Effect of Precursor Concentration on the Microstructure of Aluminum Oxide Coating Made through the Solution Precursor Plasma Spray Process

In this research, the equipment required to produce ceramic coatings based on Solution Precursor Plasma Spray (SPPS) method was first identified and manufactured by exploring the relevant sources and contained information. Then, aluminum oxide coating was applied to the substrate with MCrAlY bond coat using the set-up. Further, a solution of aluminum sulphate with the concentrations of 0.5 and 1 molar was prepared and used as a precursor injected into the plasma plume in order to evaluate the effect of the precursor concentration on the coating microstructure. The results revealed that the alumina coating obtained from the more diluted precursor had a more porous structure than its counterpart, and its microstructure contained some bubble-like fractured shells as well as small spherical particles. However, the coating obtained from the precursor with higher concentration was found to be denser mainly due to the phenomenon occurring during the deposition through the SPPS process. The XRD analysis yielded similar results for both coatings where the α-Al2O3 was the predominant phase in the coating.