| Summary: | 碩士 === 臺灣大學 === 材料科學與工程學研究所 === 98 === Direct forming of dispersive mica particulates and G1A5 (47BaO-21B2O3-27SiO2-5Al2O3, in mol%) glass powder was used to prepare ceramic foams with extremely low thermal conductivity and nearly no shrinkage by 1000oC treatment. Optimized formulation and processing parameters are proposed for the preparation of the ceramic foams. The effects of foaming agents, mica/glass ratio, solid content, microwave drying steps, wetting behavior of the glass on mica, and consolidation of the foam were investigated in consideration of foam stability. Besides, the properties of sintered foams, including porosity, pore size, compressive strength, permeability, and thermal conductivity were also analyzed. One ceramic foam which undergoes thermal treatment at the temperature as low as 950oC for 1 h is the best having a lowest thermal conductivity of 0.08 W/m K, 0.14 W/m K and 0.18 W/m K at the temperature of 25oC, 600oC and 800oC, respectively, as well as having a density of 0.26 g/cm3, porosity of 91.2%, gas permeability of 0.1 10-7 cm2, and compressive strength of 440 kPa. The results show that the photon conduction and air conduction are two dominated mechanisms of the foams from room temperature to 800oC.
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