Development of a pressureless sintered silicon carbide monolith and special-shaped silicon carbide whisker reinforced silicon carbide matrix composite for lightweight armor application

A pressureless sintered alpha-silicon carbide ceramic is developed for lightweight armor applications. The benefits of pressureless sintering are high volume and lower cost compared to current silicon carbide ceramics produced by hot pressing- The alpha-silicon carbide monolith is sintered to over 98% of theoretical density with boron and carbon sintering aids. Additionally, composites utilizing shape-modified, silicon carbide ceramic whiskers are investigated with the goal of increasing the toughness of an otherwise brittle silicon carbide ceramic. The ceramic reinforcement whiskers are heat treated at high temperature in an inert atmosphere to produce rounded ends (bone-shaped whiskers) via atomic transport. Ballistic testing was conducted on the silicon carbide ceramics with and without whisker reinforcements. Initial results indicate the ballistic properties of the pressureless sintered silicon carbide monoliths approach that of hot pressed silicon carbide. The whisker-reinforced composite exhibited reduced ballistic efficiency, most likely due to exaggerated grain growth and low-fired density. Physical/mechanical properties, photomicrographs and ballistic test results are reported and compared to commercial-grade silicon carbide ceramic armor. Finished armor tiles are estimated at less than $140/kg (-$65/lb).