铈对纳米晶锌镀层耐蚀性能的影响

在酸性硫酸盐直流电沉积纳米晶锌镀层的镀液体系中,引入铈盐后沉积得到新的纳米镀层。运用AES（原子发射光谱）、XRD及SEM等方法表征了含铈纳米晶锌镀层的化学组成与结构,采用电化学方法研究了铈对纳米晶锌镀层耐腐蚀性能的影响。结果表明,镀液中加入硫酸亚铈后,能够沉积得到含有少量铈的纳米晶锌镀层,并且晶粒也发生了轻微的细化;与单纯锌镀层相比,含铈的锌镀层具有更高的耐蚀性能,其原因在于腐蚀过程中形成了更为致密的、以Zn₅（OH）₈Cl₂·H₂O为主的产物层,且Zn₅（OH）₈Cl₂·H₂O的择优取向与纯锌镀层不相同。     

Anchoring Fe(OH)3 nanoparticles on Ni-MOF nanosheets for efficient electrocatalytic oxygen evolution

<正>It is vital to develop highly efficient and earth-abundant electrocatalysts for accelerating the sluggish oxygen evolution reaction (OER).Herein,a facile room-temperature immersion method is proposed to prepare heterogeneous Ni-MOF/Fe(OH)₃ composite by anchoring Fe(OH)₃nanoparticles on Ni-MOF nanosheets.As a synergistic electrocatalyst,Ni-MOF/Fe(OH)₃ composite shows extre-mely high activity towards OER.     

超级双相不锈铸钢电化学极化表面腐蚀产物的XPS分析

采用X射线光电子能谱(XPS)技术研究了超级双相不锈铸钢在人工海水中经电化学极化后表面腐蚀产物。结果表明：双相不锈钢在人工海水中极化后的钝化膜表层主要以CrO₃、CrOOH、Cr(OH)₃和Fe(OH)₃等氢氧型化合物为主,内层主要以CrO₃、Cr₂O₃、FeO和Ni₂O₃等氧化物为主,同时膜内层存在Fe、Cr、Ni和Mo单质。MoO₄^2-和NH₄⁺吸附在钝化膜表面,对钝化膜起到保护作用。     

热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气环境中的腐蚀行为研究

目的 为详细研究热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气下的腐蚀行为及作用机理,同时为热浸镀Zn-Al-Mg镀层在湿热海洋大气环境中服役提供数据参考。方法 采用腐蚀失重、XRD、SEM、电化学等测试方法对热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气环境下的腐蚀行为进行研究。结果 腐蚀产物主要由Zn₅(OH)₈Cl₂·H₂O组成,腐蚀一段时间后,发现少量ZnO、Zn₅(OH)₆CO₃,腐蚀产物具有与锌腐蚀类似的层状结构,1 848 h呈“三明治”型,相比于上下两层暗色物质,中层亮色腐蚀产物富集更多的Cl元素。热浸镀Zn-Al-Mg镀层腐蚀速率大体随时间延长呈上升趋势,只在672～840 h腐蚀速率下降,对比镀锌在模拟环境和锌在湿热大气环境中的腐蚀,热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气中表现出较好的耐蚀性。结论热浸镀Zn-Al-Mg镀层在模拟湿热海洋大气下腐蚀产物演变与腐蚀过程中Mg的参与有关。腐蚀672～840h阶段腐蚀速率...     

稀土对机械镀无结晶形成过程及镀层性能的影响

采用机械镀方法制备了锌基稀土无结晶镀层,用扫描电子显微镜(SEM)、X射线荧光光谱分析(XRF)等研究了稀土添加对机械镀无结晶镀层形成过程及镀层特性的影响.结果表明,稀土金属盐复合添加剂能影响无结晶镀层形成时金属微粉的集聚、吸附和沉积特性,使金属粉趋于面状吸附一沉积,改善了镀层的形成条件.机械镀锌基稀土合金镀层外观平整、光亮,密度、显微硬度、耐腐蚀性和电化学特性明显优于传统机械镀锌层.     

核桃青皮提取物与Nd(NO3)3对Al在HCl溶液中的缓蚀协同效应

采用失重法、极化曲线、电化学阻抗谱(EIS)、扫描电子显微镜(SEM)和原子力显微镜(AFM)研究核桃青皮提取物(WGHE)和稀土盐Nd(NO₃)₃复配缓蚀剂对Al在HCl溶液中的缓蚀协同效应及作用机理。结果表明：由失重法测试得出WGHE与Nd(NO₃)₃在对Al在1.0 mol/L HCl介质的腐蚀具有中等程度的缓蚀效率，25 oC时最大缓蚀率分别为67.8%和79.1%，将二者复配使用后产生缓蚀协同效应，40 oC时0.5 g/L WGHE和1.0 g/L Nd(NO₃)₃的缓蚀率高达90.4%。WGHE和Nd(NO₃)₃复配前后均在铝表面吸附形成缓蚀保护膜，并且吸附规律符合Langmuir吸附等温式。WGHE与Nd(NO₃)₃复配后更能有效抑制阴极反应。Nyquist图谱近似呈“椭圆”特征，WGHE与Nd(NO₃)₃复配...     

两种电弧喷涂涂层在中性盐雾环境下的耐蚀性能对比研究

采用电弧喷涂技术在EH36钢表面制备了5083铝合金涂层和Zn15Al涂层，结合扫描电子显微镜(SEM)、X射线衍射仪(XRD)、电化学测试和腐蚀失重等方法对比研究了两种涂层在中性盐雾环境下的耐蚀性能。结果表明，随着腐蚀的进行，两种涂层的腐蚀速率均逐渐下降，且5083Al合金涂层的腐蚀速率明显低于Zn15Al涂层。形貌观察结果表明，5083铝合金涂层的腐蚀产物呈致密块状，Cl^-无明显渗入；而Zn15Al涂层的腐蚀产物呈疏松的细针状，盐雾腐蚀10 d后有Cl^-沉积在腐蚀产物层中并逐渐渗入至涂层基体。5083铝合金涂层的腐蚀产物主要为Al(OH)₃,Zn15Al涂层腐蚀产物主要由Zn(OH)₂和Zn₅(OH)₈Cl₂·H₂O组成。结合溶度积常数Ksp和过饱和度的理论计算，Al(OH)₃沉积所需Al³⁺浓度更低、沉积速度更快，因此5083铝合金涂层更倾向于形成致密的腐蚀产物层...     

预镀层不锈钢/铝异种金属高频感应钎焊接头界面及力学性能分析

文中通过热浸镀一层纯铝到不锈钢表面,再对0Cr18Ni9不锈钢和LF21铝合金采用高频感应钎焊.当热浸镀时间从10 s增加到50 s时,镀层厚度从7 μm增加到20 μm,反应层由FeAl₃向Fe₂Al₅发生转变.在热浸镀温度为750℃,浸镀时间为10 s时,镀层成型最好,高频感应电流为270 A,加热时间30 s时,抗拉强度达到167.12 MPa,比不浸镀的接头强度高63.8%.主要是因为镀层限制钢中的Fe原子和Al-Si钎料中的Al,Si原子的相互扩散,在热浸镀不锈钢与铝合金反应中使Fe₂Al₅转化为Fe（Al,Si）₂固溶体而未形成5-Al₈Fe₂Si化合物,降低了界面上硬脆化合物的含量,力学性能随之提高.     

锌铝镁镀层中合金相与耐蚀性关系的研究进展

随着材料服役环境的恶化,Zn-Al-Mg (ZAM)镀层因其具有优良的耐蚀性而受到广泛关注。本文从合金元素入手,探讨了其对ZAM中合金相的形成乃至镀层耐蚀性能的影响及作用机制;同时通过对ZAM在大气环境中的腐蚀行为特征的归纳,从腐蚀产物的角度阐述了镀层的腐蚀机理。一般认为,MgZn₂作为阳极优先被腐蚀,从而产生Mg²⁺和Zn²⁺。Mg²⁺可以抑制腐蚀环境pH值的升高,从而防止在高pH值条件下保护性腐蚀产物Zn₅(OH)₈Cl₂·H₂O向非保护性腐蚀产物ZnO转变。Zn²⁺的产生更有利于形成保护性腐蚀产物LDH(双层氢氧化物)。但目前的研究仍存在不足,特别是对高铝含量的ZAM镀层中复杂的相结构所带来的腐蚀机理仍不明晰。这些都是未来ZAM镀层的研究重点。     

氧化镱对碳钢表面化学镀 Ni-Zn-P 合金的影响

目的改善Ni-Zn-P合金镀层的制备工艺和镀层的物理性能。方法鉴于稀土镧系元素因特殊电子结构表现出优异的物理和化学性能,向基础镀液中添加Yb2O3,在低碳钢钢管表面化学镀沉积NiZn-P合金镀层。通过称量法算得沉积速率,通过盐水浸泡实验测试镀层耐蚀性,采用扫描电镜观察镀层的表面形貌,用X-射线衍射仪检测镀层的晶体结构,考察镀液中Yb2O3浓度对镀层的沉积速率、表面形貌、耐蚀时间、晶体结构等的影响。结果随着Yb2O3浓度的增大,镀层的沉积速率呈先升高、后下降的趋势,镀层的表面形貌、耐蚀时间和晶体结构均是先得到改善,而后被削弱。向基础镀液中添加15 mg/L Yb2O3后,镀速提高了21.6%,耐蚀时间延长了16.7%,镀层由粗糙、灰暗、不均匀和有缺陷,变为平整、光亮、均匀和致密,镀层的非晶相程度得到一定强化,耐蚀性能有所提高。结论基础镀液中添加Yb2O3的适宜质量浓度为15 mg/L,该条件下可提高Ni-Zn-P合金的镀速,并改善镀层的质量。     

Influence of Zn and Mg Alloying on the Corrosion Resistance Properties of Al Coating Applied by Arc Thermal Spray Process in Simulated Weather Solution

In this study,Al–Zn and Al–Mg coatings were deposited on steel substrates by an arc thermal spray process.X-ray diffraction and scanning electron microscopy were used to characterize the deposited coatings and corrosion products.Open circuit potential(OCP),electrochemical impedance spectroscopy,and potentiodynamic studies were used to assess the corrosion characteristics of these coatings after exposure according to the Society of Automotive Engineers(SAE)J2334 solution of varying durations.This solution simulates an industrial environment and contains chloride and carbonate ions that induce corrosion of the deposited coatings.However,the Al–Mg alloy coating maintained an OCP of approximately-0.911 V versus Ag/Ag Cl in the SAE J2334 solution even after 792 h of exposure.This indicates that it protects the steel sacrificially,whereas the Al–Zn coating provides only barrier-type protection through the deposition of corrosion products.The Al–Mg coating acts as a self-healing coating and provides protection by forming Mg_6Al_2(OH)_(16)CO_3(Al–Mg layered double hydroxides).Mg_6Al_2(OH)_(16)CO_3has interlocking characteristics with a morphology of plate-like nanostructures and an ion-exchange ability that can improve the corrosion resistance properties of the coating.The presence of Zn in the corrosion products of the Al–Zn coating allows dissolution,but,at the same time,Zn_5(OH)_6(CO_3)_2and Zn_6Al_2(OH)_(16)CO_3are formed and act to reduce the corrosion rate.     

Growth and corrosion behavior of rare earth film on hot-dip galvanized steel

1Introduction For a long time,chromate compounds Cr(VI)have been used as effective and inexpensive corrosion inhibitors for zinc and zinc coating.However,with the advent of increasing environmental awareness,the toxicity and carcinogenic nature of Cr(VI)b…     

The preparation and characteristics of a rare earth/nano-TiO2 composite coating on aluminum alloy by brush plating

Nano-TiO₂ modified rare earth composite coatings are prepared on 2024 aluminum alloy by brush plating. The composite coating is composed of mainly Ce(OH)₃, Ce(OH)₄, CeO₂ and TiO₂, with less cracks and lower porosity. The addition of nano-TiO₂ enhances the adhesive strength of the rare earth coating to Al substrate, results in refined coating grains and increases the micro-hardness of the coating. The nano-TiO₂ modification obviously improves the corrosion resistance of the rare earth coating. For the composite coating containing 2% TiO₂, both the corrosion current density and the impedance are reduced by more than one order of magnitude in contrast to the values for the pure rare earth coating. The higher barrier ability and increased Ce³⁺ content in the Ce oxides may explain the increase of the corrosion resistance.     

Corrosion resistance of chromium nitride and oxynitride layers produced under glow discharge conditions

The paper presents the results of investigations of the structure and corrosion resistance of chromium nitride, oxynitride and oxide layers produced on steels by electrochemical chromium deposition combined with glow discharge assisted nitriding, oxynitriding and oxydizing processes. The layers obtained were of the types: CrN+Cr₂N+Cr+(Cr,Fe); Cr₂N+Cr+(Cr,Fe); CrN+Cr₂N+Cr+(Cr,Fe)₇C₃; Cr₂N+Cr+(Cr,Fe)₇C₃; Cr(N,O)+Cr+(Cr,Fe)₇C₃ and Cr₂O₃. The corrosion resistance of the layers is high and can be modified by changing the process parameters, such as the temperature and chemical composition of the gas atmosphere.     

海洋大气环境中电镀锌板的腐蚀行为与机理

通过2 a现场暴晒实验,采用腐蚀形貌宏观观察、SEM、XRD及失重法,对电镀锌板在青岛和西双版纳大气环境中的腐蚀行为进行了研究。通过电化学阻抗谱研究了电镀锌板在不同Cl^-浓度溶液中的腐蚀电化学行为。结果表明：电镀锌板在青岛和西双版纳大气环境中的平均腐蚀速率分别为0.76和0.1935 μm/a,在青岛大气环境中暴晒2 a后局部有红锈产生,主要腐蚀产物为Zn₅(OH)₈Cl₂H₂O,ZnO和Zn(OH)₂,在西双版纳大气环境中表面有少量白色锈点,主要腐蚀产物为2ZnCO₃3Zn(OH)₂,ZnO和Zn(OH)₂。电镀锌板在青岛和西双版纳大气环境中主要表现为均匀腐蚀,并伴有局部不均匀坑蚀;青岛大气环境中的Cl^-使电镀锌板在青岛大气环境中的腐蚀加剧。     

Corrosion Behavior of Epoxy-Coated Rebar with Pinhole Defect in Seawater Concrete

Experiments were carried out to investigate the corrosion behavior of epoxy-coated rebar(ECR) with pinhole defect(diameter in hundreds of microns) immersed in the uncarbonated/carbonated simulated pore solution(SPS) of seawater concrete. Corrosion behavior was analyzed by electrochemical impedance spectroscopy. The composition and morphology of corrosion products were characterized by X-ray diffraction, energy-dispersive spectrometry and scanning electron microscopy. Meanwhile, oxide film produced by preheating before spray coating was investigated by X-ray photoelectron spectroscopy and Mott–Schottky technology. Results indicated that corrosion behavior of ECR with pinhole defect exhibited three stages when immersed in the uncarbonated/carbonated SPS. In the initial stage, steel in defect was passivated when exposed in the uncarbonated SPS and corroded when exposed in the carbonated SPS, due to competitive adsorption between chloride and hydroxyl ions. In the second stage, the oxide film under coating reconstituted(the thickness and defects density decreasing) in the uncarbonated SPS, which was caused by the synergy between high hydroxide and chloride activity, while in the carbonated SPS, crevice corrosion happened under the coating around pinhole,because of the different oxygen concentrations cell at the coating/steel interface. In the third stage, localized corrosion occurred under the coating around the pinhole in the uncarbonated SPS, which was probably induced by ion diffusion at the nano-scale coating/steel interface. The corrosion products adjacent to the defects were re-oxidized from FeCl_2·4H_2O and Fe_2(OH)_3Cl to Fe_2O_3·H_2O, and the corrosion area was expanded outward in the carbonated SPS.     

电解液浓度对镁合金微弧氧化层耐蚀性与溶血率的影响

在电解液中加入 (NaPO₃)₆并在镁合金表面制备微弧氧化层,研究 (NaPO₃)₆浓度对镁合金微弧氧化层的影响.结果显示,微弧氧化层中含有MgO,Mg₂SiO₄,Mg₃(PO₄)₂等物质;随 (NaPO₃)₆浓度增加,微弧氧化层厚度增加,表面微孔孔径变大,当 (NaPO₃)₆浓度达到7 g/L时,微弧氧化层截面出现较明显的微裂纹;微弧氧化处理后的镁合金的耐蚀性明显高于基体的.当 (NaPO₃)₆浓度为5 g/L时其耐蚀性最佳;镁合金基体溶血率为72.3%,在不同浓度 (NaPO₃)₆下微弧氧化处理的镁合金溶血率均在1%~2.5%之间,溶血作用消除.     

Influence of pre-treatments in cerium conversion treatment of AA2024-T3 and 7075-T6 alloys

The role of pre-treatment in the formation of a cerium conversion coating is investigated for the protection of AA2024-T3 and 7075-T6 alloys. The alloys were alkaline-etched and de-smutted in nitric acid, prior to cerium treatment in Ce(NO₃)₃ at 85 °C with H₂O₂ accelerator. Potentiodynamic polarization studies in 3.5% NaCl solution revealed a large shift of  300 mV of the corrosion potential below the pitting potential for the 7075-T6 alloy, which correlated with the development of a finely-textured, uniform coating. However, the formation of a uniform coating and protection was dependent upon the time of de-smutting, with non-uniform coatings resulting from extended times of de-smutting. In contrast, non-uniform coatings developed on the 2024-T3 alloy, with pitting potential at the corrosion potential, irrespective of the time of de-smutting. Findings for the 2024-T3 alloy indicate that extended de-smutting affects the enrichment of alloying elements.     

添加不同稀土元素对固体包埋法在 304 不锈钢表面制备 Ti / Cr-RE 双层涂层电化学性能的影响

目的选择合适的稀土制备Ti/Cr-RE双层涂层,提高不锈钢的耐腐蚀性能。方法采用两步粉末包埋法,先在304不锈钢表面渗Ti,再制备稀土改性Cr涂层,获得Ti/Cr-RE双层涂层。通过添加不同的稀土氧化物Y2O3和Ce O2,获得两种双层涂层,对比分析涂层的表面形貌、断面形貌及物相组成,利用电化学测试方法测定304不锈钢基体及两种Ti/Cr-RE双层涂层在3.5%(质量分数)Na Cl溶液中的电化学腐蚀性能。结果添加不同稀土元素钇、铈,都能在渗Ti不锈钢表面形成一层致密、连续的稀土改性渗铬层。在两种稀土元素改性的Cr涂层中,稀土元素分别与Cr,Fe,Ni,Ti形成了金属间化合物。304不锈钢基体的自腐蚀电位为-0.324 V,腐蚀电流密度为0.1363μA/cm2;钇改性铬涂层的自腐蚀电位为-0.341 V,腐蚀电流密度为0.2058μA/cm2;铈改性铬涂层则具有更高的自腐蚀电位(-0.263 V)及更低的腐蚀电流密度(0.030 86μA/cm2)。结论钇改性铬涂层不能提高304不锈钢基体的耐腐蚀性能,铈改性铬涂层可以明显提高基体的耐腐蚀性能。