Corrosion resistance of new copper alloy containing 29Zn, 10Ni and up to 5Mn vis-a-vis Cu-10Ni in sulphide polluted synthetic seawater

Cu-10 Ni alloy suffers from accelerated corrosion in sulphide-polluted seawater. New copper alloys containing 29% Zn, 10Ni and 3 or 5% Mn have been found to be more corrosion resistant than Cu-10Ni alloys in sulphide polluted synthetic seawater. The studies were carried out in synthetic seawater (ASTM D 114–75) and sulphide was added through Na₂S (1 gpl ≈ 41ppm S²⁻). Testing was carried out using cathodic and anodic potentiodynamic polarization methods. Corrosion product film formed on the Cu-29Zn-10Ni-5Mn alloy in sulphide polluted synthetic seawater was characterized using SEM and XRD. The film was found to contain Cu₂O, Cu₂S, NiS and ZnS. Better corrosion resistance of new alloys as compared to that of Cu-10Ni alloy is attributed to formation of ZnS, a bad conductor, in the film and incorporation of Mn³⁺ cations in Cu₂O and Cu₂S lattice.     

Effect of Zn addition on corrosion resistance of Cu-10Ni alloy in clean and sulphide contaminated seawater

Cu-10Ni alloy has an outstanding resistance to corrosion in seawater due to formation of protective Cu₂O film. However, in presence of S^2? ions, it suffers accelerated corrosion. The present paper investigates the corrosion behaviour of Cu-10Ni, Cu-10Ni-6Zn and Cu-10Ni-12Zn alloys using weight loss, electrochemical impedance spectroscopy and potentiodynamic polarisation technique. The experiments were performed in clean seawater and sulphide contaminated seawater. The Cu-10Ni-6Zn and Cu-10Ni-12Zn alloys were found to exhibit lower corrosion rate than Cu-10Ni alloy in clean and sulphide contaminated seawater. Lower corrosion rate of Zn containing alloys in clean seawater is attributed to the incorporation of Zn²⁺ ions in Cu₂O lattice. Lower corrosion rate of Zn containing alloys sulphide contaminated seawater is attributed to formation of ZnS in the film.     

Effect of zinc addition to copper in improving its corrosion resistance in sulfide polluted synthetic seawater

In an endeavor to develop a cost effective substitute of Cu-10Ni alloy for seawater application (especially for sulfide polluted seawater) few Cu-Ni-Zn-Mn alloys were developed in our laboratory. The Cu-Ni-Zn-Mn alloy was found to have better corrosion resistance than Cu-10Ni both in clean and sulfide polluted synthetic seawater. Resistance to sulfide in Synthetic Seawater was attributed to the formation of ZnS. To ensure that the resistance to sulfide attack is due to Zn alone, a series of studies were carried out with binary alloys of Cu and Zn with increasing weight percentage of Zn (12% and 36%). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) was used for the purpose. Polarization studies gave the corrosion data and EIS was effective in depicting the nature of corrosion product (film). It was found that among the test alloys, Cu-36Zn is most corrosion resistant in sulfide polluted seawater due to formation of ZnS in the film. As it is a binary alloy, the corrosion resistance against sulfide is attributed to Zn alone.     

Combined effect of chloride and pH on corrosion resistance of Cu-10Ni alloy

Cu-10Ni alloy is a standard heat exchanger material for saltwater (including seawater) applications owing to its excellent thermal conductivity and corrosion resistance. The excellent corrosion resistance is due to formation of Cu₂O film, which accords protection. However, when varying amount of H⁺, OH^? and Cl^? ions are present, CuCl₂ ^? may also form. The CuCl₂ ^? is not protective as Cu₂O and hence corrosion resistance may be affected. Present paper investigates combined effect of chloride ion and pH on corrosion resistance of Cu-10Ni alloy. Cathodic and anodic polarization test results are presented for saltwater containing various amounts of NaCl at pH 6 and 8. It is found that, i_corr increases with increasing chloride concentration. The results are discussed using dissolution mechanisms, semi-conducting behaviour of Cu₂O film and deterioration of the film in presence of chloride ions.     

稀土对Cu-Ni-Al合金耐冲刷腐蚀性能的影响

在冲蚀试验机上模拟了耐蚀Cu-Ni-Al合金在人工海水冲刷作用下的腐蚀情况,分析了不同冲刷时间、不同海水流速下Cu-Ni-Al合金的腐蚀行为,重点研究了稀土元素对Cu-Ni-Al合金耐海水冲刷腐蚀性能的影响.结果表明,冲刷腐蚀96 h以前,腐蚀速率随着时间延长逐渐降低,96 h以后趋于稳定;海水流速对合金的腐蚀速率影响较大,5.0 m/s流速下合金腐蚀速率比1.5 m/s流速下高;相同冲刷时间和海水流速下,添加稀土后的合金腐蚀速率明显低于不添加稀土元素;1.5 m/s流速下冲刷168 h,稀土含量(质量分数)0.014 6%和0.035 2%的合金比不加稀土的合金腐蚀速率分别降低了2%和5%,在5.0 m/s流速下冲刷168 h后腐蚀速率分别降低了4%和43%;稀土添加后合金在腐蚀过程中表面钝化加快,合金的腐蚀速率降低较快,合金钝化膜质量更好.     

晶粒细化对Cu-40Ni合金在酸性含Cl-介质中耐蚀性能的影响

采用电弧熔炼（CA）和机械合金化（MA）通过热压烧结工艺制备了晶粒尺寸差别较大的Cu-40Ni合金，借助于PARM273A和M5210电化学综合测量仪，利用动电位扫描法和交流阻抗技术对比研究了上述合金在酸性含Cl^-介质中的腐蚀电化学性能以及腐蚀机制。结果表明：两种合金的腐蚀电位随时间逐渐稳定，在中性Na2SO4溶液中加入H2SO4和NaCl后，两种合金的自腐蚀电位负移；晶粒细化后，两种合金的自腐蚀电位则正移。两种合金在中性及酸性含Cl^-介质中均存在钝化现象，但在酸性含Cl^-介质中钝化区间很短，钝化能力较弱。两种合金的交流阻抗谱均由单容抗弧组成，反应由电化学过程控制。晶粒细化后，合金中存在大量晶界，参与腐蚀反应的活性原子数增加，促使MACu40Ni合金的腐蚀速度高于CACu-40Ni合金。     

添加Mn对Cu－9Ni－6Sn合金组织与性能的影响

作者对含０．４６—１．０６ｗｔ％Ｍｎ的Ｃｕ－９Ｎｉ－６Ｓｎ合金的铸造组织、时效和形变时效特征及组织交化、时效合金的耐蚀性变化作了研完。实验证明，合金的铸锭组织、时效硬化、形变时效和组织变化等基本特征与不含Ｍｎ的合金相类似。添加０．４６ｗｔ％Ｍｎ延缓了合金时效和形变时效近程，添加０．７４—１．０６ｗｔ％Ｍｎ加速了合金时效和形变时效近程，但都升高了最佳时效温度，增加了硬化效果和在酸中的耐蚀性。     

Electrochemical Behavior of Bulk Amorphous Steel Fe55M2Cr12Mo10B6C13Y2（M=Ni, Cu, Nb）

 Fe55Ni2Cr12Mo10B6C13Y2,Fe55Cu2Cr12Mo10B6C13Y2 and Fe55Nb2Cr12Mo10B6C13Y2 alloys with diameter of 4mm were produced by copper mold casting. The role of alloying additions (Ni, Cu or Nb) on corrosion resistance of Fe55Nb2Cr12Mo10B6C13Y2, Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 alloys were studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that Fe55Ni2Cr12Mo10B6C13Y2 and Fe55Cu2Cr12Mo10B6C13Y2 alloys can be cast into bulk metallic glasses. Fe55Ni2Cr12Mo10B6C13Y2 and     

Electrochemical Behavior of Bulk Amorphous Steel Fe55M2Cr12Mo10B5C13Y2(M=Ni,Cu,Nb)

Fe55Ni2Cr12Mo10B6C13Y2,Fe55Cu2Cr12Mo10B6C13Y2 and Fe55Nb2Cr12Mo10B6C13Y2 alloys with diameter of 4 mm were produced by copper mold casting. The effect of alloying additions (Ni,Cu or Nb) on corrosion resistance of Fe55 Ni2 Cr2Mo10 B6 C13 Y2,Fe55Ni2Cr12Mo10B6C13Y2 and Fe55 Cu2 Cr12 Mo10 B6 C13 Y2 alloys was studied by polarization curves and electrochemical impedance spectroscopy (EIS). The results show that Fe55Ni2Cr12Mo10B6C13 Y2 and Fe55Cu2Cr12Mo10B6C13 Y2 alloys can be cast to form bulk metallic glasses. Fe55Ni2Cr12Mo10B6C13 Y2 and Fe55Cu2Cr12 Mo10B6C13Y2 amorphous alloys with passive potential about 1500 mV exhibit good corrosion resistance in NaCl solution of 5 % and 1 mol/L HC1 solution. The passive current density of the alloy with Ni addition is lower than that of other alloys. EIS results only show one impedance element. Amorphous alloy Fe55 Ni2 Cr12 Mo10 B6 C13 Y2 with larger charge transfer reaction resistance indicates good corrosion resistance.     

铜合金的腐蚀与防护研究进展

铜合金具有良好的导电性和导热性,是应用最广泛的工业材料之一。铜合金服役过程中常与酸、碱、盐等腐蚀介质接触,易引起铜合金的腐蚀,最终导致失效,对生产制造带来危害。提高铜合金的耐腐蚀性有利于进一步扩展其应用领域。本文主要归纳了Cr, Pb, Ti, Al,Mn, Ni以及稀土元素的添加对合金耐蚀性能的影响,通过合金元素的添加可以改变铜合金表面腐蚀产物膜的组成和形貌,减小相与相之间腐蚀电位差,以及减少有害杂质的存在,以此来改善铜合金的耐蚀性能。塑性变形和热处理是改善铜合金力学性能的常用手段,经塑性变形和热处理过后的铜合金,其微观组织形貌和分布发生了变化,因此对合金耐蚀性能也有一定的影响。本文主要从合金化、塑性变形及热处理3个方面对铜合金耐蚀性能影响进行综述,最后对铜合金的腐蚀防护研究进行总结和展望。     

Structural,Micromechanical and Tribological Characterization of Zn–Ni Coatings: Effect of Sulfate Bath Composition

Zn and Zn–Ni alloy coatings were electrodeposited on mild steel from sulfate-based bath containing Sn as additive. The effect of Ni content on the microstructure, morphology, microhardness and the tribological behavior of these coatings were studied and discussed. Adding Sn in the sulfate bath had a significant effect on the surface morphology, particularly on the Zn–8 wt% Ni coatings. By increasing the Ni concentration from 8 to 14 wt%, the X-ray patterns showed that the phase structure of Zn–Ni alloy coatings was changed from η-phase Ni₃Zn₂₂ to γ-phase Ni₅Zn₂₁. The plastic deformation and delamination were found to be wear mechanisms for the investigated coatings. While the Zn–14 wt% Ni alloys had the best wear resistance, Zn films had the most severe wear volume loss and the highest friction coefficient.     

合金元素对油船用低合金钢腐蚀行为的影响

采用恒温浸泡的标准试验方法,考察了4种不同合金体系船体钢在强酸性氯离子介质中的腐蚀行为,探讨了合金元素对钢腐蚀行为的影响,结果表明:Cu和Ni对钢的耐蚀性有显著影响,随着Cu、Ni含量的增加,钢的耐蚀性逐渐提高,自腐蚀电位提高,电流密度显著降低,界面电荷传递电阻明显增大。Cu是提高钢在强酸性氯离子环境中耐蚀性的主要元素,其主要机理为其以再沉积颗粒(100~500nm)的方式在钢的表面富集,并具有较高的稳定性,该沉积颗粒钝化了钢基体,降低了钢的溶解速度。Ni元素在钢中的存在显著提高了钢的基体电位,降低了材料的腐蚀敏感性,但Ni元素在锈层中的富集特征不明显。     

Effect of rare earths on corrosion resistance of Cu-30Ni alloys in simulated seawater

Cu-30Ni-xRE(x=0-0.213 wt.%) alloy was prepared by adding rare earths(RE) in melted Cu-30Ni alloy using metal mould casting method.The effects of RE on corrosion resistance of the alloy in simulated seawater were investigated using optical microscope,scanning electronic microscope with energy-dispersive spectrometer and electrochemical measurement system.The results showed that the corrosion resistance of Cu-30Ni alloy was greatly improved by adding proper amount of RE,whereas excess addition of RE worsened ...     

Corrosion resistance of high-strength austenitic chromium–nickel–manganese steel containing nitrogen

The corrosion resistance of high-strength Cr–Ni–Mn austenitic steel containing nitrogen and copper is compared with that of Cr18Ni9 and Cr18Ni10N chromonickel steel by means of the Zive MP2 electrochemical system. The polarization curves and electrochemical characteristics of the alloys are determined in general, pitting, and intercrystallite corrosion by various media: aqueous solutions of NaCl (3%); FeCl₃ 6H₂O (100 g/L); H₂SO₄ (0.5 M); H₂SO₄ (0.5 M) + injected H₂S; and H₂SO₄ (0.5 M) + KSCN (0.01 M). The corrosion rates are calculated. The results indicate that all the steel samples are corrosion-resistant: they exhibit high resistance to intercrystallite corrosion and also to pitting and general corrosion in chloride-bearing media. No pitting corrosion is observed when Cr–Ni–Mn steel of balanced composition containing nitrogen (and especially steel containing both nitrogen and copper) is immersed in sea water, even when the steel’s nickel content is low. This steel outperforms traditional Cr18Ni9 steel in terms of strength and corrosion resistance, even in an acidic medium (0.5 M H₂SO₄).     

纳米晶Fe3Al材料的抗腐蚀性能和高温抗氧化性能

通过铝热反应熔化法制备纯纳米晶Fe3Al材料以及添加质量分数分别为10％Ni,10％Cr,10％ Mn,15％ Mo,5％ Cu和10％Cu合金元素的6种块体纳米晶Fe3Al材料;对含10％ Ni的纳米晶Fe3Al材料分别进行600 ℃、1000℃,8h的等温处理.采用质量损耗法测定不同纳米晶Fe3Al材料在质量分数为5％ H2SO4溶液中的均匀腐蚀速率;并研究各纳米晶Fe3Al材料在1200℃空气中的高温氧化性能.结果表明:添加15％Mo和添加10％Cu的纳米晶Fe3Al材料较纯纳米晶Fe3Al材料抗腐蚀性能提高明显;含10％ Ni的纳米晶Fe3Al材料经过600℃ 等温处理后的腐蚀速率略高于未等温处理的材料,而经1000℃等温处理后腐蚀速率明显下降;随着合金元素Ni、Mn、Cr、Cu的加入,纳米晶Fe3Al材料的氧化速度增大,抗氧化性能降低.     

Effect of iron as alloying element on electrochemical behaviour of 90∶10 Cu–Ni alloy

Abstract

Copper–nickel alloys have been used in many applications in marine environments, because of their excellent corrosion and biofouling resistance. In this study, the effects of iron as an alloying element on the corrosion behaviour of copper–10 wt-% nickel alloy in artificial saline solutions and natural sea water were investigated. Synthetic copper–nickel alloys were prepared in an induction furnace under an argon–7 vol.-% hydrogen atmosphere in cylindrical boron nitride crucibles. They were then homogenised at 950°C for 10 h under the same protective atmosphere. Linear sweep polarisation, cyclic polarisation, Tafel extrapolation and cyclic voltammetry techniques were performed in this investigation. Following the electrochemical measurements, the corrosion products and the passive film were analysed using a field emission scanning electron microscope (FE-SEM), electron probe microanalysis, energy dispersive spectrometry (EDS), wavelength dispersive spectrometry (WDS) and X-ray diffraction (XRD). The electrochemical behaviour of the synthetic Cu–Ni–Fe alloys depends on maintaining iron in a single phase in the solid solution (the maximum amount of iron that can be used was 1·5 wt-%). Quenching improves the electrochemical behaviour of synthetic Cu–Ni–Fe alloys containing relatively high iron content. The outer layer of the passive film is porous in the absence of iron, but when iron is added, the pores disappear and cracks appear. When no sulphate is present in the solution, the passive film formed on synthetic Cu–Ni–Fe alloys consists entirely of chlorides, and Fe₂O₃. In the presence of sulphate, FeS and NiS were detected in the corrosion film.

On a utilisé les alliages de cuivre–nickel à de nombreuses fins en milieux marins, grâce à leur excellente résistance à la corrosion et à l’incrustation biologique. Dans cette étude, on a examiné l’effet du fer en tant qu’élément d’alliage sur le comportement de corrosion d’un alliage de cuivre–10% en poids de nickel dans des solutions salines artificielles et dans de l’eau de mer naturelle. On a préparé des alliages synthétiques de cuivre–nickel dans un four à induction dans une atmosphère d’argon–7% en volume d’hydrogène dans des creusets cylindriques de nitrure de bore. On les a ensuite homogénéisés à 950°C pendant 10 heures sous la même atmosphère protectrice. Dans cette investigation, on a utilisé des techniques de polarisation linéaire à balayage, de polarisation cyclique, d’extrapolation de Tafel et de voltampérométrie cyclique. Après les mesures électrochimiques, on a analysé les produits de corrosion et le film passif en utilisant un microscope à balayage électronique à champs par émission d’ions (FE-SEM), la microanalyse par électrons, la spectrométrie des rayons X à dispersion d’énergie (EDS), la spectrométrie dispersive en longueur d’onde (WDS) et la diffraction des rayons X (XRD). Le comportement électrochimique des alliages synthétiques de Cu-Ni-Fe dépend du maintien du fer en une phase unique dans la solution solide (la quantité maximale de fer que l’on pouvait utiliser étant de 1·5% en poids). La trempe améliore le comportement électrochimique des alliages synthétiques de Cu–Ni–Fe ayant une teneur relativement élevée en fer. La couche extérieure du film passif est poreuse en l’absence de fer, mais lorsque l’on ajoute du fer, les pores disparaissent et des fissures apparaissent. Lorsqu’il n’y a pas de sulfate dans la solution, le film passif formé sur les alliages synthétiques de Cu–Ni–Fe consiste entièrement en chlorures et en Fe₂O₃. En présence de sulfate, on détecte du FeS et du NiS dans le film de corrosion.     

Retardation of intermetallic phase formation in experimental superferritic stainless steels

While superferritic stainless steels containing 29 pct chromium possess excellent resistance to corrosion, they may, under certain conditions, be embrittled by the precipitation of intermetallic phases. The extent to which the precipitation reactions can be retarded by alloying additions of aluminum and copper has been evaluated. It was found that additions of aluminum to an Fe-29 pct Cr-4 pct Mo-1.5 pct Ni base alloy suppress the precipitation of the undesirable sigma and chi intermetallic phases, but additions of up to 3 pct aluminum promote 475 ‡C embrittlement. Additions of copper slightly reduce the precipitation of sigma and chi phases under most conditions but enhance 475 ‡C embrittlement. The resistance to corrosion in 10 pct H₂SO₄ and 10 pct FeCl₃ was assessed. All the aluminum-containing alloys performed significantly better in H₂SO₄ than the base alloy; however, large additions of aluminum had a deleterious effect on the pitting resistance in FeCl₃. Additions of copper improved the resistance to FeCl₃ and lowered the rate of corrosion in the H₂SO₄ solution used.     

The effect of solidification microstructure on the corrosion behavior of a columnar aluminum-copper alloy

The morphological and kinetic nature of corrosion of directionally solidified aluminum-4.5 wt pct copper alloy in the as-cast, solutionized and solutionized-and-aged conditions in air-saturated aqueous 3.5 wt pct NaCl solution were evaluated. In the solutionized and solutionized-and-aged conditions the intergranular attack and pitting are similar to those occurring in solutionized wrought alloys; the extent of attack at long times increases with increasing severity of solidification rate. The as-cast alloy exhibits a cored dendritic structure with significant formation of interdendritic nonequilibrium eutectic. Extensive inter dendritic corrosion of the α-phase containing more than 3.2 wt pct copper is seen; α containing less than 3.2 wt pct copper and the θ-Al₂Cu phase are cathodic. Corrosion of the as-cast alloy is parabolic with time and increases with increasing severity of solidification rate in proportion to the amount of nonequilibrium second phase.     

Hot corrosion of Fe-Cr-Ni-AI-Si alloys in molten carbonate

The change in weight of five newly developed steel alloys containing Fe, 10–11.3 % Cr, 15–18.27 % Ni, 4.98–5.76 % Mn, 4.18–5.52 % Al and 0.36–1.5 % Si together with Inconel 690 and stainless steel 304 has been investigated in Na₂CO₃ + K₂CO₃ eutectic mixture at 800°C under atmospheric pressure and under isothermal and cyclic conditions. The scales formed were examined with optical and scanning electron microscopy and were analysed by energy dispersive X-ray diffraction techniques. It has been shown that the corrosion resistance of the alloys is far better than that of stainless steel 304, but slightly less than that of Inconel 690. The relatively high contents of Si and Al gave alloy 5 its highest corrosion resistance. About 0.2 % N were found to refine the grains without the danger of depleting the grain boundaries from Al and Cr. The results have been explained in the light of the alkaline conditions prevailing in the carbonate melt.