Properties of Al2O3-TiO2 coating prepared by plasma spraying with an internally-fed powder system

Alumina-titania (60: 40 by weight) coatings were prepared by low power plasma thermal spraying with two types of plasma spray systems: internally-fed and externally-fed powder system. The coatings were investigated by many techniques, respectively X-ray diffraction (XRD), scanning electron microscopy (SEM) and micro-hardness tester. It was found that the thickness of coatings by low power plasma spray with an internally-fed powder system is higher than that of the coatings with an externally-fed powder system. The internally-fed powder system not only decreases the loss of powder but also increases the deposition efficiency for more than 80%. To better qualify the characteristics of these coatings prepared from spray-dried powders, microhardness was also studied.