It was reported that it was possible to render AlN ceramics electrically conductive without losing their intrinsic high thermal conductivity by precipitating a yttrium oxycarbide grain boundary phase, the volume of which was about 1/20 that of the conducting phase in conventional ceramic composites. The electrical conductivity could be controlled by varying the sintering conditions and additive composition. In addition, the electrically conductive AlN could be shaped by electric discharge machining and converted back into insulating AlN by anodic oxidation.

Production of a Grain Boundary Phase as Conducting Pathway in Insulating AlN Ceramics. T.Kusunose, T.Sekino, K.Niihara: Acta Materialia, 2007, 55[18], 6170-5