Additive manufacturing of cemented carbide using analogous powder injection molding feedstock

Abstract

In this study, WC-8%Co cemented carbide was fabricated by extrusion-based additive manufacturing process using analogous powder injection molding feedstock. Feedstocks with powder loading content of 51 vol% (PW51) and 57 vol% (PW57) were prepared based on thermoplastic binder system composed of paraffin wax, high density polyethylene and ethylene-vinyl acetate. The results show that the extrusion of feedstock is steady and easily controlled. The binder is efficiently removed by solvent leaching and thermal decomposition. After sintering at 1400 °C, densified samples with a relative density beyond 99% are obtained. Sintered PW57 presents less and more isotropic shrinkage below 17.0%, showing a great significance in print accuracy and deformation control. Sintered PW57 has larger transverse rupture strength and fracture toughness of 1695 MPa and 7.27 Pa·m0.5, respectively. Vickers hardness of sintered PW51 is slightly larger because of finer WC grain size. Mechanical properties, microstructure and surface roughness of sintered samples are all acceptable in actual application. Three-dimensional printing using an extrusion-based additive manufacturing with analogous powder injection molding feedstock is an extremely practicable method to fabricate cemented carbide parts with complicated shape.