Surface Modification of Tantalum Sheets by Methane Plasma Carburizing

The tantalumsurfaceswere modified by carburizing with methane plasma, generated by hollow cathode, to improve its high temperature oxidation and corrosion resistances.The impact of the carburizing temperature and time on the microstructures and phase-structures was investigated with X-ray diffraction, scanning electron microscopy and Auger electron spectroscopy.The preliminary results show that depending on the temperature and time, the surface modification significantly affected the microstructures, phase-structures and mechanical properties.To be specific, carburized at 1300℃ for 20 min, 6 μm thick layers formed, comprising the Ta C (3.5 μm in thickness) and Ta₂C layers with reduced porosity and improved compactness, possibly because the penetrated C atoms reacted with Ta atoms.A gradient-descent depth profile of C was observed.In addition, as the reaction time increased, the compactness and thickness of the modified layers increased, due to an increasing Ta C phase.