Sintering of WC-12Co Powders with Different Particle Sizes by Pulsed Electric Current Sintering and Effect of Powder Characteristics on Microstructure and Mechanical Properties

摘要

WC-12Co powders were prepared from three different WC carbide and metallic Co powder grades (nano, fine and coarse) by vibrator milling for 5, 15, or 30 min in argon. Powders were characterised by laser diffractometer, SEM/EDS, and XRD. Nano-Co was cubic in the milled mixtures, while the other Co grades transformed to hexagonal. All the powders were pulsed electric current sintered by using the processing parameters 1453 K, 3 min, 50 MPa, and 100 K/min. Densification was studied by Archimedes method. Microstructure of the compacted samples was analysed by SEM/EDS, and XRD. The WC grain size and porosity were measured from SEM pictures by applying the image analysis. The mechanical properties of the compacts were studied with HV1 microhardness test and by nanoindentation for one sample. Nearly full density was obtained in compacts with fine-WCano-Co-powder, while the highest hardness 23 GPa was obtained with powders containing nano-WC.