Electrical discharge process for rapid oxycarburisation of titanium in air

Abstract

A single pulse of 2·0–3·5 kJ of input energy from a 450 μF capacitor was applied to a Ti rod. The electrical discharge process can produce rapid temperature increases of Ti from 569 to 2398°C in times as short as 159 μs, depending on the input energy. With an input energy greater than 2·5 kJ, a β→α allotropic transformation occurred, showing a typical serrated morphology. At the same time, the original surface of Ti rod with TiO₂ was modified into the form of primarily titanium oxycarbide. A much higher value of hardness that was observed at the edge of the cross-section was thus attributed to oxygen- and carbon-induced solid solution hardening during the electrical discharge process.