Mechanical and wear properties of h-BN/Si3N4 ceramic composites

h-BN/Si3N4 ceramic composites were fabricated by hot pressing using sub-micrometer sized alpha-Si3N4, h-BN powders and Y2O3-Al2O3 sintering additives. With the increasing of h-BN content, the diameters and aspect ratios of elongated beta-Si3N4 grains decrease, the bending strength and fracture toughness of these composites decrease slightly, and the elastic modulus and Vickers' hardness of these composites decrease sharply, as expected. The elastic modulus of monolithic Si3N4 and 10vol.% h-BN/Si3N4 ceramic composite are 293.5 GPa and 236.6 GPa, the Vickers' hardness of them are 14.5 GPa and 10.9 GPa respectively. The friction coefficients of h-BN/Si3N4 ceramic composites decrease with the h-BN content increased.