發(fā)布時間：2018-04-26 02:30

  本文選題：銅 + 鉬��； 參考：《南京理工大學》2017年碩士論文

【摘要】：銅以其優(yōu)良的導電、導熱、機加工等性能在越來越多的領域中發(fā)揮著重要作用,是當今社會最重要的有色金屬之一。但在一些有電弧燒蝕、摩擦磨損的工況條件下,銅合金的應用受到限制,使用壽命縮短。為了解決這一問題,可以采用在銅表面復合鉬的方法來增強銅合金的耐電弧燒蝕、耐磨損性能。由于銅、鉬在固相和液相下均完全不互溶,復合銅鉬是焊接領域的一個技術難題。本文分別采用Ni箔、Ti箔和AgCuTi釬料作為中間層來焊接復合Cμ、Mo金屬。分析了材料焊接接頭的微觀結構、力學性能和斷口組織。討論了焊接溫度、焊接時間、焊接壓力等工藝參數(shù)對結合強度、接頭微觀結構的影響。分別得到不同中間層時的最佳工藝參數(shù),并分析了 Ti中間層的焊接過程。研究結果表明:正交試驗結果表明:采用Ni箔中間層時,在焊接溫度800℃、焊接時間30min、焊接壓力7MPa的條件下,擴散焊接復合的剪切強度最高,達到了 46.7MPa;通過極差分析和方差分析,三個主要工藝因素中,影響力顯著性排序為:焊接溫度焊接壓力焊接時間。焊接復合接頭斷裂在Ni中間層中靠近鉬側的Mo-Ni互擴散區(qū)域,為脆性斷裂。AgCu釬料不能潤濕金屬Mo,而在加入Ti元素后,釬料和Mo有較好的潤濕性。這主要因為在反應過程中,Ti和Mo能形成固溶體界面,使得Mo與釬料之間的界面能降低,液態(tài)釬料才能能夠在Mo表面潤濕。隨著焊接溫度升高,Mo側的形核數(shù)目增多,組織變得致密;Cu側的柱狀組織向中間層延伸,變得粗大。在880℃下保溫30min時,接頭的剪切強度達到了 89.3MPa。采用Ti箔中間層時,隨著溫度和壓力的增大,焊接強度逐漸增大;隨著焊接時間的增加,焊接強度先增大再減小。在焊接過程中,接頭處Cu和Ti之間會發(fā)生共晶反應生成多種金屬間化合物。在880℃下,生成的液相較少,焊接后中間層Ti箔仍然存在,生成的金屬間化合物殘留在接頭孔隙處,界面處有明顯未焊透缺陷;930℃和1030℃下,生成的液相較多,大都被擠出焊接區(qū)域,接頭成形較好。以焊接接頭剪切強度為評價指標,最佳焊接復合工藝為1030℃、30min、5MPa,剪切強度達到了 201.5MPa;若兼顧剪切強度與焊接變形,最佳焊接復合工藝為1030℃、30min、3MPa,剪切強度達到了 180.3MPa。
[Abstract]:Copper plays an important role in more and more fields because of its excellent electrical conductivity, heat conduction and machining properties. It is one of the most important nonferrous metals in the society today. However, under the condition of arc ablation and friction wear, the application of copper alloy is limited and the service life is shortened. In order to solve this problem, the arc ablation resistance and wear resistance of copper alloy can be enhanced by using molybdenum compound on copper surface. Because copper and molybdenum are completely insoluble in solid and liquid phase, composite copper and molybdenum is a technical problem in welding field. In this paper, Ni foil Ti foil and AgCuTi filler metal are used as interlayer to weld composite C 渭 Mo metal. The microstructure, mechanical properties and fracture structure of welded joints were analyzed. The effects of welding temperature, welding time and welding pressure on bonding strength and microstructure of joints are discussed. The optimum process parameters of different interlayers were obtained, and the welding process of Ti interlayer was analyzed. The results show that when the interlayer of Ni foil is used, the shear strength of diffusion welding composite is the highest under the condition of welding temperature 800 鈩，

本文編號：1804094