Refractory Composite for High-Temperature Gas Containment

Hafnium diboride and zirconium diboride have properties that make them ideally suited for plasma containment vessels including high melting point, good creep resistance, high thermal conductivity, good oxidation resistance and good optical emissivity and absorptivity. Although these materials have good thermal shock resistivity compared to other structural refractories, their thermal shock resistance is not good enough for monolithic plasma containment devices. A new approach will be used to improve the thermal shock resistance of these two materials. The approach is to prepare fibrous monoliths. In the fibrous monolith approach a cellular structure is produced that will allow stress delocalization and redistribution on a microstructural level. The fibrous monolith consists of a cellular net work of the primary material separated by an interface material. The interface material must be lubricous to allow sliding of the cells of the primary material. Localized stress concentrations can not be transferred across the interfaces. The interface also allows crack deflection fracture mechanisms to further improve reliability.