对比分析了刚玉粉、α-Al2O3粉、γ-Al2O3粉和活性碳粉4种埋粉条件下热脱脂机理、传质途径和脱脂速率。结果表明当埋粉为高比表面积的活性碳和γ-Al2O3时,液相传质在低分子量粘结剂脱除的整个过程中起主导作用,而对于低比表面积的刚玉粉和α-Al2O3埋粉,液相传质主要存在于起始阶段,中、后期以气相传质为主。扩散传质方程描述了空气气氛、刚玉粉和α-Al2O3低比表面积埋粉的热脱脂过程。计算了热裂解、氧化裂解和液相挥发3种传质途径下气相产物在坯体内的扩散过程的综合扩散系数。
Thermal debinding mechanism,mass transport channel and debiding rate in four types of powder bed of corundum,α-Al2O3,γ-Al2O3 and activated carbon was analyzed.The results show that mass transfer in liquid phase predominated in the debinding of low molecular binder with higher specific surface area of γ-Al2O3 and activated carbon.For powder bed with lower specific surface area,mass transfer in liquid phase existed just in the initial stage and mass transfer in gas phase predominated in the middle and late stages.Additionally,equation of diffusion revealed the debinding process in air and with lower specific surface area powder bed of corundum and α-Al2O3.Comprehensive diffusion coefficient of mass transfer in gas phase through thermal decomposition,oxidation degradation and liquid evaporation was calculated.
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