粉末冶金温压的致密化机理

通过对铁粉的动态压制曲线、脱模力曲线、 X射线衍射、摩擦和润滑的研究, 揭示了温压的致密化机理： 温压成形过程可分为3个阶段, 在初期阶段, 粉末的颗粒重排过程占主导地位, 颗粒重排份额与冷压相比提高15%～31%; 而在后期, 温压致密化以塑性变形为主, 铁粉塑性变形程度的改善又为粉末颗粒的二次重排起了协调作用, 使铁粉获得最大程度的颗粒填充密度; 其间, 温压润滑剂对致密化起了重要作用, 它降低了摩擦因数, 改善了粉末和模壁、粉末和粉末之间的润滑条件, 有效地降低了粉末成形的摩擦阻力, 有利于粉末致密化的顺利进行.

Densification mechanism of warm compaction in powder metallurgy

To study the densification mechanism of warm compaction,the dynamic compacting curve,ejection force curve,X-ray diffraction and friction & wear properties were investigated.The results show the dynamic compacting process of warm compaction of powder metallurgy can be divided into three sections.In the initial stage,the rearrangement of the powder particles is the primary factor,the rearrangement ratio of particles in warm compaction is higher than that in cold compaction by 1531%.But in the later stage,the main factor is the plastic deformation of powder which coordinates the secondary rearrangement of particles.During the compacting,the polymer lubricant has great contribution to the densification of the powder,since it improves the condition and result of lubrication between powder and die and among the particles,efficiently decreases the friction in the forming process and is beneficial to the development of the compact density.