Control of a Plasma Spray Process for the Deposition of Ysz Coatings

A common application of plasma spray is for the deposition of ceramic thermal barrier coatings to gas turbine engine parts, used not only in jet propulsion, but also in electrical power generation. These engines operate at temperatures well above the melting points of their parts, and rely on these coatings to help maintain engine integrity. The coating deposition process, however, has its drawbacks. Over the life of a plasma gun, adjustments to various inputs are needed to create a balance between process efficiency, coating thickness gain, microstructure, and surface roughness. To date, no single broad mathematical model fully describes the impact of these inputs. The purpose of this work was to identify and measure the significant factors that contribute to the variations in properties associated with a quality deposited plasma spray ceramic coating - to eventually predictably control these inputs to maintain consistent coatings throughout the life of a plasma gun.