SRB对微弧氧化AZ91镁合金的腐蚀影响

用实验方法研究了微弧氧化AZ91镁合金在SRB培养基中的腐蚀行为,对实验结果进行了分析。结果表明:4种挂片的腐蚀程度按从大到小的顺序排列为无菌基体合金有菌基体合金有菌MAO合金无菌MAO合金;MAO膜的存在显著提高了AZ91合金在无菌培养基中的耐腐蚀性;SRB的存在加速了微弧氧化AZ91镁合金的膜下穿孔,腐蚀孔孔口的形状为近圆形。     

镁合金微弧氧化棕黑色膜的制备及性能研究

镁合金微弧氧化在汽车和电子产品等民用领域具有广泛应用,这些领域对色彩的多样性提出 要求．采用微弧氧化技术对镁合金表面进行着色处理．在以硅酸钠、偏铝酸钠、氢氧化钠和氟化钾为 电解液的基础上,添加钒酸铵作为着色盐制备了棕黑色陶瓷膜．分别应用ＳＥＭ 观察了表面形貌, ＥＤＳ检测元素构成,ＸＲＤ分析涂层的相组成,电化学工作站分析了涂层的耐腐蚀性能．结果显示： 随ＮＨ４ＶＯ３ 质量浓度的升高,陶瓷膜颜色由浅绿色逐渐变为棕黑色,陶瓷膜表面微孔尺寸减小,耐 腐蚀性能提高;陶瓷膜相组成为ＭｇＯ,ＭｇＳｉＯ３,ＭｇＡｌ２Ｏ４,Ａｌ２Ｏ３,ＶＯ２;钒的氧化物存在使陶瓷膜 显色．     

AZ31B镁合金表面微弧氧化涂层的制备及其封孔处理

采用微弧氧化法,以AZ31 B镁合金为基体,在其表面制备均匀的微弧氧化涂层并对其进行封孔处理来提高其耐蚀性.通过扫描电子显微镜(SEM)及能谱分析(EDS)研究了微弧氧化涂层的表面形貌及元素组成,通过电化学测试及浸泡实验研究了涂层的耐腐蚀性能.结果表明:镁合金表面微弧氧化涂层呈现典型的多孔结构,涂层厚度约为2μm;当硅...     

AZ91压铸镁合金在六偏磷酸盐体系中的微弧氧化工艺

采用六偏磷酸盐体系在AZ91压铸镁合金表面制备了一系列微弧氧化膜层。研究了(NaPO3)6和NaOH质量浓度、电流密度以及氧化时间对微弧氧化膜生长规律的影响,并通过扫描电镜、中性盐雾试验等方法研究了微弧氧化膜层形貌特征及耐蚀性能。结果表明:本试验所制备的微弧氧化膜层的耐蚀性属于尚耐蚀和可用等级,与基体合金相比有大幅度提高。采用六偏磷酸盐体系在AZ91压铸镁合金表面制备耐蚀性微弧氧化膜的最佳工艺参数如下:(NaPO3)6质量浓度为2 g/L,NaOH质量浓度为6 g/L,电流密度为6 A/dm2,氧化时间为10m in。     

微弧氧化对铝合金搅拌摩擦焊缝耐蚀性能的影响

为了提高搅拌摩擦焊(FSW)焊缝的耐腐蚀性能,本文采用微弧氧化技术在6082系铝合金FSW焊缝表面制备了不同电流密度下的微弧氧化陶瓷膜层,使用X射线衍射仪(XRD)和扫描电镜(SEM)对膜层进行相组成确定并观察其表面形貌,使用激光共聚焦扫描电子显微镜(CLSM)测定膜层表面粗糙度。通过电化学阻抗谱(EIS)及极化曲线(LSV)分析比较微弧氧化前、后铝合金FSW焊缝的耐腐蚀性能。结果表明:随着电流密度的增加,膜层越来越厚,击穿越来越困难。陶瓷层一旦被击穿,会形成很多的熔融物,使陶瓷层表面凹凸不平,表面粗糙度增加。此外,当电流密度为10A/dm2时,陶瓷膜层表现出较佳的耐蚀性能。     

混杂增强AZ91复合材料的制备及其显微组织和性能

采用挤压铸造方法制备了以AZ91镁合金为基体、Al2O3短纤维(Al2O3f)和石墨颗粒(Grp)混杂为增强体的复合材料。观察了不同复合材料的显微组织,测试了其力学性能,并对其摩擦磨损性能进行了研究。结果表明:用此法制备的镁基复合材料增强相分布均匀,与基体结合紧密。硬度随Grp体积分数的增加而降低,Al2O3f的加入能提高复合材料的硬度。抗拉强度和伸长率都随Grp体积分数的增加而减小。Grp体积分数增加,磨损质量损失和摩擦系数都降低。随着摩擦过程的进行,在试样表面逐渐形成一层黑色连续的润滑膜。     

镁合金环保型阳极氧化膜的耐蚀性能研究

阳极氧化能够有效地提高镁合金表面的耐腐蚀性能． 以镁合金AZ91D 为研究对象,阳极氧化 过程采用绿色环保型电解液,该电解液不含铬、氟等有毒物质,但能显著改善镁合金AZ91D 的表面 耐腐蚀性能． 对试样采用扫描电镜、浸泡实验和电化学测试等手段进行表征和分析． 分析结果表明: 生成的阳极氧化膜为致密、多孔结构,且浸泡试验和极化曲线的结果都证明此方法下制得的阳极氧 化膜能够显著的提高镁合金的表面耐腐蚀性能．     

AZ91D镁合金表面环保型钙系磷化膜的制备及其耐蚀性

采用化学转化处理的方法,在AZ91D镁合金的表面制备了均匀致密的钙系磷化膜,其中磷化液配方中不含铬、氟及亚硝酸盐等对环境有害的离子。通过场发射扫描电子显微镜和X射线衍射仪研究了磷化时间及温度对磷化膜结构和相组成的影响。结果表明:磷化时间为20min,磷化温度为40℃时,所得到的磷化膜的致密性和均匀性较好。与空白基体相比,经磷化处理后的镁合金在3.5%NaCl溶液中的耐腐蚀性能明显提高。     

SiC纳米颗粒对6060型铝合金微弧氧化膜组织结构及耐蚀性能的影响

为提高铝合金表面微弧氧化膜的耐蚀性,通过向电解液中添加SiC纳米颗粒的方式,成功获得了含有SiC纳米颗粒的复合微弧氧化膜层。采用D-MAXIIA型X射线衍射仪(XRD)、场发射扫描电镜(FESEM)和金相定量分析光学显微镜分别对陶瓷膜的相组成、微观组织结构及膜层厚度进行了检测分析;采用AutoLAB-PGSTAT302型电化学工作站对制备的微弧氧化膜进行极化曲线和交流阻抗谱的测定。结果表明:SiC颗粒在复合微弧氧化膜层中的含量随着氧化时间的增加而逐渐增加;添加SiC纳米颗粒后微弧氧化膜的厚度没有明显变化;与未添加SiC纳米颗粒的微弧氧化膜层相比,其耐蚀性明显提高。     

二氧化钛改性复合纳滤膜的制备及其性能

传统的聚酰胺(PA)复合纳滤膜是由哌嗪(PIP)和均苯三甲酰氯(TMC)通过界面聚合的方式制备而成的,但通量较低、易污染等缺点一直制约着它的工业化发展.近年来,关于提高聚酰胺复合膜纳滤通量的研究有很多,例如在水相或油相中加入纳米粒子和多孔材料等.由于二氧化钛(TiO_2)结构和官能团的优势,选择亲水TiO_2作为纳米粒子添加剂加入哌嗪中和油相TMC发生界面聚合反应,通过表面元素分析、水接触角测试(WCA)和扫描电子显微镜(SEM)等方法对膜表面的化学成分、亲水性及形貌进行表征.测试结果表明,当缚酸剂浓度达到3%时PA的水渗透性能最优,随着TiO_2的加入,膜的水接触角变小、亲水性增强,当TiO_2浓度达到0.2%时,纳米复合膜对硫酸钠溶液的通量达到20 L/(m2·h),截留率达98.73%.     

Analyses of Microarc Oxidation Coating Formed on AZ91D Alloy in Phosphate Electrolytes

This paper studied the appearance transition of microdischarges, the phase composition and the morphology evolution of the oxide film formed by microarc oxidation on AZ91D magnesium alloy. The appearance of microdischarges population experienced apparent changes in size, spatial density and color, which was related with the changes of the type and quantity of the disintegrated gas bubbles generated at the interface between the electrolyte and substrate. Correspondingly, the diameter of micropores together with net-like fine microcracks increased when a higher voltage was employed. The coating was composed of MgO, MgAl2O4 and there existed a fluoride-enriched zone of about 3-5μm at the film/substrate interface.     

Microstructure and corrosion resistance of modified AZ31 magnesium alloy using microarc oxidation combined with electrophoresis process

A top electrophoresis coating was deposited on the surface microarc oxidation (MAO) modified ceramic coating on AZ31 magnesium alloy. Microstructure and corrosion resistance of this composite coating were studied by SEM, electrochemical potentiodynamic polarization, and acid corrosion test. The results showed that the composite coating with a top electrophoresis coating on the surface of ceramic coating exhibited a better corrosion resistance compared with the coating formed by chemical conversion film combined with electrophoresis process. Corrosive ions could permeate into the substrate with corrosion time, and the composite coating was firstly destroyed around the scratch. The formation of composite coating with a higher adhesive force due to the porosity of the ceramic coating contributed to the improved corrosion resistance property.     

聚苯胺/氧化铈复合涂层的防腐性能

制备苯胺与氧化铈质量比分别为1:100,1:200,1:300的聚苯胺/氧化铈复合物,将制备的不同质量比的聚苯胺/氧化铈复合物与环氧树脂溶液共混制备防腐蚀涂料,通过测试该涂料在酸、碱、盐溶液中的交流阻抗谱与腐蚀电位,研究了聚苯胺/氧化铈/环氧树脂复合防腐涂料的防腐蚀性能.实验结果表明,以苯胺与氧化铈质量比为1:100聚苯胺/氧化铈复合粒子为填料的涂料抗腐蚀性能最好,所制备涂料抗酸腐蚀性能较差,而抗碱和抗盐腐蚀性能较好.     

稀土铈对AZ91镁合金表面腐蚀性能的影响

为解决镁合金表面处理工艺复杂、成本高且存在环境污染问题 ,采用气相扩渗法研究了稀土铈对AZ91镁合金表面的渗入及其耐腐蚀性能的影响 .结果表明 ,经过扩渗稀土铈表面处理的AZ91镁合金 ,腐蚀电阻增大近一倍 ,均匀腐蚀速率由 1.85 0mg/m2 ·s降为 0 .876mg/m2 ·s;腐蚀电位正移 ,同一电位下所对应的腐蚀电流密度明显降低 .利用X射线光电子能谱 (XPS)分析了经过扩渗稀土后AZ91镁合金表面的成分中 ,稀土铈是以化合态的形式存在于表层 ,渗入的稀土元素铈起到净化合金表面、微合金化的作用     

Effects of KMnO_4 on microstructure and corrosion resistance of microarc oxidation coatings on 2024 aluminum alloy

Microarc oxidation(MAO) coatings were prepared on 2024 aluminum alloy in a Na2SiO3-KOH electrolyte with KMnO4 addition varying from 0 to 4 g/L.The microstructure and phases of the coatings were characterized by scanning electron microscopy(SEM) and X-ray diffractometry(XRD),respectively.The corrosion resistance of MAO coatings was evaluated by electrochemical potentiodynamic polarization in 5%(mass fraction) NaCl solution.The results show that when KMnO4 is added into base electrolyte,the growth speed of oxide coatings is increased obviously.The main phase of oxide coatings is Al2O3,and the contents of MnO2 and Mn2AlO4 phases are increased at the top of oxide coatings with increasing the concentration of KMnO4.The solute elements participate in forming the oxide coatings.When a proper concentration of KMnO4(2.5 g/L) is added into the base solution,the micropores of the MAO coatings are small and compact,and the corrosion resistance of oxide coatings is increased largely.     

Cr-Si-Al复合涂层的结构与耐蚀耐热性研究

应用Ｐ－Ｃ法对中碳钢进行Ｃｒ－Ｓｉ－Ａｌ复合涂覆,用光学显微镜观察了涂层的形貌。用电子 探针及扫描电镜测定了涂层的表面成分及Ｃｒ,Ｓｉ,Ａｌ在涂层中的分布,用Ｘ射线衍射测定了涂层的结构。将经涂覆后的试样进行盐水腐蚀和高温氧化试验,结果表明,其耐蚀和抗氧化性大幅度提高。     

硅烷膜固化方式对AZ91镁合金耐蚀性的影响

为了改善AZ91镁合金的耐蚀性,采用包括加热固化、碱液固化和微电水固化在内的3种不同固化方式制备了硅烷膜,并对其耐蚀性进行了研究.采用光学显微镜和扫描电子显微镜观察了试样的腐蚀形貌,并采用极化曲线分析了硅烷膜的耐蚀性.结果表明,经硅烷化处理后,AZ91镁合金表面可以形成一层硅烷膜,且很好地抑制了镁合金的腐蚀;对比3种不同固化方式后发现,碱液固化效果最佳,其次是加热固化,微电水固化效果虽不及前两者,但也有较好的效果.     

Ho对AZ91镁合金腐蚀行为的影响

采用重力铸造方法制备了3种Ho改性AZ91镁合金。通过腐蚀实验对改性合金的自腐蚀和电偶腐蚀行为进行了研究。结果表明,随着Ho含量的增加,改性合金的自腐蚀性能和电偶腐蚀性能逐步提高,当Ho的质量分数为1.10%和2.16%时,合金的耐蚀性能较佳。此外,阴极的特性对改性合金的腐蚀性能有明显影响,4种材料的阴极作用由弱到强依次为:铝硅合金,纯铝,45#钢和球墨铸铁。Ho通过抑制β相的阴极作用,增加自腐蚀电位,提高了合金的腐蚀性能。     

Effects of KMnO4 on microstructure and corrosion resistance of microarc oxidation coatings on 2024 aluminum alloy

Microarc oxidation (MAO) coatings were prepared on 2024 aluminum alloy in a Na_2SiO_3-KOH electrolyte with KMnO_4 addition varying from 0 to 4 g/L. The microstructure and phases of the coatings were characterized by scanning electron microscopy (SEM) and X-ray diffractometry (XRD), respectively. The corrosion resistance of MAO coatings was evaluated by electrochemical potentiodynamic polarization in 5% (mass fraction) NaCl solution. The results show that when KMnO_4 is added into base electrolyte, the growth speed of oxide coatings is increased obviously. The main phase of oxide coatings is Al_2O_3, and the contents of MnO_2 and Mn_2AlO_4 phases are increased at the top of oxide coatings with increasing the concentration of KMnO_4. The solute elements participate in forming the oxide coatings. When a proper concentration of KMnO_4 (2.5 g/L) is added into the base solution, the micropores of the MAO coatings are small and compact, and the corrosion resistance of oxide coatings is increased largely.     

Influence of potential on structure and properties of microarc oxidation coating on Mg alloy

In order to obtain optimizing microarc oxidation coating on Mg alloy from a friendly-enviormental electrolyte free of Cr⁶⁺ and PO ₄ ³⁻ , constant potential regime was applied to produce it. The influence of potential on the morphology, composition, structure and other properties, such as microhardness and corrosion resistance were investigated by scanning electron microscopy (SEM), energy dispersive spectroscope (EDS), X-ray diffraction (XRD), hardness tester and electrochemical method. The results clearly show that oxidation potential plays an important role in the formation of coating’s structure and properties. The microarc oxidation coating is smooth and white, which consists of two layers. The external layer is loose and porous and enriched in Al and Si. Moreover, its content of Al and Si increases with the increasing operated potential. While the inner layer is compact and the content of Al and Si are lower than that of the external layer. The coating is composed of several phases and the major phases are MgAl₂O₄ and MgO, and the minor phases are Al₂O₃ and SiO₂ when the potential is higher. The microhardness of coating is obtained the maximum at the potential of 45 V, so does the corrosion resistance.