Surface Singularity Upon Solar Radiation Heating of Graphite/Tungsten Powder Mixture Compacts to Temperatures in Excess of 1600°C
Synthesis of single-phase tungsten sub-carbide W2C was attempted by heating pellets made out of a source of carbon (graphite-G) and W powders with G/W atom ratio between 0.35 and 0.50 to two target temperatures, namely 1600°C and 1900°C in an argon atmosphere using a solar furnace at PROMES-CNRS in Odeillo (France). The results showed that synthesis of single-phase W2C phase was difficult at either target temperature yielding the W2C co-existed with free metallic W. It was noted that the thin top surface layer of the solar-synthesised tungsten carbide pellets heated to 1900°C was distinguishable from the rest of the bulk specimen showing localised growth of nano-meter scale WC whiskers over W2C grains. Detailed XRD (X-ray diffraction) results on the effect of both G/W ratio and temperature on W2C lattice parameters are discussed.
António Torres Marques, António Fernando Silva, António Paulo Monteiro Baptista, Carlos Sá, Fernando Jorge Lino Alves, Luís Filipe Malheiros and Manuel Vieira
F. A. C. Oliveira et al., "Surface Singularity Upon Solar Radiation Heating of Graphite/Tungsten Powder Mixture Compacts to Temperatures in Excess of 1600°C", Materials Science Forum, Vols. 587-588, pp. 993-997, 2008