the process pressure. 
     
     
         7 . A method in accordance with  claim 5 , wherein a starting material for the coating is sprayed onto the body in the form of a process jet, wherein the starting material is injected into a plasma defocusing the process jet and there at least one of partly and completely changes into a liquid phase, and wherein the coating takes place by deposition from the liquid phase. 
     
     
         8 . A method in accordance with  claim 4 , wherein a starting material for the coating is sprayed onto the body in the form of a process jet, wherein the starting material is injected into a plasma defocusing the process jet and there at least partly changes into a gaseous phase, and wherein the coating takes place by deposition from the gaseous phase. 
     
     
         9 . A method in accordance with  claim 1 , wherein the body is a turbine vane and the at least one bore is a cooling air bore. 
     
     
         10 . A method in accordance with  claim 9 , wherein the turbine vane has a foot which is connected to a source for the fluid during the coating so that the fluid can flow from the foot of the turbine vane through the at least one cooling air bore to the outlet of the cooling air bore. 
     
     
         11 . A method in accordance with  claim 10 , wherein the turbine vane has a plurality of cooling air bores which are flowed through by the fluid. 
     
     
         12 . A turbine vane coated in accordance with a method in accordance  claim 1 . 
     
     
         13 . A turbine vane in accordance with  claim 9 , wherein the cooling air bore opens obliquely into the surface to be coated. 
     
     
         14 . A turbine vane in accordance with  claim 9 , wherein the thickness of the coating increases as the distance from the outlet of the bore increases until said thickness has reached its maximum value (d). 
     
     
         15 . A method in accordance with  claim 1 , wherein the fluid is an inert gas. 
     
     
         16 . A method in accordance with  claim 15 , wherein the inert gas is argon. 
     
     
         17 . A method in accordance with  claim 1 , wherein the flow rate of the fluid amounts at most to 1 SLPM. 
     
     
         18 . A method in accordance with  claim 5 , wherein a value between 100 and 800 Pa is selected for the process pressure.