Method of application for layered thermal barrier coating with blended transition

Abstract

A method includes generating a plasma plume with a plasma gun, delivering a plurality of coating materials to the plasma plume with a powder feeder assembly to vaporize the coating materials. The delivery includes delivering a first (bond coat) material from a first powder feeder to the plasma gun, ceasing delivery of the first material, increasing a rate of delivery of a second (rare earth stabilized zirconia) material from a second powder feeder to the plasma plume, increasing a rate of delivery of a third material (a rare earth stabilized zirconia material different from the second material) from a third powder feeder to the plasma plume, decreasing a rate of delivery of the second material, and decreasing a rate of delivery of the third material, and depositing the plurality of coating materials on a work piece to produce a layered coating with blended transitions between coating layers.

1 . A method of coating a work piece, the method comprising:
 positioning a work piece in a process chamber;   generating a plasma plume with a plasma gun;   delivering a plurality of coating materials to the plasma plume generated by the plasma gun with a powder feeder assembly to vaporize the coating materials, the delivery comprising:
 delivering a first material from a first powder feeder to the plasma gun, wherein the first material comprises a bond coat material; 
 ceasing delivery of the first material from the first powder feeder to the plasma plume; 
 increasing a rate of delivery of a second material from a second powder feeder to the plasma plume, wherein the second material comprises a rare earth stabilized zirconia material; 
 increasing a rate of delivery of a third material from a third powder feeder to the plasma plume, wherein the third material comprises a rare earth stabilized zirconia material different from the second material; 
 decreasing a rate of delivery of the second material from the second powder feeder to the plasma plume; and 
 decreasing a rate of delivery of the third material from the third powder feeder to the plasma plume; and 
   depositing the plurality of coating materials on the work piece with a plasma-based vapor stream to produce a layered coating with blended transitions between coating layers.   
     
     
         2 . The method of  claim 1 , the step of delivering a plurality of coating materials to the plasma plume generated by the plasma gun with a powder feeder assembly to vaporize the coating materials further comprising:
 increasing a rate of delivery of a fourth material from a fourth powder feeder to the plasma plume, wherein the fourth material comprises a rare earth stabilized zirconia material; and   decreasing a rate of delivery of the fourth material from the fourth powder feeder to the plasma plume.   
     
     
         3 . The method of  claim 2 , the step of delivering a plurality of coating materials to the plasma plume generated by the plasma gun with a powder feeder assembly to vaporize the coating materials further comprising:
 increasing a rate of delivery of a fifth material from a fourth powder feeder to the plasma plume, wherein, at least temporarily, the fifth material is delivered simultaneously with the fourth material; and   decreasing a rate of delivery of the fifth material from the fourth powder feeder to the plasma plume.   
     
     
         4 . The method of  claim 3 , wherein the fifth material comprises an inert compound having a cubic crystalline structure, and wherein the fifth material is different from the first, second, third and fourth materials. 
     
     
         5 . The method of  claim 2 , wherein the fourth material is substantially identical to the second material. 
     
     
         6 . The method of  claim 2 , wherein the fourth material is a rare earth stabilized zirconia material different from the second and third materials. 
     
     
         7 . The method of  claim 1  and further comprising:
 rotating the work piece as the coating materials are deposited, wherein the vapor stream has a substantially fixed orientation.