Microstructure assessment of suspension plasma spraying coatings from multicomponent submicronic Y-TZP/Al2O3/SiC particles

Abstract

In this research, Suspension Plasma Spraying (SPS) technique was used for the thermal deposition of a multicomponent mixture made up of an Y-TZP/Al2O3 matrix with SiC particles. Two suspensions of Y-TZP and Al2O3 with different SiC particles content (6 wt% and 12 wt%) were tested as feedstocks in the SPS process. Three stand-off distances were varied in order to assess coating microstructure and evaluate the presence of SiC in the final coatings. Coatings were characterised in terms of porosity, microstructure and phase distribution. The estimate of the amount of SiC in the coating was carried out by XRD technique.

Findings showed typical cauliflower-like SPS microstructure which intensifies with stand-off distance. Coatings porosity varied significantly between 8% and 25% whereas minimum porosity was found for the intermedium stand-off distance of 40 mm.

Microstructure analysis also revealed the presence of SiC particles in the coatings which was confirmed by EDX analysis, overall XRD tests as well as TG analysis. Finally, evaluation of SiC content in the final coatings by means of XRD analysis showed that most of SiC particles (c.a 80%) of the feedstocks were preserved in the final coatings.