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提出了改进的放电等离子烧结粉末材料的有限元模型,该模型实现了温度场、电场和位移场的耦合。考虑到放电等离子烧结的一步成形工艺,将粉末材料的热电性能参数假设为温度和密度的双变量函数。结果表明,在烧结初期,接触电阻在升温过程中起到至关重要的作用;伴随着致密化进程和电流的增大,系统的最大温度区域由石墨冲头末端向粉末内部移动;引入随位移变化的接触热阻和接触电阻有助于描述接触部位的非连续温度场变化;模具热电偶位置处的实测温度和该模型的预测结果基本吻合。
An improved finite element model of spark plasma sintering powder material is proposed. The model realizes the coupling of temperature field, electric field and displacement field. Taking into account the one-step forming process of spark plasma sintering, the thermoelectric performance parameters of the powder material are assumed to be a bivariate function of temperature and density. The results show that contact resistance plays an important role in the process of temperature rise in the initial stage of sintering. With the increase of densification and current, the maximum temperature of the system moves from the tip of graphite punch to the interior of the powder. The change of contact resistance and contact resistance help to describe the discontinuous temperature field at the contact part. The measured temperature at the position of mold thermocouple basically agrees with the predicted result of this model.