电火花复合电极强化TC4强化层耐高温试验研究

Experimental Study on High Temperature Resistance of TC4 Strengthened Layer Strengthened by the EDM Composite Electrode

通过混粉准干式电火花技术,使用石墨和紫铜复合电极,在TC4钛合金表面上加工出一层强化层,对其强化层进行耐高温试验,记录强化层上显微组织在不同保温时间的形貌变化,测量高温保温前后的磨损量变化。结果表明:不同复合电极条件加工的强化层表面形貌不同,耐磨损性能也不一样;先紫铜后石墨电极加工条件下强化层的耐磨损性能高于先石墨后紫铜电极加工的强化层;在700℃条件下,保温30 min后,强化层的磨损量一直升高,耐磨性逐渐降低,但先紫铜后石墨电极条件加工的强化层磨损量一直低于先石墨后紫铜电极条件加工的强化层磨损量,但其强化层磨损量依然低于基体表面;由不同复合电极下强化层表面观测和耐磨性能的分析结果,结合高温环境中强化层表面形貌和性能变化,发现先紫铜后石墨电极加工的强化层性能较好。

In this article,a strengthening layer was fabricated on the surface of TC4 titanium alloy by powder mixing quasi dry EDM technology using the graphite and copper composite electrode.The high temperature resistance test was carried out on the strengthened layer.The morphology changes of microstructure on the strengthened layer at different holding time were recorded,and the wear loss before and after high temperature holding was measured.The results show that the surface morphology of the strengthening layer processed by different composite electrode conditions is different,and the wear resistance is also different;the wear resistance of the strengthening layer processed by first red copper and then graphite electrode is higher than that processed with graphite first and then red copper electrode;at 700℃,after holding for 30 min,the wear amount of the strengthening layer increases all the time,while the wear resistance decreases gradually.The wear loss of the strengthening layer processed by polar condition is always lower than that processed by graphite first and then copper electrode condition,but the wear amount of the strengthening layer is still lower than that of the substrate surface.Based on observation of the surface and analysis of the wear resistance of the strengthened layer under different composite electrodes,and combining the changes of surface morphology and properties of the strengthened layer in the high temperature environment,it is found that the strengthened layer processed by the first copper and then graphite electrode has better performance.