Plasma Spray Processing of Alumina + Zircon Mixtures

A method of fabricating ZrO₂-mullite composites based on plasma spraying of alumina and zircon mixtures has been proposed and developed (3Al₂O₃+2ZrSiO₄ = 2Al₂O₃·2SiO₂ +2ZrO₂). The feedstock is prepared by a combination of mechanical alloying which allows formation of fine grained, homogeneous solid solution mixtures and following plasma spheroidization that yields rapid solidified microstructures and enhanced compositional homogeneity. The homogeneity is further realized when the plasma spray coatings are formed at last, and mullite formation temperature is expected to decrease by the unique preparation technique adopted in this study. Microstructure of the coatings were studied using the transmission electron microscope (TEM), and the mechanical properties such as hardness and fracture toughness of the coatings were measured with the indentation technique. The relationship between the mechanical properties and microstructure were investigated.