Hybrid Composite Nano-Sized WC-Co Cemented Carbide

Abstract

To improve the mechanical properties of WC-Co cemented carbides, a dual composite was studied. The compositions of granule and matrix were nano-sized WC-6 wt% Co(granule) and normal sized WC-20 wt% Co(matrix), respectively. The granules were made by spray-drying method and sintered at 1380°C for 10 minutes in vacuum. After sieving, the granules were grouped to 50, 100 and 150 ㎛ and mixed with WC and Co powders as the volume fractions of granule to matrix were 50 to 50, 40 to 60 and 30 to 70. These compacts were sintered at 1380°C for 10 minutes in vacuum. The microstructure, transverse rupture strength and wear resistance were investigated. The relative densities of the dual composites were about 98% after sintering. The mean size of the WC grains in the dual composite was about 300~400 nm. As the volume fraction of the matrix in the dual composite increased, the transverse rupture strength increased and hardness decreased. The wear resistance of the dual composite increased with decreasing matrix volume fraction and increasing granule size.