Preparation of Nanocrystalline TiN Coated Cubic Boron Nitride Powders by a Sol-Gel Process

Abstract

Cubic boron nitride (cBN) particles coated with 20 wt% nanocrystalline TiN were prepared by coating the surface of cBN particles with TiO(2), followed by nitridation with NH(3) gas at 900 degrees C. Coating of TiO(2) on cBN powders was accomplished by a sol-gel process from a solution of titanium (IV) isopropoxide and anhydrous ethanol. An amorphous TiO(x) layer of 50 nm thickness was homogenously formed on the surface of the cBN particles by the sol-gel process. The amorphous layer was then crystallized to an anatase TiO(2) phase through calcination in air at 400 degrees C. The crystallized TiO(2) layer was 50 nm in thickness, and the size of TiO(2) particles comprising the layer was nearly 10 nm. The TiO(2) on cBN surfaces was completely converted into nanocrystalline TIN of uniform particles 20 nm in size on cBN particles by nitridation under flowing NH(3) gas.