Fabrication and Characterization of Aluminum Nitride/Boron Nitride Nanocomposites by Carbothermal Reduction and Nitridation of Aluminum Borate Powders

摘要

In order to fabricate aluminum nitride/boron nitride (AIN/BN) nanocomposites by pressureless sintering, the present study investigated the synthesis of AIN-BN nanocomposite powders by carbothermal reduction and nitridation of aluminum borate powders. Homogeneous mixtures of alumina (Al{sub}2O{sub}3), boric acid (H{sub}3BO{sub}3, and carbon powder were used to synthesize AIN/BN nanocomposite powders containing 10 and 20 vol% BN. Aluminum borate was produced by reacting Al{sub}2O{sub}3 and B{sub}2O{sub}3 above 800℃, and AIN and turbostratic BN (t-BN) were produced by reacting aluminum borate with carbon powder and nitrogen gas at 1500℃. Carbothermal reduction followed by nitridation yielded an AIN/BN nanocomposite powder composed of nanosized AIN and t-BN. By pressureless sintering nanocomposite AIN/BN powders containing 5 wt% Y{sub}2O{sub}3, AIN/BN nanocomposites were obtained without compromising the high thermal conductivity and high hardness.