1. J. H. Shane, R. J. Russell andR. A. Bochman, US Patent 3 404 061 (1968).
2. Z. Huang, Runhua Yu Mifeng Vol.6 (1981) pp. 28?32.
3. L. Shi andY. Fan, Runhua Yu Mifeng Vol.27 (1981) pp. 17?24, 70.
4. R. K. Flitney,Tribology Int. 19 (1986) 181.
5. T and N Materials Research Ltd, Jpn. Kokai Tokkyo Koho JP 57 168 978 (1982).