模拟混凝土孔隙液中钢筋表面膜组成与腐蚀行为的关联

采用XPS分析钢筋经模拟混凝土孔隙液浸泡后表面膜的化学组成,结合线性极化法和动电位扫描阳极极化曲线测试,研究钢筋在模拟混凝土孔隙液中表面膜化学组成与腐蚀电化学行为的关联.结果表明:钢筋在纯模拟液中处于钝化状态.在含Cl和不同pH值的模拟混凝土孔隙液中,随着Cl~-浓度的增加和pH值的降低,钢筋的腐蚀电位负移,电流密度增大;钢筋表面钝化膜Fe~(2+)的含量增加,Fe~(3+)的含量减少.当模拟液中外加Cl~-浓度达0.6mol/L或pH值降至11.31时,钢筋表面不发生钝化,但加入0.24mol/L NaNO_2缓蚀剂后又可使钢筋钝化从而抑制腐蚀.     

氯离子对模拟混凝土孔溶液中钢筋钝性影响的电化学研究

通过动电位极化曲线,电化学阻抗谱以及Mott-Schottky曲线的测试,研究了预钝化电位对模拟混凝土孔溶液中钢筋的钝化作用及氯离子对钢筋钝性的影响.结果表日月,在室温下相对于饱和甘汞电极电位为-0.200-0.200 V范围于不同电位分别预钝化4800 s后,钢筋表面均处于钝态;钝化膜内浅层施主浓度随预钝化电位的升高而减少,深层施主浓度则增加;预钝化电位为0.200 V时,钢筋钝化膜的电荷转移电阻最大;预钝化后的钢筋在含氯离子0.01-0.08 mol/L,pH值为1250的模拟混凝土孔溶液中浸泡24 h后,其表面钝化膜表现为高掺杂的n型半导体,在015-0.47 V电位区间内表现为一种类型的施主浓度,施主浓度随氯离子浓度的升高而减小.     

新型巯基三唑化合物对HCl介质中碳钢的缓蚀作用研究

合成了两种新型巯基三唑化合物，分别采用腐蚀失重法、动电位扫描极化曲线和交流阻抗法研究了其在1．0mol／L HCl介质中对Q235钢的缓蚀作用，分析了缓蚀作用机理．结果表明：对碳钢在1．0mol／L HCl溶液中，合成的巯基三唑化合物是性能优异的缓蚀剂．     

醇胺类化合物对混凝土钢筋的阻锈作用研究

本文研究了醇胺类化合物对混凝土钢筋的阻锈作用。利用静态失重法、极化曲线等方法,在与传统缓蚀剂亚硝酸钠对照的基础上,检测和评价乙二醇和乙醇胺两种醇胺类有机缓蚀剂,对钢筋在含有NaCl的模拟混凝土孔溶液中的电化学腐蚀行为及其阻锈作用。极化曲线图表明模拟混凝土孔溶液pH=11．5和加入缓蚀剂浓度为3％（与孔溶液的体积比）时,醇胺类缓蚀剂对钢筋阻锈效果最好,钝化电位为940mV;静态失重法表明缓蚀剂为水泥重量的3％是防止混凝土钢筋发生点蚀最适宜的浓度,此时缓蚀率达94％;实验同时发现在以上条件下乙醇胺的缓蚀作用与亚硝酸钠相当,且乙醇胺与其它缓蚀剂有良好协同效应,能明显增强其对钢筋的阻锈能力。     

羟基亚乙基二膦酸对20SiMn钢在含Cl-混凝土模拟孔隙液中的缓蚀行为

采用电化学技术(动电位极化曲线、自腐蚀电位、EIS以及Mott-Schottky曲线)和表面分析方法(SEM、XPS)研究了羟基亚乙基二膦酸(HEDP)对空冷20SiMn低合金钢在含Cl-的高碱性混凝土模拟孔隙液中的缓蚀作用及机理。结果表明,HEDP对20SiMn钢在含1 mol/L NaCl饱和Ca(OH)2溶液中的缓蚀效果随HEDP浓度的升高存在极值,最佳浓度为1.441×10-4mol/L。在此浓度下HEDP将20SiMn钢的钝性保持时间从6 h延长至9 h,缓蚀效率达到46.45%～59.78%。在发生点蚀的情况下,HEDP对点蚀的发展亦有显著的抑制作用,缓蚀效率超过93%。电化学和表面分析结果表明,HEDP优先吸附在钝化膜表面,通过竞争吸附机制屏蔽了侵蚀性Cl-向钝化膜表面的附着,从而对其产生保护作用。     

硫脲-二乙烯三胺缩聚物对混凝土中钢筋的缓蚀作用

用动电位极化曲线及电化学阻抗谱研究了硫脲－二乙烯三胺缩聚物在浊凝土孔隙模拟液及混凝土中对钢筋腐蚀的抑制作用。结果表明它是一种混合型缓蚀风筋的点蚀有较好的抑制作用。在模拟液中添加１％的该缓蚀剂就可以使对氯离子的容忍度从０．０２ｍｏｌ／Ｌ提高到０．１ｍｏｌ／Ｌ。它与ＮａＮｏ３有交好的协同作用。它妈能吸附于钢筋表面,又能提高混凝土密实程度,减缓腐蚀介质向混凝土内的渗透。能谱分析的结果表明它能够富集于钢筋     

硫酸盐和温度对钢筋腐蚀行为的影响

采用动电位极化曲线及电化学阻抗法研究了硫酸根和温度对钢筋在混凝土模拟孔隙液中腐蚀电化学行为的影响。发现在有氯离子存在时,硫酸根具有缓蚀作用,提高了钢筋表面钝化膜的抗腐蚀性能;随着温度的提高,钢筋的极化电阻逐渐降低;随着ｐＨ值的提高,极化电阻逐渐增大。文中计算了不同ｐＨ值下腐蚀反应的活化能,并提出了硫酸根离子的缓蚀作用机制。     

三聚氰胺对碳钢在 HCl 介质中的缓蚀作用

目的了解在HCl介质中,三聚氰胺对碳钢的缓蚀作用和缓蚀机理。方法在1 mol/L HCl溶液中添加不同浓度的三聚氰胺,测试碳钢在溶液中的动电位极化曲线和电化学阻抗谱,获得电化学参数和缓蚀效率。再结合量子化学计算结果,分析其缓蚀机理。结果针对碳钢在1 mol/L HCl溶液中的腐蚀,三聚氰胺是一种混合抑制型缓蚀剂,随其浓度的增加,缓蚀效率增大。三聚氰胺通过分子中Mulliken电荷相对较负的氮原子吸附在碳钢表面起到缓蚀作用,吸附过程为自发过程,以物理吸附为主,且符合Langmuir吸附等温方程。结论在HCl介质中,三聚氰胺对碳钢具有一定的缓蚀作用。     

不锈钢钢筋的临界氯离子浓度

采用动电位扫描测量技术和扫描电镜测试了304L和316L不锈钢钢筋与Q235钢筋在模拟混凝土孔溶液中的临界氯离子浓度,并采用XPS分析了304L和316L不锈钢钢筋的钝化膜成分。结果表明,普通碳钢(Q235)、304L、316L不锈钢在pH=12.6的模拟混凝土孔隙液中的临界氯离子浓度分别约为0.06 mol/L、1.2 mol/L、4.0mol/L;相比304L不锈钢钢筋,316L不锈钢钢筋试样表面钝化膜中含有耐腐蚀性的Cr3+的氧化物量更高。     

白酒糟提取物对Q235钢在盐酸介质中的缓蚀作用和吸附行为

采用失重法和电化学法研究了白酒糟提取物作为酸洗缓蚀剂对Q235钢在盐酸介质中的缓蚀作用和吸附行为。失重法研究表明,白酒糟提取物在盐酸介质中能有效抑制Q235钢的腐蚀,25℃,1mol／L的HCl中,白酒糟提取物浓度为24g／L时,缓蚀率达到94．41％;电化学研究结果表明,白酒糟提取物在1mol／I,HCI中属抑制阳极...     

Untersuchungen zum kritischen korrosionsauslösenden Chloridgehalt von Stahlfasern in künstlicher Betonporenlösung

Investigations into the critical corrosion‐inducing chloride content of steel fibres in artificial concrete pore solution It is well known, that reinforcement steel in concrete is normally protected against corrosion due to the high pH‐value of the pore solution of the concrete. This alkalinity leads to a passive layer on the steel surface, which prevents further corrosion. The passive layer can be destroyed by chloride ions diffusing into the concrete. The concentration of chloride in the concrete which leads to a destruction of the passive layer and therefore to corrosion of the steel is defined as the critical chloride content. Investigations in artificial concrete pore solutions show that the critical chloride content of black steel is strongly dependent on the pH‐value of the solution: the higher the concentration of the OH⁻‐ions the higher the critical chloride content. For steel fibres earlier investigations have shown, that steel fibres do not corrode in concrete even at high chloride contents. Therefore it could be assumed, that the critical corrosion‐inducing chloride content of steel fibres in concrete is distinctly higher than of conventional reinforcing steel. To verify this assumption the corrosion‐inducing chloride content of steel fibres is investigated in artificial chloride‐containing concrete pore solutions at different pH‐values. 5 different types of steel fibres, 1 lashing wire and as reference 1 reinforcing steel are investigated at 3 different pH‐value ranges. The concentration of chloride within the pore solution is gradually increased in time steps of 12 h. The beginning of corrosion is determined by current as well as potential measurements. Furthermore additional investigations are carried out with intermediate products of the fibre production (steel wires with different diameters) to investigate if the critical chloride content of the wires is increasing gradually with decreasing diameter. The investigations show, that steel fibres in artificial chloride‐containing pore solutions indicate an distinctly increased resistance against chloride‐inducing corrosion compared with conventional reinforcing steel for high pH‐values. With decreasing diameter of wires the critical chloride content increases gradually.     

铝酸钠溶液中 Na2 S 对 Q235 钢腐蚀的影响

目的研究在含S2-的铝酸钠溶液中Q235钢的腐蚀行为。方法模拟生产条件配制种分母液,采用盐雾腐蚀实验与SEM和EDS分析技术,结合腐蚀质量损失动力学方程与极化曲线,研究Na2S质量浓度与时间对Q235钢腐蚀行为的影响。结果腐蚀产物元素主要为O,S,Al,Fe。在铝酸钠溶液中,基体的表面会覆盖一层Al2O3保护膜,可以阻碍溶液中的硫离子穿透到基体表面,对基体起到一定的保护作用。因此腐蚀初期及低质量浓度下,腐蚀速率缓慢;但随着质量浓度的增加、腐蚀时间的延长,保护膜被破坏,S2-穿过保护膜与基体反应,生成硫化物加速了腐蚀速率;当S2-质量浓度增加到6 g/L,腐蚀时间为9 d时,硫化物被氧化成具有较稳定结构的氧化物,腐蚀被抑制。结论在铝酸钠溶液中,S2-质量浓度及腐蚀时间对腐蚀有一定的促进作用,但当腐蚀时间及S2-质量浓度达到一定值时,腐蚀速率呈现减小的趋势,腐蚀被抑制。     

The use of pumice as a coating for the reinforcement of steel against corrosion and concrete abrasions

This study presents the results of corrosion resistance for pumice collected from pyroclastic exposure in the Van, Kayseri, Nevsehir and Osmaniye regions of Turkey. The corrosion resistance of reinforced steel (RS) and mass losses of concrete specimens were investigated. The specimens were exposed to 5 and 10% sodium sulphate solutions. Reinforced steel mass losses and compressive strengths of concrete were measured. Improvements of the compressive strength and corrosion resistance were observed for specimens with the increasing layers of coating. The corrosion rates of pumice coated specimens were lower than the control specimens. There was a close relationship between type of pumice coating and reinforcement corrosion. Corrosion ratio decreased with increasing amounts of reactive SiO₂. The alkalinity of the concrete, permeability of the concrete cover, the quality of the concrete and the corrosion environment were crucial factors in influencing the effectiveness of the concrete cover for corrosion protection of reinforced steel. All pumice concretes offered excellent resistance to corrosion, where Osmaniye pumice (OP) best increased corrosion resistance of reinforced steel.     

Effect of inhibitor treatment on corrosion of steel in a salt solution

This study examined experimentally different chemicals for inhibition of steel corrosion in a simulated aqueous solution for the industrial marine atmosphere of the Arabian Gulf region. The literature reported various inhibitors that can help in protection against metal corrosion in aqueous environments. Among them, 10 inhibitors (calcium silicate, cyclohexylamine, n-methylcyclohexylamine, dicyclohexylamine nitrite, sodium benzoate, sodium nitrate, sodium nitrite, sodium phosphate, sodium dihydrogen orthophosphate, and magnesium nitrate hexahydrate) were obtained and corrosion resistance of inhibitor applied steel specimens were examined in the simulated solution (2 wt.% NaCl and 1 wt.% Na₂SO₄). Test specimens were prepared from locally produced reinforcing steel products. Treatment of steel with either dicyclohexylamine nitrite or sodium dihydrogen orthophosphate both at 10 mM concentration for 1 day at room temperature resulted in significant inhibition of corrosion. No significant improvement in corrosion inhibition was observed either with an increase in inhibitor concentration at room temperature or with an increase in inhibitor application temperature at 10 mM concentration. A further study is planned to examine the inhibition performances of the two inhibitors under actual atmospheric conditions in the Arabian Gulf region (industrial marine environment).     

Electrochemical Behavior of 316 L Stainless Steel in Alkaline Environments Containing Chloride Ion

This article intends to study corrosion of 316 L stainless steel alloy in simulated concrete environments. A composition of 0.1 M sodium hydroxide plus 0.1M potassium hydroxide with different pH (9, 11 and 13) and 0, 3 and 10 wt % sodium chloride concentration has been utilized for this manner. Potentiodynamic polarization and electrochemical impedance spectroscopy were used to study electrochemical behavior. The results of potentiodynamic polarization indicate that the formed passive layer becomes more stable and its failure takes place later as increasing pH. Electrochemical impedance test also has confirmed the obtained results and also showed that the corrosion resistance of the sample assessed over dilution time. At a solution with high alkalinity (pH 13) results showed increase in total impedance after 24 h of dilution related to passive film stabilization which did not observed in samples with lower pH. In this work, electrochemical behavior of 316 L stainless steel in alkaline environments of simulated concrete is studied with chlorine ion addition and pH adjustment.     

过氧乙酸中硅酸钠对 Q235 钢的缓蚀影响

目的研究HEDP、十二烷基苯磺酸钠(SDBS)和硅酸钠的复配物在过氧乙酸溶液中对Q235钢缓蚀效率的影响。方法采用静态失重法和动电位极化曲线法,研究常温下在过氧乙酸质量浓度为2000 mg/L的体系中,硅酸钠与HEDP、SDBS复配时对碳钢的缓蚀协同效应,确定最佳配比,分析缓蚀机理。结果 HEDP、SDBS和硅酸钠的复配物,在过氧乙酸溶液中对Q235钢均有一定的缓蚀效果,缓蚀效率依次为:硅酸钠与HEDP硅酸钠与SDBS硅酸钠。当硅酸钠质量浓度为200 mg/L,HEDP质量浓度为100 mg/L复配时,缓蚀效率最高达到90.42%。当硅酸钠质量浓度为200 mg/L,SDBS质量浓度为200mg/L复配时,缓蚀效率最高达到57.76%。单一硅酸钠缓蚀剂的缓蚀效率最高达40.53%。结论硅酸钠能同时抑制阳极和阴极的反应,与HEDP有很好的缓蚀协同效应,硅酸钠与HEDP复配优于与SDBS复配的缓蚀效果。较优复配缓蚀剂为:硅酸钠200 mg/L,HEDP 100 mg/L。     

不同表面状态下钢筋的腐蚀行为研究

采用实验室加速腐蚀试验、电化学测量技术研究了不同表面状态下钢筋的腐蚀行为。结果表明:表面带有氧化皮的钢筋的腐蚀行为明显区别于裸表面钢筋。在气相加速腐蚀试验中,裸表面钢筋比氧化皮钢筋有较大的腐蚀失重量;在混凝土模拟孔隙液中,带氧化皮钢筋和端面钢筋(裸钢筋)一样可以在高碱性环境中完全钝化,但随着溶液中Cl-含量上升,钢筋裸表面的钝化膜更易受到破坏,氧化皮钢筋相对端面钢筋维钝电流密度明显减小,破裂电位明显正移,表现出较好的抗Cl-性能。     

Effect of humidity and chloride content on the corrosion of steel embedded in LWA concrete

Measurements have been made with mortar specimens with light aggregates (LWA) and the cements Norcem HS65 and MP30, corresponding to CEM I and CEM II. The w/b ratio was 0.30 and 0.40 and in one mix prewetted LWA was used. The silica fume addition was 8%. The specimens have two sets of electrodes consisting of a 10 mm reinforcing steel and a 10 mm rod of stainless steel. In the start of the experiment the chloride penetration was accelerated by applying a voltage between a negatively charged steel plate within the salt solution and a positively charged net of stainless steel embedded in the concrete above the reinforcing steels. This caused some problems and the set-up was changed to using a Plexiglas brim and a solution of calcium hydroxide and sodium chloride was applied. In the solution, a titanium net was placed and a positive voltage of 12 V was applied between the embedded steels and the net with the titanium net as the positive pole. Measuring galvanic currents, electrochemical potential and polarisation resistances have presented a good picture of the corrosion activity of the embedded steels. There is a distinct effect of the humidity upon the corrosion activity registered by the electrochemical measurements. There is a good relation between the electrochemical measurements and the observed corrosion attacks at the end of the experiments. The LWA concrete with water saturated aggregates showed more corrosion than the corresponding LWA concrete with dry aggregates. The rates of corrosion measured both as a galvanic current and as a function of the polarisation resistance showed that the concrete with watered aggregate concrete had a corrosion rate about twice as high as the corresponding LWA concrete with dry aggregates. There are marked differences in the chloride penetration for the different cements. Effects have been observed on the chloride content of the different concretes. Lower w/b ratio, MP30 cement compared to HS65 and no prewatering of the LWA gave less chloride penetration.     

Study and characterization by acoustic emission and electrochemical measurements of concrete deterioration caused by reinforcement steel corrosion

The durability of reinforced concrete structures becomes a matter of concern, due primarily to the increase of damage by the corrosion of steel reinforcements. This corrosion is not only related to the composition and to the procedure of concrete manufacturing (water/cement, sand/cement, etc.), but also to the aggressive agents as chlorides, carbon dioxide, etc. present in the surrounding medium (Cl⁻, CO₂, etc.). It is well known that the first kind of rebar corrosion (chloride) is more detrimental and that this process contains three basic components: chloride diffusion, electrochemical corrosion and concrete fracture. Therefore the early detection of possible degradation of structures by means of non-destructive testing is essential in order to ensure the functionality of these structures.

This paper presents the results of an experimental investigation on the use of acoustic emission during the corrosion of steel rebars embedded in mortar and immersed in sodium chloride solution. The process of corrosion is accelerated by various imposed potentials and is followed by acoustic emission coupled to electrochemical techniques. The experimental results show that electrochemical techniques can evaluate the corrosive character of the medium used. The acoustic emission showed an activity characteristic of the corrosion initiation phase and the corrosion propagation phase. Thus, it was significantly possible to highlight the acoustic signature of the concrete damage related to the porosity of the mortar and to chloride concentration. The results also show a perfect correlation between the evolution of the acoustic activity and the current of corrosion density.