Research of surfaces and interfaces increasing during planetary ball milling of nanostructured tungsten carbide/cobalt powder

This work is devoted to researching the kinetics of the formation of particle surfaces and interfaces during the milling of nanostructured tungsten carbide/cobalt (WC–Co) powders in a planetary ball mill. The power consumption of the mill and the energy transferred to the powder are measured. The contents of Co and WC at the surface of the particle, the specific surface areas (SSAs) of the particles, and the SSAs of the WC phase and the WC grains were determined using various methods. The features of the SSA analysis using the laser diffraction method and the Brunauer–Emmett–Teller (BET) gas adsorption method are discussed. The specific interface areas (SIAs) of the WC/WC and WC/Co boundaries were calculated based on the obtained data. The SSA of the powder and the SIA of the WC/WC linearly increased during the beginning of the milling process, the rates of growth subsequently decreased, and the SSA and the SIA approached their limits. The SIA of WC/Co increases linearly without limit. The employed model made it possible to determine the milling rates and the limits of the SSA and the SIA. Based on the obtained results and literature data, the energy that was stored in different surfaces and interfaces was calculated.

► A model of the milling kinetics of the WC-Co powder is presented.
► Contents of Co and WC at the particle surfaces were determined.
► Specific surface areas of the powder, the WC phase and the WC grains were measured.
► Specific interface areas of the grain boundaries were calculated.
► The energy stored in different surfaces and interfaces was calculated.