铝合金两种阳极氧化工艺的氧化膜性能对比

为了探讨铝合金阳极氧化配方对氧化膜层性能的影响,研究比较了硫酸-硼酸和硫酸两种阳极氧化工艺所得氧化膜层的性能。通过金相显微镜、扫描电子显微镜(SEM)和显微硬度仪观察分析了膜层表面的均匀性、封闭工艺后氧化膜的表面形貌和膜层的维氏硬度;同时,采用点滴法和动电位法研究了氧化膜在NaC l溶液中的耐腐蚀性能。结果表明,在一定条件下,经硫酸-硼酸阳极氧化所得的膜层较硫酸阳极氧化膜的平整、致密、均匀,其耐蚀性也优于硫酸阳极氧化膜的。     

铝阳极氧化膜绿色封闭工艺

探索了新的不含有害物质的铝合金阳极氧化膜绿色封闭技术;新方法使用了铈盐化学处理和钼盐溶液电化学处理相结合的工艺。对比了不同封闭方法对L3铝合金阳极氧化膜在NaCl溶液中耐蚀性的影响,包括氟化镍封闭,重铬酸钾封闭和铈-钼盐封闭。利用动电位极化法研究了封闭后阳极氧化膜的腐蚀行为。利用扫描电子显微镜(SEM)观察了封闭后阳极氧化膜的表面形貌和成分。结果表明铈-钼盐封闭工艺可以为铝合金阳极氧化膜在NaCl溶液中提供较高的耐蚀性。     

不同方法评价几种工艺封闭的铝合金阳极氧化膜的耐蚀性

使用磷-铬酸失重试验、铜加速醋酸盐雾试验和电化学技术研究了铈盐封闭的铝合金阳极氧化膜的耐蚀性,并与氟化镍封闭、沸水封闭和重铬酸钾封闭方法进行了对比。铈盐封闭的铝合金阳极氧化膜在磷-铬酸失重试验中失重小于30 mg/dm2,达到了GB/T5237.2-2000中的规定。铜加速醋酸盐雾试验和电化学试验表明,铈盐封闭的铝合金阳极氧化膜的耐蚀性与其它几种方法封闭的铝合金阳极氧化膜的耐蚀性相当。磷-铬酸失重试验、铜加速醋酸盐雾试验和电化学技术这几种方法都可以用来评价铝阳极氧化膜的耐蚀性,且评价结果基本一致。稀土封闭绿色环保,封闭效果好,应用前景良好。     

硼酸对7050铝合金硼酸-硫酸阳极氧化膜结构及耐蚀性的影响(英文)

通过 AFM、交流阻抗谱及扫描 Kelvin 探针技术,研究硼酸对 7050 铝合金硼酸?硫酸阳极氧化膜结构及耐蚀性的影响。结果表明,在硼酸-硫酸阳极氧化体系中,硼酸不会改变氧化膜阻挡层的结构,但会显著影响氧化膜多孔层的结构形式,进而影响氧化膜的耐蚀性。在 0～8 g/L 的范围内,随着电解液中硼酸含量的增加,氧化膜的多孔层电阻增大,电容减小,表面势正移,孔径缩小,耐蚀性变好。在高于 8 g/L 时,随着硼酸含量的增加,氧化膜的孔隙变大,阻抗变小,电子逸出功降低,耐蚀性变差。     

非恒温电解液中AA5083Al-Mg合金阳极氧化膜的制备及其耐蚀性

采用硼酸-硫酸-草酸电解液在铝合金表面制备有序多孔层,研究阳极氧化过程中电流随时间的变化,分析界面反应并计算膜层的生长效率。采用扫描电子显微镜、交流阻抗和动电位极化曲线研究膜层的微结构及其在不同温度环境下的耐蚀性。结果表明：在氧化层界面双离子层浓度的增大有利于提高膜层的生长效率。所制备的阳极氧化膜厚度为8-9μm,孔径为10-14 nm,膜层的微观形貌受金属基体组织结构的影响较大。在沸水封闭后膜层为分层结构,表面呈细片状。氧化膜层封闭后能够明显降低试样的自腐蚀电流密度,且耐蚀性随着环境温度的升高而具有更好的稳定性。     

化学沉积铈转化膜的工艺优化及其耐蚀性

采用化学沉积法在铝阳极氧化膜上制备铈转化膜。通过SEM和EDS表征了阳极氧化膜、化学沉积铈转化膜形貌和组成成分;用极化曲线法、EIS交流阻抗法和酸、碱点滴试验对膜耐蚀性进行了评估。结果表明,在铝阳极氧化膜上经过化学沉积可制备铈转化膜,其耐蚀性优于铝阳极氧化膜的耐蚀性。优化的铈转化膜工艺为:3 g/LCe2(SO4)3,20 ml/L H2O2,温度50℃,时间60 min。     

电解液中铈盐对LDH/AAO复合膜层耐蚀性影响

普通阳极氧化膜难以对铝合金形成有效的防护作用，须进行封孔处理以改善膜层耐蚀性差问题。采用原位生长法制备的层状双金属氢氧化物（LDH）膜对阳极氧化（AAO）膜进行封闭，得到LDH/AAO复合膜层，研究阳极氧化电解液中三价铈盐浓度对AAO膜层及LDH/AAO复合膜层耐蚀性影响。利用扫描电子显微镜（SEM）、能谱仪（EDS）、辉光放电发射光谱仪(GDOES)分别表征膜层的微观形貌和元素组成，通过电化学交流阻抗（EIS）、动电位极化曲线和酸性盐雾试验检测膜层的耐蚀性。结果表明，在阳极氧化电解液中添加铈盐能够提高AAO膜层的致密性和耐蚀性，并改善后续LDH膜层在AAO膜表面的生长。LDH可以在AAO孔洞和缺陷中生长，并完全覆盖AAO层，耐蚀性明显优于铈盐封闭，铈盐浓度为0.03 mol/L时AAO膜层与LDH/AAO复合膜层耐蚀性更好。通过对LDH层负载钒酸根缓蚀剂，进一步优化了复合膜层的耐蚀性能。复合膜层的耐蚀作用主要归因于电解液中添加铈盐提高了AAO内层的物理阻隔性能，负载钒酸根的LDH外层对腐蚀性离子的捕获及对层间缓蚀剂的释放双重作用为基体铝合金提供了长效保护。提出层状双金属氢氧化物/阳极...     

铈盐封孔对6061铝合金阳极氧化膜耐蚀性的影响

为提高6061铝合金阳极氧化膜的耐蚀性,利用铈盐溶液对其进行封孔处理。用电化学阻抗谱(EIS)和浸泡试验研究了不同工艺铈盐封孔后的氧化膜在质量分数3.5%NaCl溶液中的耐蚀性。同时,通过剥蚀试验对比研究了铈盐封孔与铝溶胶封孔和沸水封孔的效果。结果表明:氧化膜在30℃下铈盐封孔150min可获得较好的耐蚀性;铈盐封孔氧化膜的耐蚀性略低于沸水封孔氧化膜的,但优于溶胶封孔氧化膜的。     

铈盐在电场作用下对LY12铝合金阳极氧化膜的封闭作用

研究了铈盐溶液在脉冲电场作用下对LY12铝合金阳极氧化膜的封闭作用.利用扫描电子显微镜(SEM)观察了封闭后阳极氧化膜的表面微观形貌,利用动电位极化技术和电化学交流阻抗谱(EIS)研究了经铈盐封闭后的LY12铝合金阳极氧化膜在不同pH值的1 mol/LNaCl溶液中的耐蚀性,并与重铬酸钾封闭、沸水封闭进行了对比.结果表明,采用该封闭工艺得到的铝合金阳极氧化膜表面平整均匀,在耐蚀性方面优于传统封闭方法,并且降低了成本和减少了能量消耗,对环境无污染,是一种新型的绿色封闭方法,有望替代重铬酸钾封闭法.     

2024-T3铝合金在含铈盐缓蚀剂硫酸-硼酸-磷酸混合酸中的阳极氧化（英文）

研究了铈盐缓蚀剂对2024-T3铝合金阳极氧化的影响。采用带X射线能谱仪的扫描电子显微镜分析合金表面处理前后的表面组分。使用含0.1 mol/L硫酸铈盐的混合电解液作为阳极氧化电解液,该混合电解液由10%硫酸、5%硼酸和2%磷酸组成。在沸水和溶化的硬脂酸中进行密封处理,分别利用电化学交流阻抗和盐雾技术研究氧化膜的腐蚀行为和耐用性。结果表明,阳极氧化电解液中存在的铈离子导致合金更均匀,氧化膜生长率提高和氧化层的厚度增加,这些都是因为铈离子具有高的氧化能力。     

磷酸盐封孔处理对铝合金阳极氧化膜耐蚀性能的影响

为进一步提高铝合金阳极氧化膜的耐蚀性能,采用磷酸盐对其进行封孔处理.利用电化学阻抗谱 (EIS ) 分析该封孔处理对阳极氧化膜耐蚀性能的影响规律,并与常规沸水封孔和铈盐封孔进行比较.实验结果表明,磷酸盐封孔处理后可在阳极氧化膜表面形成约为15 μm厚的致密磷酸盐涂层,与常规沸水和铈盐封孔处理相比,磷酸盐封孔处理的阳极氧化膜具有更好耐蚀性和时效性.该方法可为阳极氧化膜封孔处理提供一种新途径.     

EIS evolution of anodised aluminium by cerium salt sealing in NaCl solution with exposure time

Abstract

The sealing of porous anodic oxide film on aluminium 2024 involving immersion of the anodised aluminium in an aerated solution containing cerium salt under the application of pulse power at room temperature has been proposed as an alternative to dichromate sealing method. The sealing process shows some advantages. The corrosion behaviours of the anodised aluminium unsealed or sealed by dichromate and cerium salt respectively were investigated at different exposure times up to 30 days in 1M NaCl solution by means of electrochemical impedance spectroscopy, and the damage functions were calculated in this work. The results show that the damage functions of anodised aluminium sealed with cerium salt are lower than those unsealed or sealed with potassium dichromate. Cerium salt sealing provides a better corrosion resistance of anodised aluminium in NaCl solution for long exposure time than dichromate sealing.     

稀土盐对铝合金硼硫酸阳极氧化膜层性能的影响

目的研究代替铬酸阳极氧化和稀铬酸氧化膜层封闭处理的工艺。方法在硼硫酸阳极氧化溶液中添加不同的稀土盐对铝合金进行阳极氧化,采用稀土盐对氧化膜层进行封闭处理,分析对比膜质量及膜层耐腐蚀性能。结果在硼硫酸阳极氧化溶液中加入稀土A盐能够提高氧化膜层的耐腐蚀性能,用稀土C盐溶液对该阳极氧化膜层进行封闭处理,可以进一步提高氧化膜层的耐腐蚀性能,耐中性盐雾腐蚀时间达到336 h。结论稀土A盐改进的硼硫酸阳极氧化/C盐封闭技术有望代替铬酸阳极氧化技术。     

Application of CeH–V/ sol–gel composite coating for corrosion protection of AM60B magnesium alloy

Application of a composite coating on AM60B magnesium alloy consisting of cerium–vanadium conversion coating and a hybrid sol–gel layer was investigated. Scanning electron microscopy and energy dispersive X-ray spectroscopy analyses revealed a cracked nodular structure for the cerium–vanadium conversion coating which was mainly composed of O, Ce, V, and Mg atoms. All the cracks in the conversion coating were completely sealed by a thin, compact and defect-free hybrid sol–gel film. Potentiodynamic polarization and electrochemical impedance spectroscopy experiments in Harrison's solution showed that the cerium–vanadium conversion coating provides minimal protection against corrosion while the composite coating significantly increases the corrosion resistance of the magnesium alloy. Sol–gel film provides protection against corrosion by sealing cracks in the cerium–vanadium conversion coating and acting as a barrier. Scanning electron microscopy analyses after polarization tests confirmed the results obtained by the electrochemical tests.     

Electrochemical behaviors of anodic alumina sealed by Ce-Mo in NaCl solutions

1 Introduction Aluminum is a kind of material with active chemical behavior. It can form a thin oxide film on its surface in natural environment. The structure of this amorphous film is loose, so it could not provide good corrosion resistance. Anodizing i…     

Effect of HCl pre-treatment on corrosion resistance of cerium-based conversion coatings on magnesium and magnesium alloys

The corrosion protection afforded by a cerium conversion coating, formed by immersion in a solution containing rare earth salt and hydrogen peroxide, on pure magnesium and two magnesium alloys, AZ91 and AM50, has been studied. The effect of HCl pre-treatments on the morphology and on the corrosion resistance of the cerium conversion layer was investigated. A thicker and more homogeneous distribution of the conversion coating was obtained when the sample surface was pre-treated with acid. Higher amounts of cerium on the surface of the pre-treated samples were detected. The cerium conversion coating increased the corrosion resistance of the alloys because it ennobled the corrosion potential and decreased both the anodic and cathodic current. The acid pre-treatment further increased the corrosion resistance of the coated alloys. After five days of immersion in chloride environment the untreated samples showed localized corrosion while the chemical conversion coated samples appeared unaffected.     

铝阳极氧化膜在NaCl溶液中的电化学性能

采用交流阻抗法研究了工业纯铝L3阳极氧化膜在中性NaCl溶液中交流阻抗谱的变化规律, 比较了未封闭处理与沸水封闭处理后氧化膜的交流阻抗谱的差异, 并结合等效电路分析了氧化膜多孔层与阻挡层电化学参数的变化.结果表明, 未封闭的阳极氧化膜在NaCl溶液中浸泡初期存在一个自封闭过程, 封闭处理明显提高氧化膜多孔层的初始Rp值并降低初始CPEp值; 溶液中侵蚀性离子浓度越高, 封闭处理提高铝阳极氧化膜的耐蚀性能作用越明显.     

Plasma electrolytic oxidation of AZ91D magnesium alloy with different additives and its corrosion behavior

Plasma electrolytic oxidation (PEO) of Mg‐based AZ91D alloys was investigated using 50 Hz AC anodizing technique in an alkaline borate solution, which contained a new kind of organic additive and without F, P, and Cr. The anodizing technological parameters have been optimized and a kind of ivory‐white smooth anodic film with high corrosion resistance was obtained. It was found that the formation of the anodic films was always coupled with sparking and oxygen evolution, whose intensity changed with the additive and anodizing voltage. All EIS plots have two capacitive loops and one low frequency inductive component. Two capacitive arcs present the barrier and porous layer of the PEO film and the inductive component in the low frequency domain is a complex behavior due to the porous structure connected to the electrolyte. EIS plots and fitting results show that a self‐sealing process of the PEO firm with different additives takes place in the beginning of immersion time, then corrosion attack becomes a preponderant process to promote the degradation of the film. Tafel results show that PEO treatment decreases the corrosion current density by four, even five orders of magnitude, while additives content does not affect strongly the electrochemical corrosion behavior. Salt spray test shows that the PEO film formed with NaAlO₂ and Na₂SiO₃ presents good corrosion resistance, over 600 h without any sealing treatment. The difference of corrosion resistance arose by additives examined by electrochemical techniques and salt spray test does not show strict corresponding relationship.