【作者】 于康；

【导师】 李卓然；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2010， 硕士

【摘要】 膜片类元件作为箭体阀门弹性元件,常因自身的缺陷而限制了其适用范围。本文采用GH4169合金膜盒结构代替膜片结构,研究了GH4169合金直接扩散连接和加中间层Cu或Ni箔的间接扩散连接工艺,包括表面处理状态、扩散连接温度、保温时间、扩散压力的影响。借助SEM、EDS、XRD、纳米压痕等分析测试手段,分析了工艺参数对接头界面组织结构及性能的影响。通过对GH4169合金真空直接扩散连接的试验和分析,确定采用HCl+HNO3复合酸化学酸洗处理GH4169合金表面,能有效去除其表面稳定而致密的氧化膜Cr2O3和Al2O3。接头界面没有任何反应层生成,只有扩散孔隙的存在。随着连接温度的升高,保温时间的延长,扩散压力的增大,接头扩散孔隙数量减少,尺寸变小。以抗拉强度来评价GH4169合金扩散连接接头力学性能,在T=1100℃,t=90min,P=40MPa条件时,接头扩散孔隙基本消失,接头抗拉强度可达707MPa,接头变形量为9.8%,此时接头在界面处断裂,为脆性断裂。采用纯Cu箔中间层间接扩散连接GH4169合金,接头界面处只有固溶体层的生成;随着中间层厚度的减小,接头强度逐渐提高;当Cu箔中间层厚度为20μm时,随着连接温度的升高,保温时间的延长,扩散压力的增大,固溶体层厚度先逐渐变大,后缓慢变化,接头抗拉强度也呈现先快速增长,后平缓变化的趋势。当T=950℃/t=60min/P=10MPa时,接头抗拉强度达到720MPa;接头断裂在Cu中间层。采用纯Ni箔中间层间接扩散连接GH4169合金,接头界面与直接扩散连接相似,只有扩散孔隙的存在;随着连接温度的升高,保温时间的延长,扩散压力的增大,扩散孔隙逐渐消失,接头抗拉强度呈现先快速增长后平缓变化的趋势。当T=990℃/t=75min/P=15MPa时,接头抗拉强度达840MPa;接头断裂位置在中间层Ni。最后,以Ni箔作为GH4169合金间接扩散连接的中间层材料,采用整体拘束方式间接扩散连接膜盒结构,焊后变形较小。更多还原

【Abstract】 Diaphragm foil device as rockets elastic element, were often limited by their own shortcomings. In order to use the diaphragm box to instead of diaphragm foil, the teshnics of GH4169 alloy direct vacuum diffusion bonding and indirect diffusion bonding with Cu foil or Ni foil were investigated, including the effects of the surface state, joining temperature, holding time and diffusion pressure. With the help of SEM, EDS, XRD, nanoindentation and other analysis and detection methods, the effects of process parameters on the joint interface structure and properties were analysised.Direct vacuum diffusion bonding was adopted to connect GH4169 alloy. According to the test and analysis results, HCl + HNO3 compound acid was used to treat GH4169 alloy which could effectively remove the dense oxide film Cr2O3 and Al2O3 on the surface. The results revealed that interface reaction layer was not formed between the joint where only exited diffusion pore. As the joining temperature, holding time and diffusion pressure growing, the number of joint diffusion pore reduced and its size also becomed smaller.In this paper, tensile strength was adopted to evaluate the mechanical properties of GH4169 alloy diffusion bonding joints. On the condition that T = 1100℃, t = 90min, P = 40MPa, the diffusion pore in the joints disappeared during this time while the joint tensile strength was up to 707MPa and joint deformation reached 9.8%. At this time joint fracture at the interface was proved to be brittle fracture.Pure Cu foil interlayer was adopted to GH4169 alloy indirect bonding. In this case, only solid solution layer was generated in the joint interface; with the interlayer thickness reduced, the joint strength gradually improved; when the Cu foil interlayer thickness reached 20μm, with the joining temperature increased, holding time prolonged and the pressure enhanced, the solid melts layer gradually thicken and tensile strength of joints had a trend that change in rapidly growing at first and then change gently. When T = 950℃/ t = 60min / P = 10MPa, the joint tensile strength reached 720MPa; joint fractures were in the middle layer of Cu.When pure Ni foil interlayer is adopted to GH4169 alloy indirect bonding, the joint interface was similar to the joint of direct diffusion bonding where only diffusion pores presented; with the joining temperature increased, holding time prolonged and the pressure enhanced, diffusion pores gradually disappeared and the joint tensile strength exhibited a trend that rapidly growing at first and then slowly changing. When T = 990℃/ t = 75min / P = 15MPa, the joint tensile strength is up to 840MPa; joint fractures were in the middle layer of Ni foil. Finally, Pure Ni foil interlayer was adopted to GH4169 alloy indirect bonding. In order to obtain little deformation, the method of overall binding was used to bond GH4169 alloy.更多还原