Mapping Deposition Parameters and Microstructures of Plasma Sprayed Spinel

Magnesia-alumina spinel (MgAl₂O₄) is an oxide ceramic with broad applications as a high temperature and corrosion resistant material. Its moderate coefficient of thermal expansion (7-8 x 10-6 K-1) may allow it to be used as a plasma spray coating on metallic substrates with coefficients of thermal expansion of ~12x10-6 K-1. Two important factors affecting the microstructure and properties of plasma sprayed coatings are the particle temperature (Tp) and particle velocity (Vp) 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 Tp-Vp maps provide a basis for depositing coatings with controlled structures.