M. Gevelber, M. Cannamela, D. Wroblewski, P. S. Basu, Boston University, Brookline, MA
The plasma spray process is characterized by variations that occur over multiple time-scales and events such as over the life-time of the electrodes, changing of electrode sets, arc instabilities, and torch power cycling. As a result, there can be large variations in coating thickness from part-to-part and even for a large single part. In order to reduce the effects of these sources of process variation, a number of alternative control strategies have been proposed. This paper discusses the requirements for implementing real-time control, and evaluates the performance of several alternative strategies in terms of maintaining desired coating thickness. This paper will also review the sensor requirements for implementing real-time control as well as the performance of several alterative sensing schemes in terms of how well they correlate to specific control objectives.
