铜基钎料钎焊W-Cu复合材料与不锈钢的连接机理研究

发布时间：2018-08-09 12:29

【摘要】：钨铜复合材料由于其兼具铜和钨的优异性能,在现代化的生活中越来越得到重视和应用。但是在实际的使用过程中,钨铜复合材料存在韧性不足和抗氧化性能差的缺点,所以为了提高抗氧化性能,考虑用抗氧化性好的不锈钢材料和钨铜复合材料连接在一起,这样可以扩大钨铜复合材料的应用邻域。在现行的条件下,采用银基焊料、金基焊料钎焊的时候焊接性能较好,钎焊接头的强度也较高,但是成本太高难以实现大规模使用。当采用镍基焊料时钎缝容易出现脆性层等缺点,而且一般情况下镍基钎料的接头强度较低。所以本文在研究基础之上选择铜基钎料来钎焊钨铜和不锈钢材料。本课题使用熔炼的Cu-Mn-Co-Ni3、Cu-Mn-Co-Zr3、Cu-Mn-Co-Zr5以及Cu-Ni-Ti四种成分的钎料对钨铜复合材料和不锈钢进行钎焊连接,然后分析钎缝的微观组织和元素扩散特征,测试接头的弯曲强度及断裂特征,研究钨铜复合材料和18-8不锈钢的连接机理。Cu-Mn-Co-Ni3钎料钎焊接头的组织是由Cu基固溶体和富Fe相:Cu(Mn-Fe)和Fe(Co)组成,这类组织有利于提高接头的塑韧性。其接头弯曲强度高达590MPa,接头断裂于钨铜母材近缝区,断面上出现大量韧窝。添加的Ni元素可以提高接头的耐高温性能,Ni与W在高温下固溶也有利提高接头性能。对于Cu-Mn-Co-Zr3、Cu-Mn-Co-Zr5这两种钎料而言,随着活性元素Zr的加入,提高了钎料和母材元素的扩散。钎缝主要是由Cu基固溶体和富Fe相:Cu(Mn-Fe)和Fe(Co)组成,通过分析发现Fe2Zr、CuZr_2等金属间化合物。二种钎料的钎焊接头弯曲强度都超过450MPa,但是随着Zr含量的增加会导致接头金属间化合物的增加,不利于接头性能,所以含量为5%的钎料性能不如含量为3%的钎料。对于Cu-Ni-Ti钎料而言,钎焊接头钎缝主要由(Cu-Ni)和(Fe-Ni)富铜富铁相、Cu-Ti等金属化合物以及微量的(Ti-W)、(Ni-W)固溶体组成。Ti作为活性元素添加在钎料中,可以促进钨铜中的Cu朝着钎缝扩散,Ti还能去W形成有限固溶体,Ni在高温情况下和W可以固溶,对于提高接头的塑韧性起到积极的作用,Cu-Ni-Ti钎料的钎焊接头断面主要由韧窝痕和解理面组成,性能比前面钎料稍差,弯曲强度为440Mpa。
[Abstract]:Due to its excellent properties of both copper and tungsten, tungsten and copper composites have been paid more and more attention to and applied in modern life. However, in the process of practical use, tungsten and copper composites have the disadvantages of poor toughness and poor oxidation resistance, so in order to improve the oxidation resistance, we consider using stainless steel materials with good oxidation resistance to connect with tungsten and copper composites. In this way, the application neighborhood of tungsten and copper composites can be expanded. Under the current conditions, the gold-based solder has good welding performance and high strength of brazed joints, but the cost is too high to realize large-scale use. When the nickel-based solder is used, the brazing seam is prone to appear brittle layer, and the joint strength of the nickel-based solder is low in general. Therefore, based on the research, copper-based solder is selected to braze tungsten-copper and stainless steel. In this paper, brazing of tungsten and copper composites and stainless steel was carried out by using the melting Cu-Mn-Co-Ni3CU Cu-Mn-Co-Zr5 and Cu-Ni-Ti brazing materials. The microstructure and elemental diffusion characteristics of the brazing joints were analyzed, and the bending strength and fracture characteristics of the joints were tested. The bonding mechanism between tungsten and copper composites and 18-8 stainless steel was studied. The microstructure of brazed joints with Cu-Mn-Co-Ni3 solder is composed of Cu-based solid solution, Fe-rich phase: Mn-Fe and Fe (Co). This kind of microstructure is beneficial to improve the toughness of the joints. The bending strength of the joint is as high as 590MPa, and the joint breaks near the joint area of tungsten and copper base metal, and a large number of dimples appear on the cross section. The addition of Ni element can improve the high temperature resistance of the joints. The solution of Ni and W at high temperature can also improve the properties of the joints. For Cu-Mn-Co-Zr3- Cu-Mn-Co-Zr5 solder, the diffusion of filler metal and base metal elements increased with the addition of active element Zr. The brazing seam is mainly composed of Cu-based solid solution, Fe rich phase: Cu (Mn-Fe) and Fe (Co). The bending strength of the brazed joints of the two kinds of solders is more than 450 MPA, but with the increase of Zr content, the intermetallic compounds of the joints will increase, which is not conducive to the properties of the joints. Therefore, the brazing filler metals containing 5% of the filler metals are inferior to the filler metals with the content of 3%. For Cu-Ni-Ti solder, brazing joint is mainly composed of (Cu-Ni) and (Fe-Ni) copper-rich iron phase Cu-Ti and trace (Ti-W), (Ni-W) solid solution. It can promote the diffusion of Cu in tungsten and copper towards the brazing seam. It can also remove W to form a finite solid solution, Ni and W can be dissolved at high temperature. The joint section of Cu-Ni-Ti brazing filler metal is mainly composed of dimple marks and surfaces, and its properties are a little worse than that of the former brazing filler metal. The bending strength is 440 Mpa.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG454

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