Wear Properties and Surface Structure of Ion Implanted Glassy Carbon
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WEAR PROPERTIES AND SURFACE STRUCTURE OF ION IMPLANTED GLASSY CARBON Kazuo Yoshida, Kazuhiko Okuno, Gen Katagiri and Akira Ishitani Sonoyama 1-1-1, Otsu, Siga. 520 JAPAN Toray Research Center Inc., Masaya Iwaki* The Institute of Physical and Chemical Research (RIKEN) Hirosawa 2-1, Wako, Saitama. 351-01 JAPAN
tatsuo Takahashi*,
ABSTRACT Wear properties of Li+, K+, C+, Cl+, and Ti+ implanted glassy carbons (GC) have been studied by wear tests using silicon carbide abrasive paper. It has been found that ion implantation is effective for improving wear resistance of GC. The measurements of Raman spectra revealed formation of an amorphous structure on the surface. Anomalous depth profiles with flat concentration distribution of Li and K atoms were observed by a secondary ion mass spectroscopy (SIMS). In conclusion. the formation of an amorphous structure seems to explain the improvement in wear resistance. INTRODUCTION Carbon materials have wide industrial applications such as electrodes, crucibles or biomaterials. However, it is difficult to dope impurities under thermal equilibrium conditions. By ion implantation, it is possible to introduce a variety of elements into carbon surfaces without thermal equlibrium. We have reported a modification of electrochemical properties of GCs by ZnT implantation [1]. It is well known that ion implantations have much effects on improving wear properties of metals [2). However, it has not been known whether ion
implantations have any effects on wear properties of carbon materials. In this study, we implanted various ion species into glassy carbons, and examined their wear properties and surface structures. EXPERIMENTAL Substrates used were mirror-polished plates of glassy carbon (TOKAI CARBON CO. GC-20) of about 10 mm x 10 mm area. Implanted ion species were Li+, , C, C , and Ti . Implantation was performed with a dose of xlO/ ions/cm at an energy of 150 keV using a RIKEN 200 kV low current implanter with mass separation capability. The beam current density was kept below 1.5 )jA/cm2 with which the temperature of specimens during implantation was kept below 50*C estimated by measuring the temperature of the target holder by a chromel-alumel thermocouple. Aluminum sheet masks were used to cover the half area of a GC specimen in implantation processes to prepare a reference area with much difference in wear properties compared with the implanted area. The apparatus used in the wear tests is shown in figure 1. A strip of silicon carbide abrasive paper (NIKKEN CO., CC-lOOOCW) of one millimeter width was fixed on a plate which moves back and forth horizontally by a shaft and motor mechanism with a stroke of 30 mm and an average speed of 50 mm/sec. A GC plate was fixed on the end of a vertical rod in order that the implanted surface might be in contact with the abrasive paper. A weight was loaded vertically on the head of the rod. MaL Res. Soc. Syrmp. Proc. Vol. 100. 01988 Materials Research Society
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Fig. 1
Wear test apparatus.
1. GC specimen 2. Abrasive Paper 3. Slide 4. Weight
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