Fabrication and Property of AlN-BN Composites by Hot Isostatic Pressing

AlN-BN composites were fabricated by hot isostatic pressing (HIP) without sintering aid, using aluminum nitride (AlN) and boron nitride (BN) powders as raw materials. The effects of HIP temperature and pressure on microstructure and properties of composites with two different raw material ratios (molar ratio) were investigated. The results show that increasing amount of BN has little impact on densification, but decreases the hardness and thermal conductivity while increases the volume resistivity. The higher the density of the composite is, the higher thermal conductivity, volume resistivity and hardness are. The thermal conductivity and volume resistivity values conform the formula: lambda com=lambda(2)(lambda F1+)(1-Phi))(lambda(2)-lambda(1))/lambda(2-)(1+F)(1-Phi)(lambda(2)-lambda(1)) AlN-BN composites with the ratio of n(AlN): n(BN) = 75:25 were prepared at 1600 degrees C, 90 MPa and. a dwell time of 3 h by HIP, achieving density of 98.03%, thermal conductivity of 77.29 W/(m.K) and a volume resistivity of 1.35 x 10(15) Omega.cm.