低碳钢在模拟海洋潮差区的腐蚀行为的电化学研究

利用自主设计的腐蚀实验槽模拟实海潮差,并借助恒电位仅、电化学工作站对Q235B低碳钢在潮差区不同位置以及全浸区的腐蚀过程进行原位监测.结果表明,试样处在潮差区的不同位置时的腐蚀规律不同,低碳钢在中潮区和低潮区的腐蚀速率高于最高潮区及全浸区的腐蚀速率;在一个潮差涨落周期内,低碳钢开路电位的变化与表面经历的干、湿状态及所发生的阴、阳极反应有关;在长期潮差腐蚀进程中,低碳钢开路电位的变化规律与锈层的厚、薄状态有关.     

X60管线钢在模拟潮差区初期腐蚀行为研究

在模拟潮差实验槽内,通过腐蚀形貌观察、腐蚀产物分析,以及原位开路电位监测,研究了X60管线钢在不同监测位置随潮水涨落变化的腐蚀行为与规律.结果 表明,管线钢在潮差区内不同位置的腐蚀行为各异,在中、低潮区的腐蚀速度要快于最高潮区及最低潮区的腐蚀速度;随着潮位的降低,开路电位不断降低;最高潮区阴极过程主要受氧还原控制,中、...     

电连接对Q235碳钢在海洋环境中跨区带腐蚀行为的影响

通过对腐蚀速率、微观形貌和锈层成分的测试与分析，研究了电连接状态对Q235碳钢在青岛实海环境中跨越全浸区和潮差区腐蚀行为的影响。结果表明：在非电连接状态下，全浸区试样的腐蚀速率低于潮差区，潮差区试样的腐蚀速率随着暴露高度的增加而增大；在电连接状态下，处于最低潮位线下方试样的腐蚀速率出现峰值，而在潮差区，处于中潮位区域试样的腐蚀速率出现最低值；在全浸区上部和整个潮差区试样的腐蚀形貌存在明显差异；在两种状态下潮差区试样表面锈层成分存在明显差异，在电连接状态下存在锈层的影响，随着暴露高度的增加，锈层中Ca和Mg含量逐渐增加。     

中国南海油气井隔水导管腐蚀规律研究

目的 针对我国南海海域使用过的六种材质隔水导管,系统性地分析其在60、90、180 d三个腐蚀周期及在大气区、飞溅区、潮差区、全浸区四个区带的腐蚀行为与腐蚀规律,为我国南海隔水导管材质优选提供理论依据。方法 首先,开展室内实验模拟海洋腐蚀环境,通过SEM扫描分析隔水导管在大气区、飞溅区、潮差区及全浸区的腐蚀特点,并针对六种材质挂片在四个区带的腐蚀速率开展研究,最后基于动电位极化与电化学阻抗技术分析隔水导管的抗腐蚀性能。结果 飞溅区与潮差区的腐蚀程度相比大气区及全浸区更严重,且飞溅区、潮差区及全浸区三个区带的腐蚀产物主要为γ-FeO(OH);180 d时大气区平均腐蚀速率约0.0651~0.0976 mm/a,飞溅区约0.3924~0.4857 mm/a,潮差区约0.3482~0.4281 mm/a,全浸区约0.1714~ 0.2109 mm/a。六种材料容抗弧大小为X80< X70< X65< X60相似文献   

不同海域、不同腐蚀区带Q235碳钢实海挂片腐蚀产物层内微生物调查

将Q235碳钢样品挂于不同海域(青岛和三亚)的不同腐蚀区带(潮差区和全浸区),在不同的时间点(90,180和270 d)取出,就腐蚀形貌、腐蚀速率、腐蚀产物成分进行分析,并采用传统平板分离和16S r DNA序列分析技术对腐蚀产物层中的微生物进行分离、纯化和培养。结果表明,Q235碳钢在不同海域不同腐蚀区带的腐蚀速率不同,且潮差区的腐蚀速率总是大于全浸区的;不同腐蚀区带腐蚀产物的内外层成分存在差别,外层含有Fe3O4,α-Fe OOH和γ-Fe OOH等,内层主要是Fe3O4,而不同海域形成的腐蚀产物成分差别不明显。不同时空下不同腐蚀区带Q235碳钢挂片腐蚀产物层中的细菌群落结构复杂且存在差异,主要包括硫酸盐还原菌、铁细菌和好氧/兼性厌氧菌等;在相同时空条件下,全浸区的细菌种类和数量均高于潮差区的,且更容易检测到硫酸盐还原菌的存在;好氧/兼性厌氧菌种类丰富,以弧菌属、芽孢杆菌属和假交替单胞菌属为优势菌。     

钢在厦门海域全浸和潮差区的腐蚀行为分析(摘要)

钢在厦门海域全浸和潮差区的腐蚀行为分析(摘要)林志坚,宋文桑(中国船舶工业总公司七二五研究所厦门分部,厦门361002)根据暴露在厦门海域全浸区、潮差区几种钢8年腐蚀试验结果,讨论不同的合金元素对低合金钢局部腐蚀发展倾向的影响;应用回归分析技术,计算不同钢种在潮差区平均腐蚀速度产生”逆转”的时间,讨论分析影响”逆转”现象的因素.l碳钢和IE#全钢局部腐蚀发展趋势全浸区8年取样处理时发现两种含Cr钢和09MnNb(济)钢的内锈....     

模拟高放废物地质处置环境下重碳酸盐浓度对低碳钢活化/钝化腐蚀倾向的影响

在除氧的HCO-3溶液中,采用原位测量开路电位方法研究了HCO-3浓度对低碳钢腐蚀活化/钝化状态的影响,用SEM观察了低碳钢电极在除氧的HCO-3溶液中长期腐蚀后的表面形貌,用电化学阻抗谱(EIS)方法研究了电极的腐蚀演化特征及规律,用XRD方法检测了腐蚀产物的相组成.结果表明,低碳钢的开路电位随浸泡时间的延长以及HCO-3浓度的升高而升高;长期浸泡后,在0.01 mol/L HCO-3溶液中低碳钢的阳极溶解处于极限扩散状态,而在高于0.02 mol/L HCO-3溶液中处于钝化状态;锈层的主要腐蚀产物为a-FOOH和Fe3O4.     

Al及Al合金在舟山海域的腐蚀行为

报告Al及Al合金在舟山海域的飞溅区、潮差区和全浸区3种试验条件下暴露2、4、8年的腐蚀结果及其在海水环境中的腐蚀行为.Al及Al合金在海洋环境中的平均腐蚀率较低,主要因点蚀、缝隙腐蚀而受到破坏,硬Al、超硬Al的包Al层对基体起着牺牲阳极保护作用.在飞溅区,Al及Al合金对局部腐蚀较敏感,点蚀密度较大.在飞溅区,二种带包Al层的LC4CS(BL)、LY11CZ(BL)耐蚀性较好,L3M和LF11M的耐蚀性较差;在潮差区和全浸区180YS和LF2Y2表现出较好的耐蚀性.LF11M在潮差区的耐蚀性较好,而在飞溅区和全浸区的耐蚀性较差.     

重碳酸盐溶液中SO_4~(2-)和Cl~-对低碳钢活化/钝化腐蚀行为的影响

在除O_2的0.1 mol/L NaHCO_3,0.1 mol/L NaHCO_3+0.1 mol/L Na_2SO_4以及0.1 mol/L NaHCO_3+0.1 mol/L NaCl溶液中,用恒电位法在低碳钢电极表面制备腐蚀产物,并原位监测低碳钢的开路电位,用SEM观察腐蚀形貌,用XRD确定腐蚀产物的相组成.结果表明.在0.1 mol/L NaHCO_3溶液中,低碳钢的开路电位最终处于再钝化区间,其表面未观察到明显的腐蚀现象;在0.1 mol/L NaHCO_3+0.1 mol/L Na_2SO4溶液中,低碳钢的开路电位最终处于再活化区间,其表面发生均匀腐蚀;在0.1 mol/L NaHCO_3+0.1 mol/L NaCl溶液中,低碳钢的开路电位最终亦处于再活化区间,而其表面却发生局部腐蚀,XRD结果表明,低碳钢表面的腐蚀产物主要为Fe_3O_4和α-FeOOH.     

工艺和组织对桥梁钢在模拟海洋飞溅区环境中腐蚀行为的影响

采用电化学测试和模拟飞溅区腐蚀试验研究了不同工艺制造的桥梁钢在模拟海水环境中的腐蚀行为,并与模拟全浸区的腐蚀速率进行了对比。结果表明,经回火处理后的桥梁钢,组织由粒状贝氏体非平衡组织向回火索氏体平衡组织转变,晶粒细化、组织更为均匀,因此在模拟海洋飞溅区环境中具有更好的耐腐蚀性能;模拟飞溅区的腐蚀速率约为模拟全浸区的6~10倍,模拟飞溅区腐蚀速率高的原因除了外在的环境因素外,具有还原作用的锈层与钢基体构成的局部电池形成开路以及腐蚀坑内外的电位差也是主要因素。     

Study on the Galvanic Current of Corrosion Behavior for AH32 Long-Scale Specimen in Simulated Tidal ZoneEI北大核心CSCD

The environment of the tidal zone is very complex. The interactions of dry-wet alternation and sea erosion lead to serious corrosion of steel structures, which makes it difficult to adopt protective methods. Therefore, it is of great significance to study the corrosion and protection methods of steel in tidal zone. For long-scale steel through the tidal zone and immersion zone, there is a big difference in corrosion behavior with complete immersion condition, the potential of the steel surface changes due to the influence of oxygen concentration difference and tidal fluctuations or other factors. In this study, the galvanic current and open circuit potential of the long-scale AH32 steel were monitored in simulated tidal zone. The results shows that the potential at different tide levels and different immersion depths for a long-scale AH32 specimen is not unified, with the macro cell was formed by the difference of oxygen supply, which caused internal galvanic current. The essence of the galvanic current is the net current that was generated by the sum of anode and cathode current. Galvanic current at different positions on the long-scale AH32 specimen varies with the tidal movement periodically in tidal zone. When tide is at the highest level, the galvanic current of all parts accesses a maximum value, and among these maximum values, the largest one is at the middle part of specimen, which causes the biggest anodic dissolution current density. According to the variation of the galvanic current, the time distributions of the drying, wetting and immersion states were calculated, and the results showed that the corrosion scale of the long-scale AH32 specimen at different positions depends on the time all location of wetting and immersion in tidal zone. The macro cell caused the galvanic current when all parts of the specimen were immersed. At wetting state, the solution resistance of the thin liquid film is very large, which leads to the change of the driving potential of the macro cell into the potential drop. Thus, macro cell is ineffective in the wetting state and cannot produce the galvanic current. According to the relation between wetting time and quantity of electricity at wetting state, the maximum wetting time of the long-scale AH32 specimen is shown above average mean tide level in tidal zone, which indicates that the corrosion loss of this part is maximum due to wetting state. In addition to weight loss measurements, maximum of it for long-scale AH32 specimen was obtained at the average mean tide level caused by immersion state. It can be indicated the maximum weight loss of the long-scale AH32 specimen should appear upper the average mean tide level part in tidal zone. These results were consistent with measurements of corrosion rates.     

Corrosion behaviors of arc spraying single and double layer coatings in simulated Dagang soil solution

Three kinds of single layer coatings of Zn, Zn15Al, 316L stainless steel and two kinds of double layer coatings with inner layer of Zn or Zn15Al and outer layer of 316L stainless steel by arc spraying were developed to protect the metal ends of prestressed high-strength concrete (PHC) pipe piles against soil corrosion. The corrosion behaviors of the coated Q235 steel samples in the simulated Dagang soil solution were investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and natural immersion tests. The results show that the corrosion of the matrix Q235 steel is effectively inhibited by Zn, Zn15Al, Zn+316L and Zn15Al+316L coatings. The corrosion rate value of Zn15Al coated samples is negative. The corrosion products on Zn and Zn15Al coated samples are compact and firm. The corrosion resistance indexes of both Zn and Zn15Al coated samples are improved significantly with corrosion time, and the latter are more outstanding than the former. But the corrosion resistance of 316L coated samples is decreased quickly with the increase in immersion time. When the coatings are sealed with epoxy resin, the corrosion resistance of the coatings will be enhanced significantly.     

Q235B 钢含硫污水罐的腐蚀开裂失效分析

目的对某炼油厂原料水罐Q235B钢腐蚀开裂失效原因进行分析。方法采用宏观形貌、金相组织和断口观察以及成分分析和力学性能测定等手段,分析Q235B钢腐蚀开裂失效的宏观和微观行为。结果 Q235B钢在污水罐罐顶形成的湿硫化氢环境中发生沿晶型应力腐蚀开裂。腐蚀过程中,电化学反应产生的氢渗入基体,导致微裂纹的萌生。腐蚀产物在基体表面积聚,其自身体积膨胀以及涂层的闭塞作用对基体形成非常大的拉应力。结论结合应力分析和环境分析,Q235B钢含硫污水罐的腐蚀开裂失效机制为硫化氢应力腐蚀开裂,应力来源于氢渗透和腐蚀产物膨胀。     

Microbial Activities’ Influence on Three Kinds of Metal Material Corrosion Behaviors

The corrosion behaviors of copper, 6063 aluminum alloy, and Q235 steel were investigated by open-circuit potential (OCP), anodic polarization curve analysis, and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy revealed that a small number of translucent rod-shaped bacterial colonies on the copper surface of copper, whereas plenty of rod-shaped microbes colony were detected on the surface of 6063 aluminum material. Moreover, rod-shaped bacteria and mold colonies attached to the surface of Q235 steel. The decrease in the OCP of copper, 6063 aluminum alloy, and Q235 steel led to higher corrosion tendency. EIS analysis showed that bacteria can reduce the value of AC impedance of copper, the polarization resistance, and the surface resistance, thereby accelerating corrosion. Moreover, the polarization resistance of aluminum alloy in bacterial seawater is lower than that in non-bacterial seawater, indicating the existence of bacteria accelerated the corrosion of 6063 aluminum alloy. The adherence of microbes on Q235 steel surface accelerated the dissolution of the surface layer, and then the passive film is replaced by incompact biofilm layer. Q235 steel corrodes faster under the influence of bacteria because the polarization resistance in bacterial seawater is much lower than that in non-bacterial seawater.     

NaCl对Q235钢早期腐蚀行为的影响

在实验室模拟了NaCl对Q235钢早期腐蚀的影响,研究了NaCl含量和浸泡时间对Q235钢腐蚀行为的影响。结果表明:试验条件下,当NaCl质量分数为3.5%时,Q235钢腐蚀倾向最大,电极表面的反应电阻最小,腐蚀速率最快;Q235钢的腐蚀电流密度和表面反应电阻随浸泡时间变化而出现波动,浸泡24 h后,腐蚀体系的自腐蚀电位最负,自腐蚀电流密度最大,腐蚀速率最快;电极表面的腐蚀产物对基体具有一定的保护作用,然而腐蚀产物较疏松,在电极表面的附着力小,很容易脱落而使腐蚀反应加快。     

Q235碳钢表面SiO2/PDMS超疏水涂层的制备及防腐性能研究

目的 提高Q235碳钢的耐腐蚀性能。方法 在Q235表面先提拉聚二甲基硅氧烷(PDMS),预固化后再次提拉含疏水气相二氧化硅的PDMS分散液,完全固化后在Q235表面构建一个SiO2/PDMS超疏水涂层。通过扫描电镜、激光共聚焦显微镜、能谱、接触角、砂纸磨损、划格试验对涂层的形貌、结构和表面性质进行分析;采用电化学工作站对涂层的耐腐蚀性和耐久性进行评价。结果 SiO2纳米粒子被镶嵌在PDMS中,在Q235表面形成了一种微纳粗糙结构,平均粗糙度为2.2 μm;涂层表面能仅为5.6 mJ/m²,接触角为152.6°;涂层机械稳定性和结合力优异,砂纸磨损15个周期及划格试验30个周期后,仍保持超疏水。电化学研究表明,在Q235表面引入SiO2/PDMS后,阻抗提升了2个数量级,电容降低了6个数量级;腐蚀电位正向移动了0.419 2 V,腐蚀电流密度降低了3个数量级;涂层对Q235的防腐效率高达99.8%,呈现出优异的耐腐蚀性。在腐蚀液中浸泡一周后,SiO2/PDMS涂层仍保持超疏水和优异的耐腐蚀性,表明涂层耐久性良好。结论 以PDMS为疏水层,纳米SiO2为填料构筑粗糙表面,通过条件控制实现防腐底层和超疏水表层间的界面融合,从而引入稳定的SiO2/PDMS超疏水涂层,提高了Q235的耐腐蚀性和耐久性。本研究为在金属表面构筑稳定的超疏水涂层提供了一种方法,有望拓展金属在恶劣环境中的应用。     

Galvanic Series of Metals and Effect of Alloy Compositions on Corrosion Resistance in Sanya SeawaterEI北大核心CSCD

With the development of ocean engineering, various metallic materials have been applied to the marine environment. It is an urgent requirement to study the galvanic series and alloy composition optimization of metallic materials in the tropical marine environment. In this work, open circuit potentials (OCP) and galvanic series of 36 kinds of metallic materials in Sanya seawater were studied. By considering the response of OCP to tidal changes, the anti-corrosion effects of alloying elements were also ana lyzed. The results show that the OCP of metallic materials in Sanya seawater has a large range. The galvanic series order of metallic materials from high to low in Sanya seawater is: nickel alloy, duplex stainless steel, austenitic stainless steel and pure copper, ferritic stainless steel, martensitic stainless steel, copper alloy, low alloy steel, carbon steel, cast iron, aluminum alloy and aluminum anode. Low-carbon high-alloy content carbon steel and high Cr, Ni contents stainless steel have higher OCP. The potential fluctuations of carbon steel with tidal changes involves two phases: (1) under the dynamics control, the OCP of carbon steel is more negative at high tide; (2) under the diffusion control, the OCP is more positive at high tide. The potential fluctuations of metallic materials reflect the effect of the corrosion product film on the change of ionization balance, and metals with less potential fluctuations have better inhibition on ion diffusion. In Sanya seawater, the carbon steel, which has more alloying content and less carbon content, has less potential fluctuations with the tidal changes and has good oxygen diffusion resistance. The potential fluctuations of austenitic stainless steel with tidal changes are less than that of ferritic stainless steel and martensitic stainless steel. After 2700 h immersion, austenitic stainless steel and martensitic stainless steel, which have a higher content of Mo, have more stable OCP. In other words, the corrosion film gets a better corrosion resistance. The OCP of aluminum anode in Sanya seawater environment increases when the oxygen content is brought up. The OCP of Zn-containing or Ga-containing aluminum anode remains relatively stable. Al bronze and T2 copper have less potential fluctuations with tidal changes, and perform good corrosion resistance in Sanya seawater.     

电化学方法研究环氧涂层/基体在3.5%NaCl溶液中的腐蚀行为

采用电化学方法研究了两种常用涂层-环氧沥青涂层和环氧铝粉涂层在3.5%NaCl溶液中的腐蚀行为.腐蚀电位-时间结果表明,两种涂层的自腐蚀电位都比基体的更正,都能起到屏蔽作用保护基体,浸泡中电位向负方向移动说明活化腐蚀过程在继续.电化学阻抗结果表明,腐蚀介质能够较快的渗入涂层到达界面,使涂层的屏蔽作用降低,生成的腐蚀产物可在一定程度上抑制腐蚀的发展.并提出了两种涂层的等效电路模型,对阻抗结果进行了拟合.表明在浸泡初期涂层电阻随浸泡时间延长迅速降低,随后趋于稳定.指出电化学方法能获得与涂层性能有关的定量数据,非常适合于研究涂层/基体的性能.     

壳寡糖对Q235钢在海水中的缓蚀性能

采用腐蚀浸泡试验,扫描电子显微镜以及电化学试验法等研究了海水中壳寡糖(COS)及其与无机缓蚀剂复配后对Q235钢的缓蚀作用。电化学试验结果表明:单独添加COS时,缓蚀率最大为65.73%;当COS与NaNO_2复配添加时,其协同缓蚀率为90.67%,为阳极型缓蚀剂;而当COS与Na_2MoO_4复配时,缓蚀率最大只能达到71.65%,且两者发生了抑制作用。腐蚀浸泡试验结果表明:当COS与NaNO_2复配使用时,其缓蚀率最佳,为85.90%。COS在Q235钢表面发生单分子吸附,为自发进行的化学吸附,从而起到缓蚀作用,该吸附符合Langmuir模型。