Analytical transmission electron microscopy observations on the stability of TiCN in electrically conductive α-β SiAlON/TiCN composites

Coating of α-β SiAlON granules with TiCN powder led to a continuous 3D electrically conductive network formation. Here, the stability of TiCN grains following gas pressure sintering (GPS) and its effect on the electrical properties of an α-β SiAlON/TiCN composite were analytically investigated by using transmission electron microscopy (TEM) based techniques. In situ formation of nano-sized SiC grains adjacent to TiCN and α-β SiAlON grains were observed. These SiC grains may play a role on the high electrical conductivity of α-β SiAlON/TiCN composite. Ti:C:N ratios from TiCN grains along the network showed that TiCN grains did not preserve their initial composition after sintering. Finally, Ti diffusion from TiCN grains into α-β SiAlON and triple junction phases was observed. The incorporation of Ti into the SiAlON crystal lattices contributes to the high electrical conductivity of α-β SiAlON/TiCN composite.