1050A铝合金在模拟海洋大气环境中周浸腐蚀行为

采用室内周浸试验研究了1050A铝合金在模拟海洋大气环境的腐蚀行为,采用电化学阻抗谱、失重法、扫描电镜(SEM)、X射线衍射(XRD)和能谱(EDS)等方法研究了腐蚀产物表面形貌、结构和组成。结果表明,随着腐蚀的进行,腐蚀产物增多、失重增加、阻抗值逐渐减小。腐蚀产物主要以团状和块状的形式存在,并不断向外延伸扩大,呈现不均匀的凹凸形貌;腐蚀产物主要有铝的氯化物、Al2O3,Al(OH)3和AlO(OH)等;电化学阻抗谱拟合结果显示,腐蚀速率先增加后降低。     

铝合金7A04在干湿周浸条件下的腐蚀行为研究(英文)

采用扫描电镜、X光电子能谱、失重法和电化学交流阻抗技术研究了铝合金7A04在0.6 mol/L NaCl溶液和0.6 mol/LNaCl+0.02mol/L NaHSO3溶液中干湿周浸后的腐蚀行为和规律,并测试了3种材料力学性能的变化.研究结果表明,随试验时间的延长,铝合金腐蚀产物不断增多,腐蚀失重符合指数规律C=A tn,抗拉强度和延伸率呈下降趋势;表面腐蚀产物形貌呈块状,在0.6 mol/L NaCl溶液中腐蚀产物主要为氢氧化铝和氯化铝,而在0.6 mol/LNaCl+0.02 mol/LNaHSO3溶液中腐蚀产物主要为氢氧化铝、氯化铝和硫酸铝.电化学交流阻抗谱显示铝合金7A04在0.6 mol/L NaCI+0.02 mol/0L NaHSO3溶液中的腐蚀速率远大于在0.6 mol/L NaCl溶液的腐蚀速率,并探讨了其腐蚀机理.     

铝合金阳极氧化层在江津污染大气环境中暴露腐蚀行为研究

采用扫描电镜、能谱和X射线衍射仪以及腐蚀失重等分析测试方法研究了1060纯Al、2A12和7A04铝合金表面阳极氧化膜层在江津工业大气环境中的暴晒腐蚀行为。结果表明,1060纯Al、2A12和7A04铝合金阳极氧化膜层失重与暴露时间的关系符合幂函数规律;随腐蚀时间的延长,腐蚀产物不断增多,失重增大。3种铝材腐蚀严重程度顺序由大到小依次为:2A12铝合金7A04铝合金1060纯Al。腐蚀产物呈团状和块状形貌,主要由Al2O3、Al(OH)3和硫酸铝水合物组成。3种铝材除去表面腐蚀产物的阳极氧化膜层损伤和腐蚀坑数量差别明显,腐蚀机制为Al2O3在酸性介质中的溶解。     

风电系统散热器用0359铝合金的盐雾腐蚀行为

目的研究0359铝合金的腐蚀行为,对其腐蚀使用寿命进行预测。方法采用盐雾实验模拟海洋大气环境,对腐蚀试样进行SEM、EDS、腐蚀深度、腐蚀失重、极化曲线和阻抗分析。结果 0359铝合金在盐雾腐蚀实验的条件下,腐蚀产物主要含O、Al、Si。随腐蚀时间延长,腐蚀点增多,腐蚀产物增多,且部分溶解脱落,腐蚀失重增加,腐蚀坑增大、加深。腐蚀时间由8 h逐渐增加至72 h,自腐蚀电位由-852.859 m V负移至-966.046 m V,腐蚀电流密度由0.346μA/cm~2增大至3.971μA/cm~2,腐蚀阻抗降低,腐蚀速率增加。腐蚀96 h时,自腐蚀电位正移,腐蚀电流密度减小,腐蚀阻抗增加,腐蚀速率降低。0359铝合金腐蚀失重-时间拟合曲线为y1=0.1927t~(0.6997),LC4铝合金在万宁地区户外暴露10年的腐蚀拟合失重为3.2629 g/m~2,此时,0359铝合金户外腐蚀10年的当量腐蚀深度为43.80μm,为翘片厚度的17.52%。结论 0359铝合金腐蚀形貌表现为点蚀,Al发生了吸氧腐蚀。腐蚀初期,0359铝合金表面的钝化膜阻碍了腐蚀,随腐蚀时间增加,钝化膜逐渐被破坏,腐蚀速率增加;腐蚀后期,大量腐蚀产物覆盖,阻碍了O、Cl-与铝合金的接触,降低了腐蚀速率。0359铝合金表面钝化膜和腐蚀产物具有减缓腐蚀的作用,且0359铝合金满足10年以上使用寿命。     

高强铝合金循环盐雾加速腐蚀行为与机理研究

目的 研究2A12铝合金在室内模拟及强化腐蚀环境下的腐蚀行为与机理,建立快速评价铝合金腐蚀寿命的加速试验方法。方法 利用设计的室内加速腐蚀环境试验谱,通过实施模拟海洋大气环境效应的循环盐雾加速腐蚀试验,采用外观检查、SEM、XRD及电化学测试等手段,表征了暴露不同周期样品的腐蚀失重、腐蚀形貌、腐蚀产物成分、极化曲线及阻抗谱等腐蚀性能,分析和归纳了铝合金的加速腐蚀行为与机理。结果 随着腐蚀暴露时间的延长,2A12样品腐蚀失重动力学符合幂函数规律且关系式为D=1.662t^1.061,腐蚀速率呈现短暂降低后迅速增加再逐步下降的变化趋势;腐蚀形貌从腐蚀产物均匀分布到逐渐变得集中和突出表面,后期局部出现脱落,腐蚀产物成分均以Al2O3为主,与腐蚀机理分析的化学反应过程基本一致。极化曲线Tafel拟合结果表明,腐蚀电位整体呈现稳定并缓慢减小的变化趋势(?0.509~ ?0.392 V),腐蚀电流密度呈现先波动增加后减小的变化趋势(0.271~0.882 A/cm²);阻抗谱均在高频区表现为1个容抗弧,且容抗弧半径呈现“减小—增大—减小至稳定”的变化趋势;阻抗谱等效电路拟合结果表明,腐蚀产物膜电阻Rf呈现“增大—减小—增大—减小”的变化趋势,极化电阻Rp整体呈现先减小后增大的变化趋势。结论 循环盐雾环境对高强铝合金腐蚀的加速效果显著,从腐蚀动力学、腐蚀产物形貌及成分、电化学特性等角度,能够比较全面地表征铝合金的加速腐蚀行为与机理,为进一步研究加速腐蚀试验的模拟性和相关性提供条件。     

高强铝合金在不同SO_2模拟环境中的腐蚀行为及相关性研究

采用扫描电镜(SEM/EDX)、失重法等研究了7A04铝合金在两种模拟SO2气氛条件下的腐蚀行为和规律,以及与江津大气暴晒试验结果的相关性。结果表明,随试验时间的延长,铝合金腐蚀产物不断增多,腐蚀失重与时间的关系符合指数规律C=A·t~n;表面腐蚀产物形貌呈团状或圆团状,并不断向外扩展延伸,呈现不均匀的凹凸形貌;腐蚀产物为氢氧化铝和硫酸铝水合物;从腐蚀动力学角度分析,7A04铝合金在0.067%SO_2气氛环境中间隙腐蚀的试验结果与江津户外暴露试验的相关度最高。     

汽车冷轧钢DC06和DP600在NaHSO_3溶液中的腐蚀行为

采用全浸实验、失重法和电化学阻抗谱研究了汽车冷轧低碳钢DC06和双相钢DP600在0.02 mol/L Na HSO3溶液中的腐蚀行为与规律,用SEM观察腐蚀产物形貌,用EDS分析腐蚀产物组成。结果表明,随腐蚀时间的延长,DC06和DP600钢表面腐蚀产物不断增多,失重增大;腐蚀产物形貌以团状为主,呈现不均匀的凹凸形貌;腐蚀产物主要是Fe的氧化物和硫酸盐。电化学阻抗谱拟合结果显示,DC06和DP600钢的腐蚀速率都是先升高后降低,并逐渐趋于稳定。     

高压输电耐张线夹用铝在中性溶液中的交流腐蚀行为

目的研究高压输电耐张线夹用铝在0.1 mol/L的中性Na2SO4溶液中的交流腐蚀行为。方法在耐张线夹端部截取块状腐蚀试样并包覆、打磨、清洗,利用自制设备测量试样在交变电流腐蚀作用下的Tafel曲线、交流阻抗谱和腐蚀速率,采用扫描电子显微镜分析微观腐蚀形貌,采用X射线衍射仪、能谱仪和X射线光电子能谱仪对腐蚀区元素及物相进行分析。结果交变电流密度为0~40 A/m2时,Tafel曲线负向移动;50 A/m2时,发生逆转,曲线正向移动;随交变电流密度增加,交流阻抗谱Nyquist图由单弧逐渐变为双弧,出现Warburg阻抗,Bode-Phaze图由单峰逐渐变为双峰;表面出现较多的点蚀坑和层状脱落痕迹;腐蚀产物为Al(OH)3和Al2O3。结论交变电流作用下试样的腐蚀倾向加深,腐蚀表面具有较多的空洞,垂直腐蚀和平行腐蚀交替进行,呈现层状脱落方式向基体演进,腐蚀产物与一般铝腐蚀产物相同,均为Al(OH)3和Al2O3,腐蚀速率在交变电流密度低于50 A/m2时相对较低,高于50 A/m2时大幅提高。     

海洋工程机械用Q345E钢的组织与耐腐蚀性能研究

对工程机械用Q345E钢进行了组织与腐蚀性能试验,采用失重法、极化曲线和电化学阻抗谱法研究了不同浸泡周期下Q345E钢的腐蚀行为。结果表明,Q345E钢的组织为铁素体+珠光体+少量的魏氏体组织;随着浸泡时间的延长,在开始阶段腐蚀速率会逐渐增加,而后随着腐蚀反应的进行,腐蚀产物的脱落会使得腐蚀速率降低;钢的表面腐蚀产物主要为Fe(OH)_2和Fe(OH)_3;钢的表面腐蚀形貌与腐蚀速率、极化曲线和阻抗谱的测试结果一致。     

铝及铝合金在南疆沙漠大气环境中的腐蚀行为

将铝及铝合金L3、LF21和LY12置于在南疆沙漠大气环境下进行现场暴露试验,利用扫描电镜(SEM)、能谱仪(EDS)和红外光谱仪(FTIR)分析腐蚀形貌、元素分布和腐蚀产物组成.结果表明:在南疆沙漠大气环境中,铝及铝合金发生较严重的大气腐蚀,主要腐蚀产物为Al2O3和水合Al(OH)3;铝及铝合金的腐蚀质量损失随暴露时间的变化遵循幂函数C=Ktn,短期内随着暴露时间的延长腐蚀速率会不断下降;地表浮土中的MgCl2 等成分的存在增加了金属表面的湿润时间,浮土中较高的pH值以及氯离子和硫酸根离子等的共同作用促进了铝及铝合金在南疆沙漠大气环境下的腐蚀.     

Influence of DC Current on Corrosion Behaviour of Copper–Aluminium Composite Plates

In this study, neutral salt spray accelerated corrosion test of copper–aluminium composite under 0–125 A DC current was carried out under 5% concentration. The effect of corrosion behaviour on copper–aluminium composite by DC current was carried out by a scanning electron microscope(SEM) with energy-dispersive spectroscopy(EDS), X-ray diffraction(XRD) patterns, X-ray photoelectron spectroscopy(XPS), weight-loss method and electrochemical analysis. The results show that the current can accelerate the corrosion rate. Meanwhile, the current temperature effect can reduce the corrosion rate. The current caused directional migration of ions resulting in different corrosion products on positive and negative poles of specimen, and the corrosion degree on the positive pole was more serious. The galvanic corrosion mechanism at the copper–aluminium interface is different from the pitting corrosion mechanism far away from the interface, and the latter is more affected by DC current.     

Experimental study of electrochemical corrosion behaviour of bilayer on AZ31B Mg alloy

A bilayer on AZ31B magnesium alloy was prepared by first applying anodization to modify the substrate, and then depositing a self-assembled nanophase particle (SANP) film. Structure and corrosion behaviour are characterized by scanning electron microscopy, energy dispersion spectrometry, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscope and electrochemical impedance spectroscopy. Experimental results indicate that the bilayer consists of a SNAP/loose layer and a dense layer, and provides the corrosion protection of Mg substrate for more than 354 h in 0.005 M NaCl solution. Therefore, the bilayer is effective to protect Mg alloy against corrosion for a long time.     

Microbially influenced corrosion of zinc and aluminium - Two-year subjection to influence of Aspergillus niger

Aspergillus niger. Tiegh., a filamentous ascomycete fungus, was isolated from the metal samples exposed to marine, rural and urban sites in Lithuania. Al and Zn samples were subjected to two-year influence of A. niger under laboratory conditions in humid atmosphere. Electrochemical impedance spectroscopy (EIS) ascertained microbially influenced corrosion acceleration (MICA) of Zn and inhibition (MICI) of Al. EIS data indicated a two-layer structure of corrosion products on Zn. The microorganisms reduced the thickness of the inner layer, whose passivating capacity was much higher when compared to that of the outer layer. An increase in aluminium oxide layer resistance but decrease in the layer thickness implied that MICI affected primarily the sites of localized corrosion of Al (pores, micro-cracks, etc.). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) studies indicated that bioproducts (i.e. organic acids) did not form crystalline phases with corrosion products of zinc. The study suggested a hypothesis that microorganisms could be used as corrosion protectors instead of toxic chemicals, application of which tends to be increasingly restricted.     

Effect of flow velocity on pipeline steel corrosion behaviour in H2S/CO2 environment with sulphur deposition

The effect of element sulphur on the performance of corrosion inhibitor in H₂S/CO₂ gas field solution was investigated at different velocities. The morphology and composition of corrosion products were characterised by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) methods. The results indicated that L360 QS steel surface suffered from sulphur-induced pitting corrosion at a low velocity due to insufficient sulphur-carrying fluid power. At high flow velocities, the steel surface is likely to be suffered high fluid power which can remove the inhibitor film and corrosion scales by the mechanical erosion effect. The sulphur corrosion mechanism model and the flow-induced corrosion model due to the high wall shear force have been proposed in the study. This work suggested that the gas production rate should be controlled at an acceptable level to guarantee the service safety of pipeline system.     

镁锂合金表面锌锰磷化膜的制备与性能表征

采用化学转化法在镁锂合金表面制备了外观深灰色、结构均匀致密、耐蚀性能良好的锌锰磷酸盐转化膜,并研究了磷化温度对磷化膜性能的影响。采用扫描电子显微镜(SEM)、能谱(EDS)仪、X射线光电子能谱(XPS)和X射线衍射(XRD)仪对膜层的表面形貌、化学组成及结构进行了表征。采用动电位极化曲线、电化学交流阻抗(EIS)和腐蚀失重实验对磷化膜的耐蚀性进行了研究。结果表明,锌锰磷化膜主要由Zn、Zn3(PO4)2、MnHPO4、Mn3(PO4)2组成。锌锰磷酸化膜起到了保护镁锂合金的作用,提高了镁锂合金的耐蚀性,当磷化温度为45℃时,磷化膜的腐蚀电流密度最低,腐蚀速率最小,耐蚀性能最好。     

复合气相缓蚀剂对铁质文物缓蚀机理的研究

采用乌洛脱品和胺类缓蚀剂A制成一种新的气相缓蚀剂,用模拟大气腐蚀状态的薄液膜电化学测试技术研究了复合气相缓蚀剂对铸铁试样电化学行为的影响.并通过X射线衍射(XRD)和X射线光电子能谱(XPS)分析了复合气相缓蚀剂作用于模拟带锈文物所形成的锈层结构,并探讨了其缓蚀机理.结果表明,该复合气相缓蚀剂是一种阳极型的气相缓蚀剂,对模拟带锈文物有很好的缓蚀效果,该缓蚀剂可以促进铁质文物中的不稳定锈层向稳定锈层转化,抑制基体腐蚀的进一步扩展,对铁质文物具有很好的保护作用.      

45钢表面PII-DGPSM复合强化层的耐腐蚀性能研究

针对海工装备中常用45钢表面耐腐蚀性不足的问题,采用离子注入技术(PII)注Al和双辉等离子表面冶金技术(DGPSM)渗Cr复合,在基体45钢表面制备Al-Cr复合强化层。利用X射线衍射(XRD)、光电子能谱(XPS)、原子力显微镜(AFM)、扫描电镜(SEM)和能谱(EDS)等对试样的元素分布、物相结构进行表征。并采用极化曲线和电化学阻抗谱,对比分析Al-Cr复合涂层、注Al涂层和基体在3.5wt%NaCl溶液中的耐腐蚀性,研究其腐蚀机理。研究表明,采用复合技术制备所得Al-Cr涂层的耐腐蚀性最佳,其表面形成Cr2O3和Al2O3复合钝化膜,和涂层内部形成具有优异耐腐蚀性Fe2AlCr和Al8Cr5相,阻碍Cl-的腐蚀作用;注Al层耐腐蚀性次之,其表面形成致密Al2O3钝化膜,延缓了Cl-对基体的腐蚀作用;基体耐腐蚀性最差。     

Corrosion of AA2024-T3 Part II: Co-operative corrosion

Polished specimens of AA2024-T3 alloy were immersed for up to 120 min in 0.1 M NaCl. The development of corrosion was monitored using scanning electron microscopy with energy dispersive X-ray spectroscopy (EDXS) and particle induced X-ray emission spectroscopy (PIXE). Both techniques revealed the intermetallic (IM) particle distributions and attack sites as distinguished by detection of chloride species. The earliest stages of attack involved localized attack around isolated IM particles as reported in Part I. Additionally attack occurred on a larger scale developing rapidly with rings of corrosion product surrounding clusters of IM particles. There were significantly higher numbers of IM particles within the corrosion rings, indicating that local clustering played an important role in co-operative corrosion.     

Corrosion inhibition of layered double hydroxide coating for Mg alloy in acidic corrosive environments

Layered double hydroxide (LDH) shows promising prospects in the application of intelligent coatings to prevent metals from corrosion, while it is not available under acidic conditions. This investigation aims to improve the corrosion resistance of LDH coating in an acidic environment. The surface morphology, structure, and composition of the LDH coating were characterized by scanning electron microscopy (SEM), X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, respectively. The corresponding corrosion inhibition was evaluated by electrochemical methods, including electrochemical impedance spectroscopy and Tafel curves. The significant increase in coating resistance and charge transfer resistance and the obvious decrease in corrosion current density demonstrate the remarkable improvement of the MgAl–LDH coating in corrosion inhibition. The optical pictures and SEM images show that the coating is corroded severely when sodium dodecyl benzene sulfonate (SDBS) is not added, while it is protected competently without any signs of corrosion after polarization in HCl solutions containing SDBS, which enables the application of a MgAl–LDH coating under an HCl-corrosive medium.