碳钢试片实海电化学检测与腐蚀规律的相关性

引言 由于海水腐蚀的严重性和复杂性,材料在海洋环境中的腐蚀数据积累及试验研究一直受到各国的重视.美国ASTM曾委托LaQue腐蚀试验中心开展了全球14个海水腐蚀站点的材料腐蚀试验[1],为评价世界范围内海水的腐蚀性提供了依据.     

Interactions between steels and sulphide-producing bacteria—Corrosion of carbon steels and low-alloy steels in natural seawater

Metallic infrastructure immersed in natural seawater is exposed to important corrosion phenomena, which are sometimes characterised by microorganism influenced corrosion. The presence of sulphide-producing bacteria is generally associated with catastrophic cases of material degradation. In this work, commercial steel grades (carbon steels and low-alloy steels) are immersed for approximately 1 year in two types of natural seawater, which contain different concentrations of sulphide-producing bacteria. Gravimetric, microbiological, and electrochemical measurements and corrosion product analyses indicate that in seawater the observed corrosion phenomenon is composed of two different phases. The first phase is characterized by decreased corrosion kinetics correlated with a higher concentration of sessile sulphide-producing bacteria and the formation of sulphur-containing chemical species. The second phase is marked by an increased rate of corrosion. This multidisciplinary study demonstrates the complexity of the interactions between steels and bacteria. The presence of alloying elements in the steel composition affects the rate of corrosion and growth patterns of sessile sulphide-producing bacteria. At the same time, the presence of sulphide-producing bacteria affects in the process of steel corrosion in natural seawater.     

奥氏体钢盐雾腐蚀研究

本文采用盐雾腐蚀方法评价奥氏体钢的抗盐雾腐蚀性能,利用金相、XRD对材料的组织进行了分析,对该材料在盐雾环境中的腐蚀形态进行了观测,结果表明该材料在盐雾环境中的腐蚀形态以点蚀为主,并提出在盐雾环境中使用该材料的热处理方法,以提高该材料的耐盐雾腐蚀性能.     

High-density polyethylene coating on carbon steel by an electrostatic powder spray system

Plain carbon steel specimens were surface-treated mechanically and then chemically before applying high-density polyethylene (HDPE) coating. Pretreated specimens were coated with HDPE powder, both with and without a heat stabilizer (Irganox 1010), using a spray electrostatic technique. Effects of various variables, such as surface roughness, prephosphating treatment, addition of stabilizer, and the role of curing time and temperature were investigated. Mechanical and immersion tests were conducted to measure adhesion, ductility, and corrosion resistance of the coated specimens. Scanning electron microscopy and infrared spectroscopy were used to study the microstructure of produced coating and its interface with the substrate, as well as the possible chemical changes that occurred. The results obtained revealed that, pure HDPE can be coated on plain carbon steel with a good performance. It was further observed that an addition of 0.5 wt % of heat stabilizer to HDPE powder increases the performance of produced coating significantly. This was evidenced by the measurements of adhesion, ductility, and corrosion resistance in sulfuric acid, sodium hydroxide, ferric chloride, water, and salt spray, as well as scanning electron microscopic examinations and infrared spectra. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2507–2513, 1998     

油田污水腐蚀影响因素研究

为研究各种因素对油田污水腐蚀的影响,采用室内静态挂片失重法试验了A3碳钢在不同H2S、CO2、溶解氧、SRB浓度及不同pH值和矿化度的模拟油田水中的腐蚀行为。结果表明,碳钢的腐蚀速率随H2S、CO2、溶解氧、SRB浓度的增加而增大,溶解氧会促进H2S和CO2的腐蚀,H2S会抑制CO2的腐蚀;碳钢的腐蚀速率随矿化度的增加先增大后减小,在矿化度为40 000 mg/L时达到最大;碳钢在碱性环境下的腐蚀速率比酸性环境下的腐蚀速率小的多。     

Corrosion inhibition of carbon steel under two‐phase flow (water‐petroleum) simulated by turbulently agitated system

The corrosion of carbon steel in single‐phase (water with 0.1N NaCl) and two immiscible phases (kerosene‐water) using turbulently agitated system was investigated. The experiments were carried out for Reynolds number (Re) range of 38 000 to 95 000 using circular disc turbine agitator at 40°C. In two‐phase system, test runs were carried out in aqueous phase (water) concentrations of 1% vol, 5% vol, 8% vol, and 16.4% vol mixed with kerosene at various Re. The effect of Re, percent of dispersed phase, dispersed droplet diameter, and number of droplets per unit volume on the corrosion rate were investigated and discussed. Test runs were carried out using two types of inhibitors: sodium nitrite of concentrations 20, 40, and 60 ppm and sodium hexapolyphosphate of concentrations 485, 970, and 1940 ppm in a solution containing 8% vol aqueous phase (water) mixed with kerosene (continuous phase) at 40°C for the whole range of Re. It was found that increasing Re increased the corrosion rate and the presence of water enhanced the corrosion rate by increasing the solution electrical conductivity. For two‐phase solution containing 8% vol and 16% vol of water, the corrosion rate was higher than single phase (100% vol water). The main parameters that play the major role in determining the corrosion rate in two phases were concentration of oxygen, solution electrical conductivity, and the interfacial area between the two phases (dispersed and continuous). Sodium nitrite and sodium hexapolyphosphate were found to be efficient inhibitors in two‐phase solution for the investigated range of Re.     

碳钢在固/液两相流条件下流动腐蚀的数值模拟

在单相流数值计算的基础上,引入固相颗粒运动理论,对双相流中的碳钢磨损腐蚀进行了数值模拟.结果表明：在0～18m•s^-1流速范围内,固体颗粒与材料壁面的碰撞角度、碰撞频度和碰撞速度等颗粒相力学参数对表面切应力、传质系数影响强烈,导致碳钢磨损腐蚀加剧,但对碳钢的切削磨耗作用不大.腐蚀速度的模拟计算值与实测值基本一致,验证了碳钢在两相流加剧腐蚀的协同效应中腐蚀电化学作用仍占主导地位.随着流速进一步增大,磨耗量虽小,但会有所增加.     

Effects of sulfate-reducing bacteria on the corrosion behavior of carbon steel

The influences of the growing process of sulfate-reducing bacteria (SRB) in seawater system on the medium state and corrosion behavior of carbon steel were studied by detecting solution state parameters and using corrosion electrochemical methods. The growing process of SRB in the seawater shows the three stages of growing, death and residual phases. The solution state parameters of the concentration of sulfide, the pH value and the redox potential changed during the three stages of the SRB growing process. And the corrosion rate of D36 carbon steel was accelerated during the growing phase and stable during the death and residual phases. The results indicate that the medium state and the corrosion rate of the steel do not depend on the number of active SRB, but depend on the accumulation of the metabolism products of SRB.     

Electrochemical investigation of the corrosion behavior of chromium-modified carbon steels in water

Electrochemical measurements were performed on four steels with different chromium (Cr) contents in simulated CANDU reactor coolant at room temperature to investigate the influence of chromium content on the corrosion behavior of the steels. The addition of chromium to carbon steel can promote passivation. The passive film significantly decreases the corrosion rate, and thus improves the corrosion resistance of the steels as chromium content is increased. Repassivation kinetic experiments indicate that there is a more rapid repassivation rate and a more stable passive film on steels containing a higher concentration of chromium. The slip-oxidation model was used to calculate the crack growth rate (CGR) on the steels. The 304L stainless steel has the highest CGR with an increase in potential of the steels studied. Chromium modification of steels can improve the resistance to corrosion. However, its influence on cracking and crack growth must be taken into consideration. The 2.5%Cr-1%Mo steel gave the best overall results when considering both the corrosion and the cracking behavior of the steels studied.     

Corrosion Resistance of Steels Used in Alcohol and Sugar Industry

Evaporators used in power plants for sugar production are vessels with two boxes of heat exchangers. These heat exchangers made of a low‐corrosion resistance material are frequently replaced during the alcohol production process. In view of the growing production of cane, sugar, and alcohol, and the corrosion of materials used in power plants, it was necessary to find alternative materials for carbon steel applied in the evaporators. A comparative study of the corrosion resistance of stainless steel as well as unalloyed and alloyed carbon‐manganese steels in neutral and acid sugar cane juice electrolytes is presented. The alloyed carbon steels showed the best corrosion behavior in an acid environment compared to a neutral medium. Among the alloyed carbon steels, ASTM T11 and ASTM T22 steels provided the highest corrosion resistance in sugar cane juice.     

不同镀层结构钢的耐盐雾腐蚀性能比较

通过盐雾试验模拟潮湿环境,对裸钢试片、电镀锌钢试片、化学镀镍-磷钢试片和化学镀镍-钴-磷钢试片进行了宏观形貌、微观形貌和腐蚀产物成分分析,比较了四个试片的耐盐雾腐蚀性能。结果表明:在盐雾环境中,四个试片均会发生电化学腐蚀,生成不同的腐蚀产物;在盐雾腐蚀周期内,裸钢试片的腐蚀速率最高,化学镀镍-磷钢试片和化学镀镍-钴-磷钢试片的腐蚀速率较低;四个试片在腐蚀过程中的阳极反应和阴极反应不同,腐蚀后的微观形貌存在明显差异。     

Comparative studies on the corrosion inhibition efficacy of ethanolic extracts of date palm leaves and seeds on carbon steel corrosion in 15% HCl solution

The work reports on the study carried out to comparatively assess the corrosion inhibition efficacy of crude ethanolic extracts of date palm leaves and seeds on X60 carbon steel corrosion in 15% HCl solution at 25–60 °C. The corrosion inhibition studies was carried out using weight loss and electrochemical (potentiodynamic polarization and linear polarization resistance) techniques. Preliminary phytochemical screening was performed in order to determine the phytoconstituents present in the crude extracts. The influence of extractive solvents on the corrosion inhibition performance of the extracts was also investigated. It is found that the crude extracts of both date palm leaves and seeds contain saponins, flavonoids, cardiac glycosides and reducing sugars. Tannins is only present in the leaves and absent in the seeds while anthraquinones is absent in both extracts. The crude ethanolic extracts inhibited the corrosion of X60 steel in the aggressive 15% HCl solution with the leaves extract showing superior performance. Inhibition efficiency increased with increase in concentration of the extracts and temperature. Potentiodynamic polarization results reveal that the extracts function as mixed type inhibitors. Corrosion inhibition occurs by virtue of adsorption of components of the extract on the steel surface and was found to follow Langmuir adsorption isotherm model. On the influence of the extractive solvents on the corrosion inhibition performance, the order of inhibition efficiency at 60 °C follows the trend DPLAE (73.6%) > DPLEE (62.5%) > DPSAE (59.9%) > DPSEE (55.9%) with the optimum extract concentration (2000 ppm) studied.     

Surface conductivity and stability of metallic bipolar plate materials for polymer electrolyte fuel cells

Different types of commercial stainless steels, Ni-based alloys and nitride-coated steels were evaluated as metallic bipolar plate in terms of interfacial contact resistance (ICR) and corrosion resistance in conditions typical of PEFC anode and cathode environments. Results show that stainless steel have a high ICR and undergo corrosion in both anode and cathode. Moreover, although Ni-based alloys showed an ICR comparable with graphite, their behaviour was not satisfactory in corrosive acidic medium. Only nitride-coated stainless steel demonstrated to have low ICR and very good corrosion resistance.     

水源热泵用换热设备常用金属的腐蚀性能

目前有关金属腐蚀的研究多集中在探讨影响腐蚀的因素以及防腐蚀相关技术,有关换热器金属腐蚀经济性的文献较少。本文采用挂片失重试验,结合电镜分析,分别研究了碳钢10^#、不锈钢316L、紫铜T2和铝合金LF21在海水和污水中的腐蚀速率、电偶腐蚀速率以及微观腐蚀形貌;并运用模糊综合评价法进行评价,为合理选择换热设备金属材料提供依据。结果表明,根据金属均匀腐蚀耐蚀性十级标准,不锈钢316L、紫铜T2与铝合金LF21都属于耐蚀金属,不锈钢316L在静止和流动水环境中,均具有最好的耐蚀性;在严格避免与电位较正金属偶合使用的前提下,铝合金LF21比碳钢10^#和紫铜T2耐蚀,其经济性也较为优秀;碳钢10^#虽耐蚀性差但胜在价格优势,是实际工程最常用的金属材料。     

Nanocarbon containing low carbon Al2O3–C refractories: Comparison between N220 and N990 nanocarbons

Continuous casting process is the majorly used solidification process in steel fabrication. The refractories used in this process are most commonly made up of alumina-carbon-based compositions. Generally, these functional refractories consist of about 30% residual carbon after coking. Improvements in steel industries, such as attaining clean steel and ultralow-carbon steel, require alumina-carbon refractories with low carbon content. In the present work, low carbon-containing Al₂O₃–C refractories are studied by using two different grade nanocarbons, namely, N220 and N990 with varying amounts, along with fixed 3-wt% graphite in the batch composition. The physical, mechanical, and thermomechanical properties along with the oxidation resistance are evaluated and compared. Phase analysis and microstructural developments at different temperatures were also characterized. Optimized compositions of both the nanocarbons are further studied for hot strength and oxidation resistance measurement. Based on all the obtained results, one batch composition is finalized for the thermal shock and corrosion testing. All the results are compared against a reference batch composition containing 25% graphite as a carbon source. The formation of in situ ceramic phases like aluminum carbide in nanocarbon-containing compositions provides a dense compact microstructure that improves strength, helps to inhibit oxidation, and contributes to corrosion resistance.     

碳钢化学镀Ni-P镀层在NaCl溶液中的耐蚀性

采用化学镀法得到了碳钢化学镀Ni-P镀层(以下简称镀层),通过SEM和XRD对镀层进行了表面形貌、结构与耐蚀性的表征。结果表明:镀层表面光滑致密,属非晶态结构。在为期15 d的浸泡中,20μm厚的化学镀Ni-P镀层比较稳定。     

不锈钢和低碳钢在高浓度相变储能溶液体系中的腐蚀行为

文章研究了10号钢、20号钢、314和316L不锈钢在高浓度三水醋酸钠和饱和硫酸铵铝两种相变储能溶液体系中的腐蚀行为,采用PS-268B电化学工作站测试四种钢材在这两种体系中的极化曲线。实验结果表明,316L不锈钢在高浓度醋酸钠溶液体系中耐蚀性能最好,自腐蚀电流密度为6.89×10-5 A·cm-2,与20号钢(0.855 A·cm-2)相比,少了四个数量级。316L不锈钢在饱和硫酸铵铝溶液体系中耐蚀性能最好,自腐蚀电流密度为0.025 A·cm-2,仅为20号钢(0.133 A·cm-2)的五分之一。对钢种进行归纳,综合比较,不锈钢在两种溶液中的耐蚀性能比低碳钢优异。     

High Cr ODS steels performance under supercritical water environment

This paper summarizes the results of supercritical water corrosion studies of two ferritic oxide dispersion strengthen (ODS) steels MA956 and PM2000 at the temperature of the upper limit of potential peak cladding temperature under normal operation, according to the conceptual design being developed in the EU. As the high temperature and pressure above the thermodynamic critical point of water result in higher oxidation rate for conventional austenitic alloys than observed in sub-critical light water reactor (LWR) conditions, ensuring adequate corrosion resistance is critical for thin-wall components like fuel cladding. This study concentrated on the investigation of two effects, surface finish and orientation of the cuts. Two different surface treated coupons were prepared in order to study the effect of cold work in sample surface on corrosion resistance. Samples were exposed in supercritical water at 650 °C and 25 MPa, for up to 1800 h. The corrosion rate was evaluated by measuring the weight change of the samples and by cross-section examinations. The microstructure of the oxide layers was analyzed using a scanning electron microscope (SEM) in conjunction with energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). Weight gain results of both ODS steels proved a good resistance to general corrosion. Nevertheless the cross-sectional SEM study showed signs of nodular corrosion, observed mostly on the ground specimens after long exposure times.     

碳钢浸铜处理后在盐酸溶液中的耐蚀性

采用浸渍法在碳钢表面获得了铜化学沉积膜。电化学方法初步研究了铜膜在1mol／L Hcl溶液中的耐蚀性。结果表明，浸铜处理提高了碳钢的耐蚀性能，这种铜转化膜与碳钢表面结合良好。     

PTA装置不锈钢材料腐蚀磨损的探讨

采用自制的实验装置,模拟PTA生产装置中回转式干燥机蒸汽列管工作条件,对奥氏体不锈钢0Cr18Ni9(304)、00Cr17Nd4Mo2(316 L)、00Cr19Ni13M03(317 L)和双相不锈钢00Cr22Ni5Mo3N(2205)在含有溴离子和对苯二甲酸颗粒的醋酸介质中,进行腐蚀磨损性能研究。结果表明,4种不锈钢的腐蚀磨损速率随着腐蚀介质温度的升高而增加;在低温时,腐蚀磨损速率差别不大;当温度超过80℃以后,腐蚀磨损性能的差异变大,其中2205的耐腐蚀磨损性能最好,其次为317 L,316 L,而304则最差。相同条件下,腐蚀磨损速率大于均匀腐蚀速率。建议用2205代替316 L制作PTA同转蒸汽管干燥机的加热列管。