A Comparison of Corrosion Behavior in Saline Environment: Rare Earth Metals (Y, Nd, Gd, Dy) for Alloying of Biodegradable Magnesium Alloys

Rare earth(RE) metals are widely used as the alloying elements in biodegradable magnesium alloys as medical implants.However,corrosion behavior of pure RE metals not only in physiological media but also in chlorinated saline environment is not well understood.In the present work,the RE metals Y,Nd,Gd and Dy are selected to investigate their corrosion behavior in 0.1 mol/L NaCl solution with immersion and electrochemistry techniques.As indicated,corrosion of the currently investigated RE metals is promoted in the order of Dy,Y,Gd and Nd.In terms of electrochemical response,such a sequence correlates with the increased impedance and the decreased corrosion rate(CR).These RE metals manifest weak ability for passivation in the native surface.Then,reaction with aqueous solution easily happens through the anodic dissolution and cathodic hydrogen evolution.The corrosion products,RE(OH)3,adhered on the surface of RE metals,do not have an appreciable power to resist the reaction proceeding with corrosive chloride ions.In contrast to pure Mg,the RE metals,including Y,Nd,Gd and Dy,exhibit significantly fragile corrosion resistance in saline media.Therefore,with the current findings,it is impossible to reveal a well-defined correlation of corrosion resistance between RE-containing Mg alloy and RE metal itself.     

几种线缆金属材料的土壤腐蚀特性

采用自然埋藏的研究方法,对线缆金属材料铜、铝、铅在我国各种土壤中的腐蚀试验结果和腐蚀产物进行了分析,总结了腐蚀特征和规律,探讨了土壤及微生物对腐蚀的影响.结果表明:铜、铝、铅平均腐蚀率随时间变化规律基本遵循方程式V=At8;铜在内陆盐土,铝在碱性土壤,铅在酸性土及潮湿草甸土、紫色土中呈局部斑点腐蚀;局部腐蚀产物不具保护性;影响铜、铝、铅局部腐蚀的主要因素是土壤质地,含水量,可溶性盐Clˉ、SO2ˉ4及微生物.     

功能性有机硅烷膜对金属腐蚀防护的研究现状及展望

功能性有机硅氧烷对金属表面进行处理是一种新型的表面防护处理技术,能够显著提高金属的耐腐蚀性能.介绍了功能性有机硅氧烷的结构和分类,探讨了功能性硅氧烷膜的腐蚀防护机理,总结了金属表面耐腐蚀性功能硅氧烷膜的研究现状和进展,以期对金属表面腐蚀防护提供指导和帮助.     

A review of corrosion inhibitors for rust preventative fluids

Corrosion of metals has been a widespread issue in industries for centuries. The use of corrosion inhibitors in rust preventative fluids are commonly employed to provide the temporary corrosion protection to metals. The aim of this review is to summarize the rust inhibition properties, inhibition mechanism, chemistry and development of corrosion inhibitors for rust preventative fluids. Some suggestions for further research on corrosion inhibitors have also been discussed.     

复配气相缓蚀剂对多种金属大气腐蚀的综合保护作用研究

为了应对海洋大气环境中电子设备容易被腐蚀的难题,制备了一种复配气相缓蚀剂。通过半封闭空间挥发减量试验、缓蚀膜疏水性表征、模拟环境和海洋大气环境试验等评价了复配气相缓蚀剂对钢、T2紫铜、黄铜、银、铝等电子设备常用金属的气相缓蚀性能。结果表明:复配气相缓蚀剂对以上金属均具有显著的缓蚀作用,其中对钢的缓蚀率为86.9%,对T2紫铜为58.7%,对黄铜为96.2%,对银和铝在模拟腐蚀环境中具有一级气相缓蚀能力,是一种性能优良的电子设备多金属大气腐蚀综合防护材料。     

含钼镍基焊缝金属在硝酸溶液中的腐蚀行为

研究了三种不同Mo含量的镍基焊缝熔敷金属在强氧化性介质(65%硝酸溶液)中的腐蚀行为。结果表明,熔敷金属在硝酸溶液中浸泡后发生了晶间腐蚀、点蚀以及枝晶间腐蚀等局部腐蚀。由于Mo元素促进了大尺寸Laves相在熔敷金属枝晶间的析出,在Laves相与基体之间产生了较大的电化学差异,导致Laves相在氧化性介质中腐蚀溶解,增大了熔敷金属的点蚀敏感性。在620℃焊后的去应力退火过程中,在焊缝中发生元素再分配,Mo元素降低了枝晶间Ni、Cr元素的贫化。由于枝晶间Ni、Cr元素的贫化是引起熔敷金属枝晶间腐蚀的重要因素,Mo元素降低了焊缝熔敷金属在硝酸溶液中枝晶间腐蚀敏感性。     

Mechanism of cavitation and its dependence on the corrosion resistance of metals

The role of high-frequency pulses associated with liquid microvolumes breaking away from a solid surface and the part played by corrosion in erosion damage of metals were studied. It was shown that a reduction in the intensity of cavitation is accompanied by a substantial increase in the corrosion resistance of metals.     

金属材料在铝液中腐蚀行为的研究

为获得铝液腐蚀工况下金属材料的选用原则,运用静态铝液浸没腐蚀试验,研究了QT350、HT300、H13、Cr13、Ta、Mo在铝液中的腐蚀行为.结果表明:所选金属材料在试验条件下均与铝液反应生成金属间化合物层;所选金属材料在铝液中的平均腐蚀深度由高到低依次为QT350、H13、Cr13、HT300、Ta、Mo,难熔金属Ta、Mo具有优异的耐铝液腐蚀性能;QT350、HT300、H13、Cr13腐蚀后表面形成大量点状蚀坑,其在铝液中的腐蚀为非均匀腐蚀;Ta、Mo腐蚀后表面平整,其在铝液中的腐蚀为均匀腐蚀.     

Effect of pulsed electric current treatment on corrosion of structural metals

Results of corrosion tests of structural metals previously treated using pulsed electric current of high density are presented. According to the data obtained, the treatment substantially affects corrosion of metals. In cases of HSLA steel and 5182 aluminum alloy, an increase of corrosion resistance occurs, whereas the same treatment causes a dramatic reduction of corrosion resistance of 5754 aluminum alloy. Translated from Problemy Prochnosti, No. 4, pp. 62–68, July–August, 2009.     

导电高分子聚吡咯在防腐领域的研究进展

综述了导电高分子聚吡咯在防腐蚀领域中的最新研究进展,讨论了聚吡咯膜的防腐蚀机理.     

Corrosion behavior of metals and alloys in marine-industrial environment

Abstract

This work deals with atmospheric corrosion to assess the degrading effects of air pollutants on ferrous and non-ferrous metals and alloys, which are mostly used as engineering materials. An exposure study was conducted in the Tuticorin port area located on the east coast of South India, in the Gulf of Mannar with Sri Lanka to the southeast. Common engineering materials, namely mild steel, galvanized iron, Zn, Al, Cu and Cu–Zn alloys (Cu–27Zn, Cu–30Zn and Cu–37Zn), were used in the investigation. The site was chosen where the metals are exposed to marine and industrial atmospheres. Seasonal 1 to 12 month corrosion losses of these metals and alloys were determined by a weight loss method. The weight losses showed strong corrosion of mild steel, galvanized iron, Cu and Zn and minor effect on Al and Cu–Zn alloys. Linear regression analysis was conducted to study the mechanism of corrosion. The composition of corrosion products formed on the metal surfaces was identified by x-ray diffraction and Fourier transform infrared spectroscopy.     

Corrosion behavior of metals and alloys in marine-industrial environment

This work deals with atmospheric corrosion to assess the degrading effects of air pollutants on ferrous and non-ferrous metals and alloys, which are mostly used as engineering materials. An exposure study was conducted in the Tuticorin port area located on the east coast of South India, in the Gulf of Mannar with Sri Lanka to the southeast. Common engineering materials, namely mild steel, galvanized iron, Zn, Al, Cu and Cu–Zn alloys (Cu–27Zn, Cu–30Zn and Cu–37Zn), were used in the investigation. The site was chosen where the metals are exposed to marine and industrial atmospheres. Seasonal 1 to 12 month corrosion losses of these metals and alloys were determined by a weight loss method. The weight losses showed strong corrosion of mild steel, galvanized iron, Cu and Zn and minor effect on Al and Cu–Zn alloys. Linear regression analysis was conducted to study the mechanism of corrosion. The composition of corrosion products formed on the metal surfaces was identified by x-ray diffraction and Fourier transform infrared spectroscopy.     

Corrosion behavior of Al–Si–Cu–(Sn, Zn) brazing filler metals

The corrosion behavior of Al–Si–Cu–(Sn, Zn) filler metals in a 3.5% NaCl aqueous solution were studied using electrochemical tests. The results showed that the addition of Sn or Zn to the Al–Si–Cu filler metal raised its corrosion current density sharply and caused its corrosion potential to become more active. Sn or Zn elements exert harmful effects on such low-melting-point brazing filler metals in that the corrosion resistance is degenerated, and damage is accelerated with an increase in the Sn or Zn content. Scanning electron microscopy (SEM) micrographs of the corroded surfaces of these Al–Si–Cu–(Sn, Zn) filler metals indicate that the Al-rich phase (i.e., Al–Si, Al–Si–Cu, and Al–Si–Cu–Sn eutectic phases) dissolves preferentially, while the Si particles and CuAl₂(θ) intermetallic compounds remain intact.     

离子注入对铁及其低合金、铝及其合金耐腐蚀性能的影响

离子注入对金属腐蚀行为的研究已达30年．研究结果表明离子注入对改变金属表面成分和表面性能是极为有效的技术．本文概述了离子注入对铁及其低合金、铝及其合金的腐蚀电化学行为的影响．涉及的注入离子达十余种。     

Analysis of steel structure corrosion of drinking water distribution system in family indoor environment

In this paper, corrosion investigation and analysis of steel structure of drinking water distribution system in a family kitchen have been carried out. Results indicate that galvanized corrosion and condensation corrosion under thin water layer have been found the main corrosion type. XRD analysis shows that the rust layer is composed of α‐FeOOH, γ‐FeOOH and Fe₃O₄. For preventing galvanic corrosion, using non‐conductive materials between metals of different electropotential, i.e. electrically insulating the two metals from each other has been recommended. For preventing condensation corrosion under thin water layer, cleaning the pipe external surface to minimize the condensation corrosion is necessary and a good epoxy coating on the pipe external surface may also work. The selection of PVC pipe with better quality and no leaching of inorganic pollutants into water is also a good choice, however, in this condition strong hitting to the PVC pipe should be avoided.     

Adsorption-electrochemical theory of the corrosion fatigue of metals

We show the role of H. V. Karpenko in studying the corrosion-fatigue fracture of metals and analyze the main differences between such fracture and the fatigue of metals in air. We also describe some results of our investigations of the corrosion fatigue of stainless steels and propose new approaches to determination of the corrosion fatigue limit of corrosion-resistant steels and alloys on the basis of their electrochemical studies under loading.     

Preconditions for the Existence of a Physical Limit of Corrosion Fatigue of Corrosion-Resistant Steels and Alloys

Using the results of analysis of regularities of variations in electrochemical characteristics of cyclically deformable metals in chloride-containing media, we suggest the possibility of existence of a physical limit of corrosion fatigue for corrosion-resistant steels and alloys. First of all, this is true for metals whose fracture is determined by the accelerated dissolution of microdeformed sections of the surface. The achievement of the physical limit of fatigue corrosion is experimentally confirmed for zirconium and niobium alloys in a 3% NaCl + HCl (pH 2) solution.     

Micro-beam plasma-arc surface processing for ferrous and nonferrous metals

In the paper a technique of surface treatment, micro-beam plasma-arc scanning, is reported. Surfaces of metals were melted by micro-beam plasma-arc and then self-quenched by the underlying substrates. The effects of surface treatment on the microstructure, wear and corrosion resistance of metals were investigated. The high self-quenching rates resulted in the refinement of microstructure, extended solubility of alloying elements, and even the formation of an amorphous structure. Wear and corrosion resistance of many alloys, particularly ferrous alloys, were improved. Reasons responsible for the effects are discussed.     

镁合金微弧氧化新型电解液配方研究

为优化电解液组分,提高耐蚀性能,利用正交试验法对镁合金微弧氧化电解液配方进行了优化,得出镁合金微弧氧化新型绿色电解液的最佳配方:1.10 mol/L NaOH,0.04 mol/L碱金属硅酸盐,0.50mol/L碱金属含氧酸盐或1.10 mol/L NaOH,0.04 mol/L碱金属硅酸盐,0.30 mol/L碱金属合氧酸盐,并详细分析了电解液中各组分对微弧氧化陶瓷膜腐蚀防护性能的影响.     

Corrosion behaviour of steels and refractory metals in flowing Lead-Bismuth Eutectic at low oxygen activity

The corrosion behaviours of AISI 316L and T91 steels, and several refractory metals as W, Mo and Ta, were investigated in flowing lead-bismuth eutectic (LBE) at 400°C. The tests were performed in the LECOR (Lead Corrosion) loop, at low oxygen activity in LBE. The results obtained show that all materials exhibited a weight loss after exposure to the flowing LBE, except for the case of tantalum, which exhibits a weight gain. The resistance to corrosion offered by refractory metals has been found higher in comparison to the case of both steels. Moreover, the austenitic steel behaved more resistance to corrosion induced by LBE than the martensitic steel, under the test condition adopted.