Low Temperature Processing of Boron Carbide Cement Composite for Tough, Wear Resistant Structures

Natural materials such as tooth, bone or shell consist of a high volume fraction of ceramic grains coated by thin layers of proteinaceous film. The ceramic grains are grown in situ in a pre-formed organic polymer matrix. The organic portion provides high toughness, while the ceramic component provides stiffness. This unique microstructure allows for mechanical properties superior to man-made ceramic composites. By developing processing techniques analogous to natural structures, where ceramic components are grown within a confining matrix, the structure of the composite can be manipulated such that improved mechanical properties are obtained. TPL proposes to fabricate a composite structure consisting of laminated boron carbide-polymer cement tapes. Tape porosity will be eliminated by infiltration of a polymeric cement which will hydrolyze in situ to produce a greater than 95 volume % ceramic exhibiting higher fracture toughness than bulk boron carbide. The polymeric cement will exhibit high bond strength to the boron carbide allowing for a high rate of stress transfer between the ceramic phases, and increased fracture toughness and flexural strength. The composite will be fabricated at temperatures of less than 300oC, allowing for direct film fabrication on heat sensitive materials such as glass or plastic substrates. The low temperature, high strength and toughness composite proposed for this study will have applications for body armor, bunker hardening, high performance sporting goods, and smart materials utilizing embedded sensor technology.