CAJ | 학술논문

着重分析了材料的显微结构对材料导热系数的影响:高孔隙率减弱固相传热作用从而使材料的导热系数减小,但是,高孔隙的也增大辐射传热作用.适当降低孔隙可减少辐射传热作用,这在高温时特别明显.尺寸<1 mm的孔隙中对流传热被制止,不再对传热起作用.在保持孔隙总量不变的前提下减小孔径可使孔隙数量增大,从而减小导热系数.小于100 nm的孔隙可以消除气体本身的热传导,从而极大地减小材料的导热系数.展示了几种不同显微结构的材料及其绝热性能.
착중분석료재료적현미결구대재료도열계수적영향:고공극솔감약고상전열작용종이사재료적도열계수감소,단시,고공극적야증대복사전열작용.괄당강저공극가감소복사전열작용,저재고온시특별명현.척촌<1 mm적공극중대류전열피제지,불재대전열기작용.재보지공극총량불변적전제하감소공경가사공극수량증대,종이감소도열계수.소우100 nm적공극가이소제기체본신적열전도,종이겁대지감소재료적도열계수.전시료궤충불동현미결구적재료급기절열성능.
Effect of microstructure of thermal insulation materials on their insulating property was studied. Increasing porosity leads decrease of thermal conductivity due to reduction of heat transfer through solid phase. However, high porosity enhances the heat radiation leading to increase of thermal conductivity. Therefore, decreasing properly the porosity results in decrease of thermal conductivity by reduction of heat radiation, especially at high temperature. Heat transfer by convection is eliminated in the pores with the size less than 1 mm. Thermal conductivity can be reduced, if the pore size is decreased; meanwhile the total volume of the pores remains constant. The pore size less than 100 nm eliminates the heat transfer through gas phase; therefore, the thermal conductivity of the material decreases considerably. Several insulation materials with deferent microstructure and their thermal insulating property are discussed.