Effect of H2 on 8YSZ Coatings Prepared by Arc Plasma Torch

Abstract:

The thermal barrier coatings (TBCs) are prepared using spraying technique of 8YSZ particles. In this process, H₂ is often added to the plasma torch discharge system. In order to study the effect of H₂ content on plasma discharge, this study emplyed particle velocity capture diagnostics, optical emission spectroscopy, and finite element simulation to validate the relationship between H₂ content and coating quality. The results indicate that adding H₂ increases the temperature and velocity of plasma, which in turn improves the efficiency and in-flight velocity of molten 8YSZ particles. However, when the H₂ /(Ar+H₂) is increased to 50%, the instability of arc root disturbs the arc plasma discharge, posing a challenge to maintaining the physical state of the in-flight particles. With an increase in H₂ flow rate, the coating quality shows a trend of first increasing and then decreasing, with the optimal flow rate ratio being H₂/(Ar+H₂)=37.5%. The findings of this work can serve as a theoretical guidance and reference for the preparation of TBCs via plasma.