Wear property and structure of nitrogen implanted glassy carbon

Abstract

A study has been made of the correlation between wear resistance and crystalline structure of ion implanted glassy carbon. Nitrogen ions were implanted in glassy carbon with fluences ranging from 5 × 10¹⁴ to 5 × 10¹⁶ ions/cm² at an energy of 150 keV. The target temperature during ion implantation was maintained constantly at –70, 25, and 200 °C. Wear tests were carried out with the system of glassy carbon and polishing silk disk on which water including diamond slurry was poured, using a conventional polishing machine. The surface layer structure was investigated by means of laser Raman spectroscopy. Nitrogen implantation causes the wear resistance to improve, and the reduction of wear rate is dependent on the ion fluence and the target temperature during ion implantation. As the fluence increases and the target temperature is lower than room temperature, the wear rate decreases drastically. Raman spectra show that the structure of ion implanted layers becomes what is called amorphous-like as the fluence increases and the target temperature is lowered. In conclusion, the wear resistance of glassy carbon is improved owing to the change in structure followed by nitrogen implantation at a relatively high fluence and low target temperature.