High Toughness Ceramics Containing Carbon Nanotube Reinforcement

There is a need to improve the toughness of armor materials to improve low-speed impact resistance. The approach for achieving this was to reinforce nanosized ceramic matrices with carbon nanotubes. In Phase I, it was determined that the diameters andtheir impact on dispersion of the nanotubes is the most critical factor affecting performance. Nanotubes that are too long are a particular problem resulting in low hardness and ballistic performance. Excellent results were achieved, however, usingshorter nanotubes that still have relatively high aspect ratios of ~100. For the boron carbide system in particular, significant enhancements in both strength and toughness were achieved. For one well-dispersed composition, hardness was also maintainedand even slightly increased above the base ceramic with the addition of lower aspect ratio carbon nanotubes. Ballistic testing showed a strong dependence on hardness, and thus it is proposed that shorter nanotubes and/or significant improvement indispersion techniques will be explored in the Phase II. All three systems will again be explored with Rensselaer Polytechnic Institute will perform the research on the alumina system. Extensive testing including ballistic evaluation will also beconducted. A road map for commercialization is also proposed for Phase II.Ceramic composites with improved mechanical properties would be enabling for a variety of applications including body armor, engine compoents, nozzles, kiln furniture, etc.