An improved automatic feedback control scheme enhances plasma spraying of powdered material through reduction of process variability and providing better ability to engineer coating structure. The present inventors discovered that controlling centroid position of the spatial distribution along with other output parameters, such as particle temperature, particle velocity, and molten mass flux rate, vastly increases control over the sprayed coating structure, including vertical and horizontal cracks, voids, and porosity. It also allows improved control over graded layers or compositionally varying layers of material, reduces variations, including variation in coating thickness, and allows increasing deposition rate. Various measurement and system control schemes are provided.
This invention was made with Government support under contract number DMI-9713957 awarded by the National Science Foundation. The Government has certain rights in the invention. The United States Government also has certain rights in this invention pursuant to Contract No. DE-AC07-99ID13727 between the United States Department of Energy and Bechtel BWXT Idaho, LLC.