Hybrid Spinel Composites: Unique Radiation Resistant Refractories

75832-Magnesium aluminate spinel is a promising structural and radio frequency (RF) window material for nuclear reactors, due to its remarkable neutron and ion radiation resistance at high temperatures. However, little, if any, effort has been expended in optimizing the strength, creep, toughness, and thermal shock properties of spinel structural components for advanced nuclear applications. This project will develop and demonstrate hybrid spinel composite structures that combine the best features of monolithic ceramics and fiber-reinforced spinel ceramic matrix composites (CMCs). A systematic approach will be undertaken for the fabrication of individual monolithic spinel sheets, fiber-reinforced CMC spinel sheets, and hybrid spinel structures consisting of alternating layers of the monolithic and CMC spinel sheets. In Phase I, hybrid spinel composites will be fabricated by hot pressing alternating sheets of momolithic spinel and fiber-reinforced spinel matrix CMCs. Physical and optical measurements, comprehensive mechanical property and thermal shock tests, and microstructural and crack pattern analyses will be used to examine the differences between the three structures: individual spinel monolithic, CMC, and the hybrid. Radiation testing and subsequent property measurements will be conducted in Phase II to validate the overall performance potential and benefits of the hybrid spinel concept. Commercial Applications and Other Benefits as described by the awardee: In addition to applications in future nuclear power systems, the hybrid composite spinel should find use in military and civilian vehicles, aircraft armor, and such industrial applications as boiler blower tubes, furnace windows, and oxidation-resistant turbine and rocket engine components.