自然环境腐蚀标准化工作取得实质性进展

我国的材料自然环境腐蚀工作取得进一步进展，2008年已有5项国家标准完成报批：《金属和合金的腐蚀室内大气低腐蚀性分类第1部分室内大气腐蚀性的测定与评价》（国家计划编号20072384-T-605）、《金属和合金的腐蚀大气腐蚀试验应力腐蚀室外暴露试验方法》（国家计划编号20072387-T-605）。     

磁控溅射离子镀铌贫铀的电化学腐蚀行为

利用电化学测试技术、扫描电镜(SEM)及X射线能谱(EDS)对磁控溅射离子镀铌贫铀的电化学腐蚀行为进行了研究.实验结果表明:在50μg/g Cl-的KCl溶液中,铌的腐蚀电位远高于贫铀的腐蚀电位,铌镀层对贫铀是阴极性镀层,对贫铀的保护是基于其对腐蚀介质的物理屏障作用;镀铌贫铀的极化电阻和电化学阻抗幅值远大于贫铀,腐蚀电流远小于贫铀,铌镀层对贫铀具有良好的防腐蚀性能;镀铌贫铀的腐蚀特征为局部腐蚀,并由孔蚀向电偶腐蚀转变.     

AM60镁合金大气腐蚀及动力学分析

研究了铸态和挤压态AM60镁合金在太原地区的大气腐蚀行为。试验结果表明铸态合金的腐蚀速率高于挤压态合金。铸态合金中的共晶组织比α-Mg更具耐大气腐蚀能力,但是这导致了共晶相周围的α-Mg相腐蚀严重,且腐蚀产物膜也不均匀,保护性差。挤压态合金的最大腐蚀深度要远小于铸态合金。挤压态合金的显微组织比铸态更加均匀,而且不含有共晶组织,导致挤压态合金表面的腐蚀产物膜更加致密也更具有保护性。挤压变形不会引起AM60镁合金大气腐蚀性能的下降。     

铀合金的大气腐蚀和应力腐蚀研究

概述了U-0．75Ti铀合金在典型大气环境中长期曝露和贮存时的腐蚀行为及应力腐蚀敏感性研究的一些主要结果，得到了铀合金在长期贮存条件下，能够长期保持极低的腐蚀速率和不存在明显的大气应力腐蚀的重要规律。讨论了铀合金在不同环境条件下的大气腐蚀的主要特点、规律和环境影响；讨论了铀合金大气应力腐蚀的特点、对环境条件的依存关系和有关的原因。     

贫铀表面钛镀层的抗腐蚀性能研究

利用电化学测试技术、扫描电镜(SEM)及X射线能谱(EDS)对贫铀表面钛镀层的抗腐蚀性能进行了研究。结果表明:在50μg/gCl-的KCl溶液中,钛镀层的腐蚀电位远高于贫铀的腐蚀电位,钛镀层对贫铀是阴极性镀层,对贫铀的保护是基于其对腐蚀介质的物理屏障作用;贫铀表面完整钛镀层的极化电阻和电化学阻抗幅值远大于贫铀,腐蚀电流远小于贫铀,完整钛镀层对贫铀具有良好的抗腐蚀保护作用;贫铀表面钛镀层的腐蚀特征为局部腐蚀,由孔蚀向电偶腐蚀转变;破坏的钛镀层将加速铀基体的腐蚀。     

《金属和合金的腐蚀钢铁户外大气加速腐蚀试验》等2项国家标准发布实施

<正>由中国科学院金属研究所大气腐蚀组申请立项,并负责制定的国家标准《GB/T25834-2010金属和合金的腐蚀钢铁户外大气加速腐蚀试验》和《GB/T24513.2-2010金属和合金的腐蚀室内大气低腐蚀性分类第2部分:室内大气腐蚀性的测定》已获国家标准化管理委员会批准,并正式发布实施(实施日为2011年9月1日)。这将进一步推动本领域的试验方法向规范化和标准化迈进。     

合金元素对碳钢和低合金钢在大气中耐腐蚀性的影响

对我国七个试验点十七种钢的八年大气腐蚀试验数据用动力学公式D=At~n作了回归处理,用逐步回归方法获得了主要合金元素含量与公式中系数A_1n的关系式,探讨了合金元素对碳钢和低合金钢在大气中耐腐蚀性的影响。磷、铜提高钢的耐大气腐蚀性能;硫急剧降低钢的耐大气腐蚀性;硫、磷含量在很小范围内即有明显作用。与一般概念相反,硅能提高钢的耐大气腐蚀性能,铬、镍的影响不大。     

Cu及其合金的大气腐蚀研究现状

综述了Cu及其合金的大气腐蚀机理,重点介绍了影响Cu及其合金大气腐蚀的主要因素和几种常见的大气腐蚀研究方法,并对其今后的研究趋势进行了展望。     

AZ91D镁合金在青岛海洋大气中的腐蚀行为

采用室外海洋大气暴露试验,测定了AZ91D、AZ31及防锈铝在海洋大气中的腐蚀率.含Al较高的AZ91D合金在耐海洋大气腐蚀上好于AZ31合金,经对AZ91D镁合金的扫描电镜、X衍射及能谱分析检测表明其组织由α(Mg)相和含Al较高的β(Mg17Al12)相组成.腐蚀产物由MgCO3、Al2O3、MgAl2O4组成.     

热镀Al-Zn合金镀层在模拟工业污染大气环境中的腐蚀试验及数学模型分析

1 引言 不同Al-Zn合金镀层在不同环境中的耐蚀性能差异很大,但研究它们在不同环境中腐蚀失重(ΔW)与腐蚀时间(T)关系的报道还很少见,本工作通过模拟工业污染大气环境,根据大气腐蚀常用数学模型ΔM=K×T~n,对不同Al-Zn合金热镀层的腐蚀数据进行曲线拟合,为选择大气腐蚀模拟试验方法与评价Al-Zn合金热镀层的耐蚀性提供依据。     

氮化处理的贫铀表面在盐雾环境中的腐蚀行为

利用激光共聚焦显微镜(CLSM)、扫描电子显微镜(SEM)和激光拉曼光谱(Raman Spectroscopy)等技术研究了氮化处理的贫铀表面在盐雾环境中的腐蚀行为。结果表明:盐雾环境对氮化处理的贫铀表面具有较强的腐蚀破坏作用;在含夹杂缺陷位置最先发生点蚀,随着在盐雾环境中暴露时间的延长,腐蚀加剧,氮化改性层被破坏,直接导致基体发生严重的腐蚀;盐雾环境中贫铀的腐蚀产物中含有U3O8。     

Microstructure and corrosion resistance of Cr/Cr2N multilayer film deposited on the surface of depleted uranium

Depleted uranium is widely used in national defence and nuclear energy fields. However, the inferior corrosion resistance limits its application. A Cr/Cr₂N film was prepared by magnetron sputtering on the uranium to improve its corrosion resistance. The Cr/Cr₂N film exhibits modulation structure. The introduction of the Cr/Cr₂N increases the corrosion potential; the corresponding current density decreases about three orders of magnitude. After polarization corrosion, the surface morphology of the Cr/Cr₂N-coated on uranium keeps integrated. Only a thin layer of film (∼40 nm) is oxidized. The Cr/Cr₂N film shows great potential in improving oxidation and corrosion resistance of depleted uranium.     

Corrosion behaviour of various steels and alloys in a simulated coal liquefaction environment

The corrosion behaviour of Fe-Cr, Ni-Cr and Fe-Cr-Ni alloys was studied in simulated liquefaction environments over the temperature range of 623 to 723 K. Corrosion of alloys in these environments was controlled by both sulfidation and oxidation. In the slurry, the oxygen potential was apparently higher and the corrosion rate was smaller in comparison with those in the gas phase in the solvent only environment. An oxygen-rich brown coal caused much smaller corrosion than a sub-bituminous coal. With regard to the effect of the alloy compositions, chromium content controlled the corrosion rate. The Fe-Cr-Ni austenitic alloys were the most resistant. The Fe-Cr alloys with high chromium content were fairly resistant, although they may be relatively sensitive to the variation of the environments such as temperature and H₂S content. Ni-Cr alloys of less than 20% Cr may have high corrosion rate due to their fast sulfidation. The structure of the scales formed on the alloys can be reasonably explained by the phase stability diagram of Metal-O-S system.     

Long‐term exposure of austenitic steels and nickel‐based alloys in lignite‐biomass cofiring

The aim of this study was to assess the long‐term impact that the addition of biomass provokes on superheater materials exposed to fireside corrosion environments. Alloys covering a broad range of commercially available materials were investigated. Their corrosion kinetics under different corrosive deposits and atmospheres was evaluated, and their corrosion products analyzed to deepen understanding of the underlying corrosion mechanisms. Therefore, three nickel‐based alloys and three austenitic steels containing 20–24 wt.% Cr were tested at 650°C for 7,000 hr. The long‐term exposure shows new mechanistic aspects of Type II hot corrosion that were revealed by accelerated material depletion. The formation of Ni–NiS eutectic and the formation of a Cr depleted zone close to the substrate corrosion product interface are indicative of the breakaway occurrence. Differences in the corrosion behavior are related to the balance of Ni, Mo, Co, and Cr and can serve as the material selection argument. The evaluation concluded with the finding that alloys presenting Mo and Ni might be preferentially used in fireside corrosion in the presence of biomass, whereas the use of austenitic steels suffer less corrosion if no biomass is present in the corrosive atmosphere.     

微缺陷对铀材料腐蚀的影响规律研究现状

铀及铀合金是核工业中重要的结构和功能材料,其腐蚀状态对于材料的使役有效性有重要影响。材料学因素,包括组分、组织结构、内部和表面的缺陷状态等是影响铀材料耐蚀性能的内因。本文重点综述了铀材料中微缺陷对腐蚀的影响规律的研究现状,从杂质元素、夹杂、显微组织、表面状态四个方面系统梳理了国内外公开报道的研究工作和取得的规律认识。在此基础上,简要的提出了改善和消除微缺陷以提升铀材料耐蚀性能的策略。     

湿热条件下超塑性锌铝合金的晶间腐蚀研究

评估了超塑性锌铝合金在高温高湿环境下晶间腐蚀的程度.在铝含量为(1～22)mass%的范围内,耐蚀性呈不单调变化.退火有利于提高耐蚀性.退火温度达300℃时,耐蚀性提高最多.晶间腐蚀深度由富铝相的百分比和晶粒细化两大因素综合决定.富铝相加速腐蚀,而晶粒的细化作用则阻碍腐蚀.晶间腐蚀深度随腐蚀时间延长呈线性增长.     

Localized Corrosion Characteristics of Nickel Alloys:A Review

There are a great variety of commercial nickel alloys mainly because nickel is able to dissolve a large amount of alloying elements while maintaining a single ductile austenitic phase.Nickel alloys are generally designed for and used in highly aggressive environments,for example,those where stainless steels may experience pitting corrosion or environmentally assisted cracking.While nickel alloys are generally resistant to pitting corrosion in chloride-containing environments,they may be prone to crevice corrosion attack.Addition of chromium,molybdenum and tungsten increases the localized corrosion resistance of nickel alloys.This review on the resistance to localized corrosion of nickel alloys includes specific environments such as those present in oil and gas upstream operations,in the chemical process industry and in seawater service.     

Influence of nickel additions on the corrosion behaviour of low nitrogen 22% Cr series duplex stainless steels

Four 22% Cr duplex stainless steel alloys containing varying nickel contents of approximately 5%, 7%, 9% and 13% were melted in a vacuum induction furnace, hot rolled, solution annealed and water quenched. Their corrosion behaviour was investigated in sulphuric acid and sodium chloride solutions using potentiodynamic polarization and chronoamperometric techniques. Increasing nickel contents have an appreciable influence on the observed corrosion behaviour. Polarization curves show similarities in the uniform corrosion behaviour of the alloys in the various solutions, but significant differences in their pitting resistance in chloride environments. Alloy 2209 (22% Cr - 9% Ni) generally exhibited the highest resistance to uniform corrosion, while alloy 2213 (22% Cr - 13% Ni) displayed the best pitting corrosion resistance. X-ray diffraction analysis of the surfaces of the alloys after corrosion in the different media revealed different corrosion products. Scanning electron micrographs revealed that the alloys were differently attacked by chloride ions, with different pit depths and morphologies. The corrosion behaviour exhibited by the alloys was attributed to the influence of nickel on phase modification, microstructural refinement, and the types of films formed in different environments. Uniform corrosion behaviour of the alloys was concluded to be predominantly controlled by phase composition and ratio, while pitting resistance was chiefly controlled by an alloy’s nickel contents.     

Atmospheric corrosion of two field-exposed AZ31B magnesium alloys with different grain size

A fine-grained AZ31B alloy and a commonly hot-extruded AZ31B alloy with coarser grains were exposed to marine and urban environments for 1 year, and the atmospheric corrosion behavior of the AZ31B alloys was investigated. The fine-grained AZ31B alloy displays slightly higher corrosion resistance than the commonly hot-extruded AZ31B, particularly in urban environment. Magnesium carbonate hydrate and hydromagnesite are principal corrosion products of the two AZ31B alloys in both marine and urban environments. Besides, it is found that Al–Mn intermetallic particles have little influence on the atmospheric corrosion of the AZ31B alloys.