Self-Healing Plasma Sprayed Ceramic Coatings

The current paper reports self-healing plasma sprayed Mgspinel (MgAl₂O₄) coatings. The coatings were used for electrical insulation in high temperature fuel cells. A range of potential self-healing additives consisting of SiC+X (where X was BaO, CaO, ZnO, Y₂O₃, GeO₂, Ta₂O₅, V₂O₅) were characterized and SiC+Y₂O₃ was initially selected for coating development. Coatings of spinel with 20wt% additive were developed using vacuum plasma spraying (VPS) or atmospheric plasma spraying (APS). In the developed coatings, self-healing was demonstrated after heat treatment at 1050°C in air for 10 hour. Thermophysical and thermomechanical properties of self-healing coatings were determined and compared to spinel coatings. Lastly, a modelling technique is presented to simulate the effective elastic moduli of the coatings. Numerical results based on microstructural simulations showed good agreement with experimental data.