Synthesis of niobium carbide at low temperature and its use in hardmetal

A new method of synthesizing niobium monocarbide at a low temperature (950 °C) and in a short time (2 h) is described. Conventionally, niobium monocarbide (NbC) can only be produced at 1600–1800 °C for longer periods. The method consists of the carburization of a niobium complex by a gaseous (H2+CH4) mixture. The method of preparation of the precursor and its carburization are presented. Precursor and carbide are characterized by XRD, SEM, TG/DTG and granulometry. Shape, mean size and size distribution of the NbC particles are similar to those of the niobium precursor. Reactions during carburization do not alter these characteristics. NbC particles are very large and porous. NbC powder is used in a hardmetal alloy as a WC grain growth inhibitor. Its performance is compared to that of a commercial NbC powder. NbC synthesized by the new technique exhibited a slightly higher efficiency in inhibiting the WC coarsening, evidenced by the SEM of the hardmetal structures and hardness measurements.