Sparking plasma sintering of nanometric tungsten carbide

The consolidation of nanometric powders of WC by the spark plasma sintering (SPS) method was investigated over the temperature range 1425-1800 degrees C under a uniaxial pressure of 126 MPa. Nominally stoichiometric WC powders with a grain size in the range 40-70 nm could be consolidated to near theoretical densities (99.1%) with a grain size of 305 nm when heated at a high rate to 1750 degrees C with no hold time. The sintered material, however, contained W2C and the effect of addition of carbon on the presence of this phase was investigated with these powders and with powders having a grain size of 12 nm. The effect of carbon on abnormal grain growth (AGG) was investigated as a function of temperature and carbon addition. The effect of heating rate up to the sintering temperature and the hold time at temperature was also investigated. (C) 2008 Elsevier Ltd. All rights reserved.