Evaluation of nano/submicro pores in suspension plasma sprayed YSZ coatings

Abstract

Nano-submicro pores could considerably influence the coating performances and thus should be properly designed for the intended applications. However, it is challenging to characterize accurately such small pores in coatings. In this study, YSZ coatings were firstly manufactured by suspension plasma spray (SPS) and the nano-submicro pores in as-prepared coatings were investigated using Ultra-small-angle X-ray scattering (USAXS). Afterwards, a multivariate analysis on the effect of five different process parameters was carried out. The two main results showed that: 1) the nano-submicro pores content in coatings has a negative correlation with suspension mass load and powder size, and a positive correlation with spray distance, spray step, and substrate surface roughness; 2) suspension mass load is the main factor affecting the content of nano-submicro pores. Then, a mathematical model for the prediction of nano-submicro pores was developed, and the control of nano-submicro pores content by using the predictive model was presented. Finally, the sintering effect on the evolution of nano-submicro pores was studied in-situ using USAXS as well.