Effect of Thermal Expansion Mismatch on the Thermal Diffusivity of Glass-Ni Composites |
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| Authors: | BOB R POWELL Jr G E YOUNGBLOOD D P H HASSELMAN LARRY D BENTSEN |
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| Affiliation: | Department of Materials Science and Engineering, University of California, Berkeley, California 94720;Montana Energy and MHD Research and Development Institute, Butte, Montana 59701;Department of Materials Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 |
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| Abstract: | The effect of interfacial decohesion, due to the thermal expansion mismatch, on the thermal diffusivity of a hot-pressed glass matrix with a dispersed phase of nickel was investigated by the laser-flash technique at 25° to 600°C. The interfacial gap formed on cooling acts as a barrier to heat flow and lowers the thermal diffusivity to values below those predicted from composite theory and also creates a strongly positive temperature dependence of the thermdl diffusivity. Preoxidation of the Ni spheres promotes interfacial bonding and yields values of thermal diffusivity higher than those for nonoxidized spheres and a thermal diffusivity which is relatively temperature-independent. The results of the present study also confirm the criteria for the effective thermal diffusivity of composites established by Lee and Taylor. |
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