Evaluation and Characterization of Yttria Coatings Deposited by a Conventional DC Plasma and a Novel Plasma Torch

Yttrium oxide (Y₂O₃) can be used in different applications such as corrosion resistance, high temperature performance, and semi-conductors production facilities due to its very high thermal and chemical stability. In this research, yttria coatings were deposited by using both a conventional DC plasma torch (SG-100 ) and a new type of DC plasma gun utilizing molecular gases CO₂+CH₄ developed by Center for Advanced Coating Technologies (CACT) at the University of Toronto. Physical and microstructural properties of coatings were characterized. Gas mixture of CO₂+CH₄ improves the torch efficiency due to its high thermal enthalpy and conductivity which leads to raise the powder particles temperature resulting in complete fusion of powder particles during spraying. SEM study of the coating deposited by the new gun revealed that the coating have very high density and lower porosity with no significant unmelted  particles in comparison to the coating deposited by SG-100 torch. XRD analysis of the coating showed that the coating doesn’t contain metastable monoclinic phase.