Processing and Microstructures of Tungsten/Copper Composites Produced by Plasma Spray and Cold Spray

Tungsten/copper composites were produced using an agglomerated feedstock powder by plasma spray and cold spray. In the case of the plasma spray, the external feedstock injection (EFI) and the internal feedstock injection (IFI) were adopted to compare oxidation, microstructure, porosity, and tungsten recovery in the deposits. The IFI deposit had less oxidation, denser microstructure, and more tungsten retention compared to the EFI. Especially, more tungsten particles were melted from the IFI than from the EFI at input power of 25kW. Thermal expansion coefficient of plasma sprayed composite (72W/28Cu vol.%) was approximately 5.2x10-6/K. In the cold spray, no oxidation and more dense microstructures were observed with porosity of less than 1.0 vol.%. However lots of tungsten was lost due to insufficient plastic deformation.