H. Samadi, T. W. Coyle, University of Toronto, Toronto, ON, Canada
Magnesia-alumina spinel (MgAl2O4) is an oxide ceramic with broad applications as a high temperature and corrosion resistant ceramic. Its moderate coefficient of thermal expansion coefficient of 7-8×10-6 K-1 may allow it to be used as a plasma spray coating on metallic substrates such as stainless steel with a thermal expansion coefficient of 12×10-6 K-1.
Two important factors affecting the microstructure and properties of plasma sprayed coatings are the particle temperature and velocity in the plasma jet. The particle temperature and velocity are influenced by a substantial number of operating parameters. Using a statistical design of experiments approach, deposition parameters, microstructure, and physical properties of air plasma sprayed spinel coatings are linked through mapping versus in-flight particle temperature and velocity. The T-V maps provide a basis for depositing coatings with controlled structures.
Temperature and velocity of particles during plasma spraying play an important role in the microstructure of the coating. By controlling these two, microstructure can be modified respectively.
