Taguchi optimization of YSZ/alumina/silica colloids for suspension plasma sprayed coating process

Abstract

The stability of suspensions plays a key role in the water-based suspension plasma sprayed coating process. The effects of suspension parameters, such as the solid content and the type/content of dispersants on the suspension stability were studied in this work. In this regard, a Taguchi L9 array design of experiments was used to optimize submicron-sized YSZ/nano-sized alumina/silica additive suspensions with low viscosity, high steady-state turbidity, and inter-particle electrostatic charges. The optimal stable suspension with the viscosity of 4.2 cp, the zeta potential of 65 mV, and the Nephelometric Turbidity Units (NTU) of 3503 was used as the feedstock for suspension plasma spraying. Accordingly, a typical columnar coating morphology was obtained with the porosity of almost 19.3 vol%, which is a desirable feature for high-temperature applications. In conclusion, this study reflects the merit of the Taguchi design of experiments to optimize multicomponent thermal barrier coatings.