Rate controlled sintering of binderless tungsten carbide
Prevention of the typical densification peaks of conventional constant-heating-rate sintering (CHR) by real-time densification rate control can provide better materials with less microstructural heterogeneities, residual stresses and abnormal grain growth inter alia. FAST/SPS spark plasma sintering systems are able to realize this control by a smooth adjustment of heating rate and applied force, making this technique ideal to investigate the effect of rate controlled sintering (RCS). Within this work nanoscaled binderless tungsten carbide samples were produced by conventional as well as densification rate controlled sintering realized by adjusting the applied force or heating rate during the respective sintering cycle. Especially by controlling the heating rate, the resulting samples showed an increase of density associated to around 250 HV10 higher hardness compared to the conventionally FAST/SPS sintered samples. Microstructural analysis revealed a slightly smaller grain size.