Enhanced Toughness SiC with High Hardness for Advanced Armor

Phase I research demonstrated that toughness of 8 MPa.m1/2 is attainable in advanced SiC using the SEPB technique, as compared with 2.5 MPa.m1/2 for conventional SiC. The Phase I work is currently on schedule in order to meet the objective of 5.5MPa.m1/2 toughness at a hardness of at least 24 GPa. SiC developed in Phase II work will have a hardness exceeding 28 GPa at a toughness greater than 7 MPa.m1/2. The first year of the project will demonstrate that enhanced toughness, at the same level ofhardness, results in improved ballistic performance by comparing SiC (hardness of 24 GPa) with toughness of either 2.5 or 6 MPa.m1/2. In parallel with this effort, methods for enhancing the hardness without sacrificing toughness will be evaluated. Theseinclude precipitation of secondary phases upon cooling, partial removal of the grain boundary phase, modulated microstructures, and alternative secondary phases. During the second year of the Phase II effort, an optimization study will be conducted inorder to meet the objectives. In addition, the feability of scale-up will be demonstrated. Lightweight SiC with enhanced toughness will allow improved protection for the Army, as well as law-enforcement agencies and private armored vehicles. The samematerial is expected to perform well in non-corrosive environments, such as nozzles for oil well drilling and water-jet cutting.