HIGH STRENGTH AND TOUGHNESS TUNGSTEN CARBIDE (WC) WITH NON-COBALT (Co) MATRICES

Cemented cobalt-tungsten carbide is a material with attractive properties including high hardness and fracture toughness that has found success in a wide variety of applications ranging from drilling bits to armor piercing projectiles. However, with the classification of cobalt as a strategic and critical material that the US Department of Health and Human Services has classified as"reasonably anticipated to be a human carcinogen"a replacement is necessary. Carbides represent a group of materials with inherent high hardness and strength, but that are extremely brittle. This proposal seeks to increase the fracture toughness of tungsten carbide by two parallel processes: bottom up and top down. Nanosized tungsten carbide will be used in the bottom up process to produce highly dense fine-grained structures either through the refinement of commercial powder or of the sintering parameters. While the top-down approach will utilize powder production by arc melting of tungsten carbide and tungsten to produce fine lamella structures. By controlling the final sintered microstructure, the fracture toughness of the binderless tungsten carbide will be increased by producing a dense material with high hardness and strength.