表面处理工艺对碳钢在水溶液中的腐蚀行为研究

用电化学方法评价了碳钢经喷镀Ａｌ、浸镀Ａｌ、喷镀Ｚｎ、浸镀Ｚｎ、离子注Ｎ几种处理后在含Ｈ２Ｓ、ＣＯ２水溶液中的腐蚀行为。结果表明，每种表面处理方式均使碳钢的耐蚀性能改善，以浸镀Ａｌ改性效果最好，喷镀Ａｌ次之。水溶液中溶解的Ｈ２Ｓ、ＣＯ２气体含量对材料的腐蚀速度有较大的影响。     

一种适用于强腐蚀环境下的无氰镀镉层结构

用新型氯化钾无氰镀镉工艺制备镀镉层,以低铬铬酸盐彩色钝化剂钝化,再用纳米羟基石墨烯改性封闭剂进行封闭。所制备的镀层按GB/T10125-1997《人造气氛腐蚀试验盐雾试验》进行中性盐雾试验,经过4000 h的喷雾测试,镀层表面无白色腐蚀物生成。这种镀层结构具有极高的耐蚀性,特别适用于海洋等强腐蚀环境下的防护性镀层。     

碳钢Ni-P化学镀耐碱性溶液腐蚀性能的研究

为了研究碳钢材料在碱性介质中的腐蚀以及防护方法,采用静态浸泡法以及电化学的方法,对普碳钢以及进行化学镀后的耐碱液腐蚀性能进行了研究.结果表明:普碳钢在室温碱性溶液中放置1h后,表面即发生了严重的腐蚀.在碱性溶液中浸泡24h后,出现了基体局部剥离的现象.普碳钢在碱性溶液中发生了严重的腐蚀.在施加了化学镀层后,普碳钢在碱性溶液中浸泡24h后,表面光洁完整,与未施加化学镀层相比,有很小的腐蚀电流.在碳钢表面施加化学镀层后在碱性介质中具有良好的耐腐蚀性.     

氰化电镀与无氰刷镀下触头镀银层性能比较

采用典型的氰化电镀与无氰刷镀工艺在隔离开关触头的基材表面成功制备了银镀层,比较了两种工艺条件下触头镀银层表面形貌、显微硬度、厚度均匀性、结合力及在3.5%氯化钠溶液中耐蚀性等性能的差异。结果表明,无氰刷镀银层的显微硬度达130 HV,与氰化电镀银层相当,满足DL/T 486-2010硬度要求;经刻划栅格试验镀层未剥落,基体结合力接近或达到氰化电镀银层水平。但无氰刷镀银层存在漏镀孔洞,致使该镀层在3.5%氯化钠溶液中腐蚀速率达59.6μm/a,相同腐蚀介质中的氰化电镀银层仅为1.5μm/a,且无氰刷镀银层的厚度均匀性不够稳定。     

钢板热镀55%Al-Zn层的耐盐水腐蚀性能

采用全浸、半浸和盐雾等试验方法研究了钢板热镀55 %Al-Zn合金镀层在3%NaCl的盐水溶液中的腐蚀行为.观察分析了镀层的组织结构和在盐水中 腐蚀后的表面形貌及腐蚀产物,阐述了镀层在盐水中的腐蚀过程和机理.结果表明55%Al-Zn 合金镀层比Zn镀层更耐蚀,并同样具有Zn镀层对钢基体的保护能力.     

Al—Zn热浸镀层在H2S—NaCl—H2O体系中的腐蚀行为

采用表面钝化助镀法进行热浸镀,获得了55％Al－Zn镀层。研究了溶液温度、H2S浓度、NaCl浓度、pH值及试验时间对55％Al－Zn镀层在H2S－NaCl－H2O体系中的腐蚀行为。分析了镀层腐蚀前后的表面组织形貌及腐蚀产物,阐述了镀层的腐蚀机理。结果表明,55％Al－Zn镀层具有Zn镀层的电化学保护作用,其耐蚀性是镀锌钢的2－3倍,是风Q235的10－11倍。     

H_2S对碳钢在模拟罐底水中腐蚀行为的影响

利用腐蚀失重法、电化学测试、扫描电镜(SEM)和X射线衍射(XRD)研究了Q235碳钢在含H_2S的模拟罐底水中的腐蚀行为。结果表明:增加H_2S含量,可以促进碳钢表面的析氢反应,从而增大了碳钢的腐蚀速率;碳钢表面形成由四方硫化亚铁组成的疏松、多孔的腐蚀产物膜;碳钢先后在含H_2S溶液、无H_2S且含溶解氧的溶液中进行二次腐蚀后,其腐蚀产物分为两层,内层主要组成依然是四方硫化亚铁,外层为氧化产物,其中氧化产物的生成导致硫化亚铁膜的破裂与脱落;硫化亚铁膜的存在,对碳钢在含H_2S溶液中的保护性大于其在含溶解氧溶液中的。     

镉镀层的大气腐蚀行为

采用常规氰化镀镉和无氰镀镉工艺在２０＃钢试样上镀敷镉镀层,并在青岛、江津、武汉和海南万宁大气试验站进行了５．８ａ的大气暴露试验．结果表明江津的镉镀层腐蚀速率最高,青岛与武汉的腐蚀速率接近,海南万宁的腐蚀速率最低．镉镀层不适用于有工业污染的大气环境,对海洋大气环境有较强的防护能力．无氰镀镉层的腐蚀速率与氰化镀镉接近,可以认为在一定条件下无氰镀镉能够代替氰化镀镉工艺用于上述４种典型的大气环境的腐蚀防护．     

ρ(Ca2+)对碳钢在NaHCO3- NaCI - CaCl2溶液中腐蚀行为的影响

利用计时电流和电化学阻抗测试技术,检测了碳钢在NaHCO3 - NaCl - CaCl2溶液中的腐蚀行为.通过分析计时电流法的平均腐蚀速率和试样表面相应的形貌分析以及分析电化学阻抗谱的电荷转移电阻,研究了不同的Ca2+的质量浓度对碳钢腐蚀行为的影响.结果表明:少量的Ca2+对碳钢的腐蚀有抑制作用,当溶液中的ρ(Ca2+...     

Zn在模拟酸雨溶液中及其液膜下的腐蚀

利用可控液膜厚度的闭塞电解池，研究了Zn在模拟酸雨本体溶液及薄液膜下的腐蚀行为．在pH值为2．4—3．8的模拟酸雨本体溶液中，Zn的阻抗谱由高频容抗和低频感抗构成，Zn的腐蚀受电荷传递过程控制．Zn的腐蚀速率和腐蚀电位都随着溶液pH值降低而升高．在较低pH值(2．4和27)的溶液中，由于较强的析氢过程产生表面吸附的氢气泡，使气泡周边的腐蚀重于Zn表面的其它区域，而使表面形成了明显的环形腐蚀痕迹．在薄层液膜下，随着液膜的减薄，Zn的腐蚀过程发生变化，当液膜减至100μm以下时，低频感抗为一扩散特征的Warburg阻抗代替，Zn的腐蚀控制步骤由电荷传递控制转由电荷传递和物质扩散混合控制．研究结果表明，液膜的减薄抑制了Zn腐蚀的阴极过程，Zn的腐蚀速率也随着液膜的减薄而降低。     

红壤中变电站接地网金属材料的腐蚀行为分析

采用扫描电镜 (SEM)、能谱 (EDS) 和X 射线衍射 (XRD) 等技术对红壤中变电站接地网服役长达13 a的镀锌扁钢进行了形貌分析和腐蚀产物分析。结果表明,该镀锌扁钢受到严重腐蚀,腐蚀产物主要由FeOOH,Fe₃O₄和Fe₂O₃等组成,腐蚀产物分层的原因是新生成的腐蚀产物沉积在金属/腐蚀产物层界面或腐蚀产物开裂处,同时S和Cl对内层腐蚀产物具有较大的影响。Tafel测试结果表明,在腐蚀电流峰值附近,SO₄^2-与Cl^-的百分比为1∶2时,两者对镀锌Q235碳钢在该红壤中的腐蚀性影响具有等效作用。通过室内加速实验模拟镀锌Q235碳钢在该红壤中的腐蚀发现,镀锌Q235碳钢的腐蚀速率呈现先增大后减小的规律,该加速实验在未改变镀锌Q235碳钢腐蚀机理的同时具有较好的加速效果。     

接触网部件材料在模拟典型大气环境介质中的腐蚀——热浸镀锌材料的腐蚀(I)

采用腐蚀失重法与显微镜技术,研究了电气化铁路接触网热浸镀锌部件材料在模拟典型大气环境(海洋环境、工业环境、城市环境)介质中的腐蚀及其形貌。结果表明,热浸镀锌材料在模拟城市大气环境介质中的腐蚀最为严重,工业环境次之,海洋环境腐蚀最轻。二次加工与成型会引起镀锌层局部破损致使基材局部暴露与镀锌层形成电偶对,会加重热浸镀锌部件的腐蚀,且破损面积越大腐蚀越严重。同样,热浸镀锌部件与不锈钢紧固件耦接会形成电偶腐蚀,也会加重热浸镀锌部件的腐蚀。建议针对电气化铁路各段不同的大气环境,选择不同的接触网零部件材料、或者采用相应的防腐措施。在接触网构件加工和装配过程中,建议改进加工工艺程序,避免热浸镀锌部件的二次加工或者成型;建议采用绝缘措施,以达到热浸镀锌部件与不锈钢紧固件之间的绝缘耦接,避免电偶腐蚀发生。     

镀锌钢在不同大气环境中的腐蚀行为

通过镀锌钢在全国13个大气腐蚀试验站8a的现场暴露试验,观察了镀锌钢的表面形貌,进行了表面评级,测试了腐蚀速率,并计算了碳钢与镀锌钢的腐蚀速率比值。结果表明:所有镀锌钢板均出现表面变暗的现象,在拉萨、敦煌等站其表面变化较小,在青岛、江津等站其腐蚀较为严重,表面存在一定程度的锈蚀,在万宁站其表面锈蚀最严重;在13个站点镀锌钢的腐蚀速率由大到小依次为万宁武汉青岛沈阳广州江津北京琼海西双版纳库尔勒漠河敦煌拉萨;通过计算,碳钢与镀锌钢的腐蚀速率之比为9.2~2 000.0。在实际应用中,镀锌钢在不同环境中的厚度应不同。     

Performance of galvanized and stainless steel rebars in concrete under macrocell corrosion conditions

In the recent past, the damage caused by rebar corrosion in concrete structures has been considered as one of the major durability problems affecting the service life of concrete structures. In order to prevent corrosion of steel reinforcement, various types of protective methods have been adopted. One of the protective measures is using galvanized reinforcement in concrete to enhance the service life. In the present study various types of galvanized rebars namely bare – Cold Twisted Deformed (CTD), bare – Thermo Mechanically Treated (TMT), galvanized – Cold Twisted Deformed, Galvanized – Thermo Mechanically Treated, galvanized and chromated – Cold Twisted Deformed, galvanized and chromated – Thermo Mechanically Treated and stainless steel rebars have been evaluated for their corrosion resistance in M30 grade concrete under macro cell corrosion condition over a period of one year. From the studies it has been observed that TMT bars performed better when compared to CTD bars. Among the rebars tested, stainless steel rebar has shown negligible corrosion in chloride contaminated concrete.     

Effect of height on the corrosion of steel and galvanized steel in nontropical coastal marine environments

In this study, the behavior of carbon steel and galvanized steel in nontropical coastal marine environments was evaluated. Evaluation was carried out with specimens with dimensions of 10 cm × 10 cm × 0.3 cm. These specimens were exposed to four testing stations (Iquique, Mejillones, Los Vilos, and San Vicente), where racks were installed both at ground level (ground), as well as in the upper zone of electrical transmission towers (tower). In each station, 24 specimens of A36 carbon steel and galvanized steel were placed (12 each). The corrosivity of the environment was measured using the ISO 9223, 9225, and 9226 standards. The specimens were evaluated on-site, monthly, through visual inspection and photographic record. Once withdrawn, the corrosion rate was determined and the corrosion products were analyzed through Raman and Fourier-transform infrared. The results show that, in all cases, the corrosion rate is greater in the tower than on the ground. However, even though the Los Vilos station is located farther from the sea (3,500 vs. ≈500 m), the corrosion rate of steel in the tower is the highest. This is caused by the generation of HCl from the transformation of lepidocrocite into goethite, in the presence of low chloride content, which acidifies the steel/corrosion product interface. In the case of galvanized steel, the corrosion rate is a function of the chloride content in the atmosphere, obtaining an excellent correlation between both parameters.     

Hot-Dip Galvanizing Alloys

Activity in the development of hotdip galvanizing alloys has been quite successful in achieving two major goals. First, the use of a zinc-nickel bath provides a workable solution to the problem of batch galvanizing reactive steels, to achieve both an attractive surface appearance and a thin, durable and protective coating. Second, for continuously galvanized steel products, specific zinc-aluminum alloys have provided a means to greatly increase corrosion resistance, increase the maximum use temperature of zinc coatings, achieve the fabrication of severely formed products without damage to the zinc alloy coating, and allow such products to be formed from prepainted as well as unpointed coated steel.     

Effect of Nano-oxide addition on corrosion performance of hot dip zinc coating

Corrosion performance of hot dipped zinc coating on low carbon steel was studied at the presence of different nanoand micronsize oxide particles in the liquid zinc bath. Nano-silica, nano-alumina and micro-alumina powders were loaded to the different liquid baths, in the range of 0.05–0.2 wt %. Low carbon steel specimens were immersed in the baths for a constant time of 10s. It was evident that the presence of oxide particles in the liquid bath increased the coating thickness at a constant immersing time; micro-alumina particles provided the thickest coating among the others. Salt spray and potentiodynamic polarization tests were conducted to evaluate corrosion performance of the galvanized coatings, including oxide bearing ones. The results confirmed improvement in corrosion resistance of the nano-oxide bearing zinc coatings; while incorporation of micro-alumina in the bath declined its corrosion resistance. It was shown that incorporation of nano-silica powder in the liquid bath yielded superior corrosion resistance of the zinc layer, in comparison to the other ones. The optimum corrosion performance of zinc coating was achieved via loading 0.1 wt % nanosilica to the liquid zinc bath in this work.     

镀锌钢在红沿河大气环境中的腐蚀行为

目的研究镀锌钢在红沿河地区SO2和Cl-含量较高的大气环境中的腐蚀行为与机理。方法根据GB/T 6464—1997将制备好的试样在红沿河核电厂进行现场暴晒试验,分别暴晒4、12、18、24个月后取回试样。利用失重分析、X射线衍射(XRD)和扫描电镜(SEM)等技术,观察与分析试样暴晒后的腐蚀产物。结果镀锌钢腐蚀失重随暴晒时间的延长而线性增加;随着暴晒时间的延长,锌镀层表面形成的腐蚀产物成分变化不大,以Zn12(SO4)3Cl3(OH)15·5H2O和6Zn(OH)2·Zn SO4·4H2O为主;腐蚀产物随暴晒时间的延长逐渐增加,产物形貌略有变化,以球状和针状为主。暴晒18个月后,腐蚀产物分为双两层,内层致密,外层疏松;暴晒24个月后,腐蚀产物厚度稍有增加,疏松层向致密层转变。结论 SO2与Cl-是镀锌钢在红沿河地区的大气腐蚀过程的主要影响因子。镀锌钢表面形成的腐蚀产物对锌镀层的保护作用较差。     

国产镀锌钢在不同水环境中的腐蚀行为:I淡水和盐水

利用电化学阻抗谱和电化学噪声技术对比研究了国产镀锌钢板在盐水和淡水中的腐蚀行为。结果表明,镀锌钢在两种水溶液中的腐蚀均可分为3个阶段,不同阶段表现出完全不同的电化学特征,镀锌钢在盐水中的腐蚀速率明显高于其在淡水中的腐蚀速率,其在盐水中的腐蚀产物呈棒状或片层状,对基体不具有保护性,而在淡水中的腐蚀产物形态呈规则的球状,对基体具有明显的保护作用。     

镀锌钢在东莞大气及模拟大气中的腐蚀行为

采用失重法、金相检验、扫描电镜法(SEM)、X射线衍射法(XRD)、能量色散谱法(EDS)以及电化学阻抗谱法(EIS)研究了镀锌钢在东莞大气环境和模拟大气环境中暴露不同时间后的腐蚀行为。结果显示:在东莞大气中,镀锌钢在暴露早期发生了局部腐蚀,随着暴露时间的延长,腐蚀速率先迅速降低然后逐步稳定,耐蚀性先降低后增强;腐蚀12个月后,主要腐蚀产物为ZnO和Zn4SO4(OH)6;在模拟大气环境中,镀锌钢的腐蚀速率和耐蚀性随时间的变化规律和东莞实地大气暴露试验的结果具有良好相关性。