Influence of gas environment on synthesis of silicon carbide and some carbides and carbonitrides of d-group transition metals through reaction between metal powders and amorphous carbon powders in a solar furnace at PSA (Plataforma Solar de Almeria)

Refractory carbides and carbonitrides including silicon carbide SiC, tungsten carbide WC, titanium carbide TiCx (0.5<x<1) and titanium carbonitride TiCxNy (0.5<x+y<1) were synthesised from compacted pellet composed of metal powders and amorphous carbon powders through heating in a solar furnace under controlled atmosphere (Ar or N-2) Under irradiation of the solar energy flux 1,350 kW/m(2) (ca. 1650 degrees C in terms of measured temperature) for 30 min in Ar atmosphere, Si, W and Ti were converted to SiC, WC and TiCx, respectively. By the similar reaction undertaken in N-2 atmosphere, Si and W were converted to SiC and WC, respectively, but carbonitride TiCxNy formed from Ti. No special influence of atmosphere was detected on the WC formation, but conversion to SiC from Si was somewhat retarded in N-2 atmosphere. In either Ar or N-2 atmosphere, progress of graphitisation of amorphous carbon was not detectable by X-ray diffraction analysis in the reaction with Si and Ti but graphitisation of amorphous carbon appeared to be significantly accelerated in the reaction with W.