Wear property and structure of nitrogen implanted glassy carbon
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A. Sekiguchi Science University of Tokyo, Yamazaki 2641, Noda-shi, Chiba-ken 278, Japan (Received 9 April 1990; accepted 7 August 1990)
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 x 1014 to 5 x 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 f luence 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. I. INTRODUCTION
Ion implantation is a versatile technique for the formation of new metastable alloys and compounds in material surface layers by means of a nonthermal equilibrium process.1 This feature means that it is one of the highest technologies for improving physical and chemical properties of material surfaces as one of the surface finishing treatments.2 Ion implantation in metals extends the lifetime of industrial tools, and the surface layer modification of ceramics and polymers by ion implantation has been gradually activated to obtain desirable characteristics for electric conductivity, wear resistance, chemical reaction, and so on.3 In the fields of ion beam modifications of materials, tribology is one of the most interesting subjects from the standpoint of both fundamental research subjects and practical applications. Solid carbon, which has structures such as diamond, graphite, and amorphous-like, is a suitable material for many fields of materials science and engineering. These materials have a variety of electric conductivity, thermal conductivity, hardness, and chemical reactivity. Normally, it is difficult for any element to be injected into solid carbon except for the intercalation process in graphitic carbon. On the other hand, the ion implantation process is able to introduce every element into any type of solid carbon, although it induces radiation damage simultaneously. 2562
http://journals.cambridge.org
J. Mater. Res., Vol. 5, No. 11, Nov 1990
Downloaded: 14 Mar 2015
Surface layer modification of solid carbon has spread widely from electronic devices fabrication to mechanical engineering components. It has been reporte
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