Metastable phases in yttrium oxide plasma spray deposits and their effect on coating properties

Yttrium oxide coatings were obtained by plasma spray. Structural investigations on these deposits show that, due to the drastic conditions of this technique, a minor monoclinic B phase is formed in the neighborhood of the major cubic C form. We discuss here the influence of different plasma spray parameters on the amount of the B phase formed. We describe also the main properties of Y 2O 3 B and C phases in these deposits such as structural characteristics, thermal stability and mechanical behavior.