| Abstract Scope |
High entropy oxides were first synthesized and demonstrated in 2015. Since then, a host of multiple principal component (MPC) ceramics with outstanding properties have been promoted. However, not all applications of the multi-component approach have resulted in improved properties. In this presentation, properties of MPC ceramics for high temperature aerospace applications are addressed. MPC oxides, silicates, and phosphates have shown promise for improved properties of thermal and environmental barrier coatings, reducing thermal conductivity and modifying thermal expansion. However, success using the MPC approach to improve high temperature thermochemical stability of ceramics has not been shown. Thermochemical stability of oxides is only as good as the best performing component, and often times worse. Similarly, ultra-high temperature carbides and borides proposed for hypersonic applications are shown to have worse oxidation resistance than their single component counterparts, forming low melting eutectics. General considerations for improved properties of high-temperature MPC ceramics are proposed. |
