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Metal Casting Technologies : June 2006
METAL Casting Technologies June 2006 30 TECHNICAL FEATURE wear rates. P.K.Rohatgi et al. found that Al --Si 3 % graphite particles piston resulted in 3 % reduction in specific fuel consumption, reduction in wear of piston rings and 9 % reduction in frictional horse power losses of the engine21. Emissions with aluminium graphitic piston were reduced compared to LM 13 piston material. The tests showed that hydrocarbon concentration reduced with aluminium graphitic piston22. Associated engg. co., in Italy dispersed 4 vol. % graphite in Al 18 Si alloy23, 24. Wear testing was done on this composite and compared to Al 11.48 Si alloy in heated oil. Graphite improved scuffing resistance by a factor of 2. Liners of these alloys were evaluated in two & four stroke engines and found that power generated was improved by 10%, there was no scuffing well beyond the 5 min limit along with no friction marks and negligible wear was observed. When the tests were run in a 4 stroke engine (Alfa Romeo 1300 cc) no liner wear was seen and pistons were in good condition. Aluminium graphite liners were fitted in Alfa Romeo racing cars and in formula one 1975 world championship the car was victorious. In 1975, 1976, 1977 racings no seizure was observed and power ratings were close to highest levels. ● Figure 9. Fluidity Castings Material Application Cu graphite plane bearings for automotives, electrical contacts & brushes, bearings, drive shafts, spherical bushings in auto transmission Al alloy graphite journal bearings, connecting rods, cylinder block, fan bushing Silver graphite electrical contacts and brushes Magnesium alloy pistons, structural applications in space Graphite Table 2. Applications of graphite MMC25. REFERENCES 1) T.P.D. Rajan, R.M. Pillai & B.C.Pai, Journal of Materials Science, 33, 1998, 3491 -- 3503. 2) Zweben. C, 1992 Metal matrix composites for electronic packaging, JOM 44, 15-23. 3) A.R.E. Singer, Materials Science and Engineering, A 135, p. 13, 1991. 4) R. Mehrabian. R.G.Riek & M.C. Flemmings, Metallurgical Transactions, vol.5, p. 1899, Aug 1974. 5) Young-Ho Seo, Chung-Gil Kang, Journal of Materials Processing Technology 55 (1995) 370-379. 6) B.P. Krishnan, H.R.Shetty & P.K.Rohatgi AFS Transactions, vol. 84, p 73, 1976. 7) M. K. Surappa and P.K.Rohatgi, Journal of Mat. Sci., 16, 983-993, 1981. 8) J.V. Naidich, J.N. Chuvash, J. Mater. Sci., 18, (1983), 2071-2080. 9) Flemings M.C., Solidification Processing, McGraw-Hill Inc. London, (1974). 10) Ragone D V, Adams CM, Taylor HF, Trans AFS 1956; 64:653-7. 11) P.K. Rohatgi, R. Asthana, and S. Das, Int. Met. Rev., Vol.31, 1986, p 115. 12) Pradeep Rohatgi, Cast Metal Matrix Composites, ASM Handbook, vol. 15, Casting, page 849. 13) Surappa MK, Prasad SV, Rohatgi PK, Wear 1982; 77:295--302. 14) http://mmc-assess.tuwien.ac.at/3index.htm 15) T. Donomoto et al., SAE Paper 830252, Society of Automotive Engineers, 1983. 16) Fukunaga H, Proc. of ninth intl. conf. on composite malts, edited by A.Miravete, Spain, 1993, p .355. 17) S.Elomari, D.J.Lloyd, p. 202, processing, properties & applications of cast metal matrix composites, proc. of a symposium jointly sponsored by MDMD solidification committee & Jt. SMD/MSD composite matls. committee, edited by P.K Rohatgi, 1996. 18) D.B. Miracle, Composites Science and Technology, pp. 2526-2540, Volume 65, Issues 15-16, December 2005. 19) Gorbunov V.G et al., Russian Casting Production. Translated from Liteinoe Proizvodstvo, 1974, (8), pp 20-21. 20) Bruni L. and Iguera P. Silgarf, Automotive Engineer, Feb-March, 1978, 3(1), 29-35. 21) B.P. Krishnan, N.Raman, K. Narayanaswamy & P.K.Rohatgi, Wear, 60, 1980, 205. 22) S B Singh and P D Joshi, Proceedings of the international conference on aluminium, INCAL 98, vol .2, p 33. 23) L.Bruni, P.Iguera, Automot. Engg, 1978, 3, 29. 24) P.K.Rohatgi, JOM, 1991, 43 (4), 10. 25) P.K.Rohatgi, S.Ray, Y.Liu, Intl. materials review, vol. 37, n3, 1992, p 144. Author Amit Joshi B.Engg Mechanical, A.I.Prod.E, A.I.E He is a mechanical engineer. His interests are in the field of liquid metal processing, metal matrix composites, manufacturing engg. & polymer composites.