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Reactions of chromium in SO2-containing atmospheres 总被引:1,自引:0,他引:1
The morphology and composition of scales formed on unalloyed chromium in atmospheres containing SO2 at high temperatures have been studied. SEM images show chromium sulfides formed at the metal/scale interface. The results indicate that SO2 may penetrate the scale as molecules, but the rate of this penetration is low. At 600°C formation of Cr2(SO4)3 is also observed by SEM on the scale surface formed in SO2+O2/SO3 mixtures. 相似文献
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We report on the atmospheric corrosion of different cast statue bronzes in humid air containing ppb levels of SO2 and SO2+NO2. In addition, copper, tin, zinc, and lead samples were studied in these environments. The samples were exposed to synthetic atmospheres with careful control of pollutant concentrations, relative humidity and flow conditions. Deposition of SO2 was studied using on-line gas analysis. The weight gain was registered after four weeks exposure, and corrosion products were analysed by Electron Probe Micro Analyser (EPMA), X-ray diffraction (XRD), and Fourier Transform Infrared spectroscopy (FTIR). The synergistic effect of SO2 and NO2 was remarkable on all bronze materials examined. The weight gain was correlated to alloy composition. Thus, high zinc and low lead content resulted in the greatest weight gain, while high tin content favoured a low weight increase. Lead exhibited a rapid deposition of SO2 followed by zinc and copper, while tin was unreactive towards SO2. There was no measurable indication that microstructure influenced corrosion. The corrosion product morphology found in SO2+NO2 environment indicated a localised type of attack. The anodic sites were covered by a tin-rich corrosion product close to the metal. Oxidation of soluble divalent tin by O2 at the anodic sites to form insoluble SnO2 – xH2O, is suggested to explain the corrosion protection afforded by alloying with tin. Tin was enriched in the corrosion products while no lead was found. The zinc/copper relation was higher in the corrosion products than in the alloy composition. 相似文献
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The corrosion mechanisms of T24, T92, VM12, and AISI 304 steels are studied under the influence of NaCl–KCl, NaCl–Na2SO4, and KCl–K2SO4 salt mixtures in a dry air atmosphere at 650°C for 15 days. NaCl–KCl was the most aggressive deposit and AISI 304 stainless steel exhibited the highest corrosion resistance. There was no relation between the Cr content of the ferritic steels and their corrosion resistance in NaCl–KCl. In contrast, the resistance of high-Cr steels was better when exposed to NaCl–Na2SO4 and KCl–K2SO4. The high-Cr and the low-Cr steels were more susceptible to NaCl–Na2SO4 and to KCl–K2SO4, respectively. 相似文献
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Cheng Xiangfeng Cui Zhixiang Contreras Leonel Chen Mao Nguyen Anh Zhao Baojun 《JOM Journal of the Minerals, Metals and Materials Society》2019,71(5):1897-1903
JOM - The attachment of copper matte by bubbles in slags, during the copper smelting process, plays a key role in the copper loss. This paper aims to provide an in-depth insight into the copper... 相似文献
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研究了X65管线钢与316L不锈钢、Inconel 625双金属复合管的异种金属焊缝在CO2环境下的电偶腐蚀行为,以及油酸咪唑啉的缓蚀作用。结果表明,随着电偶电位差的增大,异种金属焊缝的腐蚀速率明显升高,并且都显著高于母材。添加油酸基咪唑啉缓蚀剂能降低异种金属焊缝在CO2环境下的均匀腐蚀速率。但是,当缓蚀剂浓度添加较低时,异种金属焊接试样的碳钢一侧出现了严重的沟槽腐蚀或密集的点蚀坑;进一步增加缓蚀剂浓度才能消除沟槽腐蚀现象。讨论了缓蚀剂对异种金属焊缝电偶腐蚀的抑制机理,该项研究可为异金属焊接接头处的腐蚀防护提供借鉴。 相似文献
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目的研究H2S环境下碳钢腐蚀产物类型及失重腐蚀速率预测模型,为含硫油气田管道腐蚀防护设计与选材提供依据。方法整合H2S腐蚀模拟实验数据,采用随机森林算法对各腐蚀因素重要性进行排序,一方面以腐蚀产物类型为输出量,通过随机森林分类算法建立硫铁腐蚀产物类别预测模型,另一方面以腐蚀速率为输出量,通过随机森林回归算法建立腐蚀速率预测模型,并与其他模型进行比较。运用网格搜索方法对各类算法的超参数进行优选,以提高预测可靠性。结果随机森林算法得出的影响H2S腐蚀产物类型的因素重要性排序为:H2S分压、温度、pH值、实验周期、总压、CO2分压。基于网格搜索优化的随机森林分类模型交叉验证得分超过0.9,f1得分达到0.96,优于其他三种常用分类模型。采用网格搜索优化的随机森林回归模型预测结果与实际值的均方误差为0.86%。相关系数R值为0.979,优于其他两个回归模型。结论网格搜索优化后的随机森林分类、回归模型对含H2S复杂环境下的碳钢腐蚀产物类型及腐蚀速率预测准确性较高,能够为油气田管道腐蚀防护提供参考。 相似文献
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This work presents the results of a morphology analysis of the scale formed on Crofer 22APU steel at high temperature in atmospheres containing SO2. The studies of steel oxidation were conducted on pre-oxidised and non-pre-oxidised steel within the temperature range of 700?C900 °C in a mixture of air of a varying SO2 content and in pure air. In the case of oxidation in pure air it was established that on the surface of the Crofer 22APU a two-layer scale is formed. The outer layer of the scale contains MnCr2O4, whereas the inner layer contains Cr2O3. The scale formed in the atmosphere containing SO2 is also comprised of two layers (outer MnCr2O4 and inner Cr2O3). The analyses were carried out with the use of the 35S isotope. The analyses of the phase composition and morphology of the formed scale were conducted with the use of SEM/EDX and TEM. 相似文献
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借助金相、X射线衍射(XRD)、扫描电镜(SEM/EDX)及X射线荧光光谱仪研究了CuNiCrAl合金在H2SO4溶液中的腐蚀行为.结果表明CuNiCrAl合金在低温H2SO4溶液中,合金中的Cu相较易腐蚀;当H2SO4溶液浓度和温度达到一定值时,合金出现脱铬腐蚀现象,溶液的浓度和温度越高,脱铬倾向越大,且溶液添加NaCl能促进合金的脱铬腐蚀,还对CuNiCrAl合金的脱铬机制进行了探讨. 相似文献
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铝在含SO2湿润/干燥环境中的腐蚀规律 总被引:7,自引:0,他引:7
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。 相似文献
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油管钢在CO_2/H_2S环境中的腐蚀产物及腐蚀行为 总被引:3,自引:0,他引:3
对CO_2/H_2S环境中常规油管钢的腐蚀产物的已有研究成果进行了归纳分析,结果表明,在100℃附近,CO_2/H_2S共存环境中,油管钢表面形成的FeS膜的保护性优于FeCO_3,对金属腐蚀有抑制作用。总结出了油管钢的两类分压比规律:第一类分压比,体系中的CO_2分压保持不变,逐渐增加H_2S的分压,腐蚀速率会出现极值;第二类分压比,体系中的H_2S分压保持恒定,腐蚀速率会随着CO_2分压的升高而增加。这对于进一步完善CO_2/H_2S腐蚀理论以及油气田合理选择油套管材料均有一定指导意义。 相似文献
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Changes of the total weight of tested samples, as well as changes in the weight of the retained atmospheric corrosion products, are studied as functions of corrosion losses in different climate zones and different test duration, for carbon steel, zinc, copper, magnesium, aluminum, Д16 and AMЦ alloys, and brass. An experimental mathematical model for integral weight of formed corrosion products is suggested. Climate effects on the change in the weight of corrosion products retained by metals are studied during long-term exposure of plates and wire spirals recommended by the ISO 9226-92 Standard for the monitoring of atmospheric corrosivity.__________Translated from Zashchita Metallov, Vol. 41, No. 4, 2005, pp. 402–416.Original Russian Text Copyright © 2005 by Panchenko, Strekalov. 相似文献
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Based on an experimental work exposing structural shapes to Mexico City’s atmosphere, a statistical model defining and relating corrosion phases of such, and based on meteorological information, corrosion speeds and maximum pollutants concentration is shown. Phases of steel structural shapes corrosion are: stabilization of corrosion effect, transition of corrosion effect, meteorology effect, transition of exceeding humidity effect and initial phase or corrosion effect. 相似文献
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The study of new paint systems that are less harmful to the environment and to man than traditional solvent‐borne systems, but have identical anti‐corrosive characteristics, is an issue of great interest at the present time. The authors of this work have taken advantage of the opportunity to use different natural atmospheres in the Ibero‐American region to study the behaviour of new water‐borne, high‐solids and powder paint systems, with and without pre‐treatment. The study has involved coatings exposure in 7 natural atmospheres and different laboratory accelerated tests. It was completed with scanning electron microscopy (SEM) observations, energy dispersive spectrometry (EDS) analysis, and adhesion, water up‐take and electrochemical measurements. It has been concluded that water‐borne acrylic paint systems incorporating primers pigmented with zinc phosphate and others show deficient behaviour in marine atmospheres, but better behaviour in industrial atmospheres. In marine atmospheres, water‐borne epoxy paint systems, including zinc‐rich primers, together with epoxy and epoxy‐polyurethane high‐solids paint systems, present the most efficient anti‐corrosive behaviour. The coatings obtained with epoxy and epoxy‐polyester powder paints only show good behaviour, when applied on an adequate pre‐treatment, in atmospheres of low to medium corrosivity category (C2‐C3). Finally, the best correlation was observed between the results of natural exposure in marine atmospheres, salt spray and water up‐take measurements. It was not possible to verify good correlation between natural exposure and prohesion, adhesion and electrochemical tests. The latter are highly sensitive to the chemical nature of coatings, and seem to be significantly more useful when comparing coatings with more identical nature. 相似文献