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Electrochemical Corrosion Behavior of Nanocrystalline Materials-a Review

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Journal of Materials Science & Technology 2010年第1期26卷 1-14页

作者： Li Liu, Ying Li and Fuhui Wang state key laboratory for Corrosion and Protection, institute of Metal Research, chinese academy of sciences, shenyang 110016, china [a] state key laboratory for Corrosion and Protection institute of Metal Research chinese academy of sciences shenyang 110016 china

Nanocrystallization significantly influences the electrochemical corrosion behaviors of metals/alloys in liquid system. In active dissolution, nanocrystallization accelerates the corrosion reactions. If the corrosion products are dissoluble, the corrosion rate is increased by nanocrystallization; if the corrosion products are insoluble, the corrosion rate is decreased on the contrary because the corrosion products act as a block layer to delay the dissolution. In passivation, nanocrystallization changes the composition of the passive film, and results into different morphology and growth process of the passive film, both of which improves the formation of compact film and influences the semiconductor property. It influences the passivation depending on fast element diffusion and special adsorbed ability. The small grain size improves the element diffusion, which leads to the different composition of passive film （passive elements enrichment such as Cr, Ti）. The small grain size also changes the surface condition, which influences the ions adsorption. All increase the corrosion resistance of materials. In local corrosion, nanocrystallization increases the unstable points on the surface of the materials, which increases the possibility of local corrosion. However, the excellent ability of element diffusion helps heal the local corrosion points, which inhibits the growth of the local corrosion.

关键词： Nanocrystalline materials Electrochemical corrosion Review

Effect of Sputtered TiAlCr Coatings on Oxidation and Hot Corrosion Resistance of Ti-24Al-14Nb-3V

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Journal of Materials Science & Technology 2001年第5期17卷 501-506页

作者： Fuhui WANG, Chunhong GUAN, Zhaolin TANG and Weitao WU state key laboratory for Corrosion and Protection, institute of Metal Research, The chinese academy of sciences, shenyang 110016, china chinese Acad Sci Met Res Inst State Key Lab Corros & Protect Shenyang 110016 Peoples R China

The effect of sputtered Ti-50Al-10Cr and Ti-50A1-20Cr coatings on both isothermal and cyclic oxidation resistance at 800-900℃ and hot corrosion resistance at 850℃ of Ti-24Al-14Nb-3V was investigated. Results indicated that Ti-24Al-14Nb-3V alloys exhibited poor oxidation resistance due to the formation of Al2O3+TiO2+AlNbO4 mixed scales in air at 800-900℃ and poor hot corrosion resistance due to the spoliation of scales formed in Na2SO4+K2SO4 melts at 850℃. Both Ti-50Al-10Cr and Ti-50Al-20Cr coatings remarkably improved the oxidation and hot corrosion resistance of Ti-24Al-14Nb-3V alloy.

关键词： Ti Cr Effect of Sputtered TiAlCr Coatings on Oxidation and Hot Corrosion Resistance of Ti-24Al-14Nb-3V Al

Oxidation behavior of three-phase Cu-25Ni-30Cr alloy at 700-800℃ under high oxygen pressures

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中国有色金属学会会刊：英文版 2005年第3期15卷 491-496页

作者：曹中秋刘伟华翟广平牛焱state key laboratory for Corrosion and Protection institute of Metal Research chinese academy of sciences shenyang 110016 china Department of Chemistry Shenyang Normal University Shenyang 110034 China state key laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The thermogravimetric analysis of a ternary Cu-25Ni-30Cr alloy prepared by conventional casting was performed in 0.1MPa pure O2 at 700-800℃. The results show that the alloy is composed of three phases, where the phase with the largest copper and lowest chromium content forms the matrix, while the other two, much richer in chromium, form a dispersion of isolated particles. At variance with another three-phase Cu-20Ni-20Cr alloy, which forms complex scales containing the oxides of the various components and double oxides plus an irregular region composed of alloy and oxides, the present alloy can form a very irregular but continuous chromia layer at the base of the mixed internal region, producing a gradual decrease of the oxidation rate down to very low values. A larger chromium content needed to form chromia layer for a ternary three-phase alloy is attributed to the limitations to the diffusion of the alloy components in the metal substrate imposed by their multiphase nature.

关键词：铜-镍-铬合金三相高温氧化热解重量

Fatigue Crack Propagation Behavior of TiNi_(50.6)Shape Memory Alloy

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Journal of Materials Science & Technology 2001年第4期17卷 403-408页

作者： Guangbin RAO, Jianqiu WANG, We KE and Enhou HAN The state key laboratory of Corrosion and Protection, institute of M-tal Research, chinese academy of sciences,shenyang 110016, china chinese Acad Sci State Key Lab Corros & Protect Inst Met Res Shenyang 110016 Peoples R China

The fatigue crack propagation behavior of TiNi50.6 shape memory alloy was studied. The ex- periment results showed that the crack propagation properties of this alloy display difference and similarity in comparison with common metallic materials. Because of the stress concentra- tion there was stress induced martensite transformation (SIMT) near the crack tip though the nominal stress was lower than the threshold stress of SIMT. The position and the amount of SIMT was in situ observed by a quester remote measurement system (QRMS). The observation results showed that the position of SIMT was beside the crack tip and was not in the plastic zone of common metallic materials (in front of the crack tip). The SIMT zone at an angle of about 45°to the direction of the crack propagation, like a butterfly,appeared in the loading process, disappeared in the unloading process and grew larger with the increase of K. The crack propagation rate(da/dN) followed the linear law in lg-lg plot. Observation of the crack surface showed fatigue striation clearly. The relationship between the site and the size of the plastic zone and the SIMT zone is discussed and a model is given to explain both the similarity and the difference of the crack propagation property of TiNi50.6 to common metal materials.

关键词： Fatigue Crack Propagation Behavior of TiNi Shape Memory Alloy

In Situ Scanning-Tunneling-Microscope Observation on Dissolution of a Cu-20Zr Film

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Journal of Materials Science & Technology 2005年第3期21卷 311-314页

作者： Haibo LU, Guoze MENG, Ying LI and Fuhui WANG state key laboratory for Corrosion & Protection, institute of Metal Research, chinese academy of sciences, shenyang 110016, china laboratory for Corrosion and Protection Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A nanocrystalline coating of Cu-20Zr (in wt pct) was obtained on glass by magnetron sputtering. The corrosion behavior of the Cu-20Zr film in 0.001 mol/L HCI solution was investigated using potentiodynamic polarization and in situ electrochemical scanning-tunneling-microscopy (ECSTM). Results demonstrated that the film exhibits active behavior. Microscopic pitting corrosion and tunneling are caused by localized electrodissolution of Zr atoms and the diffusion of Cu atoms at surface defects.

关键词： Magnetron sputtering Film Potentiodynamic polarization ECSTM

A unified dynamic model for locomotion and manipulation of a snake-like robot based on differential geometry

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Science china(Information sciences) 2011年第2期54卷 318-333页

作者： WANG ZhiFeng1,3, MA ShuGen1,2, LI Bin1 & WANG YueChao1 1state key laboratory of robotics, shenyang institute of automation, chinese academy of sciences, shenyang 110016, china 2Department of robotics, Ritsumeikan University, Shiga-ken 525-8577, Japan 3Graduate University of chinese academy of sciences, Beijing 100039, china 1. state key laboratory of robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China3. Graduate University of Chinese Academy of Sciences Beijing 100039 China2. Department of Robotics Ritsumeikan University Shiga-ken 525-8577 Japan

A snake-like robot, whose body is a seried-wound articulated mechanism, can move in various environments. In addition, when one end is fixed on a base, the robot can manipulate objects. A method of dynamic modeling for locomotion and manipulation of the snake-like robot is developed in order to unify the dynamic equations of two states. The transformation from locomotion to manipulation is a mechanism reconfiguration, that is, the robot in locomotion has not a fixed base, but it in manipulation has one. First, a virtual structure method unifies the two states in mechanism (e.g., an embedding in the configuration space); second, the product-of-exponentials formula describes the kinematics; third, the dynamics of locomotion and manipulation are established in a Riemannian manifold; finally, based on the analysis of the dynamic model, the dynamics of manipulation can be directly degenerated from those of locomotion, and this degeneration relation is proved through using the Gauss equations. In the differential geometry formulation, this method realizes the unification of the dynamics of locomotion and manipulation. According to a geometrical point of view, the unified dynamic model for locomotion and manipulation is considered as a submanifold problem endowed with geometric meaning. In addition, the unified model offers an insight into the dynamics of the snake-like robot beyond the dynamic model separately established for locomotion or manipulation.

关键词： snake-like robot dynamics unified model differential geometry locomotion manipulation

Metals Supported Water Monomers:the Bonding Nature Revisited

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Journal of Materials Science & Technology 2010年第2期26卷 97-105页

作者： Jibiao Li, Shenglong Zhu and Fuhui Wang state key laboratory for Corrosion and Protection, institute of Metal Research, chinese academy of sciences, shenyang 110015, china [a] state key laboratory for Corrosion and Protection institute of Metal Research chinese academy of sciences shenyang 110015 china

A single water monomer is known as a hard-to-observe molecule even in the presence of metal surfaces as supporting matrix. This review highlights effort in experimental characterizations and theoretical modeling of transition metals supported water monomers with attention given to its structure and bonding, together with the insights that we have provided into the bonding nature of the water-interactions by the newly employed projected PDOS （partial density of states） difference analysis, which is proved to be an effective tool to be elucidate such bonding nature. The general s-d hybridization and d-shell effect are summarized, and how these effects can be tuned by tailoring local surface configurations is discussed.

关键词： Water monomer Adsorption Surface bonding Transition metals

2.5-dimensional angle potential field algorithm for the real-time autonomous navigation of outdoor mobile robots

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Science china(Information sciences) 2011年第10期54卷 2100-2112页

作者： QIU Quan 1,3 & HAN JianDa 2 1 Beijing Research Center of Intelligent Equipment for Agriculture,Beijing 100097,china 2.state key laboratory of robotics,shenyang institute of automation,chinese academy of sciences,shenyang 110016,china 3 National Research Center for Intelligent Agricultural Equipment,Beijing 100097,china 1. Beijing Research Center of Intelligent Equipment for Agriculture Beijing 100097 China3. National Research Center for Intelligent Agricultural Equipment Beijing 100097 China2. State Key Laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Shenyang 110016 China

A new real-time algorithm for the autonomous navigation of mobile robots equipped with laser scanners is proposed in this *** from the existing algorithms designed for 2-dimensional navigation problems,the new algorithm introduces the height information of the obstacles into the guidance process and behaves as a 2.5-dimensional angle potential field algorithm (2.5D-APF) to fulfill the navigation requirements under complex outdoor terrain ***,one laser scan is partitioned into two kinds of function sectors: guidance sector and inspecting ***,the guidance sector and the inspecting sectors are reconstructed to form a virtual guidance scan,where the 2.5D information is taken into ***,the conventional APF is improved to analyze the virtual guidance scan and generate the navigation *** new algorithm is tested on a tracked mobile robot,and the experimental results validate the proposed algorithm.

关键词： robot 2.5-dimensional outdoor real-time autonomous navigation

An On-line Monitoring System for Hydrogen Distribution in the Metallic Wall Caused by Hydrogen Permeation

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Journal of Materials Science & Technology 2001年第3期17卷 346-350页

作者： Gang YU shenyang University of Technology, 110023, china Xueyuan ZHANG and Yuanlong DU state key laboratory for Corrosion and Protection, institute of Metal Research, chinese academy of sciences, shenyang 110016, china E-mail: yugang@*** shenyang Univ. of Technol. Shenyang 110023 China

Based on the electrochemical permeation technique and the patent by Du, an intelligent elec-trochemical measurement system for determination of the hydrogen distribution in the wall of hydrogenation reactor has been developed and tested. It consists of a PC computer, a single chip unit, an I/V converter and an electrochemical hydrogen probe. The construction of the electrochemical hydrogen probe is described and the features of the measured system are given. The diffusion coefficient of 2.25CrlMo steel determined with present system was in good agree-ment with the value in the literature. Experimental results of hydrogen concentration in a wall of hydrogen charged testing autoclave made of AISI 321 stainless steel are presented. The present system can intelligently display hydrogen amount-of-substance concentration and mass fraction concentration, hydrogen concentration distribution curves in steels, permeation current density curve. An intelligent detection technique can be provided for predicting the susceptibility to hydrogen-induced cracks owing to hydrogen permeation in the wall of hydrogenation reactor in the field.

关键词： Hydrogen bonds