Improvement in fracture strength in electrically conductive AlN ceramics with high thermal conductivity

It is possible to impart electrical conductivity to insulating aluminum nitride (AlN) ceramics by precipitating a yttrium oxycarbide grain boundary phase with electrical conductivity. However, previously, sintering at high temperature was required to increase the electrical conductivity through the transformation of the grain boundary phase from yttrium aluminum oxide (Al2Y4O9) to rare-earth oxycarbide. As a result, the increase in electrical conductivity was accompanied with a considerable decrease in the fracture strength due to grain growth of AlN. In this study, sintering temperature and additive compositions were investigated to maintain the high strength of electrically conductive AlN without losing the high thermal conductivity.