摘要
基于粉末-粘结剂的双流体模型,采用CFX商业软件对硬质合金粉末注射成形(PIM)过程进行了数值模拟,分析了充模过程产生的偏析现象。研究表明,PIM中的偏析有两类:一类是由于粉末与粘结剂密度及粘度的差异引起的普通偏析,密度的差异主要引起浇口附近粘结剂的轻微聚集,而粘度的差异引起充模前沿粘结剂体积分数的增加;另一类是由于边界层的存在及普通偏析共同作用形成的边界偏析,这种偏析使靠近模壁的粘结剂体积分数大于其平均值。局部密度测试证明了基于双流体模型模拟PIM过程偏析现象的可靠性。
The injection molding of cemented carbide powder has been numerically simulated by CFX software based on the two-fluid model, and the segregation during the PIM filling flow process has also been analyzed. The results show that the segregation is divided into the common segregation and boundary segregation. The common segregation is caused by the differences of density and viscosity between powder and binder. Because the density of binder is less than the powder, a light concentration of the binder around the jet mostly has been caused. Moreover, the effective viscosity of the binder is less than the powder, which causes the increase of the content of binder in the front. The boundary effect and the common segregation together caused the boundary segregation, which leads to the volume fraction of binder near the die wall more than its mean value. The results of the local density test have demonstrated the reliability of the numerical simulation of segregation based on the two-fluid model.
出处
《稀有金属与硬质合金》
CAS
CSCD
2008年第2期10-14,共5页
Rare Metals and Cemented Carbides
基金
国家自然科学基金重点项目(50634010)
国家重点基础研究发展规划项目(G2000067203)
国家杰出青年科学基金资助项目(50025412)
关键词
粉末注射成形
双流体模型
数值模拟
普通偏析
边界偏析
powder injection molding
two-fluid model
numerical simulation
common segregation
boundary segregation
