研究了2008年南京长干寺出土的北宋七宝阿育王塔鎏金银基体及其腐蚀产物成分, 并根据银基体成分按传统工艺自行冶炼、加工出模拟的银试样. 用电化学、OM、XRD、XRF、SEM-EDS技术研究并比较了银试样在不同浓度Na2S溶液中的腐蚀电位与电流、腐蚀产物成分、形貌、晶粒度等. 结果表明, Na2S浓度由20 mg/L升高到5.0×104 mg/L (5% Na2S)时, 自腐蚀电位Ecorr负移0.70 V, 自腐蚀电流密度Icorr从0.274 μA/cm2升高至1.056 μA/cm2, 腐蚀倾向和速度大幅度增加. 在20 mg/L Na2S溶液中-0.31 V~1.8 V范围内极化, 银试样始终处于活化溶解状态. 在5% Na2S溶液中, 腐蚀活化区电流密度从1.056 μA/cm2迅速升高至1.56×104 μA/cm2, 并以较大的腐蚀电流密度(约1.56×104 μA/cm2)进入钝化区并维持钝态; 分别在20 mg/L和5% Na2S溶液中活化区恒电位+0.3 V、-0.8 V极化不同时间后, 腐蚀产物主要为Ag2S. 随着Na2S溶液浓度的增大, 试样表面S2-腐蚀活性中心增多, Ag2S晶体成核速率增大, 而腐蚀产物的晶粒度则由20 μm减小到1.86~5.10 nm.
Chemical composition and corrosion product of the Northern Song Dynasty Emperor Asoka Pagoda substrate were studied for the first time since it was unearthed from the Changgan Temple underground palace located at Nanjing in 2008. Silver samples based on composition of the Pagoda substrate were simulated by traditional smelting and processing technique. The corrosion potential, corrosion current of the silver sample and the composition, morpholoy, grain size of the corrosion products on the sample in corrosion medium with different concentrations of Na2S were examined by means of electrochemical technique, OM, XRD, XRF, SEM and EDS. The results showed that with the increase of Na2S concentrations from 20 mg/L to 5.0×104 mg/L (i.e. 5% Na2S), the corrosion current density Icorr increased from 0.274 μA/cm2 to 1.056 μA/cm2 and the corrosion potential Ecorr was shifted towards less value by 0.70 V. Thereby, the driving force for corrosion and corrosion rate were enhanced. Silver samples were kept in active state when polarization potential was shifted from -0.31 V to 1.8 V in 20 mg/L Na2S solution. In 5% Na2S solution, the corrosion current density for silver in the active corrosion region increased rapidly from 1.056 μA/cm2 to 1.56×104 μA/cm2, and then silver samples transferred to passive corrosion region and maintained the passivation with higher corrosion current density about 1.56×104 μA/cm2. Corrosion products of silver were mainly Ag2S after 0.3 V (20 mg/L Na2S) or -0.8 V (5% Na2S) constant potential polarization for different time intervals, respectively. The amount of S2- as corrosion active center and the growth rate of Ag2S crystals on the silver sample surface increased with the increase of the Na2S concentrations from 20 mg/L to 5%. However, the grain size of Ag2S crystals was reduced from 20 μm to1.86~5.10 nm.
利用高温高压反应釜模拟普光气田的工况环境, 研究抗硫套管钢P110SS在高含H2S/CO2环境中的腐蚀行为和硫化物应力开裂(SSC)敏感性. 结果表明, 随着温度和H2S/CO2分压的升高, P110SS的腐蚀速率先降低后升高, 而在相当于井中部工况的环境中, 钢的腐蚀速率最低, 腐蚀产物膜明显脱落. 在高含H2S/CO2环境中, 采用四点弯曲法加载达到P110SS屈服强度的90%时, 试样表面未发现裂纹, 表明SSC敏感性比较低.
The corrosion behavior and sulfide induced stress corrosion cracking sensitivity of a sulfide-resistant casing steel P110SS in hyperbaric H2S/CO2 environment were studied by high temperature/pressure reactor which simulated the operating environment of Puguang gas field. The corrosion rate of P110SS in hyperbaric H2S/CO2 environment decreased first and then rose with the increase of temperature and partial pressure of H2S/CO2. Corrosion product peeled off in an environment corresponding to the middle area of the well where the corrosion rate was minimal. The sulfide induced stress corrosion cracking sensitivity of P110SS steel in hyperbaric H2S/CO2 environment was very low revealed by four point bending test for the steel with a load of 90% yield strength, which could be attributed to the uniform tempered microstructure of sorbite with fine grain, high dislocation density and uniform dispersion of carbides of the steel.
采用自制大气腐蚀模拟试验装置模拟输电杆塔用镀锌钢的服役环境, 采用动电位极化测试技术研究沉积不同浓度NaCl和NaHSO3的镀锌钢在干湿交替作用下的腐蚀行为, 利用扫描电镜、X射线衍射仪研究干湿交替作用下镀锌钢的表面形貌以及腐蚀产物的特征. 结果表明, NaCl及NaCl和NaHSO3共存均会对镀锌钢造成腐蚀. 随着镀锌钢样品表面沉积腐蚀介质浓度的增大, 腐蚀电流密度逐渐增大. 随着暴露时间的增加, 镀锌钢的腐蚀速率先升高后降低, 同时NaCl和NaHSO3混合介质对镀锌钢的腐蚀要比单独NaCl存在时严重.
The corrosion process of galvanized steel for power transmission tower in media with different concentration of Cl- and HSO3- was investigated by using potentiodynamic polarization test and cyclic wet-dry accelerated laboratory test. Then, the surface morphology and characteristics of the corrosion products were examined by X-ray diffractometer and scanning electron microscopy. The results showed that the galvanized steel was corroded in the presence of NaCl and mixed NaCl and NaHSO3, and the corrosion current density increased with the increasing concentration of Cl- and HSO3-.The corrosion rate of galvanized steel was greater at the early stage of test and then decreased with the extension of test time. In addition, the effect of the combination of Cl- and HSO3- on the corrosion of galvanized steel was more serious than that of Cl-.
研究了Ni-Si合金分别在800 ℃空气和水蒸汽中的高温氧化行为. 在空气中, 合金表面形成的氧化膜呈双层结构, 内层是连续、致密的SiO2膜, 提高了合金的高温氧化抗力. 高温水蒸汽中合金的氧化速率显著增大,合金表面仅观察到一层富Si氧化膜, 而氧化膜的粘附性降低, 随着氧化时间的延长, 氧化膜发生明显剥落.
The high-temperature oxidation behavior of Ni-Si alloy was investigated at 800 ℃ in air and water vapor, respectively. A two-layered oxide scale formed on the Ni-Si alloy after exposure in air and the inner layer was continuous and rich in Si which could be responsible for enhancing oxidation resistance of the alloy. Water vapor promoted the formation of Si-rich scale on the alloy, while inhibited the formation of NiO during oxidation process. However, water vapor decreased the adherence of the oxide scale remarkably, as a result, heavy spallation of the oxide scale occurred with the increase of time.
用动电位极化和电化学阻抗谱测量方法研究了CT80钢连续油管钢在模拟长庆油田高矿化度油井水中的腐蚀行为, 并考察了矿化度和预腐蚀对腐蚀过程的影响. 结果表明, 随着腐蚀溶液矿化度的增大, 材料的开路电位正移, 电荷传递电阻先减小后增大, 电化学腐蚀速率与矿化度呈非直线规律. 在矿化度为23.204 g/L时, CT80钢材料具有最大的腐蚀速率. 随着预腐蚀时间的延长, 电荷传递电阻增大, 相应的电化学腐蚀速率有所降低.
Potentiodynamic polarization measurement and electrochemical impendence spectroscopy were employed to investigate the corrosion behavior of CT80 coiled tubing steel in artificial high salinity brine corresponding to the oil well water at Changqing oil field. The effect of salinity and pre-corrosion on the corrosion process was thus examined. The results showed that when salinity was increased, the free corrosion potential moved to the positive direction, the charge transfer resistance resulting from the electrochemical impendence spectroscopy decreased first but then increased, and the nonlinear correlation was observed between the corrosion rate resulting from the polarization measurement and the salinity. The maximum corrosion rate was observed at the moderate salinity of 23.204 g/L. With the increase of the pre-corrosion time, the charge transfer resistance increased, as a result, the electrochemical corrosion rates decreased.
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方法, 分析了某20钢高温输水管爆裂的原因. 结果表明, 断裂失效发生在焊缝部位, 焊缝组织存在明显蠕变现象, 断口起裂处具有典型脆性断裂特征, 裂纹内有腐蚀产物, 属于典型应力腐蚀裂纹. 裂纹扩展后期近外表面处具有蠕变疲劳裂纹特征. 应力腐蚀裂纹是该热水管爆裂失效的主要原因.
The failure analysis for hot water pipes of 20 steel was performed by means of examinations of macro-morphology, metallograph and fractured surface, as well as chemical analysis and mechanical property measurement for the relevant materials. Results showed that the fracture occurred in the weld joints with obvious deterioration in weld area due to creep. The fracture initiated and propagated with typical brittle characteristics. The occurrence of corrosion products on cracking wall and in the cracking tip revealed that stress corrosion cracking (SCC) was the dominant factor of the pipe burst. Creep crack and fatigue characteristics were also found on the fracture, which accelerated the SCC and pipe burst.
采用动态极化曲线和电化学阻抗谱方法研究了经过柠檬酸钝化后医用316L不锈钢在模拟体液中耐蚀性能的变化, 利用XPS分析了材料表面组成对不锈钢耐蚀性能的影响. 结果表明, 经过柠檬酸钝化后, 316L不锈钢的自腐蚀电位增加, 自腐蚀电流减小, 而极化电阻和电荷转移电阻增大, 说明其耐蚀性得到了很大的提高. 经过柠檬酸钝化的316L不锈钢耐蚀性提高的原因是柠檬酸选择性地溶解基体Fe元素, 而双氧水将富集的Cr氧化形成致密的Cr2O3薄膜, 从而起到保护作用.
Measurement of potentiodynamic curve and electrochemical impedance spectra (EIS) was used to study the corrosion resistance of a medical 316L stainless steel passivated by citric acid in simulated body fluid. XPS was applied to analyze the effect of surface composition on the corrosion resistance of the studied material. The results showed that after passivation by citric acid, the free corrosion potential shifted to positive side, while the corrosion current density decreased and the polarization resistance and the charge transfer resistance were enhanced, indicating a significant improvement of the corrosion resistance. XPS analysis results showed that the enhancement of the corrosion resistance of 316L stainless steel was attributed to that Fe on the surface of substrate was selectively dissoluted by citric acid and then the enriched Cr was oxidized by H2O2 to form a compact chromium oxide film to protect the substrate from corrosion.
测试潜艇常用的4种牺牲阳极在不同干湿交替周期的电化学阻抗谱, 分析了它们的耐腐蚀性能. 结果表明, 干湿交替条件下阳极失效的主要原因是腐蚀产物覆盖致使阳极表面的活性溶解点减少, 阻碍阳极的进一步活化. 经过一定的干湿交替循环后有些阳极结壳严重, 导致容抗弧增大, 阳极的活化溶解能力大大降低. 在干湿交替环境中, 合金的使用性能从差到好的顺序为: Zn-Al-Cd
Electrochemical impedance spectroscopy (EIS) was used to study the corrosion behavior of four Al-based alloys commonly used as sacrificial anode for submarine under wet-dry cyclic conditions with various drying periods. The EIS results showed that the failure of the sacrificial anodes was mainly attributed that the coverage effect of corrosion products on the surface of sacrificial anodes, leading to the decrease of the number of active sites on the anode surface. Thus, the further activation of the sacrificial anodes was prevented. After several wet-dry cycles, the severe accumulation of corrosion products on the anode surface resulted in enlargement at the capacitive loops, indicating significant decrease of the active dissolution of the anodes. The performance of the 4 Al-based alloys under wet-dry cyclic environment may be ranked as the following order: Zn-Al-Cd < Al-Zn-In-Cd < Al-Zn-In-Mg-Ti < Al-Zn-In-Mg-Ga-Mn.
采用四点弯曲试样研究25Cr2Ni4MoV钢在超高浓度盐酸(20 mass%)中的应力腐蚀行为, 得出缺口位置挠度随时间变化的关系曲线. 结果表明, 盐酸浓度的升高使25Cr2Ni4MoV钢的应力腐蚀寿命显著降低. 应力腐蚀分可区为三个阶段: 裂纹萌生、裂纹扩展与瞬间断裂. 裂纹优先在晶界处萌生并扩展, 应力的提高加速了应力腐蚀裂纹的萌生与扩展.
Four point bend specimens of 25Cr2Ni4MoV steel were used to investigate the stress corrosion cracking behavior in ultra-high concentration hydrochloric acid (20 mass%). As a result of four point bend experiments, curves of relationship between deflection and time were revealed. The results showed that the life time of stress corrosion cracking of 25Cr2Ni4MoV steel decreased as the concentration of hydrochloric acid increased. The stress corrosion cracking process of 25Cr2Ni4MoV steel under the test condition could be divided into three typical stages: crack initiation, crack propagation and instant fracture. Crack initiation and propagation had a priority along grain boundary. The increase in stress accelerated the stress corrosion cracking initiation and propagation.
收集了临床中拆除的镍铬合金烤瓷冠, 按佩戴年限分为1年组、2年组、3~4年组、5~9年组、10年以上组, 并设立对照组. 采用接触角仪测定各组试样的接触角, 利用电化学工作站测试电化学腐蚀曲线, 应用扫描电镜观察试样表面腐蚀形貌, 并进行统计学分析. 结果表明, 1年组试样腐蚀电位及腐蚀电流密度相对较小, 2年组试样腐蚀电位和腐蚀电流密度增加并显著高于其它组, 3~5年组、5~10年组、10年以上组试样腐蚀电位及腐蚀电流密度相对2年组逐渐减小, 这种变化趋势与接触角测试结果一致. 随佩戴年限的增加, 镍铬烤瓷内冠的腐蚀程度越来越严重, 即镍铬合金烤瓷冠在口腔内存在腐蚀, 且佩戴2年左右时腐蚀速度最快, 腐蚀程度随年限增加累积. 因此, 口腔临床中应采取积极的措施预防镍铬合金烤瓷冠的早期腐蚀.
The collected dismantled Ni-Cr porcelain crowns in clinic were divided into five groups according to the time for restoration as followed: (1) restored for 1 a, (2) restored for 2 a, (3) restored for 3~4 a, (4) restored for 5~9 a, (5) restored for more than 10 a, and new porcelain crown was set up as control group. The contact angles was measured, the corrosion curve was obtained by an electrochemical workstation, and the surface morphology of inner side of crowns was observed by scanning electron microscope. After then the experimental data was used for statistical analysis. The results showed that the free corrosion potential and self-corrosion current density of group 2 was significantly higher than the others, and the trend was consistent with the results of contact angle measurement. The observation under scanning electron microscope also showed that the corrosion was severer as the restoration time increased. The conclusion was that Ni-Cr porcelain crown suffered from corrosion in oral cavities, which exhibited the fastest corrosion rate at the second year. The corrosion effect was accumulated as time increased. Therefore, dental doctors should take certain measures to avoid this negative effect.
以聚氨酯改性环氧树脂为成膜物质, 磷酸锌和三聚磷酸铝为颜料, 滑石粉、绢云母、纳米二氧化硅和纳米二氧化钛为填料, 制备了聚氨酯改性环氧树脂防腐蚀底漆. 检测了底漆的机械性能、电化学阻抗谱和耐化学介质性能. 研究了磷酸锌和三聚磷酸铝两种防锈颜料的配合使用对涂层防腐耐蚀性能的影响. 结果表明, 防腐底漆的机械性能和耐蚀性能良好.
The anti-corrosion coatings for oil tanks were prepared with polyurethane modified epoxy resin, zinc phosphate, aluminum tripolyphosphate, talcum powder, sericite, nano-silica and nano- titania. The performance of the prepared coatings was examined by measurements of mechanical properties, electrochemical impedance spectroscopy (EIS) and resistance to chemical medium. The influence of the mixture of zinc phosphate and aluminum tripolyphosphate on the anti-corrosion properties were investigated. The results showed that mechanical properties and corrosion resistance of the anti-corrosion primer were superior.
针对涂层下金属的腐蚀损伤不易被观察到而造成的安全隐患问题, 制作了防腐涂层下的材料腐蚀模拟试件, 应用红外热波技术进行检测, 得到试件表面温度分布热图像, 并在腐蚀区域和正常区域中取点, 采集到相应区域的温度变化曲线和温差曲线. 结果表明, 红外热波方法对涂层下的腐蚀损伤具有较好的检测效果, 腐蚀损伤区域和正常区域的表面温差达到最大的时刻是最佳检测时间, 可用于估算涂层厚度. 通过对典型时刻热图的处理, 可实现腐蚀损伤大小和位置的定量识别, 但检测结果受材料表面的均匀度影响较大.
Infrared thermal wave technology was employed to detect the corrosion damage under coating, which could not be easily observed and caused safety problem. The infrared thermal images of surface temperature distribution on the tested specimen were captured, as well as the surface temperature history of areas with and without pre-corrosion damages, and there with the temperature difference of the two areas. Analysis of the test results showed that the infrared thermal wave technology was an effective tool in detecting corrosion damage under coating. The optimum detection moment for estimating the coating thickness and position and size of damages was when the temperature difference between corrosion area and sound area reached the maximum. The damages could be quantitatively recognized by images processing, but surface uniformity of the specimen had great impact on the damage identification.
在现代工业和生活中, 金属腐蚀已成为极为严重的破坏因素, 遍及各个工业部门. 为了抑制金属的腐蚀, 采用缓蚀剂是一种经济有效的防腐蚀方法. 目前各类缓蚀剂被广泛应用于石油、石化、能源、交通、机电及建筑等行业以及工业各过程中, 如清洗、水处理、石油开采、金属制品的储运等. 近年来, 随着人类环境保护意识的增强和可持续发展思想的深入, 对缓蚀剂的开发和应用也提出了新的要求, 新型高效及环境友好缓蚀剂的研发成为研究热点, 也将是未来缓蚀剂的发展方向[1,2]. 但是, 传统研发缓蚀剂的手段主要采用猜测和大量探索性实验, 成本高、周期长、效率低、盲目性大, 给研发工作带来了巨大的困难. 只有清楚了解缓蚀剂的作用机理才能为新型高效且环境友好缓蚀剂的研发提供可靠的理论指导, 故对缓蚀剂的缓蚀机理展开研究显得尤为重要.
材料与周围介质发生化学或电化学作用生成氧化物而丧失或减退其原有特性的现象称为腐蚀.据相关统计,全世界每年因腐蚀造成的经济损失约为7000~10000亿美元,约是地震、水灾、台风等自然灾害造成的经济损失总和的6倍,占各国国民生产总值(GDP)的2%~4%[1].因此,防腐蚀研究越来越受到各国的重视. 在众多的防腐蚀措施中, 防腐涂料是目前实际应用中较为简便、有效和经济的防腐措施之一.
铝合金在腐蚀介质和拉应力同时作用下产生的开裂, 称为应力腐蚀开裂[1,2](SCC). 自上世纪初开始使用铝合金以来, 其应力腐蚀开裂一直广受关注. 纯铝的耐蚀性非常好, 但是其强度和硬度很低. 采用Zn、Mg、Cu、Li等元素合金化后, 铝合金的强度及硬度得以提高. 然而, 当Al处在海水中或工业环境中并存在拉应力的情况下, 合金化加大了应力腐蚀开裂的敏感性. 在发生SCC期间, 铝合金表面往往看不出腐蚀的迹象, 但里面己经开裂, 这就使其具有很高的危险性. 应力腐蚀广泛存在于各种工业结构中, 应力腐蚀的存在导致构件在远低于结构设计强度的情况下失效, 引起灾难性的损失. 由于铝合金是航空航天中常用的结构材料, 其应力腐蚀性能的研究成为航空航天领域必不可少的研究内容.
据统计, 石化行业每年因腐蚀泄漏所造成的事故占总事故数的60%以上, 所带来的直接和间接损失更是难以估量. 因此, 在炼油设备管理中,腐蚀监测一直是一项十分重要而基础的工作.为了满足长周期运转的生产要求,检修周期普遍延长至4年一修或更长,同时原油劣质化、来源多样化和满负荷运转的趋势日益加剧,腐蚀监测中常用的挂片法、定点测厚、漏磁检测等因灵敏度低、间隔周期长、人工操作等缺点,难以及时准确地反映腐蚀现状[1].随着检测新技术的涌现和信息技术的发展,腐蚀监测也由便携工作模式向在线监测转变,在线腐蚀监测可以连续实时的提供多种检测参数数据,已成为设备预知维修和全寿命管理的有效手段.
随着加工原油性质的逐渐劣化,炼油装置设备腐蚀引发的安全隐患以及安全生产事故显著增加,装置被迫非计划停工检修次数也越来越多, 严重影响了装置的长周期安全运行. 为了及时发现腐蚀隐患, 有效控制腐蚀的发生与发展, 实现装置的安全生产, 必须开展有效的腐蚀监测工作[1-6]. 目前国内多数石化企业都采用包括在线监测探针在内的新型腐蚀监测技术或其它一些监测技术[7,8], 但由于腐蚀本身的特殊性、复杂性, 任何一种单一的腐蚀监测手段反映的只是腐蚀的一个方面, 不能完全反映设备的实际腐蚀状况.
某厂汽轮机组为国产100 MW双抽凝汽式机组, 由哈尔滨汽轮机厂制造, 型号CC100-8.83/4.02/1.1, 型式为: 高压、双缸、双抽、双排汽、冲动冷凝式, 额定功率100 MW. 与汽轮机配套的凝汽器型号为N7000-1型, 型式为双流程二流道, 凝汽器额定工况进汽量212.85 t/h, 最大工况进汽量287.22 t/h. 凝汽器主冷凝区铜管材质为HSn70-1A黄铜管, 铜管数量9526根, 铜管尺寸为ø25 mm×1 mm×8470 mm. 空冷区铜管材质为BFe30-1-1白铜管, 铜管数量为764根, 铜管尺寸为ø25 mm×1 mm×8470 mm. 顶部三排及通道迎气流区铜管材质为HSn70-1A黄铜管, 铜管数量330根, 铜管尺寸为ø25 mm×1.5 mm×8470 mm. 管板、中间隔板及管壳均为Q235. AF材质.
仪征-长岭原油管道(以下简称“仪长线”)是中石化沿江管道建设中极为重要的管道之一,是中石化集团十五规划的重点项目, 于2006年5月25日试投产. 干线起点为江苏省的仪征油库, 途径安徽、湖北、湖南, 终点为湖南省的长岭分公司油库, 全长996 km, 其中干线773 km, 支线223km,设计年输量为2100万吨,最大管径为864mm,最小管径为406.4mm.该管道承担着向沿江五家炼化企业(安庆石化、九江石化、武汉石化、荆门石化、长岭石化)输送原油的重任[1].
管道是油气资源输送最主要也是最经济安全的方式,由于管道大多埋于地下,输送压力高,极易受到外部压力、腐蚀、第三方破坏和自然灾害等因素的影响. 资料表明[1], 腐蚀是油气管道失效的主要原因之一, 会造成管壁减薄, 管道的承压能力下降, 严重时导致管道的破裂泄漏事故的发生, 对人员和财产造成重大损失.
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