Comparative study of densification and microstructural development in W-18Cu composites using microwave and conventional heating

Tungsten based composites such as W-Cu have been widely used as electrical contacts, especially in heavy duty applications and as spark erosion electrodes. The lack of solubility between tungsten and copper makes it very difficult to achieve full densification through liquid phase sintering. Higher sintering temperatures or longer holding times always help to improve the densification but Cu may leach out from the skeleton which leads to Cu segregation and results in non-homogeneous microstructure and poor product performance. Microwave heating has been increasingly gaining popularity in the field of sintering of particulate materials. As compared to conventional heating, microwave heating is more rapid resulting in substantial reduction in the overall sintering time. In addition to the energy efficiency, the faster heating rate achieved in microwave furnaces minimises microstructural coarsening and improves homogeneity. This study examines the effect of heating mode (conventional and microwave) and temperature on the consolidation of specially prepared commercial W-Cu powder. Near theoretical density has been achieved under optimum conditions in microwave sintering. The bulk hardness and electrical conductivity of the samples sintered by two methods have been determined and the data compared.