PMMA在MIM后续热脱脂过程中的分解行为
来源期刊：中南大学学报(自然科学版)2001年第1期
论文作者：李松林 曲选辉 李益民 黄伯云
文章页码：74 - 77
关键词：粉末注射成形;粘结剂;动力学
Key words：powder injection molding; binder; dynamics
摘 要：金属粉末注射成形(MIM)粘结剂中高分子物质的分解和排除是一个较缓慢的过程,对这一过程进行理论研究,有助于指导粘结剂的设计和脱脂过程优化.为此,当Fe-2Ni粉末的注射成形坯经充分溶剂脱脂后,用热重法对坯块中的PMMA的热分解行为进行了理论研究和实验验证.假设进行一级反应,根据各种升温速率的热重计算结果,得到了喂料中PMMA热分解反应速率的理论计算表达式:ln(1-α)=1·33×109t·exp(-1 479/T);对厚度为6.37 mm的注射坯充分溶剂脱脂后,验证了坯块中PMMA分解速率,发现在350℃和400℃时等温脱脂的速率与理论值较接近,但低于理论值;经过优化,对6.37 mm厚的注射坯,采取5~10℃/min的升温速度升温,可在2 h内完成热脱脂过程.
Abstract: Thermal degradation of polymer substances in metal injection molding feedstock is a time-consuming step.Theoretical investigation of this process will be helpful for binder design and debinding scheme modification. In this paper, feedstock containing polymethyl methacrylate(PMMA) is molded and completely solvent-debinded, and thermal degradation of PMMA in the partly debinded part is theoretically calculated and tested by experiments. First, thermograv ity(TG) measurement is used to compare degradation of pure PMMA and PMMA in the partly debinded part. PMMA degradation rate in the brown sample is obtained out of TG test and one-order reaction hypothesis. The rate can be expressed as: ln(1-α)=1·33×109t·exp(-1 479/T). And then, 6.37 mm thick sample is adopted to get the actual debinding time. It is found that the debinding rates of the samples at 350℃and 400℃are close to the theoretical calculation values. When heating at a rate of 5~10℃/min for the 6.37 mm sample, the debinding process is completed within 2 h.
