Zn挥发对Ag-Cu-Zn钎料在TiC-Ni金属陶瓷表面润湿性的影响

Influence of Zn evaporation on wetting of Ag-Cu-Zn brazing alloy on TiC-Ni cermet

采用Ag-Cu-Zn钎料对TiC-Ni金属陶瓷进行润湿.结果表明,真空条件下,以22.5℃/min的速率加热至810℃,保温10 min,Ag-Cu-Zn/TiC-Ni金属陶瓷三相线附近界面生成了连续的(Cu,Ni)组织.钎料在TiC-Ni金属陶瓷表面润湿过程先后经历孕育阶段、铺展阶段、钉扎阶段、回撤阶段和平衡阶段,最终平衡润湿角为27.3°.随着加热速率由10℃/min上升到30℃/min,Zn挥发速率加快,钎料铺展过程持续时间变短,三相线附近界面(Cu,Ni)组织数量减小,由连续的层状组织转变为断续的块状组织,且钎料在金属陶瓷表面平衡润湿角不断增大.相比真空环境,氩气环境下,Zn挥发速率降低,虽然钎料能大量溶解TiC-Ni金属陶瓷中的Ni基体,但是三相线附近界面仅有少量(Cu,Ni)形成,使其在金属陶瓷表面的润湿基底直径随时间逐渐增大,而润湿角逐渐减小,随后润湿基底直径几乎保持不变,而润湿角缓慢升高.

Wetting of Ag-Cu-Zn brazing alloy on TiC-Ni cermet was performed. The results show that continuous(Cu,Ni) layer forms at the interface of Ag-Cu-Zn/TiC-Ni cermet at 810 ℃for 10 min with a heating rate of 22.5 ℃/min in vacuum. The whole wetting process contains an incubation stage, a spreading stage, a pinning stage, a receding stage, and an equilibrium stage. The equilibrium contact angel is 27.3°.With the increase of heating rate from 10 ℃/min to 30 ℃/min,the evaporation velocity of Zn strengthens;the lasting time of the spreading process shortens, and the amount of(Cu, Ni) at the interface decreases. As a result, the equilibrium contact angel of Ag-Cu-Zn on TiC-Ni cermet increases with the heating rate. The evaporation of Zn weakens in argon. Only a little(Cu, Ni) forms at the interface of Ag-Cu-Zn/TiC-Ni cermet in argon, although the Ag-Cu-Zn brazing alloy dissolves a great amount of Ni matrix. So the base diameter firstly increases and the contact angle decreases with time, then the base diameter almost remains unchanged, and the contact angle increases slightly.