Hot-Pressing Kinetics and Densification Mechanisms of Boron Carbide

The hot-pressing kinetics of boron carbide at different stages in the hot-pressing process was investigated. Based general densification equation and pore-dragged creep model, the densification and grain growth kinetics were analyzed as a function of various parameters such as sintering temperature, sintering pressure and dwell time. Stress exponent of n approximate to 3 at the initial dwell stage suggests the plastic deformation may dominates the densification. The further TEM observations and the calculation based on effective stress and plastic yield stress also indicate that plastic deformation may occur and account for the large increase in density at the initial stage of sintering. Calculated grain size exponent of m approximate to 3 suggests that the grain-boundary diffusion dominates the densification at the final stage. During the final stage of sintering, grain growth may be determined by evaporation/condensation and grain-boundary migration.