本文選題：鎂合金 + 稀土鈰��； 參考：《哈爾濱工業(yè)大學(xué)》2017年碩士論文

【摘要】：在鎂合金表面制備疏水涂層是目前一種研究廣泛的防護(hù)手段;眾多研究表明稀土鈰的緩蝕性在鎂合金上作用明顯。本實(shí)驗(yàn)采用陰極電沉積的方法直接在AZ31鎂合金表面制備出單一的十四酸鈣和十四酸鈰以及鈣鈰混合的疏水涂層,涂層的存在顯著提高了鎂合金的腐蝕性能。通過(guò)研究制備工藝參數(shù)(沉積電壓和沉積時(shí)間)對(duì)單一Ca鹽(或Ce鹽)涂層形態(tài)以及腐蝕行為的影響,以及Ca-Ce復(fù)合涂層沉積時(shí)間比和Ca-Ce摩爾比對(duì)Ca-Ce復(fù)合涂層的形態(tài)及腐蝕行為的影響,發(fā)現(xiàn)涂層的制備工藝參數(shù)顯著影響涂層的形貌及腐蝕性能,但并不影響涂層的物相組成。Ca鹽涂層的物相組成為(CH3(CH2)12COO)2Ca,Ce鹽涂層的物相是由(CH3(CH2)12COO)4Ce和(CH3(CH2)12COO)3Ce組成的。研究結(jié)果表明,沉積電壓為50V時(shí),無(wú)論是單一Ca鹽涂層還是Ce鹽涂層,其耐蝕性能最好;對(duì)于單一Ca鹽涂層,沉積時(shí)間越長(zhǎng),其耐蝕性能越優(yōu)異;對(duì)于單一Ce鹽涂層,沉積時(shí)間60min時(shí)的耐蝕性能最好。當(dāng)在50V電壓下沉積60min,且Ca-Ce沉積時(shí)間比為2:1,摩爾比為99:1時(shí)制得的疏水涂層(即99Ca-1Ce涂層)耐蝕性能最佳,點(diǎn)蝕電位可達(dá)0.94V,比耐蝕性較好的Ca鹽涂層的點(diǎn)蝕電位還高出0.61V,且其在浸泡11d后才出現(xiàn)點(diǎn)蝕坑。99Ca-1Ce涂層具備優(yōu)良的疏水性能,且其厚度最大,與基體之間的結(jié)合力也是所有涂層中最強(qiáng)的,可見(jiàn)Ce的加入提升了Ca鹽涂層的厚度、疏水性能以及涂層與基體的結(jié)合力,并進(jìn)而提高了涂層的耐蝕性;但Ce含量過(guò)多會(huì)增加涂層缺陷,降低涂層與基體之間的結(jié)合力并影響其緩蝕作用的發(fā)揮,從而降低涂層的耐蝕性能。在含Ce的電解液中,由于離子遷移存在一個(gè)快慢順序,Ce4+Ce3+Ca2+,而Ca2+一直存在于溶液中,故在涂層沉積后階段實(shí)際發(fā)生的是Ca鹽和Ce鹽的共沉積。(CH_3(CH_2)_(12)COO)_2Ca涂層在Na Cl溶液的浸泡過(guò)程中可轉(zhuǎn)化為(CH3(CH2)12COO)2Ca·4H2O,Ce鹽涂層在浸泡過(guò)程中物相不發(fā)生轉(zhuǎn)變。在長(zhǎng)時(shí)間的浸泡下,由于涂層的溶解與脫落,基體遭受腐蝕,腐蝕產(chǎn)物為Mg(OH)_2。
[Abstract]:The preparation of hydrophobic coatings on magnesium alloys is a widely studied means of protection, and many studies show that the corrosion inhibition of rare earth cerium on magnesium alloys is obvious. In this experiment, a single hydrophobic coating of calcium tetradecrate, cerium tetradecanoate and cerium tetradecanoate was prepared directly on the surface of AZ31 magnesium alloy by cathodic electrodeposition, and the corrosion resistance of magnesium alloy was greatly improved by the existence of the coating. The effect of process parameters (deposition voltage and deposition time) on the morphology and corrosion behavior of single Ca salt (or ce salt) coating was studied. The effect of deposition time ratio of Ca-Ce composite coating and Ca-Ce molar ratio on morphology and corrosion behavior of Ca-Ce composite coating was also studied. It was found that the preparation process parameters of the coating significantly affected the morphology and corrosion performance of the coating. However, the phase composition of the coating does not affect the phase composition of the coating. The phase composition of the coating is that of the Ch _ 3H _ 3H _ 2o _ (12) COO _ (2) Ca _ (Ce) coating, which is composed of Ch _ (3) (Ch _ (2), Ch _ (2), (12COO) _ (4Ce) and Ch _ (3H _ (3) Ch _ (2) O _ (2) O _ (12) COO _ (3Ce). The results show that the corrosion resistance of the single Ca salt coating and ce salt coating is the best when the deposition voltage is 50 V, the longer the deposition time is, the better the corrosion resistance is for the single ce salt coating, and the better the corrosion resistance is for the single ce salt coating, the longer the deposition time is, the better the corrosion resistance is. The corrosion resistance of 60min is the best. When the deposition time ratio of Ca-Ce is 2: 1 and the molar ratio is 99:1, the hydrophobic coating (i.e. 99Ca-1Ce coating) has the best corrosion resistance. The pitting potential can reach 0.94V, which is higher than that of Ca salt coating with better corrosion resistance, and the pitting pit. 99Ca-1Ce coating has excellent hydrophobicity and its thickness is the largest. The adhesion between the coating and the substrate is also the strongest. It can be seen that the addition of ce enhances the thickness, hydrophobic property and adhesion between the coating and the substrate, and thus improves the corrosion resistance of the coating. However, excessive ce content will increase the coating defects, reduce the adhesion between the coating and the substrate, and affect the exertion of corrosion inhibition, thus reducing the corrosion resistance of the coating. In the electrolyte containing ce, there is a slow and fast sequence of ce 4 Ce3 Ca2 due to ion migration, while Ca2 exists in the solution all the time. Therefore, in the post-coating stage, the codeposition of Ca salt and ce salt is actually. Ch _ 3H _ 3H _ 2H _ 2 / C _ (12) COO _ (2H) 2Ca coating can be transformed into Ch _ 3H _ 2H _ 2CO _ 2O _ 2Ca _ 4H _ e salt coating during immersion in NaCl solution, and the phase does not change during soaking. After immersion for a long time, the substrate was corroded due to the dissolving and shedding of the coating, and the corrosion product was MgOH-2.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TG174.4

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