金属材料的腐蚀疲劳研究进展

由于腐蚀环境无处不在,金属材料极易被腐蚀;在腐蚀与疲劳的双重作用下,其寿命大幅降低。对腐蚀环境的分类、影响金属材料腐蚀疲劳的因素、金属材料腐蚀疲劳寿命预测模型与退化规律等方面进行综述,并展望金属材料腐蚀疲劳研究的未来发展趋势。该研究可为增强金属材料的耐腐蚀性提供参考。     

医用金属材料腐蚀疲劳性能研究进展

结合文献和课题组的研究,对医用金属材料腐蚀疲劳性能的研究进展进行了总结,分别从腐蚀疲劳的危害性、分类、设计、控制等几个方面进行了阐述。腐蚀疲劳失效首先发生于材料表面,医用材料-生理环境的界面对于植入器械手术成功与否有着至关重要的作用,可以根据裂纹扩展速度曲线特征,将腐蚀疲劳分为三类。医用金属材料的腐蚀疲劳性能研究应考量其服役环境进行设计,可以通过表面处理、合金化等方法改善医用金属材料的腐蚀疲劳性能。医用金属材料腐蚀疲劳性能研究的一些基础问题仍待解决：医用金属材料在微生物参与下的腐蚀疲劳行为及其相关机制亟待阐述;医用金属材料的微生物腐蚀疲劳研究是一个系统、长期、复杂的过程,需要合理地建立实验模型,将三维有限元与传统实验方法有机结合,进一步指导医用金属材料相关器械的设计;新的合金成分设计、新的加工制造方式所获得的新型合金生理环境下的腐蚀疲劳性能,其相关数据亟待完善,这关系到新型医用金属材料长期使用的生物安全性问题,亟需开展大量的基础研究工作。在综合评述医用金属材料腐蚀疲劳性能研究现状的基础上,对医用金属腐蚀疲劳在学科交叉研究和新材料基础研究方面的发展趋势进行了展望。     

处于盐渍土和盐湖环境下建筑物的腐蚀与防护现状

盐湖水和盐渍土环境下的腐蚀问题包含有氯离子对钢的腐蚀,还包含硫酸根离子和镁离子对混凝土结构的破坏。本文介绍了中国盐湖和盐渍土区域分布情况,盐湖水和盐渍土对结构物的腐蚀特征和腐蚀造成的危害,综述了目前国内防治盐湖水和盐渍土腐蚀的措施现状以及理论研究现状。情况表明,需要继续对盐渍土和盐湖地区的结构物的腐蚀与防护开展深入的研究。     

金属材料海洋环境生物污损腐蚀研究进展

海生物因素是影响海洋环境金属材料腐蚀行为的主要因素之一。综述了金属材料海生物腐蚀研究领域中有关生物膜的结构与功能、海水环境微生物腐蚀机理研究和宏观海生物附着引起的局部腐蚀等几个方面近年来的进展情况。并结合我国开展海生物腐蚀研究的现状提出建议和讨论。     

冲刷腐蚀的研究现状

综述了金属材料在流体冲刷条件下的腐蚀研究现状、不同环境因素和材料性质对冲刷腐蚀机理的影响规律。冲刷腐蚀主要由冲刷磨损和电化学腐蚀组成,对总腐蚀速率的贡献与各种环境因素有关。材料冲刷腐蚀防护主要可从金属材料元素含量、热处理制度和表面处理3个方面入手。同时,探讨了冲刷腐蚀研究的未来发展趋势。     

金属材料的空化腐蚀行为及影响因素研究进展

综述了金属材料的空化腐蚀行为及影响因素研究现状。介绍了现阶段金属材料空化腐蚀的主要研究方法,以及几种典型金属材料(Fe、Cu、不锈钢、Ti和形状记忆合金)的空化腐蚀行为。重点阐述了材料力学性能、材料化学成分和微观组织结构、表面形貌和外界环境等主要因素对金属材料空化腐蚀行为影响的研究情况,并指出了金属材料空化腐蚀进一步研究的方向。     

碳钢在青海盐湖卤水中的腐蚀及阴极保护的探讨

<正> 青海察尔汗盐湖是我国已探明的最大钾盐矿床。盐湖卤水含有高浓度的氯化物,对金属、非金属材料均有腐蚀性。因此,在开发盐湖的过程中,解决腐蚀问题,极为重要。但针对盐湖卤水,碳钢的腐蚀规律及其防护技术的研究还很少。为解决这一问题,本文研究了碳钢在盐湖卤水中的腐蚀规律。并进而探讨了碳钢在卤水中进行阴极保护的     

海洋用金属材料的微生物腐蚀研究进展

虽然海洋环境下所使用的金属材料的机械性能和耐蚀性能都较好,但近年来关于海洋工程材料腐蚀失效的报道却越来越多。以海洋环境下金属材料的腐蚀为背景,重点介绍了近年来逐渐引起人们重视的金属材料微生物腐蚀的研究进展。一些经典的腐蚀理论虽然能够解释一些微生物腐蚀现象,但是目前微生物腐蚀逐渐成为很多工业环境下普遍存在的严重问题,这些机理的片面性也就逐渐暴露出来。随着研究的深入,人们对微生物腐蚀机理的认识更加全面、深入。研究者逐步提出了基于生物能量学和生物电化学的微生物腐蚀理论,该理论引入了微生物胞外电子传递过程,解释了微生物为什么和如何腐蚀金属材料,并获得了学术界的普遍认可。为了解决传统抗微生物腐蚀方法的诸多不足,开发新型抗菌材料、研发环保型杀菌剂和杀菌剂增效剂将会为微生物腐蚀防治提供新思路。     

城市污水体系下金属材料的腐蚀研究初探

探讨了城市污水体系中金属材料的腐蚀特征、影响因素及其研究方法，通过分析提出了金属材料在污水体系下腐蚀研究的难点和今后的研究方向。     

微生物致裂的热力学和动力学分析

现场调查和实验研究均证实了微生物致裂的存在并提出了合理的机理模型,但是缺乏微生物致裂的热力学和动力学理论分析。基于Gutman的力学-化学交互作用理论、微生物能量学和腐蚀电化学理论,本文尝试给出SRB/NRB致裂的热力学和动力学解释。热力学计算结果表明,应力和SRB/NRB共同作用下金属材料腐蚀反应的摩尔Gibbs自由能下降,腐蚀反应向环境释放出更多的热量,从热力学上来说具有更高的腐蚀趋势。与SRB腐蚀和SRB致裂相比,铁基金属材料NRB腐蚀和NRB致裂具有更强的热力学倾向。动力学分析表明,外加应力和微生物共同作用下金属材料腐蚀速率和微裂纹扩展速率加快。本工作的研究结果能丰富人们对金属材料菌致开裂行为的认识。     

金属材料在盐湖卤水中的腐蚀研究

采用极化曲线测量、腐蚀电位测量和现场暴露试验等方法研究了典型金属材料在盐湖卤水中的电化学特性和腐蚀行为.在卤水中,Q235和16Mn的腐蚀速度受阴极氧扩散控制,腐蚀较轻.304和430不锈钢在卤水中有较轻的蚀斑和缝隙腐蚀.在卤水中T2、QSi3-1的腐蚀速度受阴极活化控制,表面腐蚀均匀,且有低的腐蚀率.L6和LF6在卤水中处于活化态.暴露181d,L6和LF6发生严重的点蚀和缝隙腐蚀.     

Hot corrosion in a temperature gradient

Hot corrosion is the accelerated attack of materials at elevated temperatures that is induced by a thin film of fused salt. Many materials that experience hot corrosion are exposed to high heat fluxes and temperature gradients. The hot corrosion of metals can be described by the dissolution of a protective metal oxide into the fused salt and the subsequent precipitation of the metal oxide in a nonprotective form. Rapp and Goto have established a criterion for the sustained hot corrosion of a pure metal that the solubility gradient of the protective oxide in the salt film must be negative at the oxide/salt interface. The influence of a temperature gradient on the metal oxide solubility gradient (and the predicted hot corrosion susceptibility) is discussed. Solubility data for NiO in Na₂SO₄ are used to illustrate the effects of a temperature gradient. The effects of a temperature gradient were determined by examining various combinations of dissolution reactions, oxidants, and transport kinetics. Based on these results, and the thinness of the molten salt films, temperature gradients are not expected to be of importance to hot corrosion fluxing mechanisms.     

Mechanistic features of molten salt corrosion in coal fired boilers

In general, the hottest outlet sections of both superheaters and reheaters in modern CEGB boilers are tubed in austenitic stainless steels. Experience over the last 10–15 years has indicated that molten salt fireside corrosion can significantly reduce design lives, corrosion rates being a function of

• (i) metal temperature
• (ii) gas temperature
• (iii) coal chlorine content
• (iv) the tube's aerodynamic position

The characteristic visual features of this form of corrosion such as “classical” wastage flats, honeycomb pitting, and localised pitting at tube geometrical features such as weld beads, and lugs is described. Also discussed are some of the metallographic features of molten salt corrosion, including substrate carburization, internal oxidation/sulphidation and corrosion scale morphology. Whilst uncertainty remains in understanding the precise mechanism, the CEGB have adopted a pragmatic approach using new/alternative materials such as shields, coatings and co-extruded tubes. However, such a policy may not be the most economic: for example, in some circumstances the alloy 50 Cr 50 Ni is required to give a guaranteed degree of protection. What is still required is the quantification of the role of Na, K, Cl etc. in fuel on deposition and corrosion rates, and the source and influence of carburization so that further operational control of this molten salt corrosion is available.     

深度轧制技术制备的纳米晶金属板材腐蚀性能研究进展

概述了目前已提出的几种纳米晶金属材料制备技术和不同纳米晶金属材料腐蚀研究进展。介绍了深度轧制技术制备纳米晶金属板材,阐述了该技术制备的纳米晶金属板材(工业纯铁、304不锈钢和工业纯铝)腐蚀性能研究进展。与相应的普通金属材料相比,深度轧制技术制备的这三种纳米晶金属材料在不同腐蚀环境(溶液、熔盐和高温气体)中耐腐蚀性能(局部腐蚀和均匀腐蚀)提高。大量纳米晶及其相应普通金属材料的腐蚀实验结果表明,传统的材料微观结构参量(成分及其分布、晶粒尺寸、位错密度和残余应力等)不是腐蚀性能的本征参量。提出了从金属材料价电子结构和氧化膜电子结构角度理解金属材料腐蚀性能及其相关腐蚀机理,并在现有工作基础上提出金属材料电化学腐蚀本征参量的概念。     

铸铁材料在盐湖卤水中的腐蚀研究

在青海盐湖卤水中试验了四种钢铁材料的腐蚀,测定了灰口铸铁表面形成的覆盖物和腐蚀产物的形貌、组成.分析了盐湖卤水及腐蚀产物对铸铁腐蚀性的影响.铸铁在盐湖卤水中表现出典型的"石墨化"腐蚀,形成的网状石墨骨架层有利于减少铸铁的腐蚀.极高的CL离子浓度未造成铸铁点蚀.     

金属材料在青海湖中的腐蚀行为

通过现场暴露试验,获得了典型金属材料在青海湖暴露4年的腐蚀结果,总结了它们在青海湖中的腐蚀行为和规律。在青海湖中Q235B、16 Mn钢表面有沿重力方向的柱状腐蚀产物,其下面形成蚀沟。在青海湖暴露4年后,304、316L没有明显可见的腐蚀。QSi3-1的腐蚀比T2严重,L6、LF6发生点蚀和缝隙腐蚀。     

Corrosion Behavior of 316L Stainless Steels Exposed to Salt Lake Atmosphere of Western China for 8 years

The evolution of corrosion behavior of 316 L stainless steels exposed to salt lake atmosphere for 8 years was investigated.The results showed that the stainless steel in salt lake atmosphere had a greater corrosion rate during the initial exposure time and relatively lower corrosion rate during the subsequent exposure time.Dust depositions accumulated on the downward surface caused severe local corrosion of stainless steel.As exposure time prolonged,the relative amount of Cr_(oxide) and Fe_(oxide)in the corrosion products gradually increased,which may directly affect the corrosion rate of stainless steels.Moreover,the maximum pit depth followed a power function with respect to exposure time.     

Corrosion Behavior of 304 Stainless Steel Exposed to a Simulated Salt Lake Atmosphere

The corrosion behavior of stainless steel exposed to a simulated salt lake atmosphere has been investigated by analyzing the evolution of surface morphologies and corrosion products, the initiation and development of pits, and the electrochemical characteristics. The results indicated that(Mg_6Fe_2(OH)_(16)(CO_3)(H_2O)_(4.5))_(0.25), a layered double hydroxide, has been detected for the first time in the corrosion products formed on stainless steel exposed to a simulated salt lake atmosphere. The specimens exposed to MgCl_2 deposit conditions were corroded more severely than those exposed to NaCl deposit conditions, which was attributed to the differences in the deliquescence relative humidity and efflorescence relative humidity values of MgCl_2 and NaCl. In addition, a special corrosion morphology consisting of a concentric circle of yellowish material was observed on the specimens exposed to MgCl_2 deposit conditions, which was attributed to the formation of Mg(OH)_2, inhibiting the diffusion and migration of OH~- ions to the anode region. The maximum pit depth followed a power function with respect to corrosion time. The corrosion mechanism of stainless steel exposed to a simulated salt lake atmosphere is also discussed.     

Corrosion properties of laser beam joints of aluminium with zinc-coated steel

This paper presents results of accelerated corrosion tests in a salt spray chamber as well as microelectrochemical measurements of thermally joint steel-aluminium mixed materials. The focus was set on analysing the corrosion behaviour of the different metallic materials (brazed seam, intermetallic phases, aluminium and steel sheet) in or within the vicinity of the brazed seam.Both corrosion tests show that the joining zone has the most negative corrosion potential and is the first to corrode. The degree of corrosive deterioration depends on the cathodic behaviour of the adjacent metal. Next to effective cathodes, such as steel or Fe-containing intermetallics, the attack is the most. However, contact to an aluminium alloy (AA6016) with its insulating oxide layer does not affect the corrosion properties of the respective filler materials.