SEDL / STP / STP1116-EB / STP16364S

Reduction of High Temperature Thermal Conductivity of Thin-Wall Ceramic Spheres

Chapman, AT
professorsgraduate student, Materials Engineering at Georgia Tech in AtlantaMetals and Ceramics Division of Oak Ridge National LaboratoryCorning Glass, Inc., OakridgeWilmington, GATNNC

Cochran, JK
professorsgraduate student, Materials Engineering at Georgia Tech in AtlantaMetals and Ceramics Division of Oak Ridge National LaboratoryCorning Glass, Inc., OakridgeWilmington, GATNNC

Ford, TR
professorsgraduate student, Materials Engineering at Georgia Tech in AtlantaMetals and Ceramics Division of Oak Ridge National LaboratoryCorning Glass, Inc., OakridgeWilmington, GATNNC

Furlong, SD
professorsgraduate student, Materials Engineering at Georgia Tech in AtlantaMetals and Ceramics Division of Oak Ridge National LaboratoryCorning Glass, Inc., OakridgeWilmington, GATNNC

McElroy, DL
professorsgraduate student, Materials Engineering at Georgia Tech in AtlantaMetals and Ceramics Division of Oak Ridge National LaboratoryCorning Glass, Inc., OakridgeWilmington, GATNNC

Pages: 12    Published: Jan 1991

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Abstract

Within the last five years, a method for fabricating millimeter sized thin-wall hollow spheres from conventional powders has been developed at Georgia Tech. On firing, the spheres develop good strength as the walls are sintered to near theoretical density. These spheres have reasonably low thermal conductivities at low temperatures but conduction increases more rapidly than desired with increasing temperature due to transparency of the sphere wall. This work presents the results of opacification of the sphere walls with thermal pores to reduce the radiative component of conductivity at high temperatures. Mie scattering was employed in an effort to select an opacifying pore size distribution with a high thermal radiation scattering efficiency. It was shown that incorporation of pores in the micron size range could significantly reduce high temperature radiative conductivity.