Q235碳钢在SO2气体中的初期腐蚀行为

通过SO2气体加速腐蚀实验,利用环境扫描电镜(XL30-FEG-ESEM)、能谱分析(EDAX)和Fourier红外光谱(FTIR)等分析技术,研究了碳钢Q235在湿热SO2气氛中的腐蚀行为和锈巢形成机制.结果表明:Q235在不同浓度SO2中腐蚀速率的变化趋势是不同的.浓度较高时,腐蚀速率随腐蚀时间延长而降低;浓度较低时,腐蚀速率随腐蚀时间延长缓慢增加.提高SO2浓度对锈层中含硫化合物的形成影响不大,但对锈层中氧化物或氢氧化物形成起到促进作用.实验条件下的腐蚀产物均含有FeSO4.7H2O,Fe2(SO4)3.9H2O,γ-FeOOH和无定形的δ-FeOOH,当SO2体积分数大于0.5%时,产物中还出现α-FeOOH.在0.05%SO2气氛中,Q235表面形成锈巢,锈巢内、外的各种元素含量差异很大.     

氯离子和电偶腐蚀对碳钢在热钾碱溶液中腐蚀的影响

研究了Cl-对碳钢和不锈钢在(K2CO3+KHCO3+ V2O5)溶液中腐蚀的影响,结果表明Cl-对阳极钝化曲线所示的腐蚀电位、钝化区间、过钝化电位和析氧过程无明显影响,未见试样有孔蚀的迹象.但随着Cl-离子浓度增大,其维钝电流密度也增大.90℃时,不锈钢-碳钢在此溶液中构成电偶腐蚀时,测得碳钢腐蚀速率为0.064 mm/a,比未成偶对时碳钢的腐蚀速率大一倍.90℃时,将已钝化的不锈钢-碳钢在(K2CO3+KHCO3)溶液中构成电偶腐蚀时,测得碳钢腐蚀速率为4.0 mm/a,比含有V2O5溶液中碳钢的腐蚀速率大64倍.     

盐渍土壤湿度变化对碳钢腐蚀的影响

利用电化学的研究方法对盐渍土壤湿度对碳钢腐蚀的影响进行了研究，由极化曲线拟合结果，对于盐湖盐渍土壤来说，最大腐蚀速度出现在20％左右的湿度。而在临界湿度左右时，腐蚀试样的阻抗弧最小，介质的阻抗最小。     

铝在含SO2湿润/干燥环境中的腐蚀规律

利用气体腐蚀试验箱、红外光谱和扫描电镜研究了铝在含SO2 的湿润气氛—不含SO2 的干燥气氛循环的加速试验条件下的腐蚀规律。并进行了未加SO2 而其它试验条件相同的对比试验。试验共分别进行 5个周期(12 0h)。随着时间延长 ,SO2 的腐蚀性作用明显加强 ,铝的腐蚀表现出正指数变化规律 ,即铝的腐蚀速率随时间延长不断增加。结果还显示出铝在含SO2 的潮湿环境中很难形成保护性好的Al2 O3 膜 ,铝在此试验环境中的腐蚀产物为Al2 (SO4 ) 3 ·18H2 O。在未加SO2 的对比试验环境中铝的腐蚀轻微 ,5个周期累计质量增加仅为 0 .0 43g/m2 ,腐蚀质量损失明显小于加SO2 时的腐蚀质量损失 ;试样表面仍很光亮。     

环境因素对锌大气腐蚀影响的试验研究

1 前言 大气中的硫污染,特别是SO_2污染对一些金属材料腐蚀的影响是非常显著的。在不同地点进行的暴露试验研究,表明环境的湿度和SO_2浓度一起对锌腐蚀产生影响。由于大气环境因素复杂,很难人为控制。而且大气暴露试验的周期很长,有必要进行实验室模拟加速试验。国内在采用SO_2模拟工业大气腐蚀研究方面,仅对碳钢做了初步的研究。本文探讨一定条件下锌在SO_2气氛中的腐蚀规律,以及温度、湿度及SO_2浓度对锌腐蚀的影响。     

影响油罐沉积水腐蚀行为的因素

通过重量法和极化曲线法,研究了油罐沉积水腐蚀行为的影响因素.结果表明,几种离子对Q235钢腐蚀的影响由大到小顺序为:Cl->SO2-4>S2-.加入Cl-后,试样表面的孔蚀明显多于加入其他几种离子,随着Cl-含量的增加,局部腐蚀的敏感性增加,且保护电位有所降低;随着Cl-、SO42-浓度的增大碳钢的腐蚀速度先变大后减小;最初刚加S2-时,腐蚀速率大幅度减低,随着加入S2-含量的增加,Q235钢腐蚀速率继续减低,但递减趋势平缓.     

磁阻探针研究碳钢在人造污染大气中的腐蚀行为

建立了一套磁阻探针大气腐蚀检测系统,实现了模拟大气环境下金属腐蚀速率的快速检测.用该检测系统研究了1018碳钢在含有NaCl、Na2SO4、NaNO3、NaCl+Na2SO4和Na2SO4+NaNO3等污染环境下的早期大气腐蚀行为.结果表明:该检测系统可用于研究金属材料的大气腐蚀行为；相同条件下SO2-4的腐蚀性最强,Cl-次之,NO-3最弱;混合污染介质对碳钢腐蚀行为的影响不是单个介质作用的简单叠加,存在较复杂的作用机理.       

预污染处理对碳钢大气腐蚀的影响

通过对北京和江津曝露站3个钢种的预污染样品大气腐蚀失重数据及北京曝露站腐蚀产物组成的分析，讨论了不同污染预处理对碳钢大气腐蚀的影响。结果表明：曝露1年和2年的碳钢在江津地区的腐蚀速率均远远高于北京的腐蚀速率；不同污染预处理对3种碳钢后期腐蚀的影响有所差异，但差别不大，其中NO2预污染处理对这3种碳钢的影响最大；尽管预污染气氛不同，曝露时间不同，但腐蚀产物具有相似的结构，而且主要都由α型羟基氧化铁和γ型羟基氧化铁组成．     

Cl-对CO2环境下的碳钢腐蚀影响

为了研究Cl-对CO2环境下的碳钢腐蚀影响,通过挂片失重实验、腐蚀产物膜形貌观察和腐蚀电化学测试,从多角度分析了Cl-对CO2环境下的碳钢腐蚀影响规律.失重实验表明,20#低碳钢的腐蚀速率随氯离子浓度的增大,出现先增大后逐渐减小的趋势.从腐蚀形貌观测的结果来看,腐蚀产物膜产生由疏松到致密的变化.腐蚀电化学测试则反映出随着Cl-浓度的增大,扩散控制作用逐渐增强以及试样表面活化面积不断的减少.     

烟道气氨法脱硫液对Q235碳钢腐蚀研究

采用静态挂片、极化曲线和长期点蚀实验，研究了氨法脱硫浆液中F^-和Cl^-以及 (NH₄)₂SO₄对Q235碳钢腐蚀的影响。结果表明，Q235碳钢在含卤硫铵溶液中的均匀腐蚀速率随F^-浓度和Cl^-浓度增大均呈现先降低后增高的趋势，随着 (NH₄)₂SO₄质量分数增加，均匀腐蚀速率降低；随着F^-浓度的增大，自腐蚀倾向增加；随着Cl^-浓度以及 (NH₄)₂SO₄质量分数的增大，自腐蚀倾向均降低；Q235碳钢在氨法脱硫模拟浆液中点蚀较严重，需采取重防腐措施。     

Laboratory Testing of the Atmospheric Corrosion of Steel

The atmospheric corrosion of a mild steel (0.09 C) has been studied in flowing atmospheres containing 1, 10 and 100ppm SO₂ at 80, 85, 90 and 96% relative humidity. The flow rate was varied to give SO₂-supplies ranging between 0.4 and 250 μg SO₂ cm^?2 h^?1. After an exposure period of 300 h testing was continued up to 5000 h in atmospheres free from SO₂ at 85–100% relative humidity. Some of the samples were sprayed with distilled water to simulate wetting by rain or condensation. The corrosion attacks were followed by successive weighings. The composition of the corrosion products was studied using X-ray diffraction, IR-spectrometry and ESCA-technique. The flow rates of the SO₂-containing atmospheres were found to have a marked influence on the corrosion attack. The corrosion rates could not therefore be related to the SO₂ concentration of the atmosphere alone but rather to the supply of SO₂ per unit surface area and time. Exposures performed at high SO₂-supply resulted in formation of corrosion products more protective than those formed at lower SO₂-supply. ESCA-analysis proved formation of suphide containing corrosion products at SO₂-supply. ESCA-analysis proved formation of sulphide containing corrosion products at SO₂-supplies ≥ 8 μg SO₂ cm^?2 h^?1. Periodic spraying of the samples with distilled water were found to cause a drastic increase in corrosion attack.     

Atmospheric corrosion of carbon steel under field exposure in the southern part of Vietnam

The corrosion behavior of carbon steel with and without shelter at four test sites (four cities) in the south of Vietnam was investigated in terms of the environmental factors such as average relative humidity, rainfall, sulphur dioxide and chloride depositions, and various exposure periods. The mass losses of the specimens with shelter at four test sites were related to SO₂ concentration at each site. Without shelter, the mass loss at HoChiMinh was lower than that with shelter, whereas those of the other sites were higher without shelter than with shelter. Although the corrosion behavior at HoChiMinh was difficult to explain based on the environmental factors, it was estimated from a protective corrosion products caused by a synergistic effect among SO₂ concentration, rain and sunlight.     

Corrosion simulation of carbon steels in atmospheric environment

Atmospheric corrosion simulation of carbon steels has been performed in order to clarify the atmospheric corrosion mechanism of carbon steel. The corrosion simulation was conducted in a chamber by controlling the environmental factors such as temperature, relative humidity and temperature of carbon steels. When the corrosion simulation was conducted using only the data of temperature and relative humidity, although the carbon steel in the corrosion simulation showed almost the same corrosion behavior as that in outdoor environment, the corroded area of the former was smaller than that of the latter. In order to simulate dew condensation, the temperature of carbon steel was controlled by a cooling-system. As a result of the corrosion simulation, both the corrosion behavior and the corroded area were almost the same as those in outdoor environment. It was concluded that the initial atmospheric corrosion of carbon steel in the shielded environment could be simulated in the chamber by controlling the temperature, the relative humidity and the temperature of materials.     

The influence of sodium chloride on the atmospheric corrosion of steel

The influence of sodium chloride on the atmospheric corrosion of mild steel has been studied. Samples covered with sodium chloride crystals (8 m?g NaCl · cm^?2) have been exposed to an SO₂-free atmosphere at different relative humidities. The combined effect of sodium chloride crystals on a steel surface and sulphur dioxide in the atmosphere has been investigated at an SO₂-supply of 1 m?g SO₂ · cm^–2 · h^–1 (1 ppm SO₂). The corrosion attack was followed by periodic weighings. The corrosion products formed have been studied using the SEM-technique. On exposure of samples with sodium chloride in an SO₂-free atmosphere the extent of corrosion increased with increasing relative humidity from 58% to 90%, interrupted by a sharp minimum at about 87% relative humidity. The SEM-studies showed that tower shaped corrosion products were formed at a high relative humidity while filiform corrosion appeared when the relative humidity was lowered. At 90% relative humidity more corrosion was observed with clean steel samples and an SO₂-supply of 1 m?g ·cm^–2 ·h^–1 than with sodium chloride crystals on the surfaces (8 m?g NaCl ·cm^–2) in the absence of SO₂. In the combined influence of sodium chloride on the steel surfaces and sulphur dioxide in the atmosphere a synergic effect was noticed at 90% relative humidity. At 70% relative humidity no influence of an SO₂-supply of 1 m?g SO₂ ·cm^–2 ·h^–1 on the corrosion of steel samples with sodium chloride crystals on their surfaces could be observed.     

Q235 钢在模拟海洋大气环境中的耐蚀性研究

目的研究Q235钢在海洋大气环境中的耐蚀性能,分析近海环境下Q235钢的腐蚀机理。方法采用盐雾试验、恒温恒湿试验等,模拟海洋大气环境,研究不同温度、相对湿度、氯离子含量下Q235钢的腐蚀规律,并利用表观腐蚀形貌分析、金相分析及XRD等技术手段,分析对应的腐蚀形貌和腐蚀产物。结果模拟海洋大气环境下,Q235钢腐蚀速率随温度升高而增加。随着氯离子含量增加,Q235钢腐蚀速率先增加后减小,当Na Cl质量分数为1.75%时,其腐蚀速率最大。相对湿度增大可以加速Q235钢腐蚀,相对湿度大于85%后,其腐蚀速率急剧增大。盐雾环境下,Q235钢的腐蚀类型为点蚀,主要腐蚀产物为Fe2O3和Fe3O4。结论海洋大气环境下,温度、相对湿度、氯离子含量均为Q235钢腐蚀的重要影响因素,腐蚀危害表现为点蚀穿孔,需要采取表面防护措施。     

The effect of H2S concentration on the corrosion behavior of carbon steel at 90 °C

The electrochemical behavior of SAE-1020 carbon steel in 0.25 M Na₂SO₄ solution containing different concentrations of H₂S at 90 °C was investigated using the methods of weight loss, electrochemical measurements, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that the corrosion rate of carbon steel increased significantly with the increase of H₂S concentration. H₂S accelerated the corrosion rate of SAE-1020 carbon steel by a promoted hydrogen evolution reaction. Severe corrosion cavities were observed on the carbon steel surface in the solutions containing H₂S due to cementites stripped off from the grain boundary. The loose corrosion products formed on the steel surfaces were composed of mackinawite.     

Corrosion behaviour of carbon steel in different concentrations of HCl solutions containing H2S at 90 °C

The corrosion behavior of SAE-1020 carbon steel in H₂S-containing solutions with different concentration of HCl at 90 °C was investigated by weight loss, electrochemical measurements, SEM and XRD analysis. The results showed that the corrosion rate of carbon steel increased with increasing HCl concentration. Uniform corrosion was found on the carbon steel surface in H₂S + HCl solutions, while corrosion cavities were observed in the solution only containing H₂S. The ratio of Faradaic process of total corrosion process increased with the increase of HCl concentration. The corrosion products were solely composed of mackinawite in the H₂S-containing solutions with or without HCl.     

High-Temperature Corrosion of A210-C Carbon Steel in Simulated Coal-Combustion Atmospheres

Corrosion of A210 C carbon steel was investigated under three different conditions: (1) using synthetic gas mixtures with varying amounts of O₂, SO₂, and HCl; (2) in the flue gas introduced from a coal-fired fluidized-bed combustor (FBC), with and without a deposit cover; and (3) within the freeboard of the FBC firing two different coals. Generally, the oxide scale formed in the temperature range of 370–560°C was mainly Fe₂O₃. The oxidation rate was significantly increased with an increase in temperature. In the synthetic gas mixtures SO₂ and HCl caused scale damage by weakening of the scale-metal interface. The combination of the gases can greatly accelerate the metal corrosion. In the FBC flue gas (condition 2), deposit additions exerted a significant effect on accelerating the metal corrosion. In the FBC freeboard tests (condition 3), the atmospheres containing a higher content of SO₂ and HCl increased the metal corrosion in comparison to corrosion in low-SO₂ and HCl-containing atmospheres. In the former case, an S-enriched phase or pits formed in the residual wastage at or near the metal. This may be the cause of wastage spallation. The HCl effect is discussed but is not conclusive. Moreover, in the FBC system, erosion and deposition appeared to play important roles in exaggerating metal recession.     

樟树叶提取液在硫酸介质中对碳钢的缓蚀作用

应用动电位极化法和电化学阻抗(EIS)研究了樟树叶提取液(CCLE)在硫酸介质中对碳钢的缓蚀性能和缓蚀机理. 结果表明, 采用酸浸泡法从樟树叶中提取的缓蚀剂, 对碳钢在10% H₂SO₄溶液中具有良好的缓蚀作用, 随着提取液浓度的增加, 缓蚀效率增大; 随着实验温度升高, 缓蚀效率减小. 樟树叶提取液为混合抑制型缓蚀剂, 提取液中的有效缓蚀成分在碳钢表面的吸附满足Langmuir等温吸附方程; 樟树叶提取液的加入使碳钢在硫酸中反应的表观活化能增加, 起到缓蚀作用.     

Corrosion behavior of twinning‐induced plasticity (TWIP) steel

In this study, the corrosion behavior of twinning‐induced plasticity (TWIP) steel i.e. Fe‐Mn‐Al‐Si steel subjected to cold‐working (0, 20, and 35%), was examined in acidic (0.1 M H₂SO₄), alkaline (0.1 M NaOH) and chloride‐containing (3.5% NaCl) environments, using potentiodynamic polarization experiments. Interestingly, cold‐working did not show any significant change in the corrosion susceptibility of TWIP steel in all the three environments. However, TWIP steel showed the highest corrosion susceptibility in acidic environment and the lowest in alkaline environment. Scanning electron microscope analysis of the corroded TWIP steel samples revealed high‐localized attack in acidic environment and some pitting corrosion in chloride‐containing solution.