Three-dimensional printing of tungsten carbide–10wt% cobalt using a cobalt oxide precursor

Tungsten carbide–10 wt% cobalt parts were formed by slurry-based three-dimensional printing (3DP™). The slurry contained either water or isopropyl alcohol as the liquid, a mixture of tungsten carbide and cobalt oxide powders, as well as dispersing and redispersing agents. The cobalt oxide is fully reduced to cobalt metal during the early stages of the sintering process. A new binder system, polyethylenimine, is described for use with powders with acidic surfaces, such as WC. Sintered densities approach the theoretical values for WC–10 wt%Co, and the microstructures produced are similar to those of conventionally processed (press and sinter) materials. Up to four parts were produced in a single print run using a layer thickness of 25 μm, with consistent dimensional features, and within the range of target dimensions after sintering.