Surface modification of ZrO2 nanoparticles with styrene coupling agent and its effect on the corrosion behaviour of epoxy coating

The surface of ZrO2 nanoparticles was modified by styrene coupling grafting method to improve the dispersion and interaction of the nanoparticles with the epoxy coating in which the modified ZrO2 nanoparticles were used as an additive. The grafting performance and microstructure of the nano- ZrO2/epoxy coating were analyzed by Fourier transformation infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The corrosion behavior of the nano-ZrO2/epoxy coating on mild steel was evaluated in neutral 3.5 wt% NaC1 solution using electrochemical impedance spectroscopy （EIS）. Both the coating capacitance and coating resistance fitted by the equivalent circuit from EIS were used to evaluate the protective performance of the coating towards the mild steel. The results show a superior stability and efficient corrosion protection by the modified ZrO2 nanoparticles. The epoxy coating containing 2 wt% modified ZrO2 nanoparticles exhibited the best corrosion performance among all the coating specimens. This research may provide an insight into the protection of mild steel using modified epoxy coatings.     

Alloy elements' effect on steel corrosion in marine environment

INTRODUCTIONBesidesprotectivecoatingandcathodicprotectionmethodsagainstcorrosionoflowalloysteelconstructuresinmarineenvironment,itisalsoimportanttoimprovethecorrosionresistanceofthelowalloysteelitself.Therearefewreportsontherelationshipofalloyelementandthecorrosionre sistanceofsteel .Larrabee (1 958)’s 5-9yearsseaexperimentusinglong scalesteelshowedthatthecorrosionresistanceof 0 .5%Ni-0 .5%Cu -0 .1 %Psteelwasthehighestinthesplashzone .HouandZhang (1 980 )consideredthataproperrelationshi…     

EFFECT OF SULPHATE-REDUCING BACTERIA ON ELECTRO-CHEMICAL CORROSION BEHAVIOR OF 16Mn STEEL IN SEA MUD

ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｗａｓｇｅｎｅｒａｌｌｙｃｏｎｓｉｄｅｒｅｄｐｒｅｖｉｏｕｓｌｙｔｈａｔｔｈｅｃｏｒｒｏｓｉｏｎｏｆｓｔｅｅｌｉｎｓｅａｍｕｄｗａｓｎｏｔｓｅｒｉｏｕｓ.Ｈｏｗｅｖｅｒ,ｉｔｗａｓｌａｔｅｒｆｏｕｎｄｔｈａｔｔｈｅｃｏｒｒｏｓｉｏｎｒａｔｅｏｆｓｔｅｅｌｉｎｓｏｍｅｓｅａｍｕｄｗａｓｈｉｇｈｅｒｔｈａｎｔｈａｔｉｎｓｅａｗａｔｅｒ(Ｋｉｎｇ,1980;Ｓｅｈｍｉｄｅ,1982;Ｇｕｏｅｔａｌ.,1997;Ｈｏｕ,1998).Ｔｈｅｒｅａｒｅｓｏｍｅｒｅｐｏｒｔｓｔｈａｔｔｈｅｃｏｒｒｏｓｉｏｎｒ…     

Study on rust layers on steel in different marine corrosion zone

IrmODUCnONTheMossbaureffect(ME)isalsoknOWnasrecoil-thenuclearresonaneabsorp-hon.MossbaursPeCboscoPy(MS)haspIDvedtobeaveryuSefultecheqUeforstudytngcormsionPimessesandcedon-cts.TheInainadvantagsofMSincormsionre-enhare:(l)thenon-deStrutivechateroftheteCboqUe;(2)possibilltyforquali-tativeandqUanitativephaanalsis;(3)uSehassinidenificationofPOOrlycrystal-lizedoramorphouscormsionpnhats.WththedeVfoPmntofInarineresomees,InansteelconstrUctionswerebulltatsea'MSwasusedforanalfongcormsion~t…     

The Study of the Varying Characteristics of Cathodic Regions for Defective Coating in 3.5% Sodium Chloride Solution by EIS and WBE

The current distributions over carbon steel under iron red alkyd primer exposed to 3.5% sodium chloride solution were mapped using the wire beam electrode(WBE). The electrochemical impedance spectroscopy(EIS) of the WBE was carried out to analyze the performance of coating delamination and corrosion behavior of carbon steel beneath defective coating. The EIS data revealed that protective capability of coating decreased with immersion time and the degree of cathodic delamination showed a rapid rise. The current density distribution of WBE indicated that cathodic sites was located at the defect at the beginning of immersion and gradually spread into the intact coating. The cathodic regions were distinguished from the anodic area and distributed over the WBE. The changes of cathodic sites could reflect the deterioration process of defective coating. The cathodic area ratio was a more useful parameter than the cathodic delamination degree to evaluate the coating cathodic delamination. The polarity reversals of electrodes at the defect and beneath coating were observed. A simple discussion of relationship between the blister and the polarity reversal was made from a standpoint of electrochemical distribution. WBE method was able to map and record the changes of local cathodic sites beneath defective coating in real time, which could provide more detailed information about the local degradation of coating.     

Electrochemical measurement of steel corrosion in seabottom sediment with “MD” method

The through one year corrosion potential and polarization resistance for 3 kinds of steels in seabottom sediment of Liaodong Bay were measured with the “MD” method. The measurements will have some theoretical and practical values. The theoretical value lies in that the recorded changing process of the practical corrosion case can be basis for indoor discussion and electrochemical research on the corrosion process. The practical value lies in that the obtained data can be basis for designing and controlling electrochemical protection systems. In fact, it is very difficult to measure in situ the corrosion parameters of steels in sea sediment. Contribution No. 2611 from the Institute of Oceanology, Chinese Academy of Sciences. This study is a major project of the Chinese Academy of Sciences.     

ELECTROCHEMICAL MEASUREMENT OF STEEL CORROSION IN SEABOTTOM SEDIMENT WITH “MD” METHOD

The tbough one year cormsion potential and polarisation resistanoc for 3 kinds of stals in seabottomedment of Liaodong Bay were measured with the “MD” method.The measurements wiIl have some thoretical and pndital talues. The thooretical valoc lies in thatthe reoorded changing process of the practital corrosion case can be basis for indoor discussion andeectrochemical on the corrosion practical value lies in that the obtained datu canbe basis for designing and controlling elatrochemical protation syttems. In fact, it is very difficult tomeasure in situ the cornosion parnders of steeIs in sea sediment.     

STRESS CORROSION CRACKING OF AISI 321 STAINLESS STEEL IN ACIDIC SEAWATER

ImooUonONSCCisoneofthemosttwortantcausoffailureofstaiuleSsstalequipmentandfacilitieS.Studiesonunh0refacilitiesshowedthatanaddicchloridesolutionfilmcouldbefo~onthescheeofstalandthatstaiuleSSstalisinaCtivedissolutionstateinaedicchloridesolutionopinetal.,l99O;Gnanamoorthyetal.,l99O).ltisgenerallythoughtxthatSCCcannotoimrwhenthematerialisinaCtiveanodicdissolutionstate,soitsomcewithresultingcasualties(0ldfieldetal.,l99O)arousedattentiont0it.SomeSCCmeCanisrnsproposedpeuang,l988,Newmanctal.,…     

Study of the Corrosion Resistance of Electroless Ni-P Deposits in a Sodium Chloride Medium

The corrosion resistance of electroless Ni-P deposits with phosphorous contents from 12% to 14% in sodium chloride solutions was studied. The deposits were immersed in 3.5% NaCl solutions for 29 d to obtain the electrochemical parameters and were examined in a standard salt spray test for 15 d respectively. The corrosion resistance of the deposits was studied by poten- tio-dynamic scan, electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and cold-field emission scanning electron microscopy (FE-SEM) equipped with an energy dispersive X-ray detector (EDX). The patterns of XRD and the results of FE-SEM showed that the prepared deposits were amorphous. But after a 15 d standard salt spray test, a few pinholes appeared on the surface of the deposit and the weight content of phosphorus on the surface of the deposit was higher (which was beneficial to the formation of the passivation films) than that before the standard salt spray test when the nickel content was lower because the dissolved weight of nickel was greater than that of phosphorus. The results from potentio-dynamic scan and EIS showed that passivation films formed on the Ni-P deposit after immersion in the NaCl solutions, which decreased the corrosion rate of Ni-P samples. The results of this work show their potential applications in marine corrosion.     

Evaluation and classification of seawater corrosiveness by environmental factors

According to the data of main environmental factors and the depth of localized corrosion of carbon steel and low alloy steels in China seas, combined with the result of grey interrelation analysis, double-factor method was proposed to evaluate and classify seawater corrosiveness. According to the temperature of seawater and the biologically adhesive area on steels, the corrosiveness of seawater from low to high level is classified into five levels （C l-C5）, which was identified by the data of corrosion depth of carbon steel immersed in water for one year.     

ELECTROCHEMICAL MEASUREMENTS FOR MARINE ATMOSPHERIC CORROSION STUDIES USING KELVIN PROBE REFERENCE ELECTRODE

A Kelvin probe was used as reference in this study on electrochemical measurements of a simulatedmarine atmospheric corrosion system (electrode covered by a very thin electrolyte layer). The experimentalsetups for improved measurements proved satisfactory for the conventional steady-state electrochemicalmeasurements in atmospheric studies.     

Corrosion performance of zinc coated steel in seawater environment

Considering the continuous exploitation of marine resources,it is very important to study the anticorrosion performance and durability of zinc coated streel(ZCS) because its increasing use as reinforcements in seawater.Tafel polarization curves and linear polarization curves combined with electrochemical impedance spectroscopy(EIS) were employed to evaluate the corrosion performance of ZCS at Qingdao test station during long-term immersion in seawater.The results indicated that the corrosion rate of the ZCS increased obviously with immersion time in seawater.The corrosion products that formed on the zinc coated steel were loose and porous,and were mainly composed of Zn_5(OH)_8Cl_2,Zns(OH)_6(CO_3)_2,and ZnO.Pitting corrosion occurred on the steel surface in neutral seawater,and the rate of ZCS corrosion decreased with increasing pH.     

ELECTROCHEMICAL STUDY ON CORROSION BEHAVIOUR OF STEELS IN SAND WITH WATER

ImooUcr0NCormsinnofsodinconatisnowrognindasaseriousproblemwithlargeere-nondconSequenas.Thecormsionproducofondatthesurfaeeofrenfontin-dutaltenSioninthernaterial,resultinginfraCtureandspillingoftheconcretefromtherenfoot(Madrinaldetal.,l99l).Asaasult,theconCretestructure'sIneCanhalstwthisgreatiytalued.0wingtothephyShaldfultyofconduCtingforchdricalexperiInentsinconare,muCoftheworkintheaasofndanisticdCtendnationsforcormsionofstalincon-~wereconduedinalkalinesolution,generallyofporewatCr(Romirz…     

Smart anticorrosion coating based on stimuli-responsive micro/nanocontainer: a review

Smart coating for corrosion protection of metal materials(steel,magnesium,aluminum and their alloys) has drawn great attention because of their capacity to prevent crack propagation in the protective coating by releasing functional molecules(healing agents or corrosion inhibitors) on demand from delivery vehicle,that is,micro/nanocontainer made up of a shell and core material or a coating layer,in a controllable manner.Herein,we summarize the recent achievements during the last 10 years in the field of the micro/nanocontainer with different types of stimuli-responsive properties,i.e.,pH,electrochemical potential,redox,aggressive corrosive ions,heat,light,magnetic field,and mechanical impact,for smart anticorrosion coating.The state-of-the-art design and fabrication of micro/nanocontainer are emphasized with detailed examples.     

地下水对混凝土的pHs分解性侵蚀判别式

针对地下水对混凝土分解性侵蚀指标pHs现行评价方法中存在水样间pHs横向没有可对比性和难以定量绘制pHs分解性侵蚀分区图等两大缺陷,推出了一个新的pHs分解性侵蚀判别式sk1,用编制的"地下水对混凝土分解性侵蚀判别式计算程序",完成了新定义的判别式sk1的计算,计算结果不但具备了水样间的每种分解性侵蚀横向对比的功能,而且还具备了定量绘制每种分解性侵蚀分区图和定量绘制3种分解性侵蚀综合评价迭加图的功能。通过实例应用,形象地印证了现行评价方法存在的缺陷及现推出的判别式、定量编绘侵蚀分区图的可行性。     

Inhibitor-concentration-induced extreme behaviour in electrochemical parameters

ImODUcrIONIngeneral,fOrmosttypesofinhibitorstheperformancecanbecontinuouslyheight-enedbyincreasingtheconeentration.Thehighertheinhibitorconcentration,thestrongertheinhibitionbomes.However,nantobservationsshowedthatsometypesofinhibitorsexhibitedbotperformanceonlywithinashortediumrangeofinhibitorconcentrationinsulfuricaddso1ution,whichistheso-cailedphenornenonofinhibitorconcenhation-indutalextreminhibition.EpelbOin(l979)reportedthattheinhibitingeffidenCyrnaxdrindataroundlmml4ofpropargylalcoh…     

三元复合驱采油污水阻垢缓蚀剂电化学分析

研制适用于三元复合驱采油污水工况条件下的MPM固体缓蚀阻垢剂,分析三元复合驱采油污水中MPM的电化学特性.结果表明:随着温度增加,20#钢在采油污水的腐蚀速率呈增加趋势,极化曲线显示钝化区表面材料在表面高温下处于钝化状态,产生的钝化膜能够降低腐蚀速度.在阻垢缓蚀剂质量浓度相同的情况下,不同温度的电化学阻抗谱在高频区出现容抗弧,显示优良的缓蚀性能.不同质量浓度MPM极化曲线表明,缓蚀率随MPM质量浓度的增加而增大,MPM极值质量浓度为80mg/L.污水体系中的Ca2+、Cl-对缓蚀率产生影响.MPM适用于高质量浓度Ca2+的三元复合驱采油污水处理.     

Research on protection of steel piles of Baoshan general steel factory wharf by using DZ and DZ-2 tapes

Steel piles at the tidal zone can be seriously corroded. Common protective methods such as painting or coating with rubber or other protective materials, etc. cannot provide full protection when used as supplementary protection because these traditional methods require strict pretreatment and sealing of the metallic surface from the corrosive mediums, and time for the protective coatings to solidify. This is very difficult under the severe action of waves and surges on the sea. With our oil-soluble DZ-2 tape, protection efficiency for hanging steel plates at the tidal and splash zones reaches to 82–99%. The protection efficiency of water soluble DZ tape at the tidal zone reaches to 92.9%. The DZ and DZ-2 tapes can rapidly reduce the original corrosion velocity to ten percent and one percent respectively as fully proved by the 500 hour rapid corrosion testing with indoor salt fog and by the relevant electrochemical parameters of instantaneous corrosion velocity, etc. DZ tape absorbs much OH⁻ to cause a pH rise. A synergistic protective effect is gained when DZ tape is used together with cathodic protection of steel piles at the tidal zone. The working principle of DZ tape is different from that of DZ-2 tape even though they are composed of the same chemical materials. The latter provides protection because of the close affinity between metal and its carboxyl group shields the active centre at the metal surface to reduce the activation energy of metal. The carbon chain forms a covering oil film of netted structure. Dai Tao, Dai Wei and Xia Caiyuan et al. participated in the research and made useful contribution. Contribution No. 1656 from the Institute of Oceanology, Academia Sinica.     

Effect of Ca(OH)2, NaCl,and Na2SO4 on the corrosion and electrochemical behavior of rebar

The corrosion of rebar in reinforced concrete in marine environments causes significant damage to structures built in ocean environments. Studies on the process and mechanism of corrosion of rebar in the presence of multiple ions may help to control damage and predict the service life of reinforced concrete structures in such environments. The effect of interactions between sulfate and chloride ions and calcium hydroxide on the electrochemical behavior of rebar are also important for evaluation of structure durability. In this work, electrochemical impedance spectroscopy(EIS) plots of rebar in Ca(OH)_2 solution and cement grout, including NaCl and Na_2SO_4 as aggressive salts, were measured for different immersion times. The results show that corrosion of rebar was controlled by the rate of charge transfer as the rebar was exposed to chloride solution. In the presence of high concentrations of sulfate ions in the electrolyte, generation and dissolution of the passive film proceeded simultaneously and corrosion was mainly controlled by the diffusion rate. When Na_2SO_4 and NaCl were added to Ca(OH)_2 solution, the instantaneous corrosion rate decreased by a factor of 10 to 20 as a result of the higher p H of the corroding solution.     

Sol－gel法制取Al_2O_3系陶瓷涂层的组织与性能

用多种分析手段分析了Ｓｏｌ－ｇｅｌ法制取的Ａｌ２Ｏ３系陶瓷涂层在烧结过程中的组织变化以及烧结后涂层的成分和组织结构；对涂层的高温抗氧化性、耐蚀性、耐磨性以及涂层与金属基体的结合力进行了测试，结果表明，Ｓｏｌ－ｇｅｌ法制取的Ａｌ２Ｏ３系陶瓷涂层由氧化物晶体、过渡相和玻璃体混合而成，涂层与基体之间有很好的结合力，金属基体的抗氧性、耐蚀性、耐磨性能有明显提高．