Controlled Introduction of Anelasticity in Plasma-Sprayed Ceramics

Recent studies on the mechanical compliance measurements of plasma-sprayed ceramic coatings have revealed anelastic response, i.e. the stress-strain relations are nonlinear and hysteretic, collectively. The anelasticity stems from the "brick" layered assemblage of spray-deposited droplets along with the presence of porosity and other geometric discontinuities. This anelastic response is reproducible and can provide a quantitative description on the mechanical properties of the sprayed ceramic coating. In this paper, we have examined strategies to manipulate and control these anelastic characteristics through plasma spray processing parameters as well as through extrinsic modifications of the defect interfaces. Plasma-sprayed ceramic coatings are fabricated under various conditions and their unique anelastic parameters are computed. These results reveal that the novel properties are tunable via process and material manipulation, opening up opportunities for microstructural design and optimization of mechanical compliance in industrially relevant coating systems.