316L不锈钢注射成形坯的热脱脂过程

利用TGA和汞压测孔仪研究了316L水雾化不锈钢粉末和多组元石蜡基粘结剂金属注射成形(MIM)坯的热脱脂过程,从微观和动力学方面分析和比较了在真空和氢气保护下脱脂过程中的孔隙结构变化和粘结剂的流动及分布,对含不同低分子量组元的粘结剂和不同升温速率条件下的热脱脂速度进行了分析和讨论,结果表明,真空条件下的热脱脂速度比氢气气氛下的热脱脂速度更快,同时,孔径大小和孔隙体积分布相对于氢气气氛条件下的分布更不均匀,而且缺陷的控制更为困难,其内在原因是真空条件下生坯内的气体压力要大于环境气压以及不同热脱脂环境导致热脱脂过程中的孔隙结构变化。

THERMAL DEBINDING PROCESSING OF METAL POWDER INJECTION MOLDING COMPACTS IN VACUUM

This paper studied the processing and the pore structure evolution during the thermal debinding in vacuum using water atomized 316 L stainless steel powder and wax-based multi-component binder by TGA and mercury porosimetry. The thermal debinding velocity in vacuum was analyzed under the condition with different binder components and different rising temperature velocity, especially the low temperature debinding kinetics in vacuum. The processing and pore structure evolution during thermal debinding in the flowing H_2 was also compared with those in vacuum. The binder removal rate in vacuum was faster than that in the flowing H_2 and the pore structure evolution in vacuum was far different from the evolution in the H_2, so the defect control was more difficult. Its intrinsic reason was that the gas pressure in the green compacts was higher than that in H_2 and the different pore structure evolution.