【摘要】 采用Ti基活性钎料对高强石墨进行了高温钎焊试验。研究了焊接温度、保温时间、焊料量、降温速率对试样连接强度的影响。通过正交实验优选工艺,确定最佳工艺为:焊接温度1420℃,保温时间20rain,焊料量280mg,降温速率10℃/min。所得连接件的最高相对抗弯强度为62.55%。微观结构研究表明,在石墨/焊料界面处C元素和Ti元素发生了显著的互扩散,生成了厚度约15μm的反应层,实现了良好的界面结合。接头区域XRD分析表明,在石墨/焊料界面上几乎全部为TiC,在焊料内部距此界面200μm处仍有部分TiC存在,但主相是纯Ti,还有部分Ti2Ni。在焊料内部距此界面400μm处主相是纯Ti,次相是Ti2Ni,无TiC存在。更多还原

【Abstract】 Joining of high strength graphite has been realized by high temperature welding with Ti+Ni solder. The effects of the technological parameters, such as welding temperature, duration of keeping temperature, solder weight and rate of decreasing temperature, on the bending strength of welded samples were studied. The optimized technological parameters are 1 420℃, 20 min, 280 mg, 10℃/min for the welding temperature, duration of keeping temperature, solder weight and rate of decreasing temperature, respectively. The bending strength of the welded samples under these conditions reaches 62.55% of normal graphite. The mechanism of bonding has been investigated based on the observation of microstructure and the determination of elements distribution of the welded area. It is shown that an interdiffusion takes place in the interfaces, forming a reaction layer of 15μm in thickness, which contributes to the good bonding of interfaces. The XRD analysis in the welded area indicates that it is almost TiC in the graphite/solder interface. In the cross section 200μ m away from the graphite/solder interface inside the solder, the major phase is Ti, while some TiC and Ti2Ni exist, but no TiC was found in the cross section 400 urn away from the interface,.更多还原