發(fā)布時(shí)間：2018-05-08 06:15

  本文選題：AlSi12Cu合金 + 微弧氧化　； 參考：《南京理工大學(xué)》2017年碩士論文

【摘要】：AlSi12Cu合金屬于鑄造鋁合金系列,具有低密度、良好的加工性能、一定的強(qiáng)度和耐蝕性等特點(diǎn),廣泛應(yīng)用于汽車、航空航天、海洋運(yùn)輸及家用工具等領(lǐng)域。但其硬度低,耐磨性差。在一些介質(zhì)中AlSi12Cu合金的耐腐蝕性也不能滿足要求,從而限制了其應(yīng)用范圍。為了提高AlSi12Cu合金的耐磨和耐蝕性能,本文采用微弧氧化(Micro-arc oxidation,MAO)技術(shù)在其表面制備氧化鋁涂層,利用正交實(shí)驗(yàn)設(shè)計(jì)方法對微弧氧化工藝的電流密度、氧化時(shí)間和頻率三個(gè)參數(shù)進(jìn)行優(yōu)化研究,采用掃描電子顯微鏡(SEM)及其附帶的能譜儀(EDS)、X射線衍射(XRD)儀分別對膜層的表面形貌、元素含量和物相組成進(jìn)行分析,并對膜層的耐蝕性和耐磨性能進(jìn)行了分析評價(jià)。為了進(jìn)一步提高膜層的耐腐蝕性能,對微弧氧化后的試樣進(jìn)行封孔處理,研究了封孔處理方法對其耐蝕性能性能的影響。通過系統(tǒng)研究,得到了如下的主要結(jié)果:通過正交實(shí)驗(yàn)確定了微弧氧化處理的最佳工藝條件:電流密度為30 A/dm2,電源頻率為600 Hz以及氧化時(shí)間為20 min。在最佳工藝參數(shù)條件下進(jìn)行微弧氧化獲得的膜層厚度為15μm左右,主要由α-Al2O3、γ-Al203、θ-Al2O3和A1組成,膜層與鋁合金基體之間結(jié)合牢固。AlSi12Cu合金經(jīng)微弧氧化處理后,耐磨性明顯提高,摩擦系數(shù)由鋁合金基體的0.64減小為0.37;經(jīng)微弧氧化的鋁合金材料在鹽霧腐蝕240小時(shí)后,還未出現(xiàn)表面腐蝕現(xiàn)象,而在洗衣粉溶液中的腐蝕速率則較鋁合金基體降低了 25倍,說明微弧氧化處理使AlSi12Cu合金得耐腐蝕性能也得到了顯著改善。利用硅酸鈉和硬脂酸封孔劑對微弧氧化膜層進(jìn)行封孔處理。結(jié)果表明,兩種封孔方法都能有效將微弧氧化膜層上的微孔及一定數(shù)量的大孔封堵,并使膜層的耐蝕性進(jìn)一步提高。其中,用硬脂酸進(jìn)行封孔處理效果更好。在3.5%NaCl溶液中的電化學(xué)腐蝕實(shí)驗(yàn)結(jié)果表明,微弧氧化鋁合金經(jīng)硬脂酸封孔處理后,腐蝕電流密度較鋁合金基體降低了100倍,腐蝕電位正移了 285 mV。
[Abstract]:AlSi12Cu alloy is a kind of cast aluminum alloy series, with low density, good processing performance, certain strength and corrosion resistance and so on. It is widely used in automobile, aerospace, marine transportation and household tools and so on. But its hardness is low, wear resistance is poor. In some media, the corrosion resistance of AlSi12Cu alloy can not meet the requirements, thus limiting its application range. In order to improve the wear resistance and corrosion resistance of AlSi12Cu alloy, alumina coating was prepared on the surface by micro-arc oxidation (Micro-arc oxidation) technique. The current density of micro-arc oxidation process was studied by orthogonal design method. Three parameters of oxidation time and frequency were optimized. The surface morphology, element content and phase composition of the film were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS / X ray diffractometer). The corrosion resistance and wear resistance of the film were analyzed and evaluated. In order to further improve the corrosion resistance of the film, the pore sealing treatment was carried out on the samples after micro-arc oxidation, and the effect of the sealing treatment method on the corrosion resistance of the samples was studied. The main results are as follows: the optimum process conditions of micro-arc oxidation are determined by orthogonal experiment: current density is 30A / dm ~ 2, power frequency is 600 Hz and oxidation time is 20 min. The thickness of the film obtained by microarc oxidation under the optimum technological parameters is about 15 渭 m. The film is mainly composed of 偽 -Al _ 2O _ 3, 緯 -Al _ 2O _ 3, 胃 -Al _ 2O _ 3 and Al _ 1. The wear resistance of the film is obviously improved by micro-arc oxidation. The friction coefficient of aluminum alloy decreased from 0.64 to 0.37, and the corrosion rate in washing powder solution was 25 times lower than that in aluminum alloy matrix after 240 hours of salt spray corrosion. The results show that the corrosion resistance of AlSi12Cu alloy is improved remarkably by micro-arc oxidation treatment. The microarc oxide film was sealed by sodium silicate and stearic acid. The results show that both of the two sealing methods can effectively block the micropores and a certain number of macropores in the micro-arc oxide film, and further improve the corrosion resistance of the film. The sealing effect of stearic acid is better than that of stearic acid. The experimental results of electrochemical corrosion in 3.5%NaCl solution show that the corrosion current density of micro-arc oxidation aluminum alloy treated by stearic acid sealing is 100 times lower than that of aluminum alloy substrate, and the corrosion potential is 285mV.
【學(xué)位授予單位】：南京理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG174.451

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本文編號(hào)：1860281