Investigation of rheological properties and stability of aqueous suspensions containing YSZ ceramic nanoparticles

Application of YSZ nanoceramic in liquid phase suspension as raw material in plasma coating process leads to thermal barrier coatings with more desirable properties. The key is to achieve a stable aqueous suspension containing these ceramic nanoparticles. In this research, the rheological properties and stability of YSZ nanoparticles in aqueous medium have been investigated. The type of dispersants added to the suspension and the chemical properties of the aqueous medium were studied as influential factors in the stability of the suspension containing by 30 weight percent. In order to characterize the properties, viscosity, zeta potential, NTU and TSI factor and sedimentation rate were performed and also the aging properties of different suspensions were studied over time. The results showed that the use of alpha terpineol dispersant with a concentration of 0.1 wt% in aqueous medium with a pH of 2.5 has led to an optimal suspension with optimum viscosity and stability conditions, defined as viscosities at 1.5 cp, zeta potential at 56 mV and Nephelometric turbidity units (NTU) 3680 were obtained. Microstructural study of the thermal barrier coating created by plasma spraying of the optimal suspension indicates the formation of a columnar structure that will have higher stability and strength properties in this type of coating.