本文選題：鎂合金 + Sn-9Zn釬料�。� 參考：《山東大學(xué)》2015年碩士論文

【摘要】：鎂合金具有高的比強(qiáng)度、比剛度和優(yōu)良的減震性、導(dǎo)熱性、電磁屏蔽性及可回收性等優(yōu)點(diǎn),在汽車交通、航空航天等領(lǐng)域日益展現(xiàn)其優(yōu)越的使用價(jià)值和廣闊的應(yīng)用前景。在鎂合金日益增加的應(yīng)用中,無論是鎂合金結(jié)構(gòu)件之間,還是鎂合金結(jié)構(gòu)件與其他材料構(gòu)件之間都離不開連接。釬焊具有加熱溫度低、對(duì)母材組織和性能的影響小、焊后應(yīng)力和變形小、工藝過程簡(jiǎn)單等特點(diǎn)。鎂合金釬焊可以避免熔化焊中常出現(xiàn)的鎂的氧化以及氣孔、裂紋等缺陷,逐漸成為鎂合金材料連接方法的首選之一。去除氧化膜作為釬焊過程中關(guān)鍵步驟,主要方法有釬劑去膜、氣體介質(zhì)去膜、機(jī)械及物理去膜。釬劑去膜作為目前應(yīng)用最廣泛有效的去膜方法,在液態(tài)釬料和母材潤(rùn)濕的過程中起主要作用。然而鎂合金釬劑的研究,特別是軟釬劑的研究、釬劑去除鎂合金氧化膜機(jī)理的研究等均剛剛開始,這些都制約了釬焊技術(shù)在鎂合金連接中的推廣和應(yīng)用。本課題從低熔點(diǎn)鎂合金釬劑入手,通過對(duì)鎂合金表面氧化膜成分分析、軟釬劑組元的選定、軟釬劑配方的設(shè)計(jì)和優(yōu)化、釬焊接頭組織和性能的研究、釬劑性能評(píng)價(jià)等一系列問題的研究,試圖找到一種適合鎂合金軟釬焊的釬劑配方。論文首先分析了AZ31B鎂合金表面氧化膜的組成。XRD和XPS數(shù)據(jù)表明,AZ31B鎂合金表面氧化膜中含有A1203以及MgO。對(duì)Sn-9Zn釬料進(jìn)行鋪展試驗(yàn)的結(jié)果表明,當(dāng)有機(jī)酸A+(5～10wt.%) NH4CI或者(1～10wt%) ZnCl2時(shí),釬料鋪展面積較大；釬劑可以以有機(jī)酸A為基體組元,ZnCl2和NH4Cl作為活性劑或者去膜劑少量加入。通過有限制的均勻設(shè)計(jì)試驗(yàn)方法對(duì)釬劑配方進(jìn)行優(yōu)化設(shè)計(jì),得到x1(NH4Cl)、x2 (ZnCl2)與鋪展面積S之間的顯著可信的回歸方程表達(dá)式為S=84.643-734.588x1+819.382x2-1408.509X1X2+3092.476x12-5144.404x22。經(jīng)過對(duì)方程求最優(yōu)解知,當(dāng)ZnC12與有機(jī)酸A質(zhì)量比為8：92時(shí)為最佳釬劑配方,此時(shí)釬料的鋪展面積最大達(dá)到117.52mm2。對(duì)釬焊接頭組織的微觀形態(tài)、組織結(jié)構(gòu)和性能研究表明,在靠近釬縫側(cè)會(huì)有一層亮白的界面層,該處可能為Mg2Sn金屬間化合物相與固溶了少量鋁、鋅的β-Sn固溶體相。釬縫中心區(qū)域主要是富鋅相和β-Sn相組成,其中有一部分細(xì)長(zhǎng)的針狀富鋅相由于耐腐蝕性差,發(fā)生選擇性腐蝕后脫落而顯示黑色的溝槽。對(duì)釬焊接頭內(nèi)各部分的顯微硬度測(cè)試發(fā)現(xiàn),由于亮白色的界面區(qū)含金屬間化合物硬質(zhì)相,硬度較釬縫有所提高,平均為130HV左右。分別對(duì)釬劑進(jìn)行分類和性能評(píng)價(jià)。結(jié)果表明,所研制的釬劑編號(hào)為FS222B,不揮發(fā)物含量高達(dá)86.4%,腐蝕率平均值為0.0133g/cm2,說明該釬劑腐蝕性很強(qiáng),焊后需要進(jìn)行徹底的清洗。
[Abstract]:Magnesium alloys have the advantages of high specific strength, specific stiffness, excellent shock absorption, thermal conductivity, electromagnetic shielding and recoverability, etc., which are increasingly showing their superior use value and broad application prospects in automotive traffic, aerospace and other fields. In the increasing application of magnesium alloy, no matter between magnesium alloy structure or magnesium alloy structure and other material components can not be separated from the connection. Brazing is characterized by low heating temperature, little influence on microstructure and properties of base metal, small stress and deformation after welding, and simple process. Magnesium alloy brazing can avoid the defects such as oxidation of magnesium, porosity, crack and so on, which becomes one of the preferred bonding methods for magnesium alloys. The removal of oxide film is a key step in brazing process. The main methods are flux defilm, gas medium film removal, mechanical and physical film removal. As the most widely used and effective method of film removal, flux film removal plays an important role in the wetting process of liquid solder and base metal. However, the research of magnesium alloy flux, especially the study of soft flux, and the mechanism of flux removing magnesium alloy oxide film are just beginning, which restrict the application of brazing technology in magnesium alloy connection. Starting with the flux of low melting point magnesium alloy, the composition of oxide film on magnesium alloy surface, the selection of soft flux component, the design and optimization of soft flux formula, the microstructure and properties of brazing joint are studied. A series of problems such as flux performance evaluation are studied to find a flux formula suitable for soft brazing of magnesium alloy. The composition of oxidation film on AZ31B magnesium alloy was analyzed. XRD and XPS data showed that A1203 and MgO were found in the oxide film of AZ31B magnesium alloy. The results of spreading test on Sn-9Zn solder show that when organic acid A (5 ~ 10wt.%) NH _ 4CI or (1 ~ 10 wt ~%) ZnCl _ 2 is used, the spreading area of the filler metal is larger, and the flux can be added with organic acid A as the base components, ZnCl _ 2 and NH _ 4Cl as active agents or defilm remover in a small amount. The formula of flux was optimized by a limited uniform design test method, and the significant and credible regression equation between x 1 (NH 4Cl) x 2 (ZnCl 2) and spreading area S was obtained as follows: s 84.643-734.588x 1 819.382x 2-1408.509x 2 3092.476x 12-5144.404x22. By finding the best solution to the equation, when the mass ratio of ZnC12 to organic acid A is 8:92, the best flux formulation is obtained, and the maximum spreading area of the solder is 117.52 mm ~ 2 mm ~ (2). The microstructure, microstructure and properties of brazed joints show that there will be a bright white interfacial layer near the brazing seam side, where there may be Mg2Sn intermetallic compound phase and 尾 -Sn solid solution phase with a small amount of aluminum and zinc solution. Zinc rich phase and 尾 -Sn phase are the main components in the center of brazing seam. Some of the thin needle-rich zinc-rich phases show black grooves due to their poor corrosion resistance and selective corrosion. The microhardness test of each part of brazed joint shows that the hardness is higher than that of brazing joint due to the intermetallic hard phase in the bright white interfacial area, and the average hardness is about 130 HV. The fluxes were classified and evaluated. The results show that the flux number is FS222B, the content of non-volatile matter is up to 86.4 and the average corrosion rate is 0.0133g / cm ~ 2, which indicates that the flux is very corrosive and needs to be cleaned thoroughly after welding.
【學(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TG425.1

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 祁慶琚,劉勇兵,楊曉紅;鎂合金的研究及其在汽車工業(yè)中的應(yīng)用與展望[J];汽車工程;2002年02期

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本文編號(hào)：2055778