脱脂是整个注射成形工艺中的关键步骤。本文以YT5硬质合金为对象,以正庚烷作为溶剂,系统研究了以多组元聚合物为粘结剂的注射坯样的溶剂脱脂行为。考查了粘结剂体系组成、脱脂温度、脱脂时间、样品厚度、样品形状对坯样脱脂率的影响及其原因。实验结果表明:在本实验所使用的三组粘结剂体系中,改进型蜡基粘结剂溶剂脱脂速度最快,脱脂效果最好,40℃、3h条件下该粘结剂体系中能被溶剂溶解的组元的脱除率达到98%;随脱脂温度的升高、脱脂时间的延长,粘结剂脱除率增大;溶剂脱脂初期为扩散控制,后期为溶解控制;粘结剂平均脱除速率与生坯表面积成正比,与生坯厚度成反比;脱脂完成后,脱脂坯边缘和中心组织均匀一致。
Debinding is the crucial step in the whole PIM process. The solvent debinding process of multicomponent binder in YT5 cemented carbide powder injection molding was studied systematically. Effects of makeup of binder system, debinding temperature, debinding time, sample thickness and sample shape on sample binder removal were investigated and corresponding reasons were advanced. The experiment results show that in the three binder system used in this experiment, the solvent debinding rate of improved wax-based binder system is highest, and its debinding effect is best. Under the solvent debinding condition of 40℃,3h, the debinding removal of the component in this binder system that can be solved by solvent reaches 98%. With the increase of temperature and time, the binder debinding ratio is higher. The beginning period of debinding is controlled by binder diffusion , and the ending period of bebinding is controlled by binder solution. Average debinding speed is in direct rate with samples' surface area, while it is in inverse proportion with samples' thickness. After bebinding, the structures between the verge and center of as solvent-debound parts ale uniform.