A Study of Effective Thermal Conduction in Lightweight Foam Corundum Refractories

Preparation of lightweight corundum-mullite thermal insulation materials by microwave sintering

“…Lightweight corundum-mullite thermal insulation materials were successfully prepared by microwave sintering. With the continuous increase of sintering temperature, the porosity of the samples decreased from 62.4% to 55.8% and the density increased from 1.31 to 1.53 g/cm 3 . The optimal sintering temperature was 1400°C, at which thermal conductivity was between 0.543-0.845 W/(m•K) at 30-950°C.…”

“…Figure 3 shows the apparent porosity and bulk density of the corundum-mullite samples fired at different temperatures for 30 min. With increasing sintering temperature from 1200 to 1600°C, the apparent porosity decreased from 62.4% to 55.8%, while the density increased from 1.31 to 1.53 g/cm 3 . This indicates that increased sintering temperature was beneficial to promote the densification of the materials.…”

“…The density had an opposite change trend with the porosity. When the addition of PMMA microspheres was 30 wt.%, the samples obtained the highest porosity and the lowest density, reaching 71.2% and 0.99 g/cm 3 , respectively. The addition of PMMA mi- crospheres might have critical value and exceeding this value would cause the samples to collapse [36].…”

“…Owing to high strength at elevated temperature, good oxidation resistance, air tightness and excellent electrical insulation, corundum refractories have great application prospects in many fields. However, the corundum refractories have low thermal shock resistance [1][2][3]. Mullite materials have the characteristics of good thermal shock resistance, low thermal expansion coefficient and thermal conductivity, but their low strength at high temperature and mechanical properties limit their application [4][5][6].…”

Preparation of Al2O3‐mullite thermal insulation materials with AlF3 and SiC as aids by microwave sintering

“…Radiant heat transfer gradually increases and became the dominant heat transfer method when the temperature was above 800°C, and the efficiency of radiant heat transfer is much higher than heat conduction and heat convection. 28,29 The thermal conductivity strongly depends on the chemical components, porosity, and pore size distribution. The thermal conductivity of Al 2 O 3 ceramics is higher than that of mullite ceramics.…”