C.S.Hu1
,
2) and Y.X.Gu3) 1) Department of Mechanical Engineering
,
Fushun Petroleum Institute
,
Fushun 113001
,
China 2) State Key Laboratory for Corrosion and Protection
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Institute of Corrosion and Protection of Metal
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The Chi nese Academy of Science
,
Shenyang 110015
,
China 3) Departmentof Materials Scienceand Engineering
,
Shenyang Polytechnic University
,
Shenyang 110023
,
China
金属学报(英文版)
Weldingthermalcyclicsimulated techniquesisemployed in thestudy. By meansof analysismetalloscope, fracture morphology and impact toughness test of the sample, the effect ofweldingthermalcycle peak temperature and dualthermal cycle on the micro structure and toughnessoflow alloy high strength steel HQ100 isinvestigated.Inner fine martensitic andbainitic microstrctureisobservedby TEM.Theresultsshow that withtheincreaseof peaktem perature, grain sizesbecomelarger,theimpacttoughness drop down .Ifthermalcycleisim posed twiceand dualthermalcyclicpeaktemperatureis1275 ℃+ 750 ℃,theimpacttoughnessisatthelowest value.Alsotheimpacttoughnessagrees withthefracture morphology.
关键词:
thermalcycle
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null
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null
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null
Corrosion Science
The early stages of the evolution of atmospheric corrosion of carbon steels exposed in both a laboratory simulated and a natural atmosphere environment in Shenyang have been observed by in situ scanning electron microscopy. In the case of laboratory cyclic wet-dry tests, even though the chloride content level is very low, filiform corrosion is initiated in the early stage. The filiform corrosion grows in random directions, forming a network of ridges. White nodules nucleate and grow on the ridges during continued corrosion and eventually connect with each other to form the initial corrosion scale. Pits were also found on the surface beneath corrosion products. In the case of a natural atmospheric environment, both filiform corrosion and other localized corrosion, such as pitting and inter-granular attack take place in the initial stage. It is obvious that there is variety of localized corrosion in the initial stage of atmospheric corrosion. (C) 2007 Elsevier Ltd. All rights reserved.
关键词:
steel;atmospheric corrosion;initial stage;localized corrosion;in-situ;iron;electrolyte;thickness
Materials Chemistry and Physics
The corrosion behaviour of CortenA weathering steel has been investigated using a laboratory accelerated test that involved cyclic wet/dry conditions in Qinghai salt lake water diluted 30 times The characteristics of the rust layers on tested samples were observed by SEM and EPMA analyzed by IRS and XRD and studied by polarization and EIS measurements The weight loss was almost linear indicating that the rust layer had no retarding effect on the corrosion process The crystalline components of the rust layers consisted primarily of beta-FeOOH magnetite (Fe(3)O(4)) and gamma-FeOOH As the corrosion proceeded the amount of beta-FeOOH decreased while that of magnetite and gamma-FeOOH increased XRD EDAX and EPMA indicated that the complex corrosion products magnesioferrite (MgFe(2)O(4)) and iowaite (Mg(4)Fe(OH)(8)OCl 4H(2)O) probably existed in the rust layer in which case they will have had an important Influence on the protectiveness of the rust layer The results of electrochemical measurements showed that the rust layer exhibited high reduction reactivity which facilitated the corrosion of weathering steel in the wetting process The large rust capacitance and small rust resistance indicated that the rust layer had a loose and porous structure which provided poor protection (c) 2010 Elsevier B V All rights reserved
关键词:
Elements;Corrosion test;Electrochemical techniques;Electron probe;low-alloy steels;atmospheric corrosion;carbon-steel;electrochemical;impedance;room-temperature;rust layers;iron;mechanism;products;environment
Journal of the European Ceramic Society
The hot corrosion behavior of Na2SO4-coated Ti2AlC was investigated by means of thermogravimetric analysis, X-ray diffraction, and scanning electron microscopy/energy dispersive spectroscopy. This carbide displays good hot corrosion resistance below the melting point of Na2SO4 while the corrosion attacks become virulent when the salt is molten. A protectively continuous Al2O3 layer forms and imparts good corrosion resistance, and consequently, the corrosion kinetics is generally parabolic at 850 degrees C. However, porous oxide scales fail to protect the Ti2AlC substrate at 900 and 1000 degrees C. The segregation of sulfur at the corrosion scale/substrate interface accelerates the corrosion of Ti2AlC. Furthermore, a convenient and efficient pre-oxidation method is proposed to improve the high-temperature hot corrosion resistance of Ti2AlC. An Al2O3 scale formed during pre-oxidation treatment can remarkably restrain the infiltration of the molten salt into the substrate and prevent the substrate from severe corrosion attacks. (c) 2005 Elsevier Ltd. All rights reserved.
关键词:
Ti2AlC;Al2O3;corrosion;high-temperature oxidation;polycrystalline ti2alc;carbides;behavior;ti3alc2;alumina;phase
Materials and Corrosion-Werkstoffe Und Korrosion
Galvanic anodic protection (GAP) of stainless steels by doped polypyrrole (PPy) was investigated using chemically synthesized PPy. Separate PPy powder-pressed electrodes with different surface areas were prepared. Electrochemical properties of PPy electrodes were studied by open circuit potentials (OCPs) and potentiostatic polarization. PPy powder-pressed electrodes were coupled with 410-stainless steel electrodes in different concentrations of sulfuric acid solutions, 5 M phosphoric acid solution, and industrial phosphoric acid solution (5 M phosphoric acid + 0.05% chloride ion). Remarkable shift of OCP to the positive direction and sharp decrease of corrosion rate were observed during the coupling experiments, which implies that 410-stainless steel was transferred to passive state. Results also showed that PPy electrode with sufficient surface area can provide corrosion protection to 410-stainless steel electrode in highly corrosive acid solution. Based on the experiment results, GAP provided by PPy and PANi (synthesized under similar conditions) was compared.
关键词:
galvanic anodic protection;organic metal polyaniline;coated;mild-steel;conducting polymers;doped polyaniline;ferrous-metals;carbon-steel;coatings;iron;passivation
F. Lu and WJ. van Ooij( Beijing Institute of Aeronautical Materials
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P.O. Box 81-5
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Beijing 100095
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China)( Department of Materials Science and Engineering
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University of Cincinnati
,
Cincinnati
,
OH 45221-0012
,
U.S.A.)
金属学报(英文版)
Zn-Al couple's galvanic coeeosion was a serious problem in acdic ainc sulfate solution .In this paper, a new pretreatment or a coating for Al was developed and tested to protect the Al effectively form corrosion when connected to pure Zinc at electroplating potential,and exposed to an acdic sulfate solution.Corrosion measurement techniques(Galvanic corrosion and DC)were used to investigate galvanic corrosion between Al cathode and Zn anode.It was found out that Al alloy purity and electroplating potential have a large effect on galvanic corrsion between Zn-Al couples.EIS,salt spray test and immersion test were performed to evaluate the method for Al cathodes in zinc electrolyte,BTSE silane pretreatment and polyurethane coating displayed better corrosion protection.Calculation showed the Al dissolution rate is small enough for Al cathode to be used in zinc plants.BTSE treatment or BTSE plus polyurethane coating has the best corrosion performance,and willprotect the Al cathode effectively in zinc electrolysis
关键词:
Al-Zn couple
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null
Polymers for Advanced Technologies
A corrosion protection coating from polyimide/polyaniline (PI/PAn) blend was prepared by solution blending and the anti-corrosion property of this coating was studied with electrochemical impedance spectroscopy technique. The results show that PAn can react with PI to form chemical bonds between these two polymers and these bonds keep these two polymers as a miscible system. The corrosion protection property of this coating increases with a growth in the PAn component and an excellent anti-corrosion effect emerges when the PAn content reaches 10-15%. The reason why PAn can improve the anti-corrosion property is that PI/PAn blend can form a dense and non-porous polymer film that would prevent some corrupting components from access to the underlying steel surface. And also, PAn may serve as a corrosion inhibiting agent to scavenge any protons and foster a local basic surface environment. Copyright (C) 2001 John Wiley Sons, Ltd.
关键词:
polyaniline;polyimide;corrosion;EIS
