Preparation of AlN-BN Composite by Composite Powders

AlN-BN composite Powders with the microstructure of micrometer-sized AlN particles coated with BN particles were prepared via a chemical reaction, which used a mixture of boric acid (H3BO3) and urea (CO(NH2)2) as reactants coated on the surface of the AlN particles to react in nitrogen ambient. The XRD and TEM studies showed that the coating layer (BN) was composed mostly of amorphous BN particles at the reaction temperature of 850oC ~1100oC. When the composite powders formed into pellets using cold isostatic-pressing, then, sintered at pressureless sintering, the relative density of the composites that contained 15wt% BN reached above 98%, and there was homogeneous microstructure.