Effects of stearic acid on synthesis of nanocomposite WC–MgO powders by mechanical alloying

The effects of stearic acid as a process control agent (PCA) on the synthesis of WC–MgO by mechanical alloying have been investigated. 0–2.0 wt% of stearic acid is added into the mixture of WO₃, Mg, and graphite powders in high-energy planetary ball milling experiments, and the as-milled powders are characterized by XRD and TEM. Results show that the mechanochemical reaction among WO₃, Mg, and graphite to form WC–MgO can be changed from a mechanically induced self-propagating reaction (MSR) to a gradual reaction by the addition of stearic acid in the range from 1.2 to 1.8 wt%, when other milling parameters are maintained at the same level. It has also been found that with the addition of stearic acid, the crystallite and particle size of WC–MgO powders can be refined, the homogeneity of particle size can be improved and the powder yield can be increased.