本文選題：AZ91D鎂合金　切入點：重復浸鋅　出處：《湘潭大學》2017年碩士論文　論文類型：學位論文

【摘要】：鎂合金具有低密度、高比強度、高比剛度以及良好的導電性能和電磁屏蔽性能等優(yōu)點,在航空航天、汽車和電子工業(yè)等領(lǐng)域有廣闊的應(yīng)用前景,但鎂合金較差的耐蝕性能是限制其實際應(yīng)用的主要因素之一。電鍍方法是提高鎂合金耐蝕性能的有效途徑之一,然而鎂在常規(guī)的電鍍液中極不穩(wěn)定。如何對鎂合金表面進行預處理并找出合適的鍍液和電鍍工藝成為當前該領(lǐng)域的研究熱點。因此,本論文以AZ91D鎂合金為研究對象,開展了鎂合金表面預處理及電鍍鎳工藝研究,同時對電鍍后鎂合金的耐蝕性能進行了評估。本文的主要研究如下:(1)對AZ91D鎂合金電鍍表面預處理工藝(酸洗、活化、浸鋅等工藝)進行了研究,結(jié)果表明,經(jīng)本工作配制的酸洗液(磷酸242mL/L+濃硝酸12mL/L)酸洗40s后進行活化浸鋅(活化4min、浸鋅15min)后得良好的浸鋅效果,且(酸洗活化后)樣品表面殘余氧化物的去除以及更少的坑蝕有利于浸鋅層的沉積,進一步研究發(fā)現(xiàn)重復浸鋅后再進行電鍍鎳制備的電鍍鎳層成分均一且其結(jié)合力優(yōu)于一次浸鋅。(2)對AZ91D鎂合金電鍍鎳工藝進行了研究,對比分析了脈沖電鍍鎳工藝和直流電鍍鎳工藝對鍍鎳層的影響。結(jié)果表明,采用直流電鍍的電鍍效率優(yōu)于脈沖電鍍,而對于脈沖電鍍(脈沖頻率1000Hz+電流密度為1.25A/dm2),占空比為20%、80%時電鍍效率較高,而直流電鍍(電流密度為1.25A/dm2)以及脈沖電鍍(脈沖頻率1000Hz+占空比為60%和80%+電流密度為1.25A/dm2)均可在AZ91D鎂合金表面制備出成分均一的電鍍鎳層,直流電鍍鎳所得鍍鎳層耐蝕性能最好,且鎳鍍層與基體結(jié)合力均符合熱震測試標準(美國材料協(xié)會標準ASTM B571-97)。(3)對AZ91D鎂合金電鍍銅鎳復合鍍層的工藝進行了研究,本文找出了一種適用AZ91D鎂合金的電鍍銅鍍液配方,并采用該配方制備出了界面結(jié)合緊密、覆蓋良好的銅鍍層。在此基礎(chǔ)上采用脈沖電鍍鎳(脈沖頻率1000Hz+電流密度為2A/dm2+占空比80%)和直流電鍍鎳(電流密度為2A/dm2)均制備出成分均一的電鍍鎳層,其中直流電鍍制備的復合鍍層的耐蝕性能優(yōu)于脈沖電鍍鍍層,鎳鍍層納米硬度達3.66GPa遠高于鎂合金基體,銅鎳鍍層與基體結(jié)合力均符合熱震測試標準(美國材料協(xié)會標準ASTM B571-97)。
[Abstract]:Magnesium alloys have many advantages, such as low density, high specific strength, high specific stiffness, good electrical conductivity and electromagnetic shielding, etc., and have broad application prospects in aerospace, automotive and electronic industries. But the poor corrosion resistance of magnesium alloy is one of the main factors restricting its practical application. Electroplating is one of the effective ways to improve the corrosion resistance of magnesium alloy. However, magnesium is very unstable in conventional electroplating bath. How to pretreat magnesium alloy surface and find out appropriate plating bath and electroplating process has become a hot research topic in this field. Therefore, this paper takes AZ91D magnesium alloy as the research object. The surface pretreatment and nickel plating process of AZ91D magnesium alloy were studied, and the corrosion resistance of the electroplated magnesium alloy was evaluated. The main research in this paper is as follows: 1) the pretreatment process of AZ91D magnesium alloy electroplating surface (acid pickling, activation, acid washing, activation). The results showed that the acid washing solution (242mL / L phosphoric acid / L concentrated nitric acid 12ml / L) prepared by this work had a good zinc dipping effect after 40 s acid washing (4 min activation, 15 min zinc dipping). Moreover, the removal of residual oxides on the surface of the sample and less pit erosion are beneficial to the deposition of the zinc dipping layer. It was found that the nickel electroplating process of AZ91D magnesium alloy was more uniform and its binding force was better than that of primary galvanizing. The nickel electroplating process of AZ91D magnesium alloy was studied. The effects of pulse electroplating and direct current nickel plating on nickel plating are compared. The results show that the efficiency of direct current electroplating is better than that of pulse electroplating. For pulse electroplating (pulse frequency 1000Hz current density is 1.25A / d m ~ (2), duty cycle is 20), electroplating efficiency is higher at 80 ~ (th). On the other hand, DC electroplating (current density 1.25A / dm2) and pulse electroplating (pulse frequency 1000Hz duty cycle 60% and 80% current-density 1.25A / dm2) can produce uniform nickel electroplating on the surface of AZ91D magnesium alloy, and direct current electroplating nickel has the best corrosion resistance. The adhesion between nickel coating and substrate is in accordance with the thermal shock test standard (ASTM B571-97Pu. 3). The process of electroplating copper-nickel composite coating on AZ91D magnesium alloy has been studied. In this paper, a formula of copper plating solution suitable for AZ91D magnesium alloy has been found out. The interface is tightly bonded by this formula. On the basis of this, nickel electroplating layer with uniform composition was prepared by pulse electroplating nickel (pulse frequency 1000Hz current density 2A / dm2 duty cycle 80) and direct current electroplating nickel plating (current density 2A / dm2). The corrosion resistance of the composite coating prepared by DC electroplating is better than that of pulsed electroplating. The nano hardness of nickel coating is 3.66 GPA, which is much higher than that of magnesium alloy substrate. The adhesion between copper and nickel coating meets the thermal shock test standard (ASTM B571-97).
【學位授予單位】：湘潭大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG174.44;TQ153.12

【參考文獻】

相關(guān)期刊論文 前10條

1 Chuan Xu;Guangmin Sheng;Hui Wang;Ke Feng;Xinjian Yuan;;Tungsten Inert Gas Welding Brazing of AZ31B Magnesium Alloy to TC4 Titanium Alloy[J];Journal of Materials Science & Technology;2016年02期

2 曾榮昌;胡艷;張芬;黃原定;王振林;李碩琦;韓恩厚;;AZ31鎂合金表面鈰摻雜鋅鈣磷酸鹽化學轉(zhuǎn)化膜的腐蝕性能（英文）[J];Transactions of Nonferrous Metals Society of China;2016年02期

3 董國君;馬福秋;王桂香;;硅溶膠封孔對AZ31鎂合金陽極氧化膜抗腐蝕性能的影響（英文）[J];稀有金屬材料與工程;2016年01期

4 王艷珍;王淑敏;;鎂合金表面防腐技術(shù)研究進展[J];江西化工;2015年05期

5 陳玉安;金李;方丹;宋裕;葉睿宇;;Effects of calcium, samarium addition on microstructure and mechanical properties of AZ61 magnesium alloy[J];Journal of Rare Earths;2015年01期

6 高陽;高揚;肖國良;李國良;張衛(wèi)東;金敏;德雪紅;卜樂平;;硼與稀土對鎂合金作用的研究進展[J];材料導報;2014年21期

7 吳道高;顏世宏;王志強;張志琦;苗睿瑛;張小偉;陳德宏;;Effect of samarium on microstructure and corrosion resistance of aged as-cast AZ92 magnesium alloy[J];Journal of Rare Earths;2014年07期

8 楊淼;劉耀輝;劉家安;宋雨來;;Corrosion and mechanical properties of AM50 magnesium alloy after being modified by 1 wt.% rare earth element gadolinium[J];Journal of Rare Earths;2014年06期

9 陶學偉;王章忠;巴志新;孔時瀟;胡期翔;;鎂合金離子注入表面改性技術(shù)研究進展[J];材料導報;2014年07期

10 李思思;馬捷;賈平平;魏建忠;;AZ31鎂合金表面化學氣相沉積鎢涂層工藝及其耐蝕性和耐磨性[J];中國表面工程;2014年01期

相關(guān)博士學位論文 前2條

1 葛亞瓊;快速冷卻下鎂合金激光表面改性行為研究[D];太原理工大學;2014年

2 雷細平;鎂合金沉積耐蝕金屬鍍層機理及工藝研究[D];湖南大學;2012年

相關(guān)碩士學位論文 前4條

1 范鵬;ZM-1鎂合金直接化學鍍鎳磷合金工藝及其性能研究[D];哈爾濱工業(yè)大學;2013年

2 劉嶺松;pH值對鎂合金化學鍍鎳影響機理的研究[D];湖南大學;2012年

3 趙磊;鎂合金化學鍍鎳工藝的研究[D];成都理工大學;2012年

4 盧神保;AZ91D鎂合金表面電鍍銅/鎳新工藝研究[D];中南大學;2009年

，

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