Electrochemical investigations regarding the bioavailability of silver after potentiodynamic corrosion load of precious metal alloys Part 2: Dental alloys

The spectrum of commercial dental alloys has been essentially expanded during the last years. The toxicological effects of dental alloys depend mainly on their element specific corrosion behaviour in the oral cavity. The present study demonstrates the electrochemical boundary conditions regarding the possible formation of AgCl-corrosion products, for which cytotoxic effects has been established, by means of specially adapted electrochemical in-vitro test programs. The prevalence of the developed corrosion mode was proved for two electrolytes and four daily used dental alloys containing different amounts of silver. The results show, that a biological relevant assessment of the released silver ions in both electrolytes, induced by anodic metal dissolution, is only reliable if the measurement takes into account the silver ions within the electrolyte as well as the superficial immobilized amount of silver chloride corrosion products. Thus especially from a biological point of view, interface processes like the formation of immobilized corrosion products seem to be a relevant parameter for the complete testing of biocompatibility of metallic biomaterials. To sum up it can be concluded, that the dental alloys investigated in the course of this study have not shown any adverse susceptibility to corrosion with respect to the clinical practice and can therefore be classified as well biocompatible.     

牙科用钛合金研究现状

本文综述了国内外牙科用钛合金发展过程及应用现状；介绍了现有牙科用钛合金弹性模量、抗拉强度、压缩强度、延伸率等力学性能，卤素元素对钛合金腐蚀的影响，不同材质与钛合金在口腔环境中电偶腐蚀，口腔环境中钛合金的微生物腐蚀，牙科钛合金表面特性特别是表面粗糙度对水基液体润湿性影响，设计新型牙科用钛合金时推荐使用的合金元素种类及计算设计采用的d-电子合金设计法等方面研究成果，并指出了目前存在的问题及努力的方向。     

深海环境下金属及合金材料腐蚀研究进展

综述了深海环境下溶解氧含量、温度、pH、溶解CO2含量、含盐度、静压力、流速以及生物环境等各项因素对金属及合金材料腐蚀的影响,认为溶解氧含量通常为金属及合金材料腐蚀的最主要因素;重点介绍了实海暴露方法和室内模拟加速腐蚀方法在深海环境下的研究进展及具体应用,指出最好将室内模拟加速腐蚀试验和实海暴露方法相结合,同时体现二者的优势以研究金属及合金材料的腐蚀行为;总结了深海环境下金属及合金材料的腐蚀状况,对其防护手段-阴极保护及涂层保护进行了概述.     

生物可降解金属材料体外腐蚀测试体系综述

随着生物可降解金属材料日益受到关注,大量的体外腐蚀测试体系被用来模拟其体内腐蚀行为。不同的测试体系具有其独特的优点和缺点。为建立一个合理的并且更接近体内真实情况的测试体系,对可降解金属材料的腐蚀机理和体外腐蚀测试体系进行总结。从电解质溶液的选择、样品表面粗糙度的影响、测试方法以及腐蚀速度的评价方法等几个方面进行阐述,得到以下初步结论：电解质溶液应该选择与体液成分接近的含有蛋白的缓冲模拟体液,样品表面粗糙度和溶液体积与样品表面积之比应该接近植入部位的实际要求,并且采用动态腐蚀测试方法,同时多种腐蚀速度评价方法应当相互参照。     

Electrochemical study of the corrosion of different alloys exposed to deaerated 80 °C geothermal brines containing CO2

Corrosion of metallic engineering materials accounts for problems during geothermal operation in the Upper Rhine Graben (URG). Herein, we study the electrochemical behaviour of various metal alloys in an 80 °C simulated geothermal environment by using potentiodynamic polarisation and open-circuit potential measurements. Two different natural geothermal waters from URG geothermal sites were used for the experiments. The measurements reveal spontaneous passivation to be a key process for all alloys. This ennoblement protects more noble alloys from significant corrosion (e.g. titanium gr. 2, alloy 625) and brings less noble alloys to failure, mostly due to pitting corrosion (e.g. 316L).     

金属系牙科材料的应用现状及部分元素的毒副作用

本文对金属纱牙科材料的组成、性能，适用场合，存在问题及发展趋势进行了综合评述。认为汞、镍，铜，铝，铍，铬，钴，钒，钯元素均具有细胞毒性作用，在牙科材料及其它生物医学材料中应尽量避免使用；而元素钛、铌，锆，锡，钼，钽和铁是无毒性元素，可以作为改善生物医学材料力学性能，耐蚀性能及生物相容性的候选元素，为新型牙科合金材料及其它生物医学材料的开发研究提供选材依据。钛合金作为牙科材料是未来牙科材料的发展趋势     

Recent Advancements in Self-Healing Metallic Materials and Self-Healing Metal Matrix Composites

Engineered self-healing materials inspired by natural biological organisms that can repair damage are receiving increasing interest in recent years. Most studies have been focused on self-healing polymers, concretes, and ceramics. Self-healing metallic materials pose challenges due to the high temperatures used in manufacturing and the chemistries involved. This article summarizes and evaluates the self-healing mechanisms used in metallic materials and reviews recent studies into self-healing in aluminum, zinc, and Sn-Bi alloys. Generalizations about the various classifications are drawn from the review highlighting major hurdles in the widespread practical application of metallic self-healing materials, as well as the potential directions for future studies.     

Introduction to corrosion of bioimplants

The review provides a general idea about the types of metallic alloys and the pure metals used as implant materials in dental and orthopedic surgery. Their corrosive behavior in both real solutions and various media that model human biological fluids is described. Based on the literature data, it is concluded that multicomponent alloys containing titanium, niobium, zirconium, tungsten, molybdenum, aluminum, and silicon are the most resistant to corrosion. Implants made of different types of stainless steel are preferred when manufacturing orthopedic devices for short-term use.     

口腔科用人工替代金属材料的耐蚀性能

通过模拟试验液中溶出的离子量，比较了口腔科用金属及合金的耐蚀性能，讨论了口腔科用金属及合金在成型及使用过程中其耐蚀性能下降的因素，如铸造、研磨、异种金属间的接触等。介绍了近年开发的口腔科用新型合金及其耐蚀性能。     

Corrosion resistance in different environments and structural features of dental casting alloys for resin bonding

The influence of different electrolytes on the corrosion behaviour of three dental casting alloys for resin bonding with different nobility was investigated. The alloys were studied in the metallurgical state representing that in the oral cavity. Structural and morphological characterisation was performed by means of optical and electronic microscopy and EDS microanalysis. The corrosion resistance was evaluated by means of potentiodynamic anodic polarization curves recorded in three different aggressive environments: artificial saliva (pH = 6.7), Ringer's solution and 0.1 N NaCl solution added with lactic acid (pH = 2). The latter solution is recommended by UNI EN ISO 8891 for the static immersion corrosion test. For comparison purposes the electrochemical behaviour of the pure alloying metals in this solution was also investigated. Results showed a satisfactory corrosion resistance of the alloys examined. The synthetic saliva was the least aggressive electrolyte for all of them but it did not allow to distinguish the corrosion behaviour of these alloys although their differences in nobility and structure. The chloride‐containing solutions showed a better distinction in the corrosion behaviour, as matter of facts, as the chloride content increased, the higher (Cu + Ag) amount was in the alloy, the higher was its current density in the immunity region of the anodic polarisation curves. The environment recommended by the normative UNI EN ISO 8891 resulted the most sensitive and effective for the discrimination of the corrosion resistance of precious metal alloys for resin bonding with different nobility by means of the potentiodynamic test.     

深海腐蚀环境下钛合金海洋腐蚀的发展现状及展望

综述了钛合金及其他合金在深海极端腐蚀环境下的研究成果,总结了深海环境下腐蚀特征及应力腐蚀开裂、低周疲劳及高压蠕变等主要腐蚀破坏形式,指明上方海水的高静水压造成深海装备等的腐蚀失效和缺陷对于深海空间站等大型装备的安全性等至关重要。深海腐蚀的电极反应受到深海高静水压的影响的与普通水溶液腐蚀大为不同,值得深入研究;另一方面,对近期利用材料计算工程方法对于深海极端环境下腐蚀过程的模拟进行了介绍和总结,并总结了自主研发的专用深海腐蚀模拟装置的发展现状。基于钛合金在深海会发生的应力腐蚀开裂、低周疲劳、高静水压力导致的高压压缩蠕变及相应的电极反应方面研究,提出了我国深海环境下钛合金腐蚀研究的主要问题和未来亟待解决的相关问题。     

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。     

Research into the Properties of Materials for Underwater Structures in the North Sea

Constructing under water has accelerated research into corrosion protection and antifouling properties of materials used below the seawater level. A special working party was founded in the Netherlands to study — theoretically and practically — the corrosion and fouling properties of materials and coatings. A special test rack was immersed at a depth of 50 m in the North Sea in 1969. Experience gained from these experiments gave rise to a joint investigation by 13 laboratories in the Netherlands; the programme involves ten test racks 50 and 100 m below sea level, in the tidal zone and in marine and land atmospheres. The materials studied were: steel with various paints and coatings; stainless steel, Cu, Al and Ti alloys; welded, brazed, nailed and glued stainless steel, Al and Ti alloys; synthetic fibers. The test methods included crevice corrosion and stress corrosion bending tests, electrochemical measurements and the regular control of the biological conditions. The results show the importance of testing in specific marine areas because the results are not readily applicable to conditions in other geographical regions.     

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。     

医用贵金属材料的研究与发展

由于贵金属材料具有独特的抗腐蚀性、生理上的无毒性、良好的延展性以及生物相容性，它在医学领域的应用日益拓展。作者在本文着重介绍贵金属材料在牙科(包括牙科汞齐合金和铸造合金)、针灸、体内植入的电子器件及医用生物传感器等方面的研究与发展，分析了牙科用贵金属材料的演变过程等。     

Electrochemical behavior of TiN film coated Ti−Nb alloys for dental materials

In order to study the electrochemical behaviors of TiN film coated Ti−Nb alloys for dental materials, Ti containing Nb up to 3, 20, and 40 wt.% was melted by a vacuum furnace and coated with TiN by EB-PVD. the electrochemical behaviors were investigated using a potentiostat in 0.9% NaCl solution and the corrosion surface was observed using SEM and XPS. Ti−3Nb and Ti−20Nb alloys have α+β phase structure. In the case of Ti−40Nb, the microstructure had a coarse β phase. The microstructural changed from equiaxed to acicular and an increase of β-phase in Ti−Nb alloys was observed with increased Nb content. The current density at 300 mV (potential of oral environment) of Ti−40Nb alloy was lower than that of the other alloys in 0.9% NaCl. The pitting corrosion resistance of Ti−40Nb was higher than that of Ti−3Nb and Ti−20Nb alloys in the 0.9% NaCl solution. The corrosion potential and pitting potential of TiN coated Ti alloy increased with increasing Nb content but the current density at 300 mV and the current density at the passive region decreased. The TiN coated Ti−40Nb alloy offers good corrosion resistance for dental implants compared with non-TiN coats alloys.     

Influence of climatic factors in cyclic accelerated corrosion test towards the development of a reliable and repeatable accelerated corrosion test for the automotive industry

Two designs of experiments made of nine accelerated tests each were used in order to study the influence of a selection of important climatic parameters such as the concentration of NaCl, the drying level, the basic humidity cycle, the frequency of salt spray and the temperature. The accelerated corrosion tests were all performed using automatic chambers. Different automotive materials were selected in order to study the resistance to cosmetic corrosion, perforation corrosion and bi‐metallic corrosion. For cosmetic materials, coated panels of cold rolled steel (CRS), zinc‐coated steel and aluminium alloys were chosen. Perforation corrosion was investigated using crevice panels of CRS, zinc‐coated steel or different grades of aluminium alloys. From the results, the influence of testing conditions on the cosmetic and perforation corrosion of different automotive materials was obtained. As an example, it was shown that an elevation of the temperature from 35 to 45 °C in the cyclic corrosion test increased the scribe creep on painted CRS and aluminium alloys while it has no significant effects on painted hot dip galvanized (HDG) panels. The results were also compared to that obtained after 2 years of exposure at a marine exposure site and on busses driving in area using de‐icing salt. It was shown that one of the tests performed gives a good correlation to field results.     

航空航天铝合金腐蚀疲劳研究进展

铝合金因具有高的比强度、比模量,好的加工性能及焊接性能,在航空航天领域应用广泛.而腐蚀疲劳是造成航空航天材料失效的重要原因之一,因其危害性高、破坏性强且难以提前预测等特点,受到了广泛关注.铝合金腐蚀疲劳问题一直是飞机日历寿命研究中的重点问题,随着可重复使用航天器理念的提出,多次空天往返和地面修复过程也使腐蚀疲劳问题在可...     

油气开采用钛合金石油管材料耐腐蚀性能研究

选取5种油气开发常用钛合金材料(Ti-6Al-4V、Ti-6Al-4V-0.1Ru、Ti-6Al-2Sn-4Zr-6Mo、Ti-3Al-8V-6Cr-4Zr-4Mo和Ti-5.5Al-4.5V-2Zr-1Mo)为研究对象,使用高温高压釜模拟国内典型严酷服役工况环境,研究了不同钛合金材料耐均匀腐蚀、局部腐蚀、点蚀、应力腐蚀开裂(SCC)及缝隙腐蚀的性能,通过使用扫描电镜和能谱分析等手段对腐蚀形貌和腐蚀产物进行了分析,并使用电化学方法对不同合金的耐腐蚀机理进行了研究。结果显示,在所测试工况条件下,所有钛合金材料腐蚀反应均为阳极控制过程,均匀腐蚀速率均低于0.001mm/a,并且对应力腐蚀开裂均有良好的抗力。Ti-6Al-4V和Ti-5.5Al-4.5V-2Zr-1Mo合金出现明显的点蚀和缝隙腐蚀问题。对腐蚀机理研究表明,在工况条件温度下,随着pH值的降低,所有钛合金均发生自腐蚀电位降低,极化电阻减小,腐蚀电流增大,耐腐蚀性能下降,其中Ti-6Al-4V耐腐蚀性能下降的最为明显,研究结果为油气开发工况下钛合金石油管的选材和缝隙腐蚀问题防治提供理论基础。     

Corrosion Resistance of Cordierite-Modified Light MMCs

Composites are one of the fastest developing materials. Research is particularly intensive in case of light metal alloys due to i.a. economic and environmental aspects. One of the innovative solutions is production of the metal matrix composites (MMC) by adding the cordierite ceramics obtained from fly ashes to magnesium alloys. In addition to obtaining new-generation materials with improved mechanical properties, also the waste is utilized which has a significant environmental and economic importance. In order to select the suitable operating conditions for such alloys, their corrosion resistance must be determined. This paper presents the results of corrosion resistance tests of AM60 magnesium alloy matrix composites reinforced with cordierite ceramics. The following issues were examined: (1) impact of the volume fraction of cordierite ceramics, 2 or 4 wt.%; (2) impact of surface roughness (two variants of surface treatment); and (3) impact of heat treatment on corrosion resistance of obtained composites. The results were compared with data recorded for the base AM60 alloy (which surface treatment was identical as of the composites). Moreover, the XRD and microanalysis of the chemical compositions by EDS method were applied to determine phases occurring in the investigated composites. Furthermore, the XRD was also performed in order to identify the corrosion products on the surface of the material. The test results indicate that the alloy reinforced with 2 wt.% addition of cordierite ceramics had the best corrosion resistance. It was also presented that surface and heat treatment affect the obtained results.