Evaluation of atmospheric galvanic aluminum corrosion in electrical transmission towers at different sites in the Valparaíso region,Chile. Wire-on-Bolt Test (CLIMAT)

This study evaluates environmental aggressiveness and atmospheric galvanic corrosivity categories in Chile (Classification of Industrial and Marine ATmospheres test) by installing bolts in electrical transmission towers in the Valparaiso region across four exposure sites: Playa Ancha, San Sebastián, Las Vegas, and San Felipe. Classifications of marine corrosion index (MCI), industrial corrosion index (ICI), and atmospheric corrosion index (ACI) used different galvanic couples: aluminum/steel for MCI, aluminum/copper for ICI, and aluminum/polyethylene for ACI. Corrosion indices varied by season (summer, autumn, winter, and spring), for which couples were exchanged every 3 months. Intraseason variation depended mainly on the meteorochemical variables of the zone, the Cl⁻/SO₂ ratio, and the presence of general and pitting corrosion in the aluminum. The results indicate that, regardless of environmental condition, the aluminum in Al/steel (MCI) and Al/copper (ICI) couples presented a higher corrosion rate than when not forming a galvanic couple (ACI). Moreover, under higher environmental chloride, these differences increase. The Playa Ancha station presented the highest ACI.     

Enhancement of resistance to galvanic corrosion of ZE41 Mg alloy by equal channel angular pressing

The galvanic corrosion behavior of as-received and ECAPed ZE41 Mg alloy coupled with Al7075 alloy is investigated using zero resistance ammeter in three different corrosive environments, 0, 0.1, and 1 M NaCl, to mimic the conditions experienced in engineering applications. The mechanism of galvanic corrosion for the ZE41 Mg–Al7075 aluminum alloy is explained. It is observed that a robust surface film containing a composite layer of oxide/hydroxide of magnesium and aluminum is established in deionized water (0 M). However, only a single layer of magnesium oxide/hydroxide is detected in chloride-containing environments. Equal channel angular pressing (ECAP) improved the resistance to galvanic corrosion by 58% and 54% when compared with the as-cast counterparts in 0 and 1 M NaCl solution, respectively. In contrast, galvanic corrosion resistance decreased by 26% in 0.1 M NaCl after ECAP while the as-received samples evinced pits unfavorable to be used in engineering applications. ECAP is a promising method to combat galvanic corrosion encountered by ZE41 magnesium alloy used in automobiles and components of military vehicles.     

Pd-Decorated Tungsten as Pt-Free Bimetallic Catalysts for Hydrogen Oxidation Reaction in Alkaline Electrolyte

Developing Pt-free catalysts for hydrogen oxidation reaction (HOR) in alkaline solution is becoming a key challenge in the development of anion exchange membrane fuel cells and electrochemical reactors. Herein, we present the preparation, HOR activity, and stability of Pd-decorated tungsten (Pd-d-W) catalysts. The Pd-d-W catalysts were prepared by the chemically activated surface of tungsten nanoparticles by Pd ions. The resultant bimetallic catalysts consisted of crystalline phases of both Pd and W nanoparticles. The CO stripping voltammograms and H-desorption (H_des) peak potential of hydrogen desorption in Pd suggests that the enhancement of HOR catalytic activity observed in Pd-d-W catalyst can be ascribed to the modification of electronic property of Pd and availability of OH_ad near-surface Pd atoms.     

Acidification of the electrolyte during the galvanic corrosion of AA7075: A numerical and experimental study

The electrochemical interactions between aluminum alloy 7075 and low-carbon steels under gelled electrolytes were studied. Such electrolytes provided the opportunity to investigate both thick and thin electrolyte systems. The electrolyte was chemically modified to visually track the acidic fronts during the anodic reaction and the subsequent hydrolysis process. Two mathematical models were validated for both thick and ultrathin electrolytes. The acidification of thick electrolytes was extended some millimeters beyond the aluminum alloy surface, whereas the acidic front was localized next to the metallic joint using ultrathin electrolytes. The combination of both numerical and experimental results allows proving (and explaining why) that the acidification process is more aggressive under dilute than under concentrated electrolytes.     

超级13Cr不锈钢腐蚀性能的研究现状与进展

针对超级13Cr不锈钢管材料在各种环境下所面临的腐蚀问题,介绍了其CO2腐蚀机理及其影响因素,分析了腐蚀产物膜成分破坏机理,简要说明了超级13Cr不锈钢几种常见的腐蚀类型,并提出了今后超级13Cr不锈钢及其腐蚀行为研究的重要方面,为今后油套管材料提供参考。     

海洋环境钛金属的应用现状及其防护技术研究

钛金属具有优异的耐海水和海洋大气腐蚀性能,因此在海洋装备中有广泛应用。但是钛金属在严酷海洋环境中应用表现出一些不足之处,如耐磨蚀性能差、易生物污损和电偶腐蚀等问题,严重影响了钛金属结构件的长寿命和安全可靠服役。介绍了钛金属在海洋环境中的应用现状,揭示了存在上述不足问题的本质原因。如海洋环境磨损与腐蚀的交互作用导致耐磨性能差的钛金属磨蚀损耗加剧,钛金属良好的生物相容性使其产生严重的生物污损,钛金属相比于其他金属具有较高的正电位,在介质环境中与异种金属偶接时作为阴极被保护从而加速偶接合金的腐蚀。鉴于钛金属优异的海洋耐候性,其在海洋环境中的应用必将越来越广泛,但是合适的表面处理和涂层防护是必不可少的。综述了国内外钛金属在海洋环境应用相关防护技术的研究现状,并对海洋环境中钛金属表面防护技术的发展方向和趋势进行了展望：金属陶瓷涂层和可控纳米结构氧化物陶瓷涂层是海洋环境钛金属运动部件耐磨蚀保护有效的技术手段;防污剂释放型和纳米缓释涂层技术是实现钛金属长效防生物污损很有前途的技术方法;钛金属表面低导电表面改性层的设计和制备可降低与其接触异金属的电偶腐蚀速度。     

Effect of Silane on Galvanic Corrosion between EW75 Magnesium Alloy and TC4 Alloy

硅烷处理对镁合金具有良好的保护性。为了抑制 Mg-7Gd-5Y-Nd-Zr (EW75) 稀土镁合金和 Ti-6Al-4V (TC4) 钛合金的电偶腐蚀作用,以自腐蚀镁合金为对照组,对硅烷改性和未改性的镁合金与TC4钛合金的电偶腐蚀进行了研究。用数码照片和扫描电镜 (SEM) 观察分析了浸泡 48 h 后的镁合金表面形貌,样品的自腐蚀电流密度和电偶腐蚀电流密度分别用极化曲线和电偶腐蚀测量来表征获得。结果表明,硅烷膜可以减少失重比,使腐蚀形式由点腐蚀变为均匀腐蚀,因此硅烷改性的镁合金比未改性的镁合金具有更好的抗电偶腐蚀能力,其原因是硅烷膜可以提高镁合金的电位,并减小电偶腐蚀电流密度