交变电场下不锈钢的电化学行为

主要研究了交变电场下SS304不锈钢在2.5 mol/L硫酸 溶液中的表面成膜情况.运用电位阶跃研究了不锈钢在交变电场高电位、低电位下的电化学 反应；用AFM准现场地观察了不锈钢在交变电场下各个阶段的成膜状况；用XPS分析了膜层的 纵向组成结构.结果表明：交变电场下不锈钢表面钝化膜的生长机制不同于直流钝化.最后 分析了不锈钢在交变电场下的电化学反应和成膜机理.     

交变电场对不锈钢钝性和钝化膜性质的影响

总结了交变电场对不锈钢自腐蚀电位、钝性和钝化膜性质的影响，概述了交变电场下钝化膜的生长机制。不锈钢载波钝化与彩色钝化的结果表明，控制在适当的参数条件下的交变电场对不锈钢钝化膜的综合性能有较大幅度的提高，显示了该领域的研究价值。     

电位及后处理对304不锈钢表面膜组成及其稳定性的影响

通过5.6mol/LH_2SO_4中活性溶解能力和含氯离子介质中点蚀破裂电位E_b的测量,证明304不锈钢过钝化膜的耐酸活化溶解能力远远优于钝化膜。钼酸盐溶液的后处理,可使304不锈钢过钝化膜的点蚀破裂电位升高。304不锈钢这些稳定性的提高,与钝化膜中各组成结构的变化紧密相关。运用AES和XPS表面分析手段研究了304不锈钢表面膜的组成结构与外加极化电位,膜稳定性的关系。     

纳米硅溶胶改性有机复合钝化膜耐蚀性研究

研究纳米硅溶胶改性剂对水溶性丙烯酸树脂和钼酸盐组成的有机复合膜微观形貌及腐蚀行为的影响.结果表明,含有硅溶胶的有机物钝化膜耐蚀性能优于丙烯酸树脂与钼酸盐组成的钝化膜,对镀锌层腐蚀具有良好的抑制作用.这是因为纳米硅溶胶粒子不仅降低了有机物钝化膜的通透性,阻滞了引发腐蚀的物质穿入膜内,而且,它还能与锌离子结合生成硅酸锌,吸附于镀锌层表面,起到与沉积膜型缓蚀剂相同的效果.     

不锈钢载波钝化膜的生长过程

运用电化学交流阻抗分析(EIS)、电量测定并结合原子力显微镜(AFM)研究了304不锈钢载波钝化膜的生长过程．研究了在交变电场下钝化膜层中微孔的产生及其对膜层生长的作用；并运用钝化膜生长过程中的电量时间响应和原子力显微镜扫描分析对不锈钢载波钝化膜的生长机理进行验证分析．结果表明：载波钝化膜具有很高的生长速度是由于交变电场对膜层的作用改变了膜层的生长方式，使之不同于直流钝化条件下钝化膜的生长过程．     

锌酸盐镀锌层的三价铬溶液钝化

采用电化学方法、扫描电镜和X射线光电子能谱研究了锌酸盐镀锌层的三价铬钝化膜的电化学性能、表面结构与成膜机理。结果表明：锌酸盐镀锌层的三价铬钝化膜表面结构致密、无明显裂纹，具有较好的耐腐蚀性能；这种钝化膜表层与里层的组成不同，表层的组成为Cr2O3-Cr（OH）3-ZnO共混物；里层（离表层10-30nm处）的主要组成为Cr2O3-ZnO-Zn共混物；钝化膜的成膜过程可能包括镀锌层的溶解、碱性薄层的形成、胶状膜的形成和胶状膜转化成钝化膜4个步骤。     

载波钝化及其后处理对不锈钢钝化膜组成及稳定性的影响

一、前言钝化是不锈钢得以广泛应用的前提之一,人们不断地探索提高钝化膜稳定性的新途径。一些学者认为,交变电场对钝化膜具有破坏作用。这种看法有一定的片面性。我们曾发现,在直流钝化电位基础上叠加一定频率,幅值和波形的交变电场对不锈钢进行载波钝化,所得到的载波钝化膜再经适当的后处理,其稳定性远远优于相同条件下得到的直流钝化膜,其中最佳的载波钝化及后处理条件可使不锈钢钝化膜稳定性提高5个数量级左右。本工作通过AES等分析手段,从钝化膜组成变化角度探讨载波钝化及后处理提高钝化膜稳定性的原因。     

热镀Zn层钼酸盐钝化工艺

研究了用低毒性钼酸盐取代剧毒的重铬酸盐对热镀 Zn层进行钝化的工艺,探讨了钝化液组成、pH值、钝化处理温度及时间对钝化成膜及膜层耐 蚀性的影响.中性盐雾腐蚀(NSS)试验表明,采用该工艺可获得耐蚀性与低Cr钝化相当的具有 较为均匀的淡黄或浅蓝色钝化膜.     

铝及铝合金无铬钝化研究进展

铝合金可加工成各种板材、型材、铝铸件,为了减少其在工业环境中的腐蚀损失,需进行钝化处理.钝化常作为涂层的预处理步骤,钝化膜能增强铝合金表面与有机涂层的结合力,进一步提高涂层对基体的防护能力.目前无铬钝化主要是钼酸盐钝化、稀土盐钝化、锆/钛盐钝化及有机物钝化,因此对这几种主要化学钝化法的研究进程及现状进行了综述.钼酸盐复配其他盐协同缓蚀,能够获得更强的耐腐蚀性能.稀土盐中加入强氧化剂和成膜促进剂,可以简化处理工艺,降低腐蚀电流.锆、钛盐中加入有机物形成复合膜,能够改善单一膜层的耐腐蚀性能,提高与基体的结合力.硅烷在铝合金表面形成交联结构,从而表现出良好的封闭效果.在硅烷中加入纳米粒子可以获得更好的膜层表面形貌,加入稀土及其氧化物可提高耐腐蚀性能.硅烷两步法成膜过程中,成膜次序不同能够获得不同的膜层物理性能和耐蚀效果.最后,对未来无铬钝化工艺的研究方向进行了展望.     

电镀锌板钼酸盐体系钝化膜的制备和腐蚀性能研究

采用钼酸盐作为主成膜物质对电镀锌板进行钝化处理,采用低浓度铬酸盐作为对比试验。用硫酸铜点滴试验、电化学交流阻抗、极化曲线和金相显微镜观察等方法检验膜层的腐蚀性能。结果表明:钼酸盐-硅烷、钼酸盐-硅烷-有机酸复合钝化可有效提高电镀锌层的腐蚀电位,降低腐蚀电流密度,抑制腐蚀的电化学过程,所以提高了镀锌板的耐腐蚀性,而且比低浓度铬酸盐钝化膜耐蚀性更好。     

原子吸收光谱法研究不锈钢电极在交变电场下的溶解与沉积

采用原子吸收光谱结合电化学技术研究了交变电场对304型不锈钢电极表面的溶解和沉积的影响.通过对钝化膜层和溶液中金属离子的含量分析,研究了不同交变电场参数对电极中各金属元素的溶解和沉积.结果表明:电极电化学反应总量随着交变电场频率的升高而减少,随着占空比的增加出现峰值,随着高、低电位的绝对值的增加而增加.同时对交变电场下电极表面各元素的选择性溶解进行了探讨,并通过电化学测试对研究结果进行了分析.     

无铬复合钝化膜的微观组织结构及耐腐蚀性能

目的解决热镀锌钢板表面六价铬钝化工艺所产生的环境污染问题。方法以钼酸铵、纳米硅溶胶、单宁酸、硅烷偶联剂KH151和KH792为主要原料配制新型环保的无铬复合钝化液,在镀锌板表面制备钝化膜。采用扫描电子显微镜(SEM)、能谱仪(EDS)和X射线光电子能谱仪(XPS)分析无铬复合钝化膜表面的微观形貌、元素组成和化学成分,用电化学工作站测试Mo元素对镀锌板耐蚀性的影响,使用中性盐雾实验研究不同皮模量时膜层的耐蚀性。结果无铬复合钝化膜中的Mo元素可以抑制微裂纹的产生和发展,阻挡腐蚀性介质向金属基体扩散,提高复合硅烷膜的电阻。复合钝化膜的电化学交流阻抗比硅烷钝化膜提高了1.6倍,与六价铬钝化膜接近,可以有效抑制腐蚀电化学反应的发生,降低反应速度,提高膜层的耐蚀性。皮膜量为892 mg/m2时,膜层的腐蚀面积为0,耐蚀性达到六价铬钝化膜水平;皮膜量为1252 mg/m2时,耐蚀性能优异。结论制备的无铬复合钝化膜结合了硅烷钝化膜和钼酸盐钝化膜两方面的优点,提高了膜层的致密性和结合性,膜层耐腐蚀性接近/达到了六价铬钝化的效果。     

Influences of alloyed molybdenum and molybdate addition on the corrosion properties and passive film composition of stainless steels

The influences of alloyed molybdenum and molybdate addition on the corrosive properties and passive film composition of stainless steels were evaluated. Anodic polarization measurement, solution analysis, and surface analysis were conducted to investigate the influences. The roles of alloyed molybdenum and molybdate addition were observed to vary with the environment. In addition, the role of molybdate addition depended on the presence of nitrogen in the alloy. The composition of the passive film formed by alloyed molybdenum was found to be different from that of the film formed by molybdate addition. These observations suggest that when the thermodynamical condition in the film is suitable for the formation of molybdate, it first forms in the film and then later partially dissolves into a solution and partially evaporates.     

The coupled kinetics of film growth and dissolution of stainless steel repassivating in acid solutions

The kinetics of growth of passivating films on freshly generated 304L stainless steel in perchloric acid solutions is presented. The passive film grows initially by oxidation of all components of the alloy with the rate of film thickening being controlled by ion migration under high electric field. As the film thickens oxidised iron begins to dissolve from the passive film into the strongly acidic electrolytes; dissolution commences when the electric field across the growing film has relaxed to a particular value. The rate of dissolution is described quantitatively in terms of simple non-steady state diffusion of Fe^2- through the film, and composition profiles of the film are deduced. This form of dissolution is constructive in that it provides repassivation by virtue of a chromium enriched oxide. No direct dissolution from the bare metal surface can be detected.     

载波钝化电场条件对不锈钢着色膜的影响

采用功波钝化法在硫酸溶液中获得了不锈钢的彩色钝处理,探讨了所载方波的参数对着色的影响。结果表明,载波钝化所载方波的各参数对着色膜厚度的影响都有一定的规律。运用极化曲线对方波各参数的影响作了初步分析,以便提高着色工艺并为进一步研究着色机理提供实验数据。     

Influence of molybdate species on the tartaric acid/sulphuric acid anodic films grown on AA2024 T3 aerospace alloy

AA2024 T3 alloy specimens have been anodised in tartaric acid/sulphuric media and tartaric acid/sulphuric media containing sodium molybdate; molybdate species were added to the anodising bath to enhance further the protection provided by the porous anodic film developed over the macroscopic alloy surface. Morphological characterisation of the anodic films formed in both electrolytes was undertaken using scanning electron and transmission electron microscopies; the chemical compositions of the films were determined by Rutherford backscattering spectroscopy that was complemented by elemental depth profiling using rf-glow discharge optical emission spectrometry. The electrochemical behaviour was evaluated using potentiodynamic polarisations and electrochemical impedance spectroscopy; the corrosion performance was examined after salt spray testing. The porous anodic film morphology was little influenced by the addition of molybdate salt, although thinner films were generated in its presence. Chemical composition of the anodic film was roughly similar; however, addition of sodium molybdate in the anodizing bath resulted in residues of molybdate species in the porous skeleton and improved corrosion resistance measured by electrochemical techniques that was confirmed by salt spray testing.     

不锈钢载波钝化参数对钝化膜层耐蚀性的影响

运用电化学交流阻抗谱、原子力显微镜研究了在不同的载波钝化参数下形成的不锈钢钝化膜的耐蚀性,测定了极化电阻值Rp和相应的钝化膜的表面形貌。结果表明：载波钝化条件参数对膜层的耐蚀性有较大的影响,各参数(频率、占空比、高电位、低电位)的变化使得电极表面钝化膜的形貌发生很大的变化,从而影响到膜层的耐蚀性。     

The effect of water and oxyanions on the passivation of iron in mixed dimethylformamide-water solvents

The passive film on iron has been produced anodically in mixed dimethylformamide-water solvents with and without oxyanion, and reduced cathodically in phosphate-borate buffer solution of pH 8.5. The thickness of the passive film was estimated from the chronopotentiogram. The passivation was expedited by the addition of water, molybdate and chromate. These species were directly involved in the passivation process to form the passive film, but the extent of the involvement relied on the nature of oxyanion. The addition of greater quantities of water led to no formation of the passive film. The film growth process was dependent evidently on the stability of the ferric hydroxide and/or (FeL)_ads (L : oxyanion) in the DMF-water media.     

An X-ray photo-electron spectroscopic study on the role of molybdenum in increasing the corrosion resistance of ferritic stainless steels in HC1

X-ray photo-electron spectroscopy has been used to investigate the correlation between composition of surface films and the beneficial effects of molybdenum addition to high purity, 30Cr ferritic stainless steels in improving the corrosion resistance properties in HCI. It has been found that the passive films formed consist mainly of hydrated chromium oxy-hydroxide and the composition of the films on 30Cr and 30Cr-2Mo stainless steels is essentially the same, except for the existence of a small amount of hexavalent molybdenum on the latter steel. The surface film formed in the active region contains a large amount of hexavalent molybdenum. The beneficial effects of molybdenum have been interpreted as follows: molybdenum eliminates the active surface sites through the formation of molybdenum oxy-hydroxide or molybdate on these site, on which it is difficult to form the stable passive film. This leads to the appearance of a homogeneous steel surface and to the formation of a homogeneous passive film.