Cr合金化对HRB400钢筋腐蚀行为的研究

应用动电位极化、电化学阻抗谱、周浸腐蚀实验的方法研究了HRB400普通碳钢钢筋和两种Cr合金化的低合金钢筋在2%NaCl溶液中的腐蚀行为。结果表明：相比HRB400钢筋,Cr合金化的钢筋的开路电位明显正移,Cr加入提高了钢的热力学稳定性;随着Cr含量的增加,钢筋的自腐蚀电流密度减小,极化电阻增大,Cr合金化的钢筋具有相对较小的电化学腐蚀速率;周浸加速腐蚀72 h后,HRB400钢筋以均匀腐蚀为主,Cr合金化的钢筋以局部腐蚀为主,添加Cr可以显著降低HRB400钢筋的均匀腐蚀速率。     

高等级公路中钢筋的锈蚀行为研究

模拟高等级公路中的腐蚀环境,通过添加不同浓度十二烷基肌氨酸钠来改变模拟孔隙液的成分,研究了不同孔隙液中30MnSi钢筋的电化学腐蚀行为。结果表明,随着孔隙液中十二烷基肌氨酸钠浓度的提高,钢筋的缓蚀效率先增加而后降低,在十二烷基肌氨酸钠浓度为100 mg/L时取得最大缓蚀效率74.62%;随着钢筋在孔隙液中浸泡的延长,钢筋腐蚀电流密度并没有显著变化,说明当钢筋在高等级公路孔隙液中缓蚀作用不会随着浸泡时间的延长而发生巨大变化,而是对孔隙液的成分有显著影响。     

温度对Q235钢在大港模拟溶液中腐蚀行为的影响

主要利用极化曲线、线性极化和电化学阻抗谱(EIS)等电化学方法研究了Q235钢在不同温度下的大港模拟溶液中的腐蚀行为。试验表明:在20~50℃的范围内,其腐蚀电位比较接近阳极反应的平衡电位,其腐蚀过程受阴极反应氧的传输过程控制,随温度升高,Q235钢的腐蚀电位逐渐降低,腐蚀电流密度逐渐增大,线性极化电阻Rp以及电荷转移电阻Rt逐渐减小,在较高温下主要是通过促进阴极反应的传质过程增加了Q235钢的腐蚀速度。     

温度对Q235钢在碱性土壤中腐蚀行为的影响

采用失重法、极化曲线和电化学阻抗谱研究了Q235钢在不同温度碱性土壤中的腐蚀行为。试验结果表明:Q235钢的极化电流密度随着温度的升高而增大,结合层电阻R_1和电荷转移电阻R_t逐渐减小,提出了该体系的等效电路图。     

癸胺在金属铝上的缓蚀作用研究

采用电化学极化曲线、红外光谱等方法,对不同温度下癸胺对盐酸介质中铝的缓蚀性能进行了研究,计算了相关热力学函数,讨论了癸胺在铝表面的吸附模型.电化学极化测试表明,癸胺在铝表面吸附后,铝的腐蚀电流密度减小,极化电阻增大,缓蚀效率提高;红外光谱测试表明,癸胺通过竞争吸附形式在金属表面成膜.     

多相流动淡水体系中碳钢的中刷腐蚀行为

利用圆桶式冲刷腐蚀实验机,在含砂淡水体系中进行了几种碳钢的冲刷腐蚀失重实验和线性极化电阻测试,讨论了冲刷腐蚀作用的机理.结果表明水流速度加快,含砂粒径增大,冲刷腐蚀失重增加;但当水流速度、砂粒粒径超过一定范围后,冲蚀失重的增加变得不明显.碳钢在水体流动条件下的极化电阻比静态下要小得多,在两相含砂水流中的极化电阻比单相水流中小.实验条件下,碳钢的冲刷腐蚀是机械磨损和电化学腐蚀共同作用的结果,但随着水流速度的增加,机械冲刷的贡献逐渐占主导.     

多相流动淡水体系中碳钢的冲刷腐蚀行为

利用圆桶式冲刷腐蚀实验机 ,在含砂淡水体系中进行了几种碳钢的冲刷腐蚀失重实验和线性极化电阻测试 ,讨论了冲刷腐蚀作用的机理 .结果表明水流速度加快 ,含砂粒径增大 ,冲刷腐蚀失重增加 ;但当水流速度、砂粒粒径超过一定范围后 ,冲蚀失重的增加变得不明显 .碳钢在水体流动条件下的极化电阻比静态下要小得多 ,在两相含砂水流中的极化电阻比单相水流中小 .实验条件下 ,碳钢的冲刷腐蚀是机械磨损和电化学腐蚀共同作用的结果 ,但随着水流速度的增加 ,机械冲刷的贡献逐渐占主导     

氟康唑在3.5%NaCl溶液中对Cu的缓蚀性能研究

采用电化学测试和腐蚀浸泡的方法研究了氟康唑在3.5%NaCl溶液中对Cu的缓蚀性能,初步分析了其对Cu的缓蚀机理。结果表明,氟康唑具有良好的缓蚀作用,在NaCl溶液中随着氟康唑浓度的增加,缓蚀效率增大;随着温度的升高,缓蚀效率减小。电化学研究结果表明,氟康唑对Cu在NaCl溶液中的腐蚀表现为混合抑制型缓蚀剂。表面形貌的分析也指出氟康唑对Cu在NaCl溶液中的腐蚀具有良好的缓蚀效果。     

J55油管钢在模拟CO_2驱油环境下电化学腐蚀行为

本文通过电化学交流阻抗法研究了模拟某CO2驱环境下温度和两相缓蚀剂对J55油管钢腐蚀行为的影响。利用软件拟合Nyquist图获得了电化学腐蚀动力学参数,分析了J55钢的腐蚀行为特征,计算了不同浓度下缓蚀剂对J55钢的缓蚀效率。结果表明,未加缓蚀剂时电荷传递电阻和中间产物电阻均随温度升高而降低;添加缓蚀剂后的电荷传递电阻均远远大于空白试验条件下电荷传递电阻;该两相缓蚀剂用量大于80mg/L时其缓蚀效率大于95%,具有优越抗CO2腐蚀性能。     

空蚀对20SiMn在3%NaCl溶液中的电化学腐蚀行为的影响

利用带电化学测试系统的磁致伸缩空蚀试验机研究了 20SiMn低合金钢在3%NaCl水溶液中的电化学腐蚀行为，通过空蚀和静态条件下的自腐蚀电位变化以及交流阻抗谱和动电位极化曲线的比较，分析了空蚀加速20SiMn低合金钢电化学腐蚀的机理.结果表明，空蚀使20SiMn低合金钢的自腐蚀电位正移200 mV，并显著降低电荷转移电阻和线性极化电阻，使电化学腐蚀速率增大约54倍；随着空蚀的进行，电荷转移电阻和线性极化电阻减小，空蚀3 h后逐渐趋于稳定.     

钢筋在混凝土模拟孔隙液中腐蚀电化学行为

采用动电位极化曲线法研究了钢筋在混凝土模拟孔隙液中腐蚀电化学行为.结果表明:随着Cl-离子浓度升高,PH值下降,腐蚀电流(Icorr)增大,破裂电位(En)降低:致使钢筋表面钝化膜破裂的临界Cl-离子浓度与孔隙液的pH值之间存在对数关系.提出了Cl-和OH-在钝化膜局部区域上的竞争吸附模型,并解释了实验结果.     

An embedded multi‐parameter corrosion sensor for reinforced concrete structures

A prototype of an embedded corrosion sensor has been developed for assessing the corrosion status of reinforcing steel bar (rebar) in concrete. The integrated sensor unit includes an Ag/AgCl probe, a metallic oxide probe, a multi‐electrode array sensor (MAS), and a four‐pin (Wenner) array stainless steel electrode for chloride content, pH, microcell corrosion current, and localized concrete resistivity measurements, respectively. A stable solid probe was used as the reference probe in this unit to express the potentiometric measurement of chloride content and pH probes. In this study, the chloride and pH probes were calibrated in simulated pore solutions (SPSs) regarding temperature and pH fluctuations. The corrosion current results of the MAS probe in SPSs matched very well with those obtained by the linear polarization resistance technique, which was conducted on companion carbon steel specimens. A sensor prototype was embedded into a paste cylinder for long‐term performance evaluation. Up‐to‐date results show that the sensor probes exhibit excellent sensitivity and reliability through 1 year of monitoring. Continuous monitoring in the laboratory for extended periods is underway.     

钢筋在混凝土模拟液中腐蚀行为的EIS特征

研究了钢筋在不同ｐＨ和Ｃｌ＾－浓度的混凝土模拟液中的电化学阻抗谱。发现钢筋在稳定钝化区，孔蚀诱导以及孔蚀发展期的阻抗谱具有不同特征。稳定钝化时，是具有一个时间常数的单容抗曲线；在孔蚀诱导期，低频区阻抗实部呈现电感性收缩现象；在孔蚀发展期，是具有两个时间常数的曲线，建立了相应的等效电路模型，解释了钢筋在混凝土模拟液中的腐蚀机理。     

新型热扩散法制备耐海洋环境腐蚀钢筋及其耐蚀性

通过热扩散工艺在自行研制的钢筋原坯表面形成一层化学成分满足不锈钢要求且耐蚀性能优异的"类不锈钢"表面层。采用XRD、SEM及EDS对热扩散层的相结构、表面形貌和截面成分分布进行了分析和表征。通过浸泡加速腐蚀试验、动电位极化曲线和电化学阻抗谱研究了HRB400、316L以及"类不锈钢"钢筋试样在含氯离子混凝土模拟孔隙液中的腐蚀行为及规律。结果表明,热扩散层主要由Cr_(23)C_6、Fe-Cr和Cr_2N等相组成。在含有氯离子的混凝土模拟孔隙液中,"类不锈钢"钢筋的耐蚀性比HRB400提高了287.4倍,比316L提高了1.4倍。"类不锈钢"钢筋的腐蚀电流密度是HRB400的1/299,是316L的1/223。"类不锈钢"钢筋的极化电阻R_p值是HRB400的28.7倍,是316L的4.5倍。因此,"类不锈钢"钢筋在混凝土模拟孔隙液中的耐氯离子腐蚀性能优于316L和HRB400。     

Characterisation of coating on rebar surface using Hot-dip Zn and Zn-4.9Al-0.1 misch metal bath

The corrosion of rebar is one of the primary causes of premature deterioration of the concrete structure. The ideal option to overcome this situation would be to provide corrosion protection right at the time of manufacturing of the rebar before it is encased in the concrete and hence, warrants the use of corrosion resistance rebar.The present paper outlines characterisation of coating obtained on rebar surface from pure Zn and Zn-4.9Al-0.1 misch metal bath. The coating was characterised by SEM, EDS, Galvanostatic and XRD techniques. In case of pure Zn bath, distinct phases such as eta, zeta, delta and gamma 1 and gamma were identified in coating where as in case of Zn-4.9Al-0.1 misch metal bath no such distinctive phases were found. The coating obtained from Zn-4.9Al-0.1 misch metal bath was thinner and consisted of outer Al₂O₃ phase followed Zn-Al phase resulting in better ductility compare to the coating obtained from pure Zn bath. Comparative corrosion resistance performances of both types of coating respect to uncoated rebar were evaluated by salt spray and tafel test. were conducted in simulated aggressive chloride and concrete pore solution of coated and The coating obtained form Zn-4.9Al-0.1 misch metal bath was found to be more anodic and showed 1.5-3 times better corrosion resistance in concrete pore solution and 2.5 times better resistance against aggressive chloride attack compare to the coating obtained from pure Zn bath. Both the coatings dissolved in faster rate in highly alkaline environment (pH = 13.6) where as dissolution rate decreased with decrease of pH in pore solution. The sacrificial as well as barrier protection of Zn-Al alloy coating was found to be more effective than pure Zn coating. Both types of coated bars showed reduction in bond strength in concrete structure. It is attributed by the faster dissolution of the coating, leading to hydrogen gas evolution thereby creating a gap between the rebar surface and concrete structure.     

Corrosion behaviour in alkaline medium of zinc phosphate coated steel obtained by cathodic electrochemical treatment

The present work evaluated the ability of zinc phosphate coating, obtained by cathodic electrochemical treatment, to protect mild steel rebar against the localized attack generated by chloride ions in alkaline medium. The corrosion behaviour of coated steel was assessed by open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. The chemical composition and the morphology of the coated surfaces were evaluated by X-ray diffraction and scanning electron microscopy. Cathodically phosphated mild steel rebar have been studied in alkaline solution with and without chloride simulating the concrete pore solution. For these conditions, the results showed that the slow dissolution of the coating generates the formation of calcium hydroxyzincate (Ca(Zn(OH)₃)₂·2H₂O). After a long immersion time in alkaline solution with and without Cl⁻, the coating is dense and provides an effective corrosion resistance compared to mild steel rebar.     

Effect of Chloride Ions on the corrosion behaviour of iron-nickel alloys in sulphuric acid solutions

The effect of chloride ions on the corrosion behaviour of binary iron-nickel alloys in sulphuric acid solutions has been investigated using polarization resistance and potentiodynamic polarization measurements. A moderate inhibition effect of the chloride ions on the corrosion of these alloys has been found, which depends on the pH of the medium, as well as on the composition and the structure of the alloys investigated. It has been shown that the action of the chloride ions on the partial corrosion reactions is reflected by an inhibition of the cathodic hydrogen evolution reaction and by an activation of the anodic metal dissolution reaction, the first effect being stronger. Using atomic absorption analysis it has been established that no preferentional dissolution of the alloy components in the presence and in the absence of chloride ions occurs during the corrosion of the iron-nickel alloys.     

不锈钢在模拟混凝土孔隙液中的腐蚀行为研究

利用动电位扫描和交流阻抗法研究了普通碳钢与不锈钢在模拟混凝土孔隙溶液中的腐蚀行为及其差别,以及Cl-浓度、溶液pH值对腐蚀行为的影响,从而探讨了不锈钢取代碳钢作为混凝土钢筋骨架的可能性.结果表明：即便混凝土碳化导致孔隙液pH值下降后,氯离子对不锈钢的影响仍然较小,钝化膜致密完好,而普通碳钢的耐蚀性明显变差,钝化膜极易被氯离子侵蚀而破坏.     

Effectiveness of pretreatment method to hinder rebar corrosion in concrete

Abstract

This paper aims to evaluate the ability of phosphate pretreatments applied on steel rebars to hinder the corrosion reinforcements using synthetic pore electrolyte and mortar contaminated by chloride ions. The electrochemical behaviour of the pretreated substrate was assessed by corrosion potential, polarisation resistance and electrochemical impedance spectroscopy measurements. The results have demonstrated that the treatment of the rebar by immersion in the Na₃PO₄ (0·5M) solution favours the formation of a passive layer on the steel rebar surface, which increases the resistance to corrosion initiation up to 0·3M Cl^– instead of 0·1M Cl^– without treatment. The pretreatment also provides enhancement of corrosion protection of the steel rebar in mortar. The evolution of the impedance spectra in function of chloride concentration is in a fairly good agreement with the results obtained from R_P measurements.     

混凝土保护涂层抗氯离子渗透性研究

在NaCl溶液中对混凝土保护涂层进行干/湿循环加速腐蚀实验,用电化学循环极化法和高压渗水法对混凝土保护涂层的防护效果进行了研究,并将两种方法研究结果进行对比.结果表明：氯盐环境中,混凝土保护涂层可以有效提高混凝土的抗渗性,降低氯盐对钢筋的腐蚀破坏;循环极化测试法可用于研究钢筋钝化膜的溶解特性和钢筋的锈蚀趋势. 