多物理场耦合活化烧结中电热循环次数对致密化的影响

Influence of Electro-heating Cycles on Densification in Multi-physics Fields Coupling Activated Sintering

多物理场耦合活化烧结是一种快速、高效制备零件的新技术,其中零件的成型过程往往涉及到力、热、电的综合应用,因此工艺参数设计困难。为了研究电热循环次数对粉末体系致密化的影响,以纯Cu粉末为研究对象,采用Gleeble-1500D热模拟机,让Cu粉末在外加压力100 MPa,升温速度50℃/s的条件下,分别在400~600℃电热循环1、3、5次,成功制备出3个Φ4 mm×4 mm微型纯铜圆柱体。通过观察试样烧结过程的轴向收缩曲线和SEM形貌,发现电热循环次数越多烧结试样的致密度越高。这是由于伴随着试样在400~600℃之间的热循环次数增加,粉末体体系在电流和热压的循环作用下获得的能量更多,以至于让颗粒界面发生物态转变,使颗粒界面熔节点逐渐减少,空隙逐渐缩小,快速实现致密化过程。

In order to investigate the influence of electro-heating cycles on densification in multi-physics fields coupling activated sintering,copper powders were sintered with parameters of external pressure 100 MPa,electro-heating cycle intensity 50 ℃ / s,electro-heating cycle range 400 ~ 600 ℃ and electro-heating cycle number is 1,3,5.The whole process was carried out by Gleeble-1500 D thermal simulation instrument.Three Φ4 mm × 4 mm miniature copper cylinders were fabricated successfully.The analysis results showed that temperature-rise period in the cycle sintering stage played an important role in powder densification and the more electro-heating cycles the density is better.This is due to the electro-heating effect.With the temperature cycling between 400 ~ 600 ℃ several times,the powders got more energy,leading to generate local liquid,the liquid phase flows on the surface of solid particles and wets them under the effects of applied pressure and capillary force.The presence of a liquid phase enhances the pore closure of a porous body by capillary force,resulting in fast densification of the compacts.