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Title: Nanostructured silver-graphite electrical contact materials processed by mechanical milling
Authors: Rehani, Bharati R
Joshi, P B
Kaushik, V K
Keywords: Silver-graphite contact materials;High-energy milling;Nanocomposite powders;Powder metallurgy process
Issue Date: Aug-2009
Publisher: CSIR
Abstract: In last few decades there has been a growing interest in nanostructured materials in view of their improved mechanical, physical and chemical properties. A wide variety of techniques have been developed to synthesize nanopowders including high-energy milling or mechanical alloying (MA) for producing bulk nanostructures. High-energy milling is used for preparation of elemental and composite powders of different metals and non-metals. Literature reports the synthesis of ductile-ductile composites such as aluminium-graphite and copper-graphite by MA owing to its potential benefits in terms of improved mechanical properties. Reports are also there on the application of this technology for processing of silver-graphite contact materials offering improved switching properties. The present investigation deals with a comparative study on synthesis of silver-graphite nanocomposite powders in a planetary ball mill using two different approaches, namely milling of a blend of silver and graphite powder particles in one case and milling of only elemental silver powder in the other. The study revealed that somewhat inferior properties are obtained for the AgC bulk solids prepared from powders synthesized by the former approach. This is in view of the tendency of graphite to coat silver during milling, leading to very poor silver-silver interparticle contacts and resultant bulk solid with high porosity. However, an alternative approach of milling silver alone in the planetary mill is found to offer not only improved properties but also reduction in sintering temperature.
Page(s): 281-287
ISSN: 0975-1017 (Online); 0971-4588 (Print)
Appears in Collections:IJEMS Vol.16(4) [August 2009]

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