Corrosion behavior of Ti‐xNb‐13Zr alloys in Ringer's solution

Ti‐6Al‐4V alloy has been widely used in restorative surgery due to its high corrosion resistance and biocompatibility. Nevertheless, some studies showed that V and Al release in the organism might induce cytotoxic effects and neurological disorders, which led to the development of V‐free alloys and both V‐ and Al‐free alloys containing Nb, Zr, Ta, or Mo. Among these alloys, Ti‐13Nb‐13Zr alloy is promising due to its better biomechanical compatibility than Ti‐6Al‐4V. In this work, the corrosion behavior of Ti, Ti‐6Al‐4V, and Ti‐xNb‐13Zr alloys (x = 5, 13, and 20) was evaluated in Ringer's solution (pH 7.5) at 37 °C through open‐circuit potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. Spontaneous passivity was observed for all materials in this medium. Low corrosion current densities (in the order of 10^?7 A/cm²) and high impedance values (in the order of 10⁵ Ωcm² at low frequencies) indicated their high corrosion resistance. EIS results showed that the passivating films were constituted of an outer porous layer (very low resistance) and an inner compact layer (high resistance), the latter providing the corrosion resistance of the materials. There was evidence that the Ti‐xNb‐13Zr alloys were more corrosion resistant than both Ti and Ti‐6Al‐4V in Ringer's solution.     

干湿交替周浸模拟加速腐蚀试验装置的建立

设计建立了一套模拟多种大气环境,同时能够进行电化学测试的、可靠的智能型干湿交替周浸加速腐蚀实验装置。实现了模拟加速自然环境的大气腐蚀,快速评价金属材料和涂层在大气环境下的腐蚀行为和耐蚀性能的目的。     

Comparison of SBF and DMEM in terms of electrochemical properties of common metallic biomaterials

Corrosion behavior is an important parameter for metallic biomaterials used in the body environment. To mimic bodily fluids, simulated body fluid (SBF) has been used extensively. Even though many studies focus on corrosion inside SBF, SBF has a very time consuming and delicate preparation procedure and contains no essential and organic components for the cell environment, which may affect corrosion kinetics. We aimed to investigate whether corrosion behavior or kinetics change in different solutions, SBF and Dulbecco's modified Eagle medium (DMEM). For this purpose, five commonly used metallic biomaterials, AISI 316 stainless steel, CoCrMo alloy, CP-Ti, Ti6Al4V, and Ti6Al7Nb were subjected to open circuit measurements, cyclic polarization, and electrochemical impedance spectroscopy. Quantitative analyses were performed and surface topography was investigated via scanning electron microscope and a roughness tester. We observed that the materials exhibited similar behaviors in SBF and DMEM but the corrosion kinetics were somewhat different and the results obtained from DMEM were time dependent.     

In vitro electrochemical investigations of advanced stainless steels for applications as orthopaedic implants

Potentiodynamic anodic polarization experiments on advanced stainless steels (SS), such as nitrogenbearing type 316L and 317L SS, were carried out in Hank’s solution (8 g NaCl, 0.14 g CaCl₂, 0.4 g KC1, 0.35 g NaHCO₃, 1 g glucose, 0.1 g NaH₂PO₄, 0.1 g MgCl₂, 0.06 g Na₂HPO₄ 2H₂O, 0.06 g MgSO₄ 7H₂O/1000 mL) in order to assess the pitting and crevice corrosion resistance. The results showed a significant improvement in the pitting and crevice corrosion resistance than the commonly used type 316L stainless steel implant material. The corrosion resistance was higher in austenitic stainless steels containing higher amounts of nitrogen. The pit-protection potential for nitrogen-bearing stainless steels was more noble than the corrosion potential indicating the higher repassivation tendency of actively growing pits in these alloys. The accelerated leaching study conducted for the above alloys showed very little tendency for leaching of metal ions, such as iron, chromium, and nickel, at different impressed potentials. This may be due to the enrichment of nitrogen and molybdenum at the passive film and metal interface, which could have impeded the releasing of metal ions through passive film.     

Models for the propagation phase of reinforcement corrosion – an overview

The deterioration of a concrete structure by reinforcement corrosion proceeds in two phases: the initiation stage and the propagation stage. The first stage describes the time to onset of corrosion due to carbonation of the concrete or chloride ingress. The second stage is the actual deterioration stage. Most methods for life time assessments refer only to the first stage, what is on the safe side with respect to design of structures, but also a model for the second stage can be of interest, e.g. if the remaining life time of an existing structure has to be estimated. This paper presents and discusses the state‐of‐the‐art of models for the propagation stage with regard to their different approaches.     

低比例甲醇汽油对金属的腐蚀研究

目的减轻甲醇汽油的腐蚀性。方法以汽车油路系统常用的紫铜、黄铜、钢、铁、铝等金属材质为研究对象,采用金属试片的腐蚀度和颜色变化相结合的方法,分析判断甲醇汽油的腐蚀性,通过考察不同金属试片在不同含量甲醇汽油、含水甲醇汽油以及添加缓蚀剂甲醇汽油中的腐蚀情况,分析甲醇汽油腐蚀的主要原因,并根据缓蚀机理筛选缓蚀剂。结果低比例甲醇汽油对不同金属材质都有明显的腐蚀作用,与93#汽油相比,加入5%(体积分数)的甲醇就能使紫铜、黄铜、钢、铝的腐蚀度增加一倍以上。少量水分可加剧甲醇汽油的腐蚀,但当水含量达到一定程度时,腐蚀度减小。缓蚀剂B对铜系金属材质的腐蚀有较好的抑制作用,缓蚀剂C对铁片腐蚀有较好的抑制作用,复配缓蚀剂H对所选金属材质都有良好的缓蚀效果,可使紫铜、黄铜、铁和铝的缓蚀率分别减小82.1%、81.5%、85.3%和89.5%。结论复配的缓蚀剂能够有效地减缓甲醇汽油对金属的腐蚀。     

银离子注入Mg-Ca-Zn合金在模拟体液中的耐腐蚀性研究

研究了Mg-1.0Ca-0.3Zn合金在银离子剂量为1.5×1017 cm-2注入条件下,在模拟体液(simulated body fluid,SBF)中的耐腐蚀性。通过纳米压痕和三电极体系法对合金的表面硬度和弹性模量、在SBF中的极化曲线测定表明：经过银离子注入后,合金的表面硬度和弹性模量增加,表面硬度在250 nm深度达到最大;同时,合金的极化阻力增加,提高了合金的耐腐蚀性能;在1~48 h内SBF溶液的pH值逐渐增加,加快了SBF溶液的碱化     

Modelling of reinforcement corrosion – Corrosion with extensive cathodes

Reinforcement corrosion is the most common reason for the premature deterioration of a concrete structure. In case of a partial depassivation of the reinforcement macrocells are formed with considerable metal removal rates. Thus an assessment of the macrocell current becomes of great concern. To find out, whether this can be achieved by numerical calculations, specimens have been fabricated and simulated by the use of a boundary element program. In this paper the results of the calculations are presented and compared to electrochemical measurements on the real specimens.     

腐蚀对复合银钎料的影响

采用恒温浸泡腐蚀、电化学腐蚀、润湿铺展测试和扫描电子显微镜(SEM)、万能力学试验机等手段研究了复合银钎料中钎剂与钎料合金的腐蚀及钎料腐蚀对钎焊性能的影响。结果表明,银钎料处于含水钎剂环境中,会被钎剂腐蚀。在钎料中加入1.5%~2.5%的Sn,缩小了Ag-Cu-Zn合金中Ag-Zn相与Cu-Zn相之间的电位差,降低了两相之间的微电池效应,Sn细化Ag-Cu-Zn钎料中的共晶相,降低银钎料发生腐蚀的敏感性;用被腐蚀的银钎料钎焊钢,钎焊接头抗拉强度损失,在钎料中添加Sn可抑制损失程度。     

含有金属黏结相的热喷涂WC涂层在盐雾中的腐蚀行为

研究黏结相化学成分对涂层材料的耐盐雾腐蚀性能的影响,对采用超音速火焰喷涂制得的WC?17Co和WC?10Co?4Cr涂层进行电化学试验和长时间的盐雾腐蚀实验(浓度为5%的NaCl溶液,温度35°C)。结果表明：WC?10Co?4Cr涂层的耐盐雾腐蚀性能优于WC?17Co涂层。对于WC?17Co涂层,主要腐蚀行为除了粘结金属的腐蚀外还包括WC颗粒与粘结相金属之间发生的微点偶腐蚀;对于WC?10Co?4Cr涂层,形成的氧化物有利于抑制金属相与粘结相的腐蚀。说明金属材料成分是影响超音速火焰喷涂WC基涂层耐盐雾腐蚀性能的重要因素之一。     

椭圆偏振测量术在金属腐蚀与防护领域的应用

椭圆偏振测量术是一种高度灵敏的、非破坏性的原位表征技术,是金属腐蚀与防护研究的一种重要工具.本文基于对椭圆偏振测量原理的简介,结合椭圆偏振仪和数据解析技术的最新进展,综述了椭圆偏振测量术在金属腐蚀与防护领域的应用现状并讨论了椭圆偏振测量术的发展趋势.     

金属材料在含氯化物水基环境中的耐腐蚀性能

腐蚀,特别是海洋环境中发生的点蚀,导致材料服役寿命锐减并造成巨大的经济损失甚至环境破坏和灾难事故.在过去的十年中,针对材料在含氯化物水基环境的腐蚀行为开展了大量的研究工作.在此,综述从金属整体材料到包括有机涂层、金属及其合金或化合物涂层在内的表面处理的失效机理以及提高材料耐腐蚀性能和耐腐蚀?磨损性能的最新研究进展.其中...     

DFG‐research‐group: Modelling reinforcement corrosion – overview of the project

A strong interest for the durability of reinforced concrete structures currently exists in industry and research [1]. Against the background of immense costs for maintaining reinforced concrete structures and repairing damage caused by corroding reinforcement steel, this interest lead to a German joint research project. The aim of this network‐based (www.bam.de/dfg537.htm) research group is, to deliver the basic knowledge of the corrosion propagation and to make a probabilistic tool available for engineers so that a complete design for durability, concerning reinforcement corrosion, will be possible.     

模拟浓缩液桶内干燥过程干燥桶腐蚀原因分析

目的通过对模拟浓缩液桶内干燥试验过程中出现泄漏的干燥桶泄漏处取样分析,明确干燥桶泄漏的主要原因。方法采用切割取样的方式在干燥桶泄漏处取样,根据后续分析测试手段对样片进行分解制样。对干燥桶材质进行化学组分分析和金相组织及晶粒度测试,通过扫描电镜对干燥桶腐蚀区域微观形貌进行观察,此外对腐蚀产物进行能谱分析,并和相关标准进行比较。结果干燥桶材质符合ASME A240中304不锈钢化学成分含量规定,非金属夹杂物满足一般工程用钢对非金属夹杂物的要求,其金相组织为奥氏体和条状铁素体,与304不锈钢金相不符,晶粒度为6.5级。样品存在大量腐蚀坑点,孔洞及坑点周围附着有较多腐蚀产物,坑点内呈现"冰糖块"状形貌,未形成坑点的区域同样存在腐蚀现象,观察到清晰的晶粒,腐蚀属于不锈钢的点腐蚀,在腐蚀产物中发现了Cl,F元素。结论桶体材质存在奥氏体和铁素体两相金相组织引发不锈钢点蚀是导致干燥桶腐蚀泄漏的主要原因,此外,不能排除Cl和F离子对干燥桶腐蚀的影响。     

Corrosion and elution of harmful metals from metal buttons

Metals present in metal items may due to the corrosion processes that occur in sweat cause adverse health effects, such as allergic reactions, on direct and prolonged contact with the skin. For example, 20% of female population and about 6% of male population are allergic to nickel. Therefore, three different textile accessories were tested for metal leaching: the samples were kept at 30 °C in the artificial sweat solution for different time periods and quantified. The results have shown that the limits prescribed by international standards were much exceeded. Samples of such properties present a high risk for human health and should be used with special attention.     

激光表面重熔NiTi形状记忆合金组织及腐蚀性能

采用2kWNd：YAG激光器对NiTi合金进行表面重熔处理，利用扫描电镜、X射线衍射、X光电子能谱分析重熔层成分和组织结构，利用电化学测试研究重熔层耐腐蚀性能。结果表明：NiTi合金经过激光重熔处理后，可得到致密的重熔层；根据激光处理参数的不同，在重熔层中会出现TiNi、TiNi3等新相，重熔层表面Ti／Ni及Ti^4 /Ti比显著提高；电化学极化曲线表明激光重熔后NiTi合金的耐蚀性得到了显著改善。     

Corrosion behavior of CuCrFeNiMn high entropy alloy system in 1 M sulfuric acid solution

Immersion tests and potentiodynamic polarization measurements were conducted in 1 M sulfuric acid solution (H₂SO₄) at ambient temperature (～25 °C) to investigate the corrosion behavior of CuCrFeNiMn alloy system. The results show that the alloys display a good general corrosion resistance that is mainly influenced by the Cu content and elemental segregation degree. The corrosion resistance degrades when increasing Cu content and elemental segregation degree. Among the tested alloys, the CuCr₂Fe₂Ni₂Mn₂ alloy with low Cu content and elemental segregation degree displays a better general corrosion resistance. On the contrary, the Cu₂CrFe₂NiMn₂ alloy with high Cu content and elemental segregation degree exhibits the worst general corrosion resistance.