Spark plasma sintering of nanostructured powder composites (WC-Ni) prepared by carboreduction reaction

This work reports the production of WC-10 wt%Ni nanostructured powders synthesized via carboreduction of a mixture of APT and low-temperature nickel nitrate with a short reaction time in a single synthesis process. The powders were characterized by XRD, TG/DSC, SEM, EDS, TEM and particle size analysis. The WC-10 wt%Ni powders were consolidated by the Spark Plasma Sintering process at different temperatures (1350 degrees C and 1450 degrees C). The effect of the sintering temperature on the mechanical properties and microstructure of the sintered composites was investigated through Vickers hardness and density measurements, as well as by SEM and EDS analyzes. The produced powders presented an average crystallite size of 24 nm for the WC and 41 nm for Ni. The samples sintered at 1350 degrees C showed the best results in terms of morphology and mechanical properties of Vickers hardness (2120 HV) and density (97.67%) when compared to samples sintered at 1450 degrees C which showed Vickers hardness of 945 HV and a density of 94.60%. The preparation of nanocomposite powders by carboreduction is a highly promising strategy for manufacturing hard metals by SPS, ensuring homogeneity of the phases and refined grain sizes, as well as providing good densification and excellent WC-Ni hardness.