Effects of fabrication process and coating of reinforcements on the microstructure and wear performance of Stellite alloy composites

Stellite 712 composites were developed with the reinforcement of bare TiC or Ni-coated TiC using powder metallurgy (PM) technique. Sintering with hot isostatic pressing (HIP) separated process and HIP'ing powder consolidation process were employed. The emphasis of this research was on the effect of the fabrication process and the Ni coating of TiC on the microstructure and wear performance of the developed composites. Calorimetric effects of the mixed composite powders were investigated using the differential scanning calorimetry (DSC) technique, which provided the basis of the sintering and HIP'ing cycles designed. The microstructures of the composites were examined and the wear resistance of the materials was evaluated. It was found that the phases in the microstructures of the specimens fabricated with the two PM processes were identical but the wear resistance between the specimens was different significantly. The Ni coating on the TiC particles has improved the ductility of the composites, but detracted the interfacial bonding strength, leading to the reduction of wear resistance.