Plasma spraying process

Abstract

The application relates to a process for producing a coating by thermal spraying, in particular by plasma spraying, in which a component, in particular a cylinder liner, is internally coated with an alloy, wherein a plasma nozzle, to which a plasma gas and a transporting gas are fed, rotates about a wire and is movable along a longitudinal axis of the bore, such that the bore is coated as seen from the inside all around and in the axial direction of the bore. What is proposed is a variable gas stream or a variable flow rate of the transporting gas and/or of the plasma gas, it being possible for the flow rate to be set over the axial length (x) of the bore to be coated.

1 . A process for producing a coating by thermal spraying, including by plasma spraying, comprising:
 internally coating a component including a cylinder liner, with an alloy, wherein a plasma nozzle, to which a plasma gas is fed, and auxiliary nozzles, to which a transporting gas is fed, rotate about a wire and move along a longitudinal axis of a bore, such that the bore is coated as seen from the inside all around and in an axial direction of the bore, wherein   a variable gas stream or a variable flow rate of the transporting gas and/or of a plasma gas set over an axial length (x) of the bore to be coated.   
     
     
         2 . The process as claimed in  claim 1 , wherein the plasma spraying is a PTWA internal coating. 
     
     
         3 . The process as claimed in  claim 1 , wherein the wire is a homogeneous wire. 
     
     
         4 . The process as claimed in  claim 1 , wherein
 a low pore proportion can be set in the coating with a high flow rate of the plasma gas and/or of the transporting gas.   
     
     
         5 . The process as claimed in  claim 1 , wherein
 a flow rate in a top dead center region has a lower value, and wherein   a flow rate in a top cover region and in a central region has a higher value.   
     
     
         6 . (canceled) 
     
     
         7 . The process as claimed in  claim 1 , wherein
 provision is made of a control element, which controls a flow rate of the transporting gas and/or of the plasma gas depending on an axial position of a plasma spraying apparatus inside the bore, it being possible for the control element configured as a solenoid valve.   
     
     
         8 . The process as claimed in  claim 7 , wherein
 the variable gas stream or the variable flow rate of the transporting gas and/or of the plasma gas set variably during the coating operation depending on the axial position inside the bore to be coated.