To　determine　the　high　temperature　thermal　conductivity　of　small　samples　such　as　granular　or　powder　materials which　can　not　be　measured　by　any　existing　method，the　method　to　estimate　their　values　from　the　thermal　conductivity of　the　mixture　of　small　samples　and　gases　was　proposed．　From　a　result　of　investigating　the　relation　between　the　thermal　conductivity　for　the　mixture （λm，measured　by　a　transient　hot　wire　method　at　high　temperatures） of　a　granular solid　with λs／gas　withλf　and　an　absolute　temperature（T），the　following　experimental　relation　obtained　by　modifying the　Fricke’s　equationλF　was　established． 　　　　λm＝λF＋4×10-4（T／100）3 For　cases　where　the　thermal　conductivity　of　granuar　materials　is　less　than　3W・m-1K-1，the　thermal　conductivity　of granular　materials　at　high　temperatures　can　be　estimated　by　the　relation．

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