本文選題：AZ63鎂合金 + 腐蝕　； 參考：《中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院海洋研究所)》2017年博士論文

【摘要】：AZ63鎂合金(名義成分Mg-6 wt%Al-3 wt%Zn)由于其優(yōu)異的力學(xué)性能和電化學(xué)性能,已作為結(jié)構(gòu)材料和犧牲陽(yáng)極材料被廣泛應(yīng)用。本論文以3.5 wt%NaCl溶液為電解液,通過材料表征、物相分析、浸泡實(shí)驗(yàn)和電化學(xué)測(cè)試,對(duì)AZ63鎂合金的腐蝕機(jī)理,In元素合金化電化學(xué)活化機(jī)理以及In、Ga元素對(duì)AZ63鎂合金腐蝕和放電行為的影響進(jìn)行了研究。本論文的主要研究工作如下:(1)研究熱處理對(duì)AZ63鎂合金的腐蝕行為的影響。對(duì)制備的鑄態(tài)、固溶態(tài)(T4)、時(shí)效態(tài)(T5)的三種微觀組織結(jié)構(gòu)不同的AZ63鎂合金進(jìn)行了腐蝕行為研究,結(jié)果表明:T4態(tài)鎂合金由于表面氧化膜具有較好的保護(hù)性,在浸泡初期腐蝕速率為三者中最低。但隨著氧化膜消耗殆盡,T4態(tài)鎂合金表面產(chǎn)物膜對(duì)基體保護(hù)性最差,使得其腐蝕速率變成三者中最高。鑄態(tài)和T5態(tài)鎂合金晶界有析出物的存在,會(huì)與晶粒形成微電偶,在浸泡初期表現(xiàn)為高的腐蝕速率,但它們生成的腐蝕產(chǎn)物容易粘附于電極表面,因此對(duì)腐蝕的發(fā)展起到了一定抑制作用。(2)提出了In元素合金化對(duì)AZ63鎂合金電化學(xué)活化的機(jī)理。向AZ63鎂合金中添加0.5 wt%的In元素并與鎂形成固溶體,可以通過協(xié)同作用活化鎂合金,協(xié)同作用具體包括:促進(jìn)晶界第二相的析出、生成易脫附的腐蝕/放電產(chǎn)物以及In元素的“溶解-再沉積”作用。(3)In元素合金化提高了鎂合金的腐蝕和放電活性。通過向AZ63鎂合金中添加不同質(zhì)量分?jǐn)?shù)(1 wt%,1.5 wt%,2 wt%)的In元素,結(jié)果表明:In元素合金化在鎂合金自腐蝕和放電情況下均能起到活化作用。主要通過細(xì)化合金晶粒、促進(jìn)Mg17Al12相析出和In元素的“溶解-再沉積”來實(shí)現(xiàn)。Mg-6 wt%Al-3 wt%Zn-1.5wt%In合金自腐蝕速率最高,但放電性能卻并不理想,說明由Mg17Al12相引起的電流屏蔽作用在陽(yáng)極極化條件下得到了強(qiáng)化。(4)Ga元素合金化降低了鎂合金的腐蝕速率卻提高了放電活性。通過向AZ63鎂合金中添加2 wt%的Ga元素,結(jié)果表明:由于Ga元素促進(jìn)了第二相Mg17Al12和GaMg2在晶界上的析出,第二相形成了網(wǎng)狀結(jié)構(gòu),該結(jié)構(gòu)能有效屏蔽腐蝕電流,因此含Ga的AZ63鎂合金的自腐蝕過程受到抑制。然而,Ga元素的合金化卻可以使鎂合金的放電電位顯著負(fù)移,提供高的電流密度,形成有利于電解液滲透的薄而細(xì)的產(chǎn)物膜,提高陽(yáng)極材料的電流效率,提高鎂合金作為陽(yáng)極材料的放電能力。
[Abstract]:AZ63 magnesium alloy (nominal composition Mg-6 wt%Al-3 wtZn3) has been widely used as structural material and sacrificial anode material due to its excellent mechanical and electrochemical properties. In this paper, 3.5 wtNaCl solution was used as electrolyte, which was characterized by material, phase analysis, immersion test and electrochemical test. The corrosion mechanism of AZ63 magnesium alloy and the electrochemical activation mechanism of in alloying and the effect of Ingallium on corrosion and discharge behavior of AZ63 magnesium alloy were studied. The main work of this thesis is as follows: 1) the effect of heat treatment on corrosion behavior of AZ63 magnesium alloy is studied. The corrosion behavior of three kinds of AZ63 magnesium alloys with different microstructure, such as as-cast, solid solution T4N, aged T5), was studied. The results showed that the oxidation film on the surface of the WT4 magnesium alloy had better protection, and the corrosion behavior of the AZ63 magnesium alloy with different microstructure was studied, and the corrosion behavior of the AZ63 magnesium alloy with different microstructure was studied. The corrosion rate was the lowest in the initial soaking stage. However, with the depletion of oxide film, the surface product film of T4 magnesium alloy has the worst protection to the substrate, which makes the corrosion rate of magnesium alloy become the highest of the three. There are precipitates in the grain boundaries of as-cast and T5 magnesium alloys, which will form microelectric couples with the grains and exhibit a high corrosion rate at the beginning of soaking, but the corrosion products produced by them are easy to adhere to the surface of the electrode. The mechanism of in alloying on the electrochemical activation of AZ63 magnesium alloy was proposed. Adding 0.5 wt% in element to AZ63 magnesium alloy and forming solid solution with magnesium can activate magnesium alloy by synergistic action, which includes promoting the precipitation of the second phase in grain boundary. The corrosion and discharge activity of magnesium alloys were improved by the formation of easily desorption corrosion / discharge products and the "dissolution-redeposition" effect of in elements. By adding in elements of different mass fractions of 1 wtand 1.5 wtand 2 wts to AZ63 magnesium alloy, the results show that the in alloying of AZ63 magnesium alloy can be activated under the condition of self-corrosion and discharge. Mg-6 wt%Al-3 wtZn-1.5wtIn alloy has the highest self-corrosion rate, but the discharge performance is not ideal, mainly by refining the alloy grain, promoting the precipitation of Mg17Al12 phase and "solution-redeposition" of in element. The results show that the current shielding effect caused by mg _ (17) Al _ (12) phase increases the corrosion rate of mg _ (17) Al _ (12) alloy and increases its discharge activity. By adding 2 wt% Ga to AZ63 magnesium alloy, the results show that the second phase forms a network structure because Ga can promote the precipitation of Mg17Al12 and GaMg2 on the grain boundary, and the structure can shield corrosion current effectively. Therefore, the self-corrosion process of Ga-containing AZ63 magnesium alloy is restrained. However, the alloying of Ga can significantly shift the discharge potential of magnesium alloy, provide high current density, form thin and thin product film which is favorable to electrolyte permeation, and improve the current efficiency of anode material. The discharge capacity of magnesium alloy as anode material was improved.
【學(xué)位授予單位】：中國(guó)科學(xué)院大學(xué)(中國(guó)科學(xué)院海洋研究所)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG172

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