Lightweight Composite Armore Tile

Microwave sintering of ceramics has many advantages compared to the conventional process, for example, reduction in manufacturing cost and processing times, improving product uniformity, microstructures, properties, and yield. Pressureless sintering of B4C by microwave resulted the final products with high density and high mechanical strength in a much faster sintering rate (10 to 50 times faster) than the conventional process. The internal heating and enhancement of diffusion by microwave can lowe the reaction temperature and increase the reaction rate for carbothermal reduction. By microwave heating, reaction-sintering of B4C by carbothermal reduction of B2O3 become possible. By using a carbon fiber preform (either carbon fiber weaves or carbon/resin composite) that interact strongly with microwave to melt B2O3, B4C can be formed by carbothermal reduction, and B4C fiber weaves can be achieved. A glassy phase can than be filled in to the pores followed by a controlled crystallization to convert to a glass-ceramic matrix. This microwave-induced B4C fiber-reinforced glass-ceramic armor tile should have a density lower than the conventional B4C ceramic tiles with the equal or even better ballistic strength. Many studies on microwave processing and our preliminary results further indicate the feasibility. Successful development of this microwave reaction sintering and controlled-crystalization process will provide a revolutional processing technique for high temperature, high strength materials.