Processing, Microstructure And Properties Of In Situ Copper Reinforced Tungsten Carbide Nanostructured Composite

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dc.contributor.authorYusoff, Mahani
dc.date.accessioned2018-07-26T06:55:44Z
dc.date.available2018-07-26T06:55:44Z
dc.date.issued2012-05
dc.description.abstractThe present work investigates characteristics and properties of in situ nanostructured copper-tungsten carbide composite prepared by mechanical alloying (MA) and powder metallurgy (PM). Elemental powders of Cu (copper), W (tungsten) and graphite (C) were milled in a planetary ball mill using different ball size, milling time and milling speed. Then the product was compacted at different pressures and sintered at different temperatures and times. In situ tungsten carbide phases (WC and W2C) were only present after a combination of MA and sintering. W2C was first to be observed and the formation of WC began with longer milling times and speeds, in accordance to a decreased crystallite size and an increased of internal strain of Cu during MA. W2C was formed as a result of C deficiency whereas WC through transformation from W2C to WC during sintering. Hardness of composite was enhanced but electrical conductivity was reduced with increasing milling time and milling speed. Higher applied pressure leads to higher densification of composite where hardness and electrical conductivity was also improved. However, the hardness was not improved even though densification has been enhanced with increasing sintering temperature which was resulted from the increased of porosity within the composites. Upon increasing milling time, ball size with 20 mm did not lead to smaller crystallite size and larger internal strain compared to that of 10 mm. Consequently, in situ WC was formed earlier with 10 mm ball than with 20 mm ball size. Due to greater impact energy that has been produced by collision frequency (with 10 mm ball size) rather than impact force (with 20 mm ball size) at increasing milling time, the result of hardness and electrical conductivity was shown better for 10 mm ball. However, the increase of milling speed (100 to 300 rpm) with 20 mm ball size was observed to have better properties than 10 mm ball. Upon increased of compaction pressure and sintering temperature both hardness and electrical conductivity is higher for 10 mm ball compared to that of 20 mm. High conductivity copper-based composite was produced through milling at 40 h and 400 rpm with 10 mm ball associated with compaction at 300 MPa and sintering temperature at 900°C.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/6045
dc.language.isoenen_US
dc.publisherUniversiti Sains Malaysiaen_US
dc.subjectProcessing, microstructure and properties of in situen_US
dc.subjectcopper reinforced tungsten carbide nanostructured compositeen_US
dc.titleProcessing, Microstructure And Properties Of In Situ Copper Reinforced Tungsten Carbide Nanostructured Compositeen_US
dc.typeThesisen_US
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Pusat Pengajian Kejuruteraan Bahan dan Sumber Mineral - Tesis