Nitride Based Ceramic Nanocomposites with Multifunctionality

Two types of Aluminum nitride (AlN) based ceramic nanocomposite with multifunctionality were investigated to improve machinability or electrical conductivity of AlN ceramics with high thermal conductivity. The AlN/BN nanocomposite was fabricated by pressureless sintering AlN-BN composite powder, which was prepared by reducing and heating AlN particles coated with a mixture of boric acid, urea and carbon. The nanocomposite containing 20 vol.% BN showed high strength, good machinability and relatively high thermal conductivity. On the other hand, the electrically conductive AlN ceramics with high thermal conductivity were attained by precipitating yttrium oxycarbide at grain boundaries. Their electrical conductivities were high enough to be machined by electric discharge machining.