烧结硬焊连接粉末冶金件的技术开发

Technical development for joining of powder metallurgical parts by sinter brazing

在皮带滑座生产中,机械加工耗费了一半以上的工时,为此作者采用烧结硬焊技术,将皮带滑座制备工艺改变为皮带座硬焊接合滑座圆盘工艺。为评估不同商用硬焊填料在烧结炉中的熔融硬焊结合行为,将硬焊填料安置于粉末冶金试片结合处,再放入一般的铁系烧结炉中进行30 min的烧结硬焊(烧结温度为1 120℃、烧结气氛为裂解丙烷),观察不同硬焊填料在试片之间产生的扩散行为与结合状况,借以判定在铁系合金烧结条件下较适合的硬焊填料;而后将此硬焊填料应用于由烧结硬化合金钢所压制的皮带座与滑座圆盘的组合上。实验结果表明,硬焊填料适当的扩散能力,将促使填料与粉末冶金零件压坯间产生适当的扩散层,既维持大部分零件基体的原有特性,又能保留大量的硬焊填料存留于粉末冶金坯体间,因而形成渐层结构的高强度硬焊界面。与传统粉末冶金工艺相比,采用烧结硬焊技术后,皮带滑座的制造成本降低30%,而皮带滑座的结合力仅减小约10%。

The present paper mainly discusses the sinter brazing technical development for improving the manufacture process of PM strap skate. Because of more than half of the total process time of strap skate being wasted by machining, it is necessary to develop a sinter brazing technology to change the original manufacture process into a new process of joining strap seat and skate disk by brazing. For evaluating the fused braze joining behavior of different commercial braze fillers, the author set the fillers over the joint of PM parts and put them into a conventional iron-based sintering furnace respectively, then the sinter brazing experiment was carried out in 30 min at 1120 ℃ by using cracking propane as sintering atmosphere. By observing the diffusion behavior and joining condition of fillers among the parts, it is expected to find a preferable brazing filler in iron--based sintering condition, and further , more, making the filler in application to the joining of parts produced by sinter hardening. The results show that appropriate diffusion abilities of brazing fillers lead to the formation of relevant proper diffusion layers. These diffusion abilities can not only maintain the properties of mostly parts matrix, but also reserve abundant of fillers among the parts. So using this technology can make the formation of high strength brazing interface having gradual layer structure. Contrast with conventional PM process, this technology can make the cost for manufacturing strap skate go down 30% while binding force only decrease about 10%.