Ion Beam Modification of Glassy Carbon
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ION BEAM MODIFICATION OF GLASSY CARBON LESZEK S. WIELUNSKI, JOHN T.A. POLLOCK and MATTHEW FARRELLY CSIRO Division of Materials Science and Technology, PMB-7, Menai, Australia.
NSW.
2234,
ABSTRACT 2
Implanted glassy carbon (GC; 50 keV, 1016 N+ cm- ) is reported to be 400 times more wear-resistant to 1 pm diamond polishing than unimplanted GC. 15 N to produce the modified surface A number of samples were implanted with and1 2 to allow a very high sensitivity measurement of wear, using the layer 5 1 N(p,a) C nuclear reaction. Samples Optical interferometric wear measurements are also reported. 2 indicated that the enhanced wearimplanted with I MeV N to 1015 ions cmresistance is correlated with the nuclear energy loss density within the ion Mechanisms likely to be responsible for the enhanced wear resistance range. are also discussed.
INTRODUCTION
They Several forms of 'tangled' structural graphites are available. fall into two main groups - pyrolytic (and other vapour deposited) carbon The former are usually relatively thin (PC) and glassy carbon (GC) [1]. Their density, and layers (1 mm thick) built on precursors such as graphite. hence strength, may be varied by adjusting the process parameters and/or Glassy carbons are alloying to produce strong, wear-resistant surfaces. formed by the controlled, heat-induced degradation of resinous hydrocarbons to drive off volatiles, leaving a hard carbon residue which may be up to 10 The GCs are generally, restricted in density to about 1.5 g cm-3 mm thick. less strong and, more importantly, less wear resistant than the pyrolytic However, they do not require a precursor, and have good forming and carbons. Any improvement in the mechanical properties thickness of section qualities. of GC leading to a more wear-resistant surface could, together with these This could be achieved using ion advantages, provide a more useful material. implantation as the method of surface modification. Elsewhere, we have reported on the enhancement of wear-resistant report Here 1 we properties of GC following implantation with He and N [2,3]. 12 5 C N(p,a) an accurate measurement of the wear-resistance of implanted GC by The correlation of wear-resistance and ion damage nuclear reaction analysis. profiles and the likely mechanisms for the generation of enhanced wear resistance are also discussed.
EXPERIMENT
Slices of glassy carbon (VC 20, Atomergic Chemicals Corp., New York) were polished to a 1 um diamond finish. After cleaning in alcohol, some 5 with 50 keV 1 N to samples were attached firmly to steel blocks and implanted 2 2 Sample temperatures (beam current "i0 VA cm- ). a dose of 1016 ions cm-
Mat.Res. Soc. Symp. Proc. Vol.100. ©1988 Materials Research Society
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during implantation were not measured but they are unlikely to have been greater than 500 K [4]. Other samples were partly implanted with 1 MeV N to 2 a dose of 1015 ions cm- using a 3 MeV Van de Graaff accelerator. These 16 samples were subsequently implanted with 50 keV N to a dose of 10 ions cm- . The implanted zones (-u2
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