HIGH TEMPERATURE EROSION WEAR OF SiC-TaC CERAMIC COMPOSITES

Abstract

Highly densified SiC composites were prepared with 10, 20 or 30 wt% TaC addition by spark plasma sintering of SiC and TaC powders at 1800°C at 55 MPa for 5min in Ar atmosphere. The sintered ceramic composites were subjected to erosion by a stream of silicon carbide particles (45-75 μm particle size) impinging at normal angle of incidence at a mass flow rate of 3 g/min and impact velocity of 50m/s at ambient and 400°C using a high temperature erosion tester. Microstructures of the sintered composites consisted mostly of equiaxed grains. Fracture surfaces show mixed mode of fracture, with the large extent of transgranular fracture observed in SiC ceramics containing 10 wt% TaC. With increase in TaC content, micro hardness decreased from 26 to 23 GPa and fracture toughness slightly increased from 3.48 to 3.85 MPa.m1/2. Eroded surface of the composites showed fracture, and pull-out of SiC grains and TaC particles. Erosion rate of the composites varied from 53 mm3/kg to 166 mm3/kg for 90°, with minimum erosion rate observed for SiC ceramics containing 30 wt% TaC.