海洋平台用中锰钢飞溅区海水腐蚀行为

通过干湿交替腐蚀实验研究了海洋平台用低碳中锰钢在海洋环境下飞溅区的海水腐蚀行为.通过电子显微镜研究了腐蚀产物的形貌特征,利用电子探针(EPMA)表征了锈层的截面形貌及腐蚀产物中元素的分布,采用X射线衍射仪对腐蚀产物进行了物相分析.结果表明:随着腐蚀时间的延长,腐蚀速率先是快速增加,达到峰值后下降,最后趋于稳定.腐蚀产物结构由疏松多孔状逐渐转化为致密厚实状,锈层对基体的保护能力逐渐增强.在高浓度氯离子环境下,腐蚀产物以γ-Fe OOH为主,并出现了锰的氧化物和铁锰氧化物两种物相,它们促进了腐蚀过程中的电化学反应.     

三种桥梁耐候钢在模拟海洋大气环境中的耐蚀性能比较

通过室内周期浸润加速腐蚀实验,结合腐蚀形貌观察、物相分析及电化学测试,对三种耐候桥梁钢Q355NHD、Q450NQR1、Q460q在模拟海洋大气环境(3.5%NaCl溶液)下的腐蚀行为进行对比研究。结果表明,三种耐候钢在实验周期内,腐蚀速率均呈先增大后减小的趋势。腐蚀前期,耐蚀性差异主要是由显微组织决定的,以铁素体和珠光体复相组织为主的Q355NHD、Q450NQR1钢腐蚀速率高于以粒状贝氏体为主的Q460q钢。腐蚀后期,微量合金元素在锈层中富集使其致密化,显著提高了三种钢的耐蚀性能。其中Q460q钢锈层最为致密,锈层保护因子α/γ*和电化学阻抗值|Z|最大,在该环境下表现出了最佳的耐蚀性能。     

低合金耐候钢在含氯离子环境中的腐蚀行为

利用干湿周浸加速腐蚀实验对比研究了低合金钢A588和SPA--H在含氯离子环境下腐蚀行为,并利用金相显微镜、扫描电镜、X射线衍射和电子探针等方法分析了Ni、Mn对于低合金钢腐蚀行为的影响.结果表明:实验钢锈层中的物质主要由α--FeOOH、γ--FeOOH和Fe3O4组成,但其含量存在差异;Ni元素在内锈层含量高于外锈层,Mn元素在锈层的孔洞处富集;内锈层的致密程度高于外锈层;提高合金元素Mn和Ni的含量,可以提高内锈层的致密性,从而提高低合金钢的耐蚀性能.     

Cu-P-RE耐候钢的耐蚀性能

通过干湿周浸加速腐蚀实验研究了不同稀土含量的耐候钢和对比普碳钢的腐蚀行为及其耐蚀性能.采用失重法测得了各试样的腐蚀率;结果发现,稀土耐候钢的腐蚀率远远低于普碳钢的,不同稀土含量的耐候钢的耐腐蚀性不尽相同.采用电化学交流阻抗技术对带锈钢样的表面锈层结构及电化学反应过程进行了研究,提出在本实验条件下钢电化学腐蚀的等效电路模型,计算出锈层电阻、极化阻抗等表征锈层性能的电化学元件参数值.稀土耐候钢锈层中存在半无限扩散和有限厚度扩散两种过程,有限厚度扩散极化阻抗反映了耐候钢内锈层的保护性能.     

10CrMoAl钢热轧薄板的周浸实验对比分析

为了系统地研究10CrMoAl钢的耐腐蚀性能,对其周浸试验各周期试样进行了腐蚀速率分析、SEM分析、XRD分析及电化学分析.结果表明:腐蚀速率最快的阶段是72～168 h腐蚀阶段,其次是0～72 h腐蚀阶段,最慢的是168～240 h腐蚀阶段.经过168 h腐蚀后,锈层厚度平均为80 μm,是经过72 h腐蚀后的试样锈层厚度的近2倍.经过240 h的腐蚀后,锈层仍然维持在80 μm左右,却出现了50 μm的过渡层.经过168 h和240 h腐蚀所形成的锈层几乎完全阻止了γ-FeOOH和α-FeOOH等稳定产物的形成,从而有效地阻碍了基体的继续腐蚀.此外,锈层中Cr、Mo和Al的富集,也对阻碍腐蚀的进行起到一定的作用.     

E690海洋平台用钢力学性能和海洋大气腐蚀行为

以传统的E36海洋平台钢为对比钢,研究三种E690海洋平台钢的组织和力学性能,以及模拟海洋大气环境下的腐蚀行为.通过失重法测得实验钢在不同腐蚀时间下的腐蚀速率,利用扫描电镜和X射线衍射仪观察并测定了锈层的形貌特征和相组成,采用电子背散射衍射技术对实验钢的晶界类型进行分析.结果表明:以贝氏体组织为特征的E690海洋平台钢具有优异的力学性能,-40℃的冲击值超过了200J;晶界类型主要为3°～15°的亚晶界和大于50°的大角度晶界;E690海洋平台钢周浸16 d后的锈层致密且腐蚀速率已趋于稳定,最低腐蚀速率为0.84 mm.a-1,远低于组织为铁素体+珠光体钢的1.4 mm.a-1,实验钢的锈层主要由Fe3O4、α-FeOOH、β-FeOOH及γ-FeOOH四种晶态相和非晶无定形物组成.通过分析得出,热处理工艺和组织构成对材料的初期腐蚀行为有重要影响,而化学成分和锈层自身的致密性对材料后期腐蚀行为起决定作用.     

10CrMoAl钢在含Cl~-环境中不同周期腐蚀的对比分析

为了探索在含Cl-环境中10CrMoAl钢的耐腐蚀机制,对10CrMoAl钢进行不同周期(72、168和240 h)的盐雾腐蚀试验,进而对其腐蚀结果进行对比分析,并对试样进行腐蚀速率分析、场发射扫描电子显微镜(FESEM)分析、能谱分析、X线衍射(XRD)分析及电化学阻抗谱分析。结果表明:随着腐蚀时间的延长,腐蚀速率逐渐降低。经过72、168和240 h腐蚀后,10CrMoAl钢的腐蚀速率分别为1.512、1.254和1.232 mm/a;当锈层厚度最大时,Cr和Mo在锈层内富集程度也达到最大,而且伴随着锈层的腐蚀脱落,Cr和Mo又在基体与锈层交界处逐渐富集,有效地阻碍了基体的腐蚀。此外,锈层中FeCr_2O_4的出现导致了Fe_3O_4逐渐消失和γ-Fe_2O_3相对量逐渐增加。锈层中FeCr_2O_4的出现明显改变了腐蚀产物的形成过程。     

氧化铁皮对低碳钢大气腐蚀行为的影响

利用干湿交替腐蚀试验模拟工业大气环境,研究了层状结构氧化铁皮对热轧低碳钢工业大气腐蚀行为的影响.采用SEM和电化学手段对比分析带氧化铁皮和不带氧化铁皮试样的腐蚀增重行为、锈层结构和电化学行为.结果表明,带氧化铁皮试样的腐蚀速度远低于无氧化铁皮覆盖的基体钢,带氧化铁皮试样的自腐蚀电位低于基体钢,单一物相层状结构的氧化铁皮具有很好的耐腐蚀性,能够有效保护基体钢板;氧化铁皮的完整性是保护带钢基体不被腐蚀的前提,如果氧化层被破坏,在破损位置处,氧化铁皮与钢基体接触发生电偶腐蚀,加速腐蚀反应的进行.     

用穆斯堡尔谱学等方法研究低合金钢在海水中的锈层

本工作用穆斯堡尔谱学等方法对几种钢的海水锈层进行了分析研究。主要分析了锈层的相组成。宏观观察表明以硅铬铜镍为合金元素的C-4钢内锈层比较致密,较厚,较坚硬,连成较大的板状块。而以锰钛为主要合金元素的C-2钢的内锈层较薄、不均匀、较脆。甚至有时不能连成一块。穆斯堡尔谱学、X射线、热差分析,都说明内锈层的主要组成相是针铁石(α-FeooH),其颗粒的线度尺寸约为3×10~2(?)。电子探针的锈层微区域成份分析表明,铬、硅在内锈层中有富集。而锰元素与此相反,不但没有富集,反而有所消失。钛的富集情况不明显。根据本文研究结果,可以得出以下初步看法:①低合金钢中的少量合金成份对锈层的物相组成没有明显的影响;②各合金元素在内锈层中富集与否可能影响内锈层的致密度及厚度,从而影响抗腐蚀的能力;③锈层中的物相不是非晶质的。内锈层中的主要组成粒度已小到使其表现为超顺磁状态的程度,但在液氮温度显示反铁磁性状态。     

12SiMoVNbAl低合金钢高温腐蚀锈层的研究

本文主要研究了12SiMoVNbAl低合金钢耐含硫原油长期高温腐蚀的锈层之组织结构。用金相及岩相方法观察了锈层的组织结构。锈层主要分里、外两层。里层緻密,外层疏松。用电子探针及扫描电镜观察并测定了合金元素在基体金属和锈层中的分布。在高温腐蚀条件下,该钢合金元素含量虽然较低,但仍具有较好的抗高温腐蚀的性能。硅、铝等合金元素在里锈层中的富集是提高其抗高温腐蚀性能的主要原因。     

Na2CO3–K2CO3熔盐电化学法除锈

The formation of a rust layer on iron and steels surfaces accelerates their degradation and eventually causes material failure. In addition to fabricating a protective layer or using a sacrificial anode, repairing or removing the rust layer is another way to reduce the corrosion rate and extend the lifespans of iron and steels. Herein, an electrochemical healing approach was employed to repair the rust layer in molten Na₂CO₃?K₂CO₃. The rusty layers on iron rods and screws were electrochemically converted to iron in only several minutes and a metallic luster appeared. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses showed that the structures of the rust layer after healing were slightly porous and the oxygen content reached a very low level. Thus, high-temperature molten-salt electrolysis may be an effective way to metalize iron rust of various shapes and structures in a short time, and could be used in the repair of cultural relics and even preparing a three-dimensional porous structures for other applications.     

Electrochemical derusting in molten Na_2CO_3–K_2CO_3

The formation of a rust layer on iron and steels surfaces accelerates their degradation and eventually causes material failure.In addition to fabricating a protective layer or using a sacrificial anode, repairing or removing the rust layer is another way to reduce the corrosion rate and extend the lifespans of iron and steels.Herein, an electrochemical healing approach was employed to repair the rust layer in molten Na_2CO_3-K_2CO_3.The rusty layers on iron rods and screws were electrochemically converted to iron in only several minutes and a metallic luster appeared.Scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS) analyses showed that the structures of the rust layer after healing were slightly porous and the oxygen content reached a very low level.Thus, high-temperature molten-salt electrolysis may be an effective way to metalize iron rust of various shapes and structures in a short time, and could be used in the repair of cultural relics and even preparing a three-dimensional porous structures for other applications.     

低碳钢在湿热工业海洋大气中的腐蚀特征

以0.1 mol·L-1 NaCl+0.01 mol·L-1 NaHSO3溶液为腐蚀介质,采用干/湿周浸加速腐蚀实验、腐蚀失重、X射线衍射、扫描电镜和能谱分析等方法,研究了湿热工业海洋大气中低碳钢的腐蚀行为.结果表明:实验钢的腐蚀过程均遵循幂函数d=Atn分布规律,钢种不同,常系数A、n的值不同;腐蚀产物主要由非晶物质和少量Fe3 O4、α-FeOOH、β-FeOOH、γ-FeOOH晶体组成.所得锈层可分为主体锈层和界面疏松带两部分,由内至外锈层中Fe、O含量梯度变化很小.Cl-、SO2与水分的长期协同作用会导致内锈层结构变差,而添加稳定性或耐蚀性较高的元素可以改善锈层质量,进而增强钢材的耐腐蚀性能.     

环境中氯离子浓度对耐候钢耐腐蚀性能的影响

研究海水环境中氯离子浓度对耐候钢耐蚀性能的影响,用扫描电镜和红外光谱仪等对试样耐蚀机理进行观察分析。结果表明,耐候钢在低Cl-浓度下的耐蚀性能要好于高Cl-浓度下的耐蚀性能;两组试样中均存在较致密的内锈层和疏松的外锈层,锈层成分主要为Fe3O4和γ-Fe2O3;低Cl-浓度下,合金元素容易在锈层富集,形成较致密且厚的内锈层,使材料耐蚀性能增强。     

Corrosion behavior and corrosion products of a low-alloy weathering steel in Qingdao and Wanning

A newly developed low-alloy weathering steel has been exposed in two coastal sites (Qingdao in the north, Wanning in the south) in China for one year. The samples in Wanning corroded far more seriously than those in Qingdao. The rust layer formed on the steel was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), N₂ adsorption approach, polarization curves, and electrochemical impedance spectroscopy (EIS). The rust formed in Qingdao contains more X-ray amorphous compounds and is more compact than that formed in Wanning. Cr and Cu are enriched in the rust layer near the steel matrix, and the phenomenon is more obvious in Qingdao than in Wanning. The rust layer formed in Qingdao suppresses the anodic and cathodic reaction more remarkably than that formed in Wanning does. The rust layer formed in Qingdao possesses a higher ability to block the permeation of chloride ions than that formed in Wanning does.     

Relationship between the specific surface area of rust and the electrochemical behavior of rusted steel in a wet-dry acid corrosion environment

The relationship between the specific surface area (SSA) of rust and the electrochemical behavior of rusted steel under wet-dry acid corrosion conditions was investigated. The results showed that the corrosion current density first increased and then decreased with increasing SSA of the rust during the corrosion process. The structure of the rust changed from single-layer to double-layer, and the γ-FeOOH content decreased in the inner layer of the rust with increasing corrosion time; by contrast, the γ-FeOOH content in the outer layer was constant. When the SSA of the rust was lower than the critical SSA corresponding to the relative humidity during the drying period, condensed water in the micropores of the rust could evaporate, which prompted the diffusion of O₂ into the rust and the following formation process of γ-FeOOH, leading to an increase of corrosion current density with increasing corrosion time. However, when the SSA of the rust reached or exceeded the critical SSA, condensate water in the micro-pores of the inner layer of the rust could not evaporate which inhibited the diffusion of O₂ and decreased the γ-FeOOH content in the inner rust, leading to a decrease of corrosion current density with increasing corrosion time.     

大气腐蚀锈层的电感耦合等离子体光谱研究

概述了电感耦合等离子体光谱法的特点,并运用该光谱法对青岛和成都两地的大气腐蚀锈层样品进行了比较测试,得出了锈层中各元素的相对含量及其随腐蚀环境和时间的变化情况．     

Influence of mill scale and rust layer on the corrosion resistance of low-alloy steel in simulated concrete pore solution

Electrochemical impedance spectroscopy, cyclic potentiodynamic polarization measurements, and scanning electron microscopy in conjunction with energy-dispersive X-ray spectroscopy were used to investigate the influence of mill scale and rust layer on the passivation capability and chloride-induced corrosion behaviors of conventional low-carbon (LC) steel and low-alloy (LA) steel in simulated concrete pore solution. The results show that mill scale exerts different influences on the corrosion resistance of both steels at various electrochemical stages. We propose that the high long-term corrosion resistance of LA steel is mainly achieved through the synergistic effect of a gradually formed compact, adherent and well-distributed Cr-enriched inner rust layer and the physical barrier protection effect of mill scale.