Novel,water-based high-performance primers that can replace metal pretreatments and chromate-containing primers

In previous research it was demonstrated that simple rinses with organofunctional silanes can be used to protect metals against various forms of corrosion. Such treatments also improve paint adhesion. However, when unpainted, the silane filsm are too thin to provide long-term corrosion protection. In this paper it will be shown that much thicker, primer-like coatings can be obtained from silanes if the silanes are mixed with organic resins and small particles, preferably nanosize. Self-priming coatings of up to 20 μm in thickness have been obtained with outstanding adhesion and corrosion protection properties. The components of such “superprimer” systems are all water-based, and they do not contain chromates or other toxic ingredients. Thus, they are environmentally friendly. This paper describes several successful superprimers and presents their performance data. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana, and appears on pp. 374–81 of the Proceedings.     

Oxide coatings on Al/SiC composite formed by plasma-electrochemical method

The processes of film growth and characteristics of film formation in an aqueous phosphate-borate or borate electrolyte are studied. After 2 h, films with thicknesses of 30–40 μm and surface microhardnesses of 9–13 GPa are obtained. The elemental and phase compositions of the films and their corrosion resistance estimated using thes drop technique are discussed.     

金属表面硅烷化防护处理及其研究现状

综述了一种新型的金属表面防护处理技术--硅烷化处理的研究现状.对硅烷膜的制备工艺、表征及膜覆盖电极的性能进行了详细介绍.文中也同时探讨了硅烷溶液的水解与失效问题,这两个基础问题的研究有助于了解金属表面硅烷膜的形成,并对制备工艺的优化起到决定性作用.最后还介绍了更具发展潜力的电沉积制备硅烷膜技术并提出了展望.     

电沉积法制备Co–LDHM超疏水膜及性能研究

目的 采用电沉积法在不锈钢网上构筑稳定的钴层状双氢氧化物微球(Co–LDHM)超疏水薄膜。方法 首先,通过第1次电沉积在不锈钢网上制备出ZIFs纳米片阵列结构(ZIF–NFA),并以此为牺牲模板,然后在第2次电沉积作用下制备出微纳米尺寸的Co–LDHM,最后通过浸泡硅烷降低其表面能。通过溅射试验、耐磨性实验、油水分离实验及电化学试验,分别评价经超疏水改性后不锈钢网的抗污、耐摩擦、油水分离及耐蚀性能,并通过接触角,用扫描电子显微镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FTIR)对不锈钢网表面的疏水程度及膜表面的形貌与结构进行分析。结果 经两步电沉积处理后的不锈钢网表面类似浴球状,具有微米/纳米多级表面形貌结构;接触角测试表明,所制备的薄膜呈现出良好的超疏水性能,静态接触角达到159.4°±2°;经过30个耐摩擦实验周期,其表面接触角为141.3°±2°,仍具有较高的疏水性;油水分离效率均大于97%,重复20次以上分离效率仍保持在96%,且具有一定耐蚀性能和良好的抗污性。结论 通过两步电沉积法构筑的Co-LDHM超疏水不锈钢网具有优异的超疏水性能,为MOFs在制备超疏水材料方面的应用提供了一个新的思路。     

镀锌钢表面硅烷膜的耐蚀性能研究

采用浸涂技术,在热镀锌（HDG）钢板表面制备3-氨丙基甲基二乙氧基硅烷膜。通过电化学方法研究硅烷膜在3．50％的氯化钠溶液中的耐蚀性能,并用SEM研究存在硅烷膜的镀锌钢在腐蚀前后的形貌变化。结果表明,形成硅烷膜的镀锌钢在3．50％的氯化钠溶液中的自腐蚀电流密度下降到2．434×10^-8A·cm^-1自腐蚀电位正移。经SEM测试表明,硅烷膜在腐蚀前后的形貌几乎不变,耐蚀性能明显优于空白样镀锌钢。     

40Cr钢表面TEOS改进硅烷膜的制备及其耐腐蚀性能研究

目的为了提高钢材表面的耐腐蚀性能。方法采用含正硅酸乙酯(TEOS)的硅烷液,在40Cr合金钢表面制备TEOS改进硅烷保护膜,并采用正交试验法优选出了最佳TEOS改进硅烷液的工艺参数。采用扫描电子显微镜(SEM)、中性盐雾实验失重法、电化学阻抗法和极化法对其成膜性能和耐腐蚀性进行测试。结果 TEOS改进硅烷膜的耐硫酸铜腐蚀时间相对于硅烷膜提高了近50%。电化学极化测试可以看到TEOS改进硅烷膜的腐蚀电位正移,腐蚀电流密度大幅度下降至1.883×10-6 A/cm2。电化学阻抗谱测试中,在阻抗-频率Bode图中低频区,杂化硅烷膜试样的阻抗值大于硅烷膜试样的阻抗值,表现出良好的抗腐蚀性能;相角-频率Bode图显示TEOS改进硅烷膜在中高频区出现一个宽大的平台区,而且在中高频区相位角度数大于硅烷膜的相位角度数,表现出良好的容抗性能,表明TEOS改进硅烷膜能大幅度提高40Cr的耐腐蚀性。结论所制备的TEOS改进硅烷保护膜具有较好的成膜性,该硅烷膜坚实致密,且所形成的膜结构具有较好的耐腐蚀性能。     

冷轧钢表面硅烷膜的制备及耐蚀性能研究

采用浸涂技术,在冷轧钢板(CRS)表面制备3-氨丙基甲基二乙氧基硅烷(APDMS)自组装膜。利用扫描电镜观察了该膜的形貌,运用极化曲线和交流阻抗图谱等电化学方法考察了APDMS膜在3.50%NaCl溶液中的耐蚀性能。研究表明:硅烷、乙醇、去离子水的体积比为4∶9∶87,溶液pH为11.0,水解温度40℃,水解时间30h为最佳水解工艺条件;在该条件下形成的硅烷膜耐蚀性能十分优越。     

Electrodeposition of sol–gel films on Al for corrosion protection

Sol–gel films were electrodeposited on aluminum electrodes following the methodology we have developed and is based on applying negative potentials. This increases the pH at the surface, causing acceleration of the polymerization. Our process follows the “two step method”, in which the monomer is first hydrolyzed in acidic solution (pH 4) and only then the negative potential is applied, which consumes protons and releases hydroxyl ions, thus enhancing the condensation.Films made of different monomers, i.e., tetraethoxysilane (TEOS), methyl trimethoxysilane and phenyl trimethoxysilane (PTMOS), were prepared, characterized and examined for their corrosion inhibition properties. Potentiodynamic polarization, electrochemical impedance spectroscopy, optical and scanning electron microscopy as well as atomic force microscopy have been used as a means of film characterization. Hydrophobic and steric silanes, such as PTMOS showed a considerable corrosion inhibition capacity as compared to the capacity exhibited by less hydrophobic and steric derivatives such as TEOS. The difference between the conventional dip-coating method and the electrodeposition approach for depositing sol–gel films was also examined, indicating a clear advantage of the latter.     

A comparative study of molybdate/silane composite films on galvanized steel with different treatment processes

Two types of molybdate/silane composite films were obtained on the surface of hot-dip galvanized steel sheets by either directly immersing in a solution containing silane and molybdate as additive (single-step process), or firstly immersing in a molybdate solution, then in a silane solution (two-step process). The chemical compositions and microstructures of the films were examined by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflection absorption infrared spectroscopy (RAIR). The corrosion resistances were investigated by electrochemical measurements and neutral salt spray (NSS) test. The results showed that the molybdate/silane composite film formed in the single-step process had a similar double-layer structure as that obtained in the two-step process. The inner layer was composed mainly of the elements O, Mo, Zn, and P, similar to the single molybdate film; whereas the outer layer was composed mainly of the elements C, O and Si, similar to the single silane film. Compared with the single molybdate or silane film, the corrosion current of the composite films was reduced and the impedance of the films was increased. Accordingly, the corrosion resistance of the composite films was remarkably enhanced to a level which was comparable to or even surpassing that of the conventional chromate passivation film.     

镀锌钢板钛盐/硅烷复合膜的耐蚀性研究

研究了镀锌钢板上钛盐钝化膜、硅烷转化膜、钛盐/硅烷复合转化膜的表面形貌和化学成分,并对比了这3种转化膜与普通铬酸盐转化膜的电化学行为和耐盐雾腐蚀性能。结果表明:镀锌钢板钝化后,腐蚀电流密度降低,极化电阻及交流阻抗得到极大提高;钛盐/硅烷复合膜的耐蚀性已经接近普通铬酸盐钝化。SEM和EIS分析表明,硅烷膜是一层物理遮盖膜。     

Electrodeposition of cerium (III)-modified bis-[triethoxysilypropyl]tetra-sulphide films on AA2024-T3 (aluminum alloy) for corrosion protection

The doping of rare earth salts, like Ce(III), has shown to enhance the corrosion performance of silane films due to their self-healing behaviors. In the present paper, the Ce(III)-doped bis-[triethoxysilypropyl]tetrasulphide (BTESPT) films with higher corrosion resistance were prepared by electro-assisted technique. The films were investigated using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), water contact angle measurements and Fourier transform reflection absorption IR (FTRA-IR). The results showed that both the cathodic deposition and cerium-doping can promote the formation of thicker and compacter silane films and enhance their protectiveness in the early stage of immersion in the corrosive media. However, it seems that the Ce(III)-doped BTESPT films prepared by electrodeposition lose their self-healing abilities after long-term immersion. The reason is still unclear, but might be attributed to the precipitation of Ce(III) oxides or hydroxides during the electrodeposition of doped silane films.     

硅烷处理对 EW75 M 稀土镁合金阴极电泳涂层性能的影响

目的探究硅烷处理对阴极电泳涂层的耐腐蚀性能及其与基体间结合力的影响。方法对稀土镁合金表面进行硅烷前处理,再沉积阴极电泳涂层,评价涂层的耐腐蚀性能、抗溶胀性能,分析涂层的腐蚀微观形貌、组织结构及界面结合。结果硅烷膜层具有一定的防护性能,能够减少阴极电泳涂层针孔、橘皮的出现,增强阴极电泳涂层的致密性。硅烷改性能够提高阴极电泳涂层与基体的结合力,硅烷预处理的电泳试样在NMP溶液中浸泡102 h,依然结合完好;而未经硅烷预处理的电泳试样浸泡7 min后,涂层就完全剥落。此外,硅烷处理能够极大地改善阴极电泳涂层的阻抗性能,使涂层在3.5%(质量分数)NaCl溶液中浸泡227 h的极化电阻Rp仍在108数量级以上。结论硅烷阴极电泳复合涂层具有良好的耐蚀性能和抗溶胀性能,值得推广应用。     

Composite coatings incorporating solid lubricant phases

The concept of incorporating a solid lubricant, silver (Ag), within a hard carbide film for vacuum tribology applications is investigated in this paper. SiC/Ag and HfC/Ag films were deposited by magnetron cosputtering at 200 °C onto Si and 440C steel substrates. The composition, phase structure, and morphology in these films was examined using x-ray diffraction, scanning electron microscopy, and x-ray photoelectron spectroscopy. The microstructural analysis showed that Ag was incorporated both within and on the surface of the films. There was a strong tendency for Ag to segregate to the film surface. Vacuum tribology tests were conducted using a ball-on-disk test in a vacuum of 1.33 μPa with a 1 N load for 10 000 cycles. For both the SiC/Ag and HfC/Ag films, the average friction coefficients were reduced when sufficient Ag was present. These tests show that carbide-Ag composite films hold promise for vacuum tribology applications. This paper was presented at the 2nd International Surface Engineering Congress sponsored by ASM International, on September 15–17, 2003, in Indianapolis, Indiana, and appears on pp. 554–59 of the Proceedings.     

Corrosion inhibition using superhydrophobic films

Neutron reflectivity (NR) was used to study the effectiveness of superhydrophobic (SH) films as corrosion inhibitors. A low-temperature, low-pressure technique was used to prepare a rough, highly porous organosilica aerogel-like film. UV/ozone treatments were used to control the surface coverage of hydrophobic organic ligands on the silica framework, allowing the contact angle with water to be continuously varied over the range of 160° (SH) to <10° (hydrophilic). Thin (∼5000 Å) nano-porous films were layered onto aluminium surfaces and submerged in 5 wt% NaCl in D₂O. NR measurements were taken over time to observe interfacial changes in thickness, density, and roughness, and therefore monitor the corrosion of the metal. NR shows that the SH nature of the surface prevents infiltration of water into the porous SH film and thus limits the exposure of corrosive elements to the metal surface.     

耐海洋环境中霉菌腐蚀有机涂层的研究

为了提高铝合金耐海洋环境中霉菌腐蚀的性能,先在铝合金表面涂覆硅烷膜作为过渡层,然后在硅烷膜上涂覆成分配比不同的有机硅改性环氧树脂涂料.对比研究了涂层的表面形貌、相组成及霉菌腐蚀的性能.并探讨了涂层与基体的结合机理.结果表明:硅烷膜与铝合金基体、有机涂层之间发生了化学反应,使涂层与铝合金基体结合良好;按有机硅改性环氧树脂...     

The mechanism of formation of thin oxide coatings and nanopowders at the anodic oxidation of zirconium in molten salts

At the oxidation of zirconium in molten salts up to 813–1073 K, the growth of oxide phases is found to proceed chiefly due to the diffusion of oxygen ions via the oxide film toward the metal-oxide interface. An oxide film formed in the initial period of zirconium oxidation in a chloride-nitrate melt decelerates the process but does not prevent the ion exchange at the metal-melt boundary. As the oxide formation proceeds and the steady-state conditions of the corrosion process are reached, the oxidation rate becomes limited by the diffusion of oxygen ions from the film surface deep into the metal. Along with the diffusion of O²⁻ ions at temperatures of 813 to 1073 K, zirconium ions can also migrate in the metal, which makes interpreting the whole process much more difficult. At the oxidation, the films of various colors (from black to light gray) with diverse corrosion and protective properties, as well as fine-dispersed powder of zirconium dioxide with a mean size of particles up to 30 nm, are formed. Original Russian Text ? L.A. Elshina, V.Ya. Kudyakov, V.B. Malkov, N.G. Molchanov, B.D. Antonov, 2008, published in Zashchita Metallov, 2008, Vol. 44, No. 3, pp. 276–282.     

Improvement in the corrosion resistance of TiB2/A356 composite by molten-salt electrodeposition and anodization

This study reported a novel treatment to improve the corrosion resistance of TiB₂/A356 composites. The method was employed in combination of the molten-salt electrodeposition and subsequent electrochemical anodization technique. By means of molten-salt electrodeposition, the Al coatings were deposited on the surface of TiB₂/A356 composites. It was found that the morphology of the Al coatings is closely related to the current density. Thus, under the suitable condition, a dense and uniform Al coating can be obtained, with the crystal size in the range of 0.5–2 μm and the coating thickness of ~ 9 μm. This continuous Al layer can eliminate the adverse corrosion contribution of TiB₂ particles in Al matrix. The following step of anodization was designed to convert the Al film to an anodized Al oxide film for further corrosion protection. The electrochemical corrosion behavior was evaluated by potentiodynamic polarization curves and electrochemical impedance spectroscopy. These results showed the corrosion resistance was greatly enhanced in TiB₂/A356 composites with an anodized Al-coating than that of the anodized composites. It is evident that the new treatment of metal electrodeposition in molten salts and following anodization is an effective method of anti-corrosion in composites.     

冷轧钢表面氨丙基甲基二乙氧基硅烷膜的制备及其耐蚀性能研究

采用正交实验法设计多种氨丙基甲基二乙氧基硅烷的水解工艺条件,在冷轧钢表面制备硅烷膜,通过对比每种条件所得硅烷膜样品在3.50%NaCl溶液中的塔菲尔极化曲线,获得了最佳水解工艺,并用稳态极化曲线和扫描电子显微镜,研究了该工艺制备的硅烷膜对冷轧钢耐蚀性能的影响.研究表明:硅烷、乙醇、去离子水的体积比2:10:88,水解温...     

A corrosion study of hot-dip galvanized steel sheet pre-treated with γ-mercaptopropyltrimethoxysilane

In the present work an organofunctional silane, γ-mercaptopropyltrimethoxysilane (γ-MPS), has been deposited on hot-dip galvanized cold rolled steel from different silane solution concentrations. Painted and unpainted silane treated samples were corrosion tested and painted samples were adhesion tested. The surface chemistry of the unpainted silane treated samples was investigated with AES, ToF-SIMS and EDS and the surface morphology was studied with SEM.The results show that the silane film thickness is dependent on the silane concentration in the silane solution and a higher silane concentration gives a thicker film. Moreover, thicker films tend to give films with a pronounced crack pattern and even detachment of film debris. Corrosion tests of unpainted samples show that γ-MPS can not work as a passivation treatment but gives a very good adhesion to the paint.     

Corrosion and biocompatibility of PPy/PEG coating electrodeposited on Ti6Al7Nb alloy

This work aims to improve the corrosion rate of Ti6Al7Nb alloy and to increase its biocompatibility at the same time, obtaining polymer composite films based on polypyrrole/polyethylene glycol (PPy/PEG). The elaboration method was electrodeposition. FT‐IR analysis was performed in order to emphasize the formation of the PPy‐PEG composite film by incorporating PEG into the polymer structure. The paper is focussed on PEG (400 molecular weight) effect on the corrosion in bioliquids (as tested electrochemical bioliquid was chosen Hank's balanced salt solution) and on the biocompatibility properties. The PPy film significantly improves the biocompatibility of the Ti6Al7Nb alloy. The PEG presence in the polymerization solution leads to more stable composite polymer films on the titanium alloy surface with a better corrosion resistance and a more hydrophilic behaviour comparing with the PPy film. The increase of cell viability and proliferation potential as compared to the PPy film is not important.