十二烷基苯磺酸钠增强AZ91D镁合金阳极氧化膜耐蚀性研究

在碱性硅硼电解液中对AZ91D镁合金进行电化学阳极氧化处理,考察十二烷基苯磺酸钠(SDBS)添加剂对镁合金阳极氧化膜微观结构和耐腐蚀性能的影响。结果表明,电解液中加入SDBS可以增大氧化膜电阻,提高阳极氧化电压。SDBS使镁合金阳极氧化过程中熔融物的流动性得到提升,流平性更好,从而得到微孔少、裂纹小及平整性好的氧化膜。SDBS质量浓度为0.4 g/L时所得的氧化膜具有最正的开路电位和最大的膜层电子传递电阻,镁合金基底具有最好的耐腐蚀性能。     

AZ91D镁合金磷酸盐转化膜的制备及性能

提出了一种压铸镁合金AZ91D表面磷酸盐化学转化工艺,其配方及操作条件为:磷酸8mL/L,氧化锌3 g/L,酒石酸3 g/L,氨水4 g/L,硝酸钠3 g/L,氟化钠1 g/L,温度25～30℃,时间5min.研究了该无铬转化膜的表面和截面形貌,化学成分,物相组成,结合力,孔隙率和耐蚀性.结果表明:磷酸盐转化膜主要由Mg、Zn、Al12Mg17和Zn3(PO4)2·4H2O组成,结合力均＞8分,孔隙率由封孔前的27.91%降为封孔后的6.98%,耐中性盐雾时间均可达到24 h.电化学实验结果显示,转化膜的腐蚀电位比基体提高了64 mV,封孔处理后腐蚀电位提高了122 mV,腐蚀电流密度均降低了两个数量级.     

醋酸镍对AZ 63B镁合金微弧氧化膜耐蚀性的影响

在硅酸盐体系电解液中添加适量的醋酸镍及配位剂后,对AZ 63B镁合金进行微弧氧化处理,在AZ 63B镁合金表面制备了微孤氧化膜.研究了醋酸镍对微弧氧化膜耐蚀性的影响.结果表明:在电解液中添加醋酸镍,经微弧氧化后,镁合金表面生成了含Ni化合物的咖啡色氧化膜,耐蚀性得以提高.     

热水和硅酸钠封孔法对镁合金磷化膜耐蚀性的影响

为了进一步提高镁合金磷化膜的耐蚀性,采用热水法和硅酸钠法对磷化膜进行了封孔处理。借助扫描电镜观察磷化膜的形貌并测试了其成分,通过动电位极化和交流阻抗等方法测试了磷化膜的耐蚀性。结果表明:两种封孔方法获得的磷化膜更加光滑,缺陷数量减少,且表现出更低的自腐蚀电流密度和更大的电荷转移电阻,特别是硅酸钠封孔后的磷化膜表现出更佳的耐蚀性。     

各参数对AZ91D镁合金微弧氧化膜层质量影响的研究

使用自行研制的微弧氧化电源,研究分析了电解液成分、电参数及氧化时间等因素对AZ91D镁合金氧化膜层质量的影响.研究表明:电解液成分决定着膜层的成分与性能,铝酸盐体系电解液中形成的氧化膜层耐蚀性、耐磨性和硬度明显不如硅酸盐体系电解液;带放电回路的脉冲电源要明显地优于其它电源;电压、电流密度、脉冲宽度、氧化时间、频率和占空...     

铝溶胶对镁-锂合金微弧氧化膜耐蚀性的影响

通过添加铝溶胶对微弧氧化电解液进行改进,制得了理化性能更加优良的镁-锂合金微弧氧化陶瓷膜。分析了铝溶胶的体积分数对膜层性能的影响。得出结论:加入铝溶胶后,微弧氧化膜表面单位面积内的微孔数量减少,且孔径变小;随着铝溶胶的体积分数的增大,膜层的电阻增大;当铝溶胶的体积分数为11.7mL/L时,微弧氧化膜的耐蚀性最好。     

微弧氧化和化学氧化处理镁合金的耐蚀性研究

通过电化学分析和盐雾腐蚀试验,对镁合金微弧氧化和黑色化学氧化后表面膜的耐蚀性能进行了比较.结果表明:镁合金经过微弧氧化和黑色化学氧化后,耐蚀性能均有提高,但是黑色化学氧化后镁合金的耐蚀性提高更为显著.     

铬酸盐对镁合金微弧氧化膜耐蚀性的影响

研究在硅酸盐溶液中添加K2CrO4对AZ91D镁合金微弧氧化膜耐蚀性的影响。结果表明：在含有K2CrO4的硅酸盐系溶液中进行微弧氧化处理的镁合金表面能够获得黄绿色的氧化膜层,主要由MgO、Mg2SiO4、MgAl2O4及MgCr2O4等耐蚀物相组成,其中具有尖晶石结构的MgCr2O4对提高膜层耐蚀性有极大的促进作用,同...     

AZ91D镁合金表面磷酸锌转化膜最优工艺及其耐蚀性研究

采用正交试验的方法,以耐蚀性为指标,探究了磷酸锌转化膜的最佳制备工艺.利用扫描电子显微镜和动电位极化曲线等表征手段,对转化膜的形貌和耐蚀性进行了研究。最佳的磷化液配方为:1.25g/L NaNO_3,3g/L C_6H_8O_7·H_2O,2.5g/L NaF,5.5g/L ZnO,12.5mL/L H_3PO_4。     

四硼酸钠对AZ91D镁合金微弧氧化膜特性的影响

利用微弧氧化技术在AZ91D镁合金基体上制备了一系列陶瓷膜层。利用扫描电镜、膜层测厚仪、超景深光学显微镜分别研究了陶瓷膜层的微观形貌特征、厚度及表面粗糙度;采用交流阻抗谱测试了膜层在3.5%NaCl溶液中的耐蚀性能。结果表明,四硼酸钠质量浓度的变化对微弧氧化过程中的起弧电压和终止电压影响不大,适量的四硼酸钠可以稳定微弧氧化过程的控制电压;随着四硼酸钠质量浓度的增加,微弧氧化膜层的厚度先增加后降低,膜层表面粗糙度随着四硼酸钠质量浓度的增加呈先增加后降低的变化趋势;当四硼酸钠质量浓度为3g/L时,膜层较致密,表现出良好的耐蚀性能。     

ZE10镁合金微弧氧化膜层的制备及耐蚀性研究

采用含硅酸钠14g/LK、氟化钠14g/L、氢氧化钠2g/L和甘油5 mL/L的电解液,以微弧氧化技术在ZE10镁合金的表面成功制备了微弧氧化膜.采用涡流测厚仪、扫描电镜、X射线衍射、电化学工作站等,研究了电压和时间对镁合金微弧氧化膜的厚度、表面形貌和耐蚀性的影响.结果表明,微弧氧化膜层主要由MgO、MgF2和Mg2S...     

Preparation and corrosion resistance studies of zirconia coating on fluorinated AZ91D magnesium alloy

Novel anti-corrosion zirconia coating was prepared via the sol–gel method for AZ91D magnesium alloy using zirconium nitrate hydrate as a precursor modified with acetylacetone (AcAc). Magnesium alloy substrates were first fluorinated in 20% HF aqueous solution at room temperature for 20 h, then, the zirconia coating was deposited on the fluorinated sample by dip coating. Basing on the sol–gel process, a chelate complex from the reaction of zirconium coordinating AcAc was formed which was supported by UV–vis spectrum analysis. The result showed that the absorption peak could be seen for the sol at 308 nm, which was red-shifted by 36 nm from that of methanol form of AcAc (272 nm). Moreover, Fourier transform infrared (FT-IR) spectrum analysis was performed to examine the structural differences between the gel and AcAc. The results indicated that the chelate complex with a bidentante structure was formed through the interaction chemically between zirconium nitrate and AcAc. The surface morphology of the zirconia coating was characterized by scanning electron microscope (SEM), an uniform coating can be obtained on the fluorinated sample. The corrosion resistance of the substrate, the fluorinated with and without the zirconia coating in the 3.5 wt.% NaCl solution was studied using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests, respectively. The results demonstrated that the zirconia coating could greatly improve the corrosion resistance of the AZ91D magnesium alloy. Furthermore, the effect of the different heat-treatment temperatures for the zirconia coating on corrosion resistance was also discussed.     

铈对镁合金微弧氧化膜微观结构和耐蚀性的影响

利用扫描电镜、电化学工作站等,研究了不同铈盐添加方法对ZE10镁合金在由硅酸钠14 g/L、氟化钠14g/L、氢氧化钠2 g/L、甘油5mL/L组成的溶液中,于电压300 V、脉冲频率1 kHz、占空比15％的条件下微弧氧化20 min所得微弧氧化膜厚度、形貌和耐蚀性的影响.结果表明,先进行铈盐转化处理再微弧氧化和在电...     

镁合金微弧氧化工艺及陶瓷层耐蚀性能研究

通过单因素试验讨论了镁合金微弧氧化电解液各组分对成膜的作用,得到电解液最佳配方:10g/L(NaPO3)6,5g/LNH4F,6g/LKOH,6mL/LC3H8O3。用扫描电镜(SEM)、X射线衍射(XRD)和能谱(EDS)分析了陶瓷膜层的表面形貌、截面形貌、相组成及元素组成;采用点滴试验、交流阻抗和盐雾试验考察了陶瓷层的耐腐蚀性能。结果表明:膜层表面分布着大量均匀的放电微孔,孔径在1~3μm之间,膜层截面内层与基体过渡部分呈犬牙交错状态,结合良好;膜层由大量非晶态相及少量MgO组成,耐蚀性能优良。P与F元素的存在,证明了电解液组分较好地参与了微弧氧化反应。     

Novel copper immersion coating on magnesium alloy AZ91D in an alkaline bath

Copper immersion coating of magnesium alloys has, to date, been conducted only in acidic baths. This article describes a novel alkaline bath for copper immersion coating on AZ91D magnesium alloy. Prior to the coating process, a chemical etching process of the magnesium substrate was optimized using orthogonal experimental methodology. The copper immersion coating was then investigated with regard to the effect of pH and fluoride content in the deposition bath. It was revealed during the coating process that an increase of pH and fluoride content led to a surface film formation on the magnesium substrate. The surface film formation occurred simultaneously with copper reduction, rendering a controlled magnesium dissolution, thereby a controlled copper deposition. With optimized conditions of chemical etching and immersion coating processes, uniform copper deposits were achieved.     

Corrosion resistance of plasma-anodized AZ91D magnesium alloy by electrochemical methods

Anodic coatings formed on magnesium alloys by plasma anodization process are mainly used as protective coatings against corrosion. The effects of KOH concentration, anodization time and current density on properties of anodic layers formed on AZ91D magnesium alloy were investigated to obtain coatings with improved corrosion behaviour. The coatings were characterized by scanning electron microscopy (SEM), electron dispersion X-ray spectroscopy (EDX), X-ray diffraction (XRD) and micro-Raman spectroscopy. The film is porous and cracked, mainly composed of magnesium oxide (MgO), but contains all the elements present in the electrolyte and alloy. The corrosion behaviour of anodized Mg alloy was examined by using stationary and dynamic electrochemical techniques in corrosive water. The best corrosion resistance measured by electrochemical methods is obtained in the more concentrated electrolyte 3 M KOH + 0.5 M KF + 0.25 M Na₃PO₄·12 H₂O, with a long anodization time and a low current density. A double electrochemical effects of the anodized layer on the magnesium corrosion is observed: a large inhibition of the cathodic process and a stabilization of a large passivation plateau.     

镁合金微弧氧化陶瓷层的生长过程研究

采用扫描电镜(SEM)、X射线衍射(XRD)和膜厚测量等方法,研究了MB8镁合金在硅酸盐体系中不同的微弧氧化时间对陶瓷膜层的截面形貌、相组成及生长速度的影响。结果表明:微弧氧化初期,阳极表面主要生成MgO相并向基体内部生长;随后,膜层沿基体向外生成Mg2SiO4相;在氧化末期,膜层同时向内和向外生长,且向内生长占主导地位,但陶瓷层相组成与氧化中期时相同。氧化膜的厚度随时间呈线性增长。提出了陶瓷层在不同阶段的生长机制。     

AZ91D镁合金电镀Al-Zn复合镀层及耐蚀性研究

为了提高AZ91D镁合金的抗腐蚀性能,在其表面电镀Al-Zn复合镀层.研究了镀层的物相组成、微观形貌、结合力及抗腐蚀性能.结果表明,镀铝为中间层能得到较好的组织和性能,镀层表面为纯锌,镀Zn层分布致密均匀,镀锌层约6μm,中间铝层约4μm且组织疏松;电流密度3.5 A/dm2、电镀时间1 min时镀层具有较好的结合力与...     

AZ31镁合金稀土转化成膜工艺研究

本文对AZ31镁合金表面稀土转化成膜工艺进行了研究。分析了不同的成膜工艺参数丽土盐溶液组成、转化成膜时间）对稀土转化膜的形貌及耐蚀性能的影响。扫描电镜分析了不同成膜工艺形成的稀土转化膜的表面形貌;极化曲线研究了转化膜的电化学腐蚀行为。结果表明：当转化液中硝酸铈浓度为4．3423g·L^-1和硝酸镧浓度为4．3302g·L^-1时,转化膜的耐蚀性能最好;成膜时间对膜的耐蚀性也有不同程度的影响。