Apparatus and method for controlling powder deposition in a plasma spray process

Apparatus for controlling a powder deposit pattern in a plasma spray process comprising:

• means for generating a plasma plume having an axial extent;
• target means having a deposit surface facing said plasma plume for receiving thereon a deposit of a powder transported by said plasma plume;
• means for injecting said powder into said plasma plume, said powder comprising a plurality of particles entrained in a carrier gas, said powder injecting means comprising an injector tube disposed to inject said powder into said plasma plume at an orientation substantially normal to said axial extent of said plume, said powder injecting means further including means for selectively bypassing a desired amount of said carrier gas prior to said carrier gas and said powder entering said injector tube;
• sensor means for generating an image representative of a temperature distribution of said powder deposited on said target, said sensor means further having means for identifying a location of an impact point of said powder upon said target means;
• and
• control means responsive to said sensor means for selectively adjusting the amount of said carrier gas bypassed before said carrier gas and powder enter said injector tube to selectively move said powder impact point on said target.

A method for controlling a powder deposit pattern in a plasma spray process comprising the steps of:

• generating a plasma plume;
• directing said plasma plume to impinge on a target means;
• injecting, with a powder injecting means, a powder comprising a plurality of particles into said plasma plume to be deposited on said target means, said powder being entrained in a carrier gas;
• generating an image representative of a temperature distribution of said powder deposited on said target means;
• identifying in said image a location of an impact point of said powder upon said target means;
• and
• selectively adjusting a powder injection velocity by modulating a carrier gas flow rate in said powder injecting means to selectively adjust said location of said impact point of said powder upon said target.

A method for controlling a powder deposit pattern in a plasma spray process comprising the steps of:

• generating a plasma plume having an axial extent;
• directing said plasma plume to impinge on a target means;
• injecting a powder through a powder injector tube into said plasma plume at an orientation substantially normal to said axial extent of said plasma plume, said powder comprising a plurality of particles entrained in a carrier gas;
• selectively bypassing a desired amount of said carrier gas prior to said carrier gas and said powder entering said injector tube;
• generating an image representative of a temperature distribution of said powder deposited on said target means;
• identifying in said image a location of an impact point of said powder upon said target means;
• and
• selectively adjusting, in response to said identified impact point, said amount of said carrier gas bypassed prior to said carrier gas and said powder entering said injector tube to change a powder injection velocity and to selectively adjust said location of said impact point of said powder upon said target.