Fabrication and characterization of aluminum nitride/boron nitride nanocomposites by carbothermal reduction and nitridation of aluminum borate powders.

Takafumi Kusunose, Nobuaki Sakayanagi, Tohru Sekino, Yoichi Ando

Index: J. Nanosci. Nanotechnol. 8(11) , 5846-53, (2008)

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Abstract

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 (Al2O3), boric acid (H3BO3), and carbon powder were used to synthesize AIN/BN nanocomposite powders containing 10 and 20 vol% BN. Aluminum borate was produced by reacting Al2O3 and B2O3 above 800 degrees C, and AIN and turbostratic BN (t-BN) were produced by reacting aluminum borate with carbon powder and nitrogen gas at 1500 degrees C. 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% Y22O3, AIN/BN nanocomposites were obtained without compromising the high thermal conductivity and high hardness.