Microstructures and properties in aluminum nitride-titanium nitride composite ceramics

Aluminum nitride-titanium nitride (AlN-TiN) composites (TiN content; 0, 5 a nd 10 vol.%) were prepared using mixtures of fine AlN and TiN powders. Pres sureless sintering of the AlN-TiN powder mixtures was done at 1850 degrees C for 1 to 20 h, using yttrium oxide powder as a sintering aid. Sintered sa mples achieved almost full density. While AlN grains grew isotropically wit h sintering time, TiN particles in the composite maintained their small and nearly round shape. The TiN grains were present at both grain boundary and within AlN grains. Heat treatment of these composites caused both microstr uctural change and improvements in thermal diffusivity. Inhibition of AlN g rain growth was greatest for the 10 vol.% TiN-AlN composites. (C) 1999 Else vier Science B.V. All rights reserved.