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建立了PIM脱脂过程中高分子高温裂解脱除的数学模型 ,分析了生坯中的应力分布 ,考察了恒加热速率、恒失重速率、保温处理工艺等对生坯应力的影响。结果显示 ,生坯内气体压力、径向应力、切向应力分布呈现中高外低分布 ,径向应力在生坯表面为零 ,而切向应力在表面不为零。与恒加热速率比较 ,恒失重速率和保温处理工艺可以有效降低生坯应力 ,但热脱脂工艺时间仍较长。采用恒应力方法对工艺进行优化设计 ,既可以有效降低生坯内应力 ,又可以大幅度缩短脱脂工艺时间。
A mathematical model for the removal of polymer during high temperature pyrolysis was established. The stress distribution in the green body was analyzed. The effects of constant heating rate, constant weight loss rate and heat preservation process on the green stress were investigated. The results show that the distribution of gas pressure, radial stress and tangential stress in the green body is medium-high and low-lying. The radial stress is zero at the green body and the tangential stress is not zero at the surface. Compared with the constant heating rate, the constant loss rate and heat preservation process can effectively reduce the green stress, but the thermal degreasing process is still a long time. Using constant stress method to optimize the process design can not only effectively reduce the green body stress, but also can greatly shorten the degreasing process time.