电解液中的Na_2SiO_3浓度对2024铝合金微弧氧化陶瓷膜层组织与耐腐蚀性的影响

采用微弧氧化工艺在航空用2024铝合金基材表面制备陶瓷膜层。探究电解液(Na_2SiO_3+KOH)中的Na_2SiO_3浓度对微弧氧化膜层表面形貌、膜层厚度及其耐腐蚀性的影响。研究结果表明:随着Na_2SiO_3浓度增大,微弧氧化陶瓷膜层的厚度先快速增加,在ρ(Na2Si O3)=9 g/L后转为微小波动型的缓慢增加。随着Na_2SiO_3浓度的增加,表面微孔的数量与孔径也呈缓慢增大的趋势。当ρ(Na_2SiO_3)=11 g/L时,表面出现裂纹。当ρ(Na_2SiO_3)=5 g/L～7 g/L时,陶瓷膜层具有良好的耐腐蚀性能。     

KH-550对AZ31B镁合金表面微弧氧化膜结构及性能的影响

通过微弧氧化(MAO)的方法在Na_2SiO_3-KOH-NaF电解质溶液中处理AZ31B镁合金,利用SEM、XRD和电化学等表征手段,研究了硅烷偶联剂KH550对MAO膜结构及性能的影响。结果表明,KH-550浓度在0~20 mL/L范围内增加时,MAO膜表面微孔尺寸和粗糙度先减小后增大,膜层厚度和耐蚀性能先增加后降低;引入KH-550后并未改变MAO膜的物相结构。分析认为KH-550通过硅烷醇的吸附和化学作用,增加了阳极表面薄弱区域离子移动的阻力,抑制镁合金在MAO过程的弧光放电,从而提高了膜层的生长效率,细化并均匀化微孔,改善了MAO膜的耐蚀能力。     

镁合金微弧氧化复合膜研究进展

微弧氧化（MAO）表面处理技术常用于改善镁合金的特定性能,但MAO膜容易产生微孔和微裂纹从而降低镁合金的耐蚀性。为了提高镁合金微弧氧化膜的使用寿命,主要综述了国内外MAO工艺过程调节措施和MAO膜后处理技术的最新研究进展,重点介绍了近年来国内外镁合金MAO复合膜的研究热点。着重介绍了通过工艺过程调节提高镁合金MAO膜长期保护性能的几项措施：通过电参数和电源类型调节协同电解液成分调整提高MAO膜耐蚀性;通过加入电解液添加剂提高MAO电解液稳定性和电导率;利用具有自封孔作用的添加剂可以参与成膜的特点提高MAO膜致密性;通过复合工艺在MAO膜传统封孔后进一步封闭孔隙。此外,详细介绍了包括疏水涂层、化学镀、类金刚石涂层、生物膜涂层等复合膜工艺的研究进展,强调了复合膜不仅耐蚀性高而且具有功能化应用前景：超疏水复合膜对镁基底具有主动的腐蚀保护作用,超疏水膜协同MAO膜可以提高表面的疏水性;镀镍层致密无微孔且与MAO膜交错咬合能够改善镁MAO膜的导电性和耐蚀性;MAO涂层代替金属缓冲层能够提高类金刚石涂层和基体界面结合强度;生物复合涂层不仅耐蚀性高还具有促进细胞增殖和分化生物活性的作用。最后,基于镁...     

KOH 对镁合金微弧氧化过程及膜层耐蚀性的影响

在微弧氧化电解液中引入了KOH添加剂,并在镁合金表面制备了陶瓷膜层,研究了KOH浓度对微弧氧化过程中的膜层生长及膜层耐腐蚀性能的影响。结果表明:在镁合金微弧氧化电解液中引入KOH添加剂可以有效降低微弧氧化过程的起弧电压和工作电压,但是KOH浓度过高会使起弧电压增大;KOH的引入会使膜层中的大尺寸孔隙数目减少,孔隙率提高。为了得到较高的膜层生长速率和较好的耐蚀性,电解液中的KOH剂量以1～3 g/L为宜。     

碱处理对钛合金表面微弧氧化涂层中磷灰石形成的影响（英文）

使用3种不同浓度的氢氧化钠溶液对钛合金表面的微弧氧化涂层(MAO)进行改性处理,以提高微弧氧化涂层的生物活性。通过分析经不同浓度碱溶液处理后样品的微观形貌、化学成分、相组成、表面粗糙度、接触角和磷灰石的形成程度等因素,研究碱处理对微弧氧化涂层的影响。实验结果表明,碱处理后的微弧氧化涂层中生成了Na2Ti6O13和Na2Ti3O7相,这两相的生成增加了微弧氧化涂层的表面粗糙度,减小了模拟体液与涂层的接触角。因此,采用不同浓度碱处理能够促进微弧氧化涂层中磷灰石的形成,使涂层表面的生物活性增加。     

氟化钾对AZ91D镁合金微弧氧化膜的生长及微观结构的影响

通过在NaOH和Na_2SiO_3组成的基础电解液中,分别不加及加入KF,对AZ91D镁合金进行微弧氧化处理,研究了KF的有无对镁合金微弧氧化膜的生长、微观结构及耐蚀性能的影响。结果表明:与不加KF相比,加入KF后,试样的起弧电压明显降低,击穿变得剧烈,试样表面火花较大,膜层的生长速率明显提高,膜层厚度显著增大,表面孔隙率稍有增大,但表面微孔数量减少。KF的加入有利于MgF_2、MgAl_2O_4的生成,与同样来自电解液的Si、O两元素相比,F~-更易被基体中的Mg所吸附,也容易通过已成膜层迁移到膜层的内部。电解液中含有KF时,膜层厚度显著增大,MgAl_2O_4物相含量增加,并生成新物相MgF_2,这些都有利于膜层耐蚀性的提高。     

一种化学还原镀金液复合配位剂的研究

目的研究由乙二胺四乙酸二钠(EDTA-2Na)、乙二胺四亚甲基膦钠(EDTMPS)和柠檬酸三铵(C_6H_5O_7(NH_4)_3)组成的复合配位剂,在不同浓度及pH下,对金沉积速率、镀金液稳定性、金镀层结构及性能的影响。方法用化学镀的方法在树脂基体上先预镀覆Cu-Ni-Pd金属层,然后制备金镀层。采用正交实验法,研究复合配位剂浓度及pH对金层沉积速率、镀金液稳定性、结合力、光亮度的影响。借助扫描电镜及能谱,分析不同优化组合镀液配方制备的镀层形貌及成分。结果以镀金沉积速率为评价指标时的最优组合为A_2C_3D_3B_2,以镀液稳定性为评价指标时的最优组合为A_2C_2B_3D_2,以镀层结合力为评价指标时的最优组合为A_2D_2B_2C_2,以镀层光亮度为评价指标时的最优组合为A_3C_1D_2B_2。将4个单一评价指标的最优组合重复实验,实验结果表明,当EDTA-2Na为15 g/L、EDTMPS为3 g/L、C_6H_5O_7(NH_4)_3为30 g/L、pH为6.0时,镀液稳定性最高,可达6 MTO;镀层沉积速率最快,可达0.0066μm/min;镀层结合力可达5级,光亮度可达1级。结论采用EDTA-2Na、EDTMPS和C_6H_5O_7(NH_4)_3组成的复合配位剂,在适当的pH下能够提高镀层沉积速度及镀液稳定性,改善镀层表面形貌。     

AZ91D镁合金微弧氧化膜的制备工艺研究

在NaAlO_2电解液体系中,采用自制微弧氧化成套设备对AZ91D镁合金进行微弧氧化。采用5因素4水平正交设计试验法,以膜层厚度和耐蚀性为指标,综合考察了各因素对膜层结构和性能的影响,确定最佳工艺条件为20g/L NaAlO_2,7g/L Na_2B_4O_7,频率500Hz,正占空比20%,氧化时间30min。对该工艺下制备的微弧氧化膜层进行SEM、XRD分析,膜层含有较多的NaAlO_2、MgO和Al_2O_3晶体相;相对基体而言,微弧氧化膜层耐蚀性提高2~3个数量级。动电位极化曲线及电化学交流阻抗测试进一步表明,AZ91D镁合金微弧氧化后,其耐蚀性明显提高。     

氨基酸类有机添加剂对镁合金阳极氧化的影响及其作用机制研究

为了进一步改善镁合金表面阳极氧化膜的质量和性能,在Na OH+Na_2SiO_3基础电解液中添加氨基酸类有机添加剂对AZ31镁合金进行阳极氧化,研究了氨基酸类有机添加剂对镁合金阳极氧化过程及氧化膜厚度、表面形貌、结构及耐蚀性的影响。探讨了有机添加剂在镁合金阳极氧化中的作用机制。结果表明:不同的氨基酸对镁合金阳极氧化过程及氧化膜性能影响不尽相同,其中乙二胺四乙酸和L-鸟氨酸醋酸盐可显著提高阳极氧化的击穿电压,起到明显的抑弧作用,大幅度提高了氧化膜的厚度、致密性和耐蚀性能。有机添加剂主要通过缓蚀、抑弧和表面活性剂3方面的综合作用来影响镁合金阳极氧化的过程及氧化膜的性能。     

氧化时间对AZ31B镁合金微弧氧化涂层结构及性能的影响

目的 探索氧化时间对AZ31B镁合金表面微弧氧化（MAO）涂层结构及性能的影响规律。方法 通过恒压MAO的方法在硅酸盐电解液体系中制备涂层,采用扫描电子显微镜（SEM）、Image-J图像分析法、测厚仪、表面粗糙度仪、摩擦磨损试验机、盐雾试验箱来研究涂层表面微观形貌、表面孔隙率、厚度、粗糙度、摩擦性能以及耐蚀性能。结果 涂层孔隙率随着氧化时间的延长而减小,氧化25 min所得涂层孔隙率最小,为5.404%。涂层厚度随时间的延长而增大,但是厚度增长速率减小,氧化5 min时涂层厚度为9 μm,而25 min时涂层厚度为10.4 μm。涂层粗糙度与摩擦系数随时间的增加而增大,磨损率随氧化时间的增加,呈现先增大后减小的趋势,氧化15 min所得样品磨损率最高,氧化5 min所得涂层耐蚀性最差,氧化25 min的涂层耐蚀性最好。结论 恒压条件下,氧化时间的延长可以有效地减小涂层表面孔隙率,增加涂层厚度,显著改善涂层的耐磨、耐蚀性能。     

Effects of Voltage on Microstructure and Corrosion Resistance of Micro-arc Oxidation Ceramic Coatings Formed on KBM10 Magnesium Alloy

Micro-arc oxidation (MAO) coatings on KBM10 magnesium alloy were prepared in an electrolyte system with sodium silicate, potassium hydroxide, sodium tungstate, and citric acid. The effects of voltage on the microstructure and corrosion resistance of MAO coatings were studied using stereoscopic microscopy, scanning electron microscopy, x-ray diffraction, scratch tests, potentiodynamic polarization, and electrochemical impedance spectroscopy. The results showed that the roughness of the MAO coatings, diameter, and number of pores increase with the increase in voltage. The coating formed at the voltage of 350 V exhibited the best adhesive strength when evaluated by the automatic scratch tester. The coatings were mainly composed of MgO, MgWO₄, and Mg₂SiO₄, and the content of Mg₂SiO₄ increased with the increase in voltage. The corrosion resistance of MAO coatings could be improved by changing the applied voltage, and the best corrosion resistance of MAO coating was observed at the voltage of 350 V.     

The influence of sodium tungstate concentration and anodizing conditions on microarc oxidation (MAO) coatings for aluminum alloy

Microarc oxidation (MAO) coatings on 5052 aluminum alloy are prepared in silicate–hypophosphite electrolytes with sodium tungstate. The effects of sodium tungstate concentrations and current density on the surface morphology, phase composition and properties of the coatings are investigated. With the addition of sodium tungstate in the electrolyte and increase of current density, the final voltage at the microarc discharge process increases. The results also show that the MAO coatings are composed mainly of α-Al₂O₃ and γ-Al₂O₃ and the proportion of α-Al₂O₃ and γ-Al₂O₃, pore size, surface roughness as well as thickness of the coatings strongly depend on the sodium tungstate concentration and current density. Thus, the hardness, friction coefficient and corrosion resistance of the coatings are significantly influenced by the magnitude of the current density and sodium tungstate concentration. These oxide films on aluminum were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thickness gage, and polarization curves, respectively.     

Corrosion characterization of microarc oxidation coatings formed on Mg–7Li alloy

Ceramic coatings with thickness of 27 µm were fabricated on Mg–7Li alloy in Na₂SiO₃–C₆H₁₈O₂₄P₆ solution by microarc oxidation (MAO). The morphology and phase composition of MAO coatings were characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The corrosion behavior of the bare and MAO coated Mg–7Li alloy was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Results showed that the MAO coatings were composed of MgO, Li₂O, and Mg₂SiO₄, and there existed some micropores on the coating surface with a diameter of 3–20 µm. The corrosion potential (E_corr) and corrosion current density (I_corr) of the MAO coated alloy were about ?1.4761 V and 7.204 × 10^?7 A/cm², respectively. The E_corr of the MAO coated alloy increased by 109.6 mV and its I_corr decreased by three orders compared with that of the bare Mg–7Li alloy. The EIS plots indicated that the impedance of the MAO coated alloy was 15 times higher than that of the bare alloy. The fitting parameters showed that the resistance of the MAO coatings was far greater than that of the bare alloy. The dense intermediate layer and the transition layer of the MAO coatings acted as a barrier to hinder the proceeding of solution permeation, remarkably improving the corrosion resistance of the Mg–7Li alloy.     

Characterization and corrosion behavior of ceramic coating on magnesium by micro-arc oxidation

In this study, the commercial pure magnesium was coated in different aqueous solutions of Na₂SiO₃ and Na₃PO₄ by the micro-arc oxidation method (MAO). Coating thickness, phase composition, surface and cross sectional morphology and corrosion resistance of coatings were analyzed by eddy current method, X-ray diffraction (XRD), scanning electron microscope (SEM) and tafel extrapolation method, respectively. The average thickness of the coatings ranged from 52 to 74 μm for sodium silicate solution and from 64 to 88 μm for sodium phosphate solution. The dominant phases on the coatings were detected as spinal Mg₂SiO₄ (Forsterite) and MgO (Periclase) for sodium silicate solution and Mg₃(PO₄)₂ (Farringtonite) and MgO (Periclase) for sodium phosphate solution. SEM images reveal that the coating is composed of two layers as of a porous outer layer and a dense inner layer. The corrosion results show the coating consisting Mg₂SiO₄ is more resistant to corrosion than that containing Mg₃(PO₄)₂.     

Anti-corrosion microarc oxidation coatings on SiCP/AZ31 magnesium matrix composite

The corrosion-resistant ceramic coatings up to 80 μm thick were fabricated on SiC_P/AZ31 magnesium matrix composite by microarc oxidation (MAO) technique in Na₃PO₄ + KOH + NaF solution. The microstructure, composition and phase constituent of ceramic coatings were analyzed by SEM and XRD, and the electrochemical corrosion behaviour of coatings was evaluated by the electrochemical polarization method. The thicker coating is compact and displays a good adhesion to the composite substrate. The ceramic coatings consist of MgO, Mg₂SiO₄, MgF₂, Mg₃(PO₄)₂, furthermore, a few residual SiC phases were also found in the coatings by means of SEM observation and EDX analysis. Most of SiC reinforced particles in the oxidized composite substrate have transformed into the oxides under microarc discharge sintering, but a few residual SiC reinforcements in the MAO coatings have not disrupted the continuity of coatings. So the corrosion resistance of the SiC_P/AZ31 composite is greatly improved by MAO surface treatment, however, the corrosion resistance of coated composite also depends on the coating thickness.     

Effects of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Nano-Particles on Corrosion Performance of Plasma Electrolytic Oxidation Coatings Formed on 6061 Aluminum Alloy

Corrosion resistance improvement of plasma electrolyte oxidation coatings on 6061 aluminum alloy in silicate electrolyte containing Al₂O₃ nano-particles was studied, with particular emphasis on the microstructure, coating growth, and corrosion behavior in 3.5 wt.% NaCl solution. The microstructure of coatings, their thickness, and phase composition were characterized using scanning electron microscopy and x-ray diffraction. All characterization data showed that the maximum coating thickness and lowest amount of porosity were obtained in a low concentration of KOH, a high concentration of Na₂SiO₃, and moderate concentration of Al₂O₃ nano-particles in the electrolyte. This combination describes the optimum plasma electrolytic oxidation electrolyte, which has the best conductivity and oxidizing state, as well as the highest incorporation of electrolyte components in the coating growth process. On the other hand, incorporation and co-deposition of Al₂O₃ nano-particles were more pronounced than SiO₃ ^2? ions in some level of molar concentration, which is due to the higher impact of electron discharge force on the adsorption of Al₂O₃ nano-particles. The electrochemical results showed that the best protective behavior was obtained in the sample having a coat with the lowest porosity and highest thickness.     

用优化的双电解液制备AZ91D镁合金微弧氧化膜(英文)

在含有Na2SiO3、NaAlO2、Na2B4O7、NaOH、C3H8O3和C6H5Na3O7的电解液中,采用交流脉冲电源对AZ91D镁合金进行微弧氧化处理。利用SEM、膜层测厚仪、EDS和XRD分别研究膜层的表面和截面微观形貌、厚度、成分及相结构。利用交流阻抗和动电位极化曲线试验测量膜层在3.5%NaCl中性溶液中的耐蚀性能。结果表明,正交试验得到的双电解液成分为15g/LNa2SiO3、9g/LNaAlO2、2g/LNa2B4O7、3g/LNaOH、5mL/LC3H8O3和7g/LC6H5Na3O7。经过微弧氧化处理而得到的膜层较致密,其腐蚀电流密度较镁合金基体的降低了2个数量级,自腐蚀电位提高了近73mV。EIS结果认为膜层的耐蚀性取决于内部致密层。微弧氧化膜主要组成元素为Mg、Al、O和Si,主要组成相为MgO、Mg2SiO4和MgAl2O4。     

电压对AZ31镁合金微弧氧化涂层微观结构及腐蚀性能的影响

为研究过程参数对镁合金微弧氧化涂层的微观结构及耐腐蚀性能的影响,在AZ31镁合金基体上,采用不同电压,在电解液磷酸三钠(Na3PO4)中制备微弧氧化涂层.采用扫描电子显微镜(SEM)及光学显微镜,分析膜层腐蚀前后的微观组织结构;通过X射线衍射仪(XRD)分析涂层样品腐蚀前后的相组成.采用动电位极化曲线和电化学阻抗谱(EIS)测试对涂层的耐腐蚀性能进行评价.结果表明:AZ31镁合金微弧氧化涂层主要由Mg3(PO4)2,MgO,Mg和少量MgAl2O4组成,腐蚀产物由Mg(OH)2,quintinite和Ca10(PO4)6 (OH)2组成.在电压为325 V,频率3 000 Hz,氧化时间为5 min下制备的微弧氧化涂层具有最致密均匀的微观形貌和最小的腐蚀电流密度,因此表现出最强的耐腐蚀性能.     

SiC纳米颗粒对TA2微弧氧化涂层组织结构及耐蚀性能的影响机制

为提高钛及钛合金防腐蚀、耐磨损等关键服役性能,本研究在TA2钛合金表面制备微弧氧化陶瓷涂层,研究纳米SiC颗粒的添加对微弧氧化涂层组织结构及耐蚀性能的影响机制.结果表明,基础电解液中SiC的加入能够大幅度提高TA2微弧氧化涂层的厚度,且随着电压的升高,涂层的厚度和表面粗糙度也随之增大,涂层表面的微孔尺寸随着电压的升高而逐渐增大,SiC的加入能够有效地抑制微弧氧化涂层表面裂纹的产生;微弧氧化涂层的物相主要有高温稳定相金红石及锐钛矿,还含有少量的SiC及SiO2;微弧氧化涂层增加TA2的开路电位及自腐蚀电位,随着处理电压的增加开路电位随着升高;SiC的加入降低了涂层的阳极电流密度,显著提高了微弧氧化涂层得耐蚀性能。     

Effect of voltage on microstructure and corrosion resistance of microarc oxidation coatings on CP-Ti

The surface modification of commercially pure titanium (CP-Ti) by microarc oxidation (MAO) under different voltages was investigated using 1%H₃PO₄ solution as an electrolyte. The microstructure, phase composition and elemental distribution of ceramic coatings were investigated using scanning electron microscopy (SEM) and X-ray diffraction. The corrosion behaviour of the coating was also examined by potentiodynamic polarisation testing in a 3·5 wt-%NaCl solution. Micropore oxide films were formed on all the sample groups by MAO. The thickness and micropore size of the MAO coating increased with the increasing voltage. Energy dispersive X-ray spectroscopy results indicate that Ti, O and P became incorporated into the MAO coatings. At a low voltage of 250 V, the MAO coatings were composed of amorphous, P₂O₅, TiP₂O₇ and titania phases (rutile and anatase). Variation of treatment voltages increased the ceramic coatings from an amorphous structure to a phase structure, and the P₂O₅ phase disappeared. The corrosion potential Φ_corr of the MAO sample shifted towards nobler directions, and the corrosion density I_corr fell significantly compared with that of the bare CP-Ti. Corrosion testing showed that the sizes of the micropore of the MAO samples obviously decrease, and the MAO surface becomes smooth.