Investigation of carburisation of tungsten-carbide formation by hot-filament CVD technique

Tungsten filaments were carburised by pyrolitical decomposition of methane and hydrogen over hot filament surface. The carburised filaments were chara cterized by Raman spectroscopy, X-ray diffraction measurements and scanning electron microscopy. Featureless micro-Raman spectra confirm a formation o f tungsten carbide layer after 10-minute carburisation. Strong WC-related p eaks in X-ray diffraction spectra are observed for carburisation temperatur es of 1600 degreesC and higher. SEM analysis of filaments fracture indicate s a creation of WC layer over W filaments, generation of deep micro cracks in WC region and a preferential creation of WC grains in thin surface layer over bulk of carburised filaments in dependence on carburisation time is o bserved. Presented results indicate that successful carburisation is practi cally self-stop process after 5 hours.