MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
Heterogeneity along the Height in Disc Specimens of Graphite/Tungsten Powder Mixtures with Sub-Stoichiometric Carbon Atom Ratios Heated by Concentrated Solar Beam to 1600°C
Nobumitsu ShohojiTeresa MagalhãesFernando Almeida Costa OliveiraLuís Guerra RosaJorge Cruz FernandesJosé RodríguezInmaculada CañadasDiego Martínez
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2010 Volume 51 Issue 2 Pages 381-388

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Abstract

Compositional heterogeneity along the thickness of compacted disc specimens of graphite/tungsten powder mixtures with sub-stoichiometric carbon atom ratios (0.35, 0.50 and 1.00) heated by concentrated solar beam to 1600°C was characterised by X-ray diffraction. Top surface of any examined test piece was consisted purely of mono-carbide WC while the bottom surface showed different constitution depending on the net initial C/W ratio of the test piece; almost pure metallic W for the C/W=0.35 specimen, dominant metallic W associated with small proportion of W2C for the C/W=0.50 and dominant W2C with trivial proportion of WC for the C/W=1.0. In the intermediate zone between the top and the bottom layers, the constitution held virtually constant depending on the nominal C/W ratio of the starting material: co-existing metallic W and W2C for the C/W=0.35, pure W2C for the C/W=0.50 and predominant WC with trace W2C for the C/W=1.00. Unlike for the top surface of the C/W=0.35 test piece heated in a solar furnace to 1900°C reported earlier, no evidence of formation of nano-meter scale WC whisker was detected for the top surface in any sample heated to 1600°C in the present work.

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© 2010 The Japan Institute of Metals and Materials
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