Fabrication of BN-AlN-TiB_2 Compound Conductive Ceramics by Self-Propagating High Temperature Synthesis and Hot Isostatic Pressing

摘要

BN-AlN-TiB_2 compound conductive ceramics from powder mixtures of BN, Al, and TiB_2 was fabricated by self-propagating high temperature synthesis (SHS) and hot isostatic pressing (HIP). The powder mixtures were shaped by isostatic cool pressing at 5-10MPa and the combustion reaction was carried at 100-200 MPa N_2 by an ignitor. XRD experiments confirmed that the reaction was complete and only A1N, BN and TiB_2 were detected. Optical microscopy as well as SEM with an electron probe microanalysis was used for microstructural analysis and revealed a relatively uniform distribution of particulates. The temperature-dependence and composition-dependence of the electrical resistivity of BN-AlN-TiB_2 ceramics were studied. The results showed that the optimum composition was 5-10wt% BN, 30-55wt% Al and 60-40wt% TiB_2, and the products had the density of 90% of the theoretical, resistivity of 80-1000 μΩ·cm and bending strength of 100-200 MPa.