Oxides in plasma-sprayed chromium steel

Products of oxidation reactions accompanying plasma spraying of chromium steel by a water-stabilized plasma gun were separated from the metallic matrix by a chemical method. This enabled gravimetric determination of the oxide content in plasma- sprayed chromium steel and characterization of the composition and structure of oxides by diffraction and spectroscopic techniques. Both the random and inherent errors of the gravimetric method were estimated. The phase composition of oxides was compared with the results of thermodynamic calculations. It was shown that in spite of the highly nonequilibrium character of plasma spraying, the thermodynamic approach can yield useful predictions for the overall phase composition and for the stoichiometry of the prevailing spinel oxide phase.