Reactive Sintering Of Diamond Enhanced Cemented Carbides

In this work, a new approach for preparation of diamond enhanced cemented carbides (DECC) has been evaluated. The main challenge to overcome is the phase transformation of metastable diamond into graphite during sintering. Despite using field assisted sintering to reduce sintering time and temperature as well as a Ni-based binder system instead of Co, graphitisation cannot be fully suppressed. To further reduce the amount of formed graphite, reactive sintering was evaluated to reduce the necessary sintering temperature, due to high sinter activity. Different approaches regarding carbon source and the extent of reactive material were pursued. Reactively sintered DECC could be successfully prepared and did help to understand the kinetics of in-situ WC formation as well as the degradation of diamond during the sintering process. Upon introducing a carbon deficit in a WC-Ni based hardmetal composition the relative density of the resulting DECC was increased at a lower sintering temperature.