Micro-electrochemical polarization study on 25% Cr duplex stainless steel
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第 55 卷第 1 期2024 年 1 月中南大学学报(自然科学版)Journal of Central South University (Science and Technology)V ol.55 No.1Jan. 2024时效处理对不同晶粒组织Al-Zn-Mg 合金腐蚀性能的影响王鹏宇1,叶凌英1, 2, 3,柯彬1,董宇1,刘胜胆1, 2, 3(1. 中南大学 材料科学与工程学院,湖南 长沙,410083;2. 中南大学 教育部有色金属材料和工程重点实验室,湖南 长沙,410083;3. 中南大学 有色金属先进结构材料与协同创新中心,长沙,410083)摘要:以中强Al-Zn-Mg 合金为研究对象,采用晶间腐蚀、电化学极化曲线测试、慢应变速率拉伸等试验,结合OM 、TEM 、SEM 、EBSD 等组织分析方法研究时效处理和晶粒组织对合金腐蚀性能的影响。
研究结果表明:随着双级时效时间的延长,再结晶晶粒合金的抗腐蚀性能逐渐提升,从欠时效处理到过时效处理,晶间腐蚀等级由4级降为2级,电化学腐蚀电流密度由27.71 μA/cm 2降为0.098 μA/cm 2,应力腐蚀指数由79.15降至18.40;纤维晶粒合金与同时效阶段的再结晶晶粒合金相比,其抗腐蚀性能显著提升,其中,晶间腐蚀最大深度降低了35.9%,电化学腐蚀电流密度降低了81.4%,年腐蚀速率降低了81.9%,应力腐蚀敏感指数降低了46.2%。
中强Al-Zn-Mg 合金腐蚀性能的提升主要源于其较低的再结晶分数和较低的大角度晶界占比。
关键词:Al-Zn-Mg ;晶粒组织;腐蚀性能中图分类号:TG146.2 文献标志码:A 开放科学(资源服务)标识码(OSID)文章编号:1672-7207(2024)01-0055-14Effect of aging treatment on the corrosion performance of Al-Zn-Mg alloys with different grain structuresWANG Pengyu 1, YE Lingying 1, 2, 3, KE Bin 1, DONG Yu 1, LIU Shengdan 1, 2, 3(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central SouthUniversity, Changsha 410083, China;3. Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center,Central South University, Changsha 410083, China)Abstract: The effects of aging treatment and grain structure on the corrosion performance of the alloywere收稿日期: 2023 −03 −02; 修回日期: 2023 −05 −11基金项目(Foundation item):国家重点研发计划项目(2022YFB3403700);河南省紧固连接技术重点实验室资助项目(JGLJ2208)(Project(2022YFB3403700) supported by the National Key Research and Development Program of China; Project(JGLJ2208) supported by Key Laboratory of Fastening Connection Technology of Henan Province)通信作者:叶凌英,博士,教授,从事高性能铝合金研究;E-mail :******************.cnDOI: 10.11817/j.issn.1672-7207.2024.01.005引用格式: 王鹏宇, 叶凌英, 柯彬, 等 .时效处理对不同晶粒组织Al-Zn-Mg 合金腐蚀性能的影响[J].中南大学学报(自然科学版), 2024, 55(1): 55−68.Citation: WANG Pengyu, YE Lingying, KE Bin, et al. Effect of aging treatment on the corrosion performance of Al-Zn-Mg alloys with different grain structures[J]. Journal of Central South University(Science and Technology), 2024, 55(1): 55−68.第 55 卷中南大学学报(自然科学版)investigated by using the medium-strength Al-Zn-Mg alloy as the research object, and using intergranular corrosion, electrochemical polarization curve test, and slow strain rate tensile tests, combined with OM, TEM, SEM, and EBSD observations, respectively. The results show that the corrosion resistance of the recrystallized grain alloy gradually improves with the extension of the double-stage aging time, the intergranular corrosion grade decreases from grade 4to grade 2, the electrochemical corrosion current density decreases from 27.71 μA/cm2to 0.098 μA/cm2, and the stress corrosion sensitivity factor decreases from 79.15 to 18.40 when the treatment method changes from the under-aging treatment to the over-aging treatment. The corrosion resistance of the fiber grain alloy is significantly improved compared with that of the recrystallized grain alloy at the same aging stage, including a 35.9% reduction in the maximum depth of intergranular corrosion, an 81.4% reduction in the electrochemical corrosion current density, an 81.9% reduction in the annual corrosion rate, and a 46.2% reduction in the stress corrosion sensitivity index. The improvement in corrosion performance is mainly due to the lower recrystallization fraction and lower percentage of large-angle grain boundary of the medium-strength Al-Zn-Mg alloy.Key words: Al-Zn-Mg; grain structure; corrosion propertiesAl-Zn-Mg合金具有中等强度和优秀的焊接性能,广泛应用于航空航天和高铁领域[1−2],但该类合金在服役过程中容易发生应力腐蚀、晶间腐蚀等局部腐蚀,对使用性能造成了显著影响[3−4]。
腐蚀电化学实验报告 Final revision by standardization team on December 10, 2020.腐蚀电化学分析杨聪仁教授编撰一、实验目的以电化学分析法测量金属在不同环境下的腐蚀速率。
二、实验原理2-1 腐蚀形态腐蚀可被定义为材料受到外在环境的化学侵蚀而导致退化的象。
大多数材料的腐蚀包含了由电化学引起的化学侵蚀。
我们可根据被腐蚀金属的表面,简便地将腐蚀型态分类,如图一。
有许多类型易被辨识,但各种腐蚀类型彼此间都有某种程度的关连。
这些类型包括:均匀或一般侵蚀腐蚀应力腐蚀化学或两金属腐蚀冲蚀腐蚀孔蚀腐蚀涡穴损伤间隙腐蚀移擦腐蚀粒间腐蚀选择性腐蚀均匀或一般侵蚀腐蚀均匀腐蚀是指当金属处于腐蚀环境时,金属整个表面会同时进行电化学反应。
就重量而言,均匀腐蚀是金属所面临的最大腐蚀破坏,尤其是对钢铁来说。
然而,它很容易藉由保护性镀层、抑制剂及阴极保护等方法来控制。
化学或两金属腐蚀由于不同金属具有不同的电化学电位,因此当要将不同金属放在一起时,必须格外小心,以免产生腐蚀现象。
两金属化学腐蚀的另一个重要考虑因素是阳极与阴极的比率,也就是面积效应(area effect)。
阴极面积大而阳极面积小是一种不利的面积比率,因为当某特定量的电流经过金属对时,例如不同尺寸的铜极及铁极,小电极的电流密度会远大于大电极,因此小阳极将会加速腐蚀。
所以大阴极面积对小阳极面积的情形应尽量避免。
孔蚀腐蚀孔蚀是会在金属上产生空孔的局部腐蚀类型。
此类型的腐蚀若造成贯穿金属的孔洞,则对工程结构会有相当的破坏效果。
但若没有贯穿现象,则小蚀孔有时对工程设备而言是可接受的。
孔蚀通常是很难检测的,这是因为小蚀孔常会被腐蚀生成物覆盖所致。
另外蚀孔的数目及深度变化也很大,因此对孔蚀所造成的破坏不太容易做评估。
也因为如此,由于孔蚀的局部本质,它常会导致突然不可预测的破坏。
蚀孔会在腐蚀速率增加的局部区域发生。
金属表面的夹杂物,其他结构不均匀物及成份不均匀处,都是蚀孔开始发生的地方。
一些物理化学专业英语词汇BET公式BET formulaDLVO理论DLVO theoryHLB法hydrophile-lipophile balance methodpVT性质pVT propertyζ电势zeta potential阿伏加德罗常数Avogadro’number阿伏加德罗定律Avogadro law阿累尼乌斯电离理论Arrhenius ionization theory阿累尼乌斯方程Arrhenius equation阿累尼乌斯活化能Arrhenius activation energy阿马格定律Amagat law艾林方程Erying equation爱因斯坦光化当量定律Einstein’s law of photochemical equivalence爱因斯坦-斯托克斯方程Einstein-Stokes equation安托万常数Antoine constant安托万方程Antoine equation盎萨格电导理论Onsager’s theory of conductance半电池half cell半衰期half time period饱和液体saturated liquids饱和蒸气saturated vapor饱和吸附量saturated extent of adsorption饱和蒸气压saturated vapor pressure爆炸界限explosion limits比表面功specific surface work比表面吉布斯函数specific surface Gibbs function比浓粘度reduced viscosity标准电动势standard electromotive force标准电极电势standard electrode potential标准摩尔反应焓standard molar reaction enthalpy标准摩尔反应吉布斯函数standard Gibbs function of molar reaction标准摩尔反应熵standard molar reaction entropy标准摩尔焓函数standard molar enthalpy function标准摩尔吉布斯自由能函数standard molar Gibbs free energy function 标准摩尔燃烧焓standard molar combustion enthalpy标准摩尔熵standard molar entropy标准摩尔生成焓standard molar formation enthalpy标准摩尔生成吉布斯函数standard molar formation Gibbs function标准平衡常数standard equilibrium constant标准氢电极standard hydrogen electrode标准态standard state标准熵standard entropy标准压力standard pressure标准状况standard condition表观活化能apparent activation energy表观摩尔质量apparent molecular weight表观迁移数apparent transference number表面surfaces表面过程控制surface process control表面活性剂surfactants表面吸附量surface excess表面张力surface tension表面质量作用定律surface mass action law波义尔定律Boyle law波义尔温度Boyle temperature波义尔点Boyle point玻尔兹曼常数Boltzmann constant玻尔兹曼分布Boltzmann distribution玻尔兹曼公式Boltzmann formula玻尔兹曼熵定理Boltzmann entropy theorem玻色-爱因斯坦统计Bose-Einstein statistics泊Poise不可逆过程irreversible process不可逆过程热力学thermodynamics of irreversible processes 不可逆相变化irreversible phase change布朗运动brownian movement查理定律Charle’s law产率yield敞开系统open system超电势over potential沉降sedimentation沉降电势sedimentation potential沉降平衡sedimentation equilibrium触变thixotropy粗分散系统thick disperse system催化剂catalyst单分子层吸附理论mono molecule layer adsorption单分子反应unimolecular reaction单链反应straight chain reactions弹式量热计bomb calorimeter道尔顿定律Dalton law道尔顿分压定律Dalton partial pressure law德拜和法尔肯哈根效应Debye and Falkenhagen effect德拜立方公式Debye cubic formula德拜-休克尔极限公式Debye-Huckel’s limiting equation等焓过程isenthalpic process等焓线isenthalpic line等几率定理theorem of equal probability等温等容位Helmholtz free energy等温等压位Gibbs free energy等温方程equation at constant temperature低共熔点eutectic point低共熔混合物eutectic mixture低会溶点lower consolute point低熔冰盐合晶cryohydric第二类永动机perpetual machine of the second kind第三定律熵third-law entropy第一类永动机perpetual machine of the first kind缔合化学吸附association chemical adsorption电池常数cell constant电池电动势electromotive force of cells电池反应cell reaction电导conductance电导率conductivity电动势的温度系数temperature coefficient of electromotive force 电动电势zeta potential电功electric work电化学electrochemistry电化学极化electrochemical polarization电极电势electrode potential电极反应reactions on the electrode电极种类type of electrodes电解池electrolytic cell电量计coulometer电流效率current efficiency电迁移electro migration电迁移率electromobility电渗electroosmosis电渗析electrodialysis电泳electrophoresis丁达尔效应Dyndall effect定容摩尔热容molar heat capacity under constant volume定容温度计Constant voIume thermometer定压摩尔热容molar heat capacity under constant pressure定压温度计constant pressure thermometer定域子系统localized particle system动力学方程kinetic equations动力学控制kinetics control独立子系统independent particle system对比摩尔体积reduced mole volume对比体积reduced volume对比温度reduced temperature对比压力reduced pressure对称数symmetry number对行反应reversible reactions对应状态原理principle of corresponding state多方过程polytropic process多分子层吸附理论adsorption theory of multi-molecular layers 二级反应second order reaction二级相变second order phase change法拉第常数faraday constant法拉第定律Faraday’s law反电动势back E.M.F.反渗透reverse osmosis反应分子数molecularity反应级数reaction orders反应进度extent of reaction反应热heat of reaction反应速率rate of reaction反应速率常数constant of reaction rate范德华常数van der Waals constant范德华方程van der Waals equation范德华力van der Waals force范德华气体van der Waals gases范特霍夫方程van’t Hoff equation范特霍夫规则van’t Hoff rule范特霍夫渗透压公式van’t Hoff equation of osmotic pressure 非基元反应non-elementary reactions非体积功non-volume work非依时计量学反应time independent stoichiometric reactions 菲克扩散第一定律Fick’s first law of diffusion沸点boiling point沸点升高elevation of boiling point费米-狄拉克统计Fermi-Dirac statistics分布distribution分布数distribution numbers分解电压decomposition voltage分配定律distribution law分散系统disperse system分散相dispersion phase分体积partial volume分体积定律partial volume law分压partial pressure分压定律partial pressure law分子反应力学mechanics of molecular reactions分子间力intermolecular force分子蒸馏molecular distillation封闭系统closed system附加压力excess pressure弗罗因德利希吸附经验式Freundlich empirical formula of adsorption 负极negative pole负吸附negative adsorption复合反应composite reaction盖·吕萨克定律Gay-Lussac law盖斯定律Hess law甘汞电极calomel electrode感胶离子序lyotropic series杠杆规则lever rule高分子溶液macromolecular solution高会溶点upper consolute point隔离法the isolation method格罗塞斯-德雷珀定律Grotthus-Draoer’s law隔离系统isolated system根均方速率root-mean-square speed功work功函work content共轭溶液conjugate solution共沸温度azeotropic temperature构型熵configurational entropy孤立系统isolated system固溶胶solid sol固态混合物solid solution固相线solid phase line光反应photoreaction光化学第二定律the second law of actinochemistry光化学第一定律the first law of actinochemistry光敏反应photosensitized reactions光谱熵spectrum entropy广度性质extensive property广延量extensive quantity广延性质extensive property规定熵stipulated entropy过饱和溶液oversaturated solution过饱和蒸气oversaturated vapor过程process过渡状态理论transition state theory过冷水super-cooled water过冷液体overcooled liquid过热液体overheated liquid亥姆霍兹函数Helmholtz function亥姆霍兹函数判据Helmholtz function criterion亥姆霍兹自由能Helmholtz free energy亥氏函数Helmholtz function焓enthalpy亨利常数Henry constant亨利定律Henry law恒沸混合物constant boiling mixture恒容摩尔热容molar heat capacity at constant volume恒容热heat at constant volume恒外压constant external pressure恒压摩尔热容molar heat capacity at constant pressure恒压热heat at constant pressure化学动力学chemical kinetics化学反应计量式stoichiometric equation of chemical reaction化学反应计量系数stoichiometric coefficient of chemical reaction 化学反应进度extent of chemical reaction化学亲合势chemical affinity化学热力学chemical thermodynamics化学势chemical potential化学势判据chemical potential criterion化学吸附chemisorptions环境environment环境熵变entropy change in environment挥发度volatility混合熵entropy of mixing混合物mixture活度activity活化控制activation control活化络合物理论activated complex theory活化能activation energy霍根-华森图Hougen-Watson Chart基态能级energy level at ground state基希霍夫公式Kirchhoff formula基元反应elementary reactions积分溶解热integration heat of dissolution吉布斯-杜亥姆方程Gibbs-Duhem equation吉布斯-亥姆霍兹方程Gibbs-Helmhotz equation吉布斯函数Gibbs function吉布斯函数判据Gibbs function criterion吉布斯吸附公式Gibbs adsorption formula吉布斯自由能Gibbs free energy吉氏函数Gibbs function极化电极电势polarization potential of electrode 极化曲线polarization curves极化作用polarization极限摩尔电导率limiting molar conductivity几率因子steric factor计量式stoichiometric equation计量系数stoichiometric coefficient价数规则rule of valence简并度degeneracy键焓bond enthalpy胶冻broth jelly胶核colloidal nucleus胶凝作用demulsification胶束micelle胶体colloid胶体分散系统dispersion system of colloid胶体化学collochemistry胶体粒子colloidal particles胶团micelle焦耳Joule焦耳-汤姆生实验Joule-Thomson experiment焦耳-汤姆生系数Joule-Thomson coefficient焦耳-汤姆生效应Joule-Thomson effect焦耳定律Joule`s law接触电势contact potential接触角contact angle节流过程throttling process节流膨胀throttling expansion节流膨胀系数coefficient of throttling expansion 结线tie line结晶热heat of crystallization解离化学吸附dissociation chemical adsorption 界面interfaces界面张力surface tension浸湿immersion wetting浸湿功immersion wetting work精馏rectify聚(合)电解质polyelectrolyte聚沉coagulation聚沉值coagulation value绝对反应速率理论absolute reaction rate theory 绝对熵absolute entropy绝对温标absolute temperature scale绝热过程adiabatic process绝热量热计adiabatic calorimeter绝热指数adiabatic index卡诺定理Carnot theorem卡诺循环Carnot cycle开尔文公式Kelvin formula柯诺瓦洛夫-吉布斯定律Konovalov-Gibbs law科尔劳施离子独立运动定律Kohlrausch’s Law of Independent Migration of Ions 可能的电解质potential electrolyte可逆电池reversible cell可逆过程reversible process可逆过程方程reversible process equation可逆体积功reversible volume work可逆相变reversible phase change克拉佩龙方程Clapeyron equation克劳修斯不等式Clausius inequality克劳修斯-克拉佩龙方程Clausius-Clapeyron equation控制步骤control step库仑计coulometer扩散控制diffusion controlled拉普拉斯方程Laplace’s equation拉乌尔定律Raoult law兰格缪尔-欣谢尔伍德机理Langmuir-Hinshelwood mechanism兰格缪尔吸附等温式Langmuir adsorption isotherm formula雷利公式Rayleigh equation冷冻系数coefficient of refrigeration冷却曲线cooling curve离解热heat of dissociation离解压力dissociation pressure离域子系统non-localized particle systems离子的标准摩尔生成焓standard molar formation of ion离子的电迁移率mobility of ions离子的迁移数transport number of ions离子独立运动定律law of the independent migration of ions离子氛ionic atmosphere离子强度ionic strength理想混合物perfect mixture理想气体ideal gas接触电势contact potential接触角contact angle节流过程throttling process节流膨胀throttling expansion节流膨胀系数coefficient of throttling expansion结线tie line结晶热heat of crystallization解离化学吸附dissociation chemical adsorption界面interfaces界面张力surface tension浸湿immersion wetting浸湿功immersion wetting work精馏rectify聚(合)电解质polyelectrolyte聚沉coagulation聚沉值coagulation value绝对反应速率理论absolute reaction rate theory绝对熵absolute entropy绝对温标absolute temperature scale绝热过程adiabatic process绝热量热计adiabatic calorimeter绝热指数adiabatic index卡诺定理Carnot theorem卡诺循环Carnot cycle开尔文公式Kelvin formula柯诺瓦洛夫-吉布斯定律Konovalov-Gibbs law科尔劳施离子独立运动定律Kohlrausch’s Law of Independent Migration of Ions 可能的电解质potential electrolyte可逆电池reversible cell可逆过程reversible process可逆过程方程reversible process equation可逆体积功reversible volume work可逆相变reversible phase change克拉佩龙方程Clapeyron equation克劳修斯不等式Clausius inequality克劳修斯-克拉佩龙方程Clausius-Clapeyron equation控制步骤control step库仑计coulometer扩散控制diffusion controlled拉普拉斯方程Laplace’s equation拉乌尔定律Raoult law兰格缪尔-欣谢尔伍德机理Langmuir-Hinshelwood mechanism兰格缪尔吸附等温式Langmuir adsorption isotherm formula雷利公式Rayleigh equation冷冻系数coefficient of refrigeration冷却曲线cooling curve离解热heat of dissociation离解压力dissociation pressure离域子系统non-localized particle systems离子的标准摩尔生成焓standard molar formation of ion离子的电迁移率mobility of ions离子的迁移数transport number of ions离子独立运动定律law of the independent migration of ions离子氛ionic atmosphere离子强度ionic strength理想混合物perfect mixture理想气体ideal gas理想气体的绝热指数adiabatic index of ideal gases理想气体的微观模型micro-model of ideal gas理想气体反应的等温方程isothermal equation of ideal gaseous reactions理想气体绝热可逆过程方程adiabatic reversible process equation of ideal gases 理想气体状态方程state equation of ideal gas理想稀溶液ideal dilute solution理想液态混合物perfect liquid mixture粒子particles粒子的配分函数partition function of particles连串反应consecutive reactions链的传递物chain carrier链反应chain reactions量热熵calorimetric entropy量子统计quantum statistics量子效率quantum yield临界参数critical parameter临界常数critical constant临界点critical point临界胶束浓度critical micelle concentration临界摩尔体积critical molar volume临界温度critical temperature临界压力critical pressure临界状态critical state零级反应zero order reaction流动电势streaming potential流动功flow work笼罩效应cage effect路易斯-兰德尔逸度规则Lewis-Randall rule of fugacity露点dew point露点线dew point line麦克斯韦关系式Maxwell relations麦克斯韦速率分布Maxwell distribution of speeds麦克斯韦能量分布MaxwelIdistribution of energy毛细管凝结condensation in capillary毛细现象capillary phenomena米凯利斯常数Michaelis constant摩尔电导率molar conductivity摩尔反应焓molar reaction enthalpy摩尔混合熵mole entropy of mixing摩尔气体常数molar gas constant摩尔热容molar heat capacity摩尔溶解焓mole dissolution enthalpy摩尔稀释焓mole dilution enthalpy内扩散控制internal diffusions control内能internal energy内压力internal pressure能级energy levels能级分布energy level distribution能量均分原理principle of the equipartition of energy能斯特方程Nernst equation能斯特热定理Nernst heat theorem凝固点freezing point凝固点降低lowering of freezing point凝固点曲线freezing point curve凝胶gelatin凝聚态condensed state凝聚相condensed phase浓差超电势concentration over-potential浓差极化concentration polarization浓差电池concentration cells帕斯卡pascal泡点bubble point泡点线bubble point line配分函数partition function配分函数的析因子性质property that partition function to be expressed as a product of the separate partition functions for each kind of state碰撞截面collision cross section碰撞数the number of collisions偏摩尔量partial mole quantities平衡常数(理想气体反应)equilibrium constants for reactions of ideal gases平动配分函数partition function of translation平衡分布equilibrium distribution平衡态equilibrium state平衡态近似法equilibrium state approximation平衡状态图equilibrium state diagram平均活度mean activity平均活度系统mean activity coefficient平均摩尔热容mean molar heat capacity平均质量摩尔浓度mean mass molarity平均自由程mean free path平行反应parallel reactions破乳demulsification铺展spreading普遍化范德华方程universal van der Waals equation其它功the other work气化热heat of vaporization气溶胶aerosol气体常数gas constant气体分子运动论kinetic theory of gases气体分子运动论的基本方程foundamental equation of kinetic theory of gases 气溶胶aerosol气相线vapor line迁移数transport number潜热latent heat强度量intensive quantity强度性质intensive property亲液溶胶hydrophilic sol氢电极hydrogen electrodes区域熔化zone melting热heat热爆炸heat explosion热泵heat pump热功当量mechanical equivalent of heat热函heat content热化学thermochemistry热化学方程thermochemical equation热机heat engine热机效率efficiency of heat engine热力学thermodynamics热力学第二定律the second law of thermodynamics热力学第三定律the third law of thermodynamics热力学第一定律the first law of thermodynamics热力学基本方程fundamental equation of thermodynamics热力学几率thermodynamic probability热力学能thermodynamic energy热力学特性函数characteristic thermodynamic function热力学温标thermodynamic scale of temperature热力学温度thermodynamic temperature热熵thermal entropy热效应heat effect熔点曲线melting point curve熔化热heat of fusion溶胶colloidal sol溶解焓dissolution enthalpy溶液solution溶胀swelling乳化剂emulsifier乳状液emulsion润湿wetting润湿角wetting angle萨克尔-泰特洛德方程Sackur-Tetrode equation 三相点triple point三相平衡线triple-phase line熵entropy熵判据entropy criterion熵增原理principle of entropy increase渗透压osmotic pressure渗析法dialytic process生成反应formation reaction升华热heat of sublimation实际气体real gas舒尔采-哈迪规则Schulze-Hardy rule松驰力relaxation force松驰时间time of relaxation速度常数reaction rate constant速率方程rate equations速率控制步骤rate determining step塔费尔公式Tafel equation态-态反应state-state reactions唐南平衡Donnan equilibrium淌度mobility特鲁顿规则Trouton rule特性粘度intrinsic viscosity体积功volume work统计权重statistical weight统计热力学statistic thermodynamics统计熵statistic entropy途径path途径函数path function外扩散控制external diffusion control完美晶体perfect crystalline完全气体perfect gas微观状态microstate微态microstate韦斯顿标准电池Weston standard battery维恩效应Wien effect维里方程virial equation维里系数virial coefficient稳流过程steady flow process稳态近似法stationary state approximation无热溶液athermal solution无限稀溶液solutions in the limit of extreme dilution物理化学Physical Chemistry物理吸附physisorptions吸附adsorption吸附等量线adsorption isostere吸附等温线adsorption isotherm吸附等压线adsorption isobar吸附剂adsorbent吸附量extent of adsorption吸附热heat of adsorption吸附质adsorbate析出电势evolution or deposition potential析因子性质property that partition function to be expressed as a product of the separate partition functions for each kind of state稀溶液的依数性colligative properties of dilute solutions稀释焓dilution enthalpy系统system系统点system point系统的环境environment of system相phase相变phase change相变焓enthalpy of phase change相变化phase change相变热heat of phase change相点phase point相对挥发度relative volatility相对粘度relative viscosity相律phase rule相平衡热容heat capacity in phase equilibrium相图phase diagram相倚子系统system of dependent particles悬浮液suspension循环过程cyclic process压力商pressure quotient压缩因子compressibility factor压缩因子图diagram of compressibility factor亚稳状态metastable state盐桥salt bridge盐析salting out阳极anode杨氏方程Young’s equation液体接界电势liquid junction potential液相线liquid phase lines一级反应first order reaction一级相变first order phase change依时计量学反应time dependent stoichiometric reactions 逸度fugacity逸度系数coefficient of fugacity阴极cathode荧光fluorescence永动机perpetual motion machine永久气体Permanent gas有效能available energy原电池primary cell原盐效应salt effect增比粘度specific viscosity憎液溶胶lyophobic sol沾湿adhesional wetting沾湿功the work of adhesional wetting真溶液true solution真实电解质real electrolyte真实气体real gas真实迁移数true transference number振动配分函数partition function of vibration振动特征温度characteristic temperature of vibration蒸气压下降depression of vapor pressure正常沸点normal point正吸附positive adsorption支链反应branched chain reactions直链反应straight chain reactions指前因子pre-exponential factor质量作用定律mass action law制冷系数coefficient of refrigeration中和热heat of neutralization轴功shaft work转动配分函数partition function of rotation转动特征温度characteristic temperature of vibration转化率convert ratio转化温度conversion temperature状态state状态方程state equation状态分布state distribution状态函数state function准静态过程quasi-static process准一级反应pseudo first order reaction自动催化作用auto-catalysis自由度degree of freedom自由度数number of degree of freedom自由焓free enthalpy自由能free energy自由膨胀free expansion组分数component number最低恒沸点lower azeotropic point最高恒沸点upper azeotropic point最佳反应温度optimal reaction temperature最可几分布most probable distribution最可几速率most propable speed1. The Ideal-Gas Equation 理想气体状态方程2. Partial Pressures 分压3. Real Gases: Deviation from Ideal Behavior 真实气体:对理想气体行为的偏离4. The van der Waals Equation 范德华方程5. System and Surroundings 系统与环境6. State and State Functions 状态与状态函数7. Process 过程8. Phase 相9. The First Law of Thermodynamics 热力学第一定律10. Heat and Work 热与功11. Endothermic and Exothermic Processes 吸热与发热过程12. Enthalpies of Reactions 反应热13. Hess’s Law 盖斯定律14. Enthalpies of Formation 生成焓15. Reaction Rates 反应速率16. Reaction Order 反应级数17. Rate Constants 速率常数18. Activation Energy 活化能19. The Arrhenius Equation 阿累尼乌斯方程20. Reaction Mechanisms 反应机理21. Homogeneous Catalysis 均相催化剂22. Heterogeneous Catalysis 非均相催化剂23. Enzymes 酶24. The Equilibrium Constant 平衡常数25. the Direction of Reaction 反应方向26. Le Chatelier’s Principle 列·沙特列原理27. Effects of VolumePressureT emperature Changes and Catalysts i. 体积压力温度变化以及催化剂的影响28. Spontaneous Processes 自发过程29. Entropy (Standard Entropy) 熵(标准熵)30. The Second Law of Thermodynamics 热力学第二定律31. Entropy Changes 熵变32. Standard Free-Energy Changes 标准自由能变33. Acid-bases 酸碱34. The Dissociation of Water 水离解35. The Proton in Water 水合质子36. The pH Scales pH值37. Bronsted-Lowry Acids and bases Bronsted-Lowry 酸和碱38. Proton-Transfer Reactions 质子转移反应39. Conjugate Acid-base Pairs 共轭酸碱对40. Relative Strength of Acids and bases 酸碱的相对强度41. Lewis Acids and bases 路易斯酸碱42. Hydrolysis of metal Ions 金属离子的水解43. Buffer Solutions 缓冲溶液44. The Common-Ion Effects 同离子效应45. Buffer Capacity 缓冲容量46. Formation of Complex Ions 配离子的形成47. Solubility 溶解度48. The Solubility-Product Constant Ksp 溶度积常数49. Precipitation and separation of Ions 离子的沉淀与分离50. Selective Precipitation of Ions 离子的选择沉淀51. Oxidation-Reduction Reactions 氧化还原反应52. Oxidation Number 氧化数53. Balancing Oxidation-Reduction Equations 氧化还原反应方程的配平54. Half-Reaction 半反应55. Galvani Cell 原电池56. Voltaic Cell 伏特电池57. Cell EMF 电池电动势58. Standard Electrode Potentials 标准电极电势59. Oxidizing and Reducing Agents 氧化剂和还原剂60. The Nernst Equation 能斯特方程61. Electrolysis 电解62. The Wave Behavior of Electrons 电子的波动性63. Bohr’s Model of The Hydrogen Atom 氢原子的波尔模型64. Line Spectra 线光谱65. Quantum Numbers 量子数66. Electron Spin 电子自旋67. Atomic Orbital 原子轨道68. The s(pdf) Orbital s(pdf)轨道69. Many-Electron Atoms 多电子原子70. Energies of Orbital 轨道能量71. The Pauli Exclusion Principle 泡林不相容原理72. Electron Configurations 电子构型73. The Periodic Table 周期表74. Row 行75. Group 族76. Isotopes Atomic Numbers and Mass Numbers 同位素,原子数,质量数77. Periodic Properties of the Elements 元素的周期律78. Radius of Atoms 原子半径79. Ionization Energy 电离能80. Electronegativity 电负性81. Effective Nuclear Charge 有效核电荷82. Electron Affinities 亲电性/电子亲合性[势]83. metals 金属84. Nonmetals 非金属85. Valence Bond Theory 价键理论86. Covalence Bond 共价键87. Orbital Overlap 轨道重叠88. Multiple Bonds 重键89. Hybrid Orbital 杂化轨道90. The VSEPR Model 价层电子对互斥理论91. Molecular Geometries 分子空间构型92. Molecular Orbital 分子轨道93. Diatomic Molecules 双原子分子94. Bond Length 键长95. Bond Order 键级96. Bond Angles 键角97. Bond Enthalpies 键能98. Bond Polarity 键矩99. Dipole Moments 偶极矩100. Polarity Molecules 极性分子101. Polyatomic Molecules 多原子分子102. Crystal Structure 晶体结构103. Non-Crystal 非晶体104. Close Packing of Spheres 球密堆积105. metallic Solids 金属晶体106. metallic Bond 金属键107. Alloys 合金108. Ionic Solids 离子晶体109. Ion-Dipole Forces 离子偶极力110. Molecular Forces 分子间力111. Intermolecular Forces 分子间作用力112. Hydrogen Bonding 氢键113. Covalent-Network Solids 原子晶体114. Compounds 化合物115. The Nomenclature Composition and Structure of Complexes 配合物的命名组成和结构116. Charges Coordination Numbers and Geometries 电荷数、配位数、及几何构型117. Chelates 螯合物118. Isomerism 异构现象119. Structural Isomerism 结构异构120. Stereoisomerism 立体异构121. Magnetism 磁性122. Electron Configurations in Octahedral Complexes 八面体构型配合物的电子分布123. Tetrahedral and Square-planar Complexes 四面体和平面四边形配合物124. General Characteristics 共性125. s-Block Elements s区元素126. Alkali metals 碱金属127. Alkaline Earth metals 碱土金属128. Hydrides 氢化物129. Oxides 氧化物130. Peroxides and Superoxides 过氧化物和超氧化物131. Hydroxides 氢氧化物132. Salts 盐133. p-Block Elements p区元素134. Boron Group (BoronAluminiumGalliumIndiumThallium) 硼族(硼铝镓铟铊)135. Borane 硼烷136. Carbon Group (CarbonSiliconGermaniumTinLead) 碳族(碳,硅,锗,锡,铅)137. Graphite Carbon Monoxide Carbon Dioxide 石墨,一氧化碳,二氧化碳138. Carbonic Acid Carbonates and Carbides 碳酸,碳酸盐,碳化物139. Occurrence and Preparation of Silicon 硅的存在和制备140. Silicic Acid,Silicates 硅酸,硅酸盐141. Nitrogen Group (PhosphorusArsenicAntimonyand Bismuth) 氮族(磷砷锑铋)142. Ammonia Nitric Acid Phosphoric Acid 氨硝酸磷酸143. Phosphorates phosphorus Halides 磷酸盐,卤化磷144. Oxygen Group (Oxygen Sulfur Selenium and Tellurium) 氧族元素(氧,硫,硒,碲)145. Ozone Hydrogen Peroxide 臭氧,过氧化氢146. Sulfides 硫化物147. Halogens (Fluorine Chlorine Bromine Iodine) 卤素(氟,氯,溴,碘)148. Halides Chloride 卤化物,氯化物149. The Noble Gases 稀有气体150. Noble-Gas Compounds 稀有气体化合物151. d-Block elements d区元素152. Transition metals 过渡金属153. Potassium Dichromate 重铬酸钾154. Potassium Permanganate 高锰酸钾155. Iron Copper Zinc Mercury 铁,铜,锌,汞156. f-Block Elements f区元素157. Lanthanides 镧系元素158. Radioactivity 放射性159. Nuclear Chemistry 核化学160. Nuclear Fission 核裂变161. Nuclear Fusion 核聚变162. analytical chemistry 分析化学163. qualitative analysis 定性分析164. quantitative analysis 定量分析165. chemical analysis 化学分析166. instrumental analysis 仪器分析167. titrimetry 滴定分析168. gravimetric analysis 重量分析法169. regent 试剂170. chromatographic analysis 色谱分析171. product 产物172. electrochemical analysis 电化学分析173. on-line analysis 在线分析174. macro analysis 常量分析175. characteristic 表征176. micro analysis 微量分析177. deformation analysis 形态分析178. semimicro analysis 半微量分析179. systematical error 系统误差180. routine analysis 常规分析181. random error 偶然误差182. arbitration analysis 仲裁分析183. gross error 过失误差184. normal distribution 正态分布185. accuracy 准确度186. deviation 偏差187. precision 精密度188. relative standard deviation 相对标准偏差(RSD)189. coefficient variation 变异系数(CV)190. confidence level 置信水平191. confidence interval 置信区间192. significant test 显著性检验193. significant figure 有效数字194. standard solution 标准溶液195. titration 滴定196. stoichiometric point 化学计量点197. end point 滴定终点198. titration error 滴定误差199. primary standard 基准物质200. amount of substance 物质的量201. standardization 标定202. chemical reaction 化学反应203. concentration 浓度204. chemical equilibrium 化学平衡205. titer 滴定度206. general equation for a chemical reaction 化学反应的通式207. proton theory of acid-base 酸碱质子理论208. acid-base titration 酸碱滴定法209. dissociation constant 解离常数210. conjugate acid-base pair 共轭酸碱对211. acetic acid 乙酸212. hydronium ion 水合氢离子213. electrolyte 电解质214. ion-product constant of water 水的离子积215. ionization 电离216. proton condition 质子平衡217. zero level 零水准218. buffer solution 缓冲溶液219. methyl orange 甲基橙220. acid-base indicator 酸碱指示剂221. phenolphthalein 酚酞222. coordination compound 配位化合物223. center ion 中心离子224. cumulative stability constant 累积稳定常数。
电化学测量方法学院:化学与生物工程学院专业:应用化学班级:应化0901学号:200967090125姓名:宁波电化学测量方法概述:电极电势、通过电极的电流是表征总的、复杂的微观电极过程特点的宏观物理量。
电化学测量的主要任务是通过测量包含电极过程各种动力学信息的电势、电流两个物理量,研究它们在各种极化信号激励下的变化关系,从而研究电极过程的各个基本过程。
Summary:Electrode potential, the current passing through the electrodes is the characterization of the total, complex micro electrode process macroscopical physics quantity. Electrochemical measurement of the main task is through the electrode process kinetics of various measurements contain information potential, current two physical quantities, study them in various polarization signals under the excitation of changes, thus studying electrode process of all the basic process.测量方法分类:基于电化学的测量规律、按照对应出现的时间顺序,电化学测量大致可以分为三类。
第一类是电化学热力学性质的测量方法,基于Nernst方程、电势-pH图、法拉第定律等热力学规律;第二类是依靠单纯电极电势、极化电流的控制和测量进行的动力学性质的测量方法,研究电极过程的反应机理,测定过程的动力学参数;第三类是在电极电势、极化电流的控制和测量的同时,结合光谱波谱技术、扫描探针显微技术,引入光学信号等其他参量的测量,研究体系电化学性质的测量方法。
动电位极化曲线英文English Answer:Introduction.Electrochemical polarization behavior is a common phenomenon in electrochemical systems. It refers to the change in electrode potential of a working electrode under the influence of an external electric field or current. The study of electrochemical polarization behavior is of great importance for understanding the kinetics and mechanisms of electrochemical reactions, and for designing and optimizing electrochemical devices.Dynamic Electrokinetic Polarization Test.The dynamic electrokinetic polarization techniquerefers to the measurement of electrode potential under the condition of continuously changing external current or voltage. This technique can be used to obtain the dynamicelectrokinetic polarization curve, which reflects the relationship between electrode potential and externalcurrent or voltage. The dynamic electrokinetic polarization curve can be used to determine the kinetic parameters of electrochemical reactions, such as exchange current density, Tafel slope, and reaction order.Experimental Setup.The experimental setup for a dynamic electrokinetic polarization test typically includes a three-electrode cell, a potentiostat, and a function generator. The working electrode is placed in the electrochemical cell, and the reference electrode and counter electrode are used tocontrol the potential of the working electrode. The potentiostat is used to apply a voltage or current to the working electrode, and the function generator is used to generate the dynamic voltage or current waveform.Data Analysis.The data from a dynamic electrokinetic polarizationtest can be analyzed using a variety of electrochemical techniques, such as Tafel analysis, impedance spectroscopy, and cyclic voltammetry. Tafel analysis is a common technique for determining the kinetic parameters of electrochemical reactions. The Tafel slope can be used to determine the rate-determining step of the reaction, and the exchange current density can be used to determine the rate of the reaction at equilibrium.Applications.Dynamic electrokinetic polarization testing has a wide range of applications in electrochemistry. It can be used to study the kinetics and mechanisms of electrochemical reactions, to design and optimize electrochemical devices, and to evaluate the performance of electrochemical materials.Advantages and Limitations.Dynamic electrokinetic polarization testing has a number of advantages over other electrochemical techniques.It is a relatively simple and inexpensive technique, and it can be used to obtain a wealth of information about the electrochemical system. However, dynamic electrokinetic polarization testing also has some limitations. It can be difficult to interpret the results of dynamicelectrokinetic polarization tests, and the technique is not always suitable for studying complex electrochemical systems.Conclusion.Dynamic electrokinetic polarization testing is a powerful tool for studying electrochemical reactions. It is a versatile technique that can be used to obtain a wealth of information about the electrochemical system. However,it is important to understand the advantages andlimitations of dynamic electrokinetic polarization testing before using the technique.Chinese Answer:简介。
bet公式bet formuladlvo理论 dlvo theoryhlb法hydrophile-lipophile balance methodpvt性质 pvt propertyζ电势 zeta potential阿伏加德罗常数avogadro’number阿伏加德罗定律 avogadro law阿累尼乌斯电离理论arrhenius ionization theory阿累尼乌斯方程arrhenius equation阿累尼乌斯活化能 arrhenius activation energy阿马格定律 amagat law艾林方程 erying equation爱因斯坦光化当量定律einstein’s law of photochemical equivalence爱因斯坦-斯托克斯方程 einstein-stokes equation安托万常数 antoine constant安托万方程 antoine equation盎萨格电导理论onsager’s theory of conductance半电池half cell半衰期half time period饱和液体 saturated liquids饱和蒸气 saturated vapor饱和吸附量 saturated extent of adsorption饱和蒸气压 saturated vapor pressure爆炸界限 explosion limits比表面功 specific surface work比表面吉布斯函数 specific surface gibbs function比浓粘度 reduced viscosity标准电动势 standard electromotive force标准电极电势 standard electrode potential标准摩尔反应焓 standard molar reaction enthalpy标准摩尔反应吉布斯函数standard gibbs function of molar reaction标准摩尔反应熵 standard molar reaction entropy标准摩尔焓函数 standard molar enthalpy function标准摩尔吉布斯自由能函数standard molar gibbs free energy function标准摩尔燃烧焓 standard molar combustion enthalpy标准摩尔熵 standard molar entropy标准摩尔生成焓 standard molar formation enthalpy标准摩尔生成吉布斯函数standard molar formation gibbs function标准平衡常数 standard equilibrium constant标准氢电极 standard hydrogen electrode标准态 standard state标准熵 standard entropy标准压力 standard pressure标准状况 standard condition表观活化能apparent activation energy表观摩尔质量 apparent molecular weight表观迁移数apparent transference number表面 surfaces表面过程控制 surface process control表面活性剂surfactants表面吸附量 surface excess表面张力 surface tension表面质量作用定律 surface mass action law波义尔定律 boyle law波义尔温度 boyle temperature波义尔点 boyle point玻尔兹曼常数 boltzmann constant玻尔兹曼分布 boltzmann distribution玻尔兹曼公式 boltzmann formula玻尔兹曼熵定理 boltzmann entropy theorem玻色-爱因斯坦统计bose-einstein statistics泊poise不可逆过程 irreversible process不可逆过程热力学thermodynamics of irreversible processes 不可逆相变化 irreversible phase change布朗运动 brownian movement查理定律charle’s law产率 yield敞开系统 open system超电势 over potential沉降 sedimentation沉降电势 sedimentation potential沉降平衡 sedimentation equilibrium触变 thixotropy粗分散系统 thick disperse system催化剂 catalyst单分子层吸附理论 mono molecule layer adsorption单分子反应 unimolecular reaction单链反应 straight chain reactions弹式量热计 bomb calorimeter道尔顿定律 dalton law道尔顿分压定律 dalton partial pressure law德拜和法尔肯哈根效应debye and falkenhagen effect德拜立方公式 debye cubic formula德拜-休克尔极限公式 debye-huckel’s limiting equation 等焓过程 isenthalpic process等焓线isenthalpic line等几率定理 theorem of equal probability等温等容位helmholtz free energy等温等压位gibbs free energy等温方程 equation at constant temperature低共熔点 eutectic point低共熔混合物 eutectic mixture低会溶点 lower consolute point低熔冰盐合晶 cryohydric第二类永动机 perpetual machine of the second kind第三定律熵 third-law entropy第一类永动机 perpetual machine of the first kind缔合化学吸附 association chemical adsorption电池常数 cell constant电池电动势 electromotive force of cells电池反应 cell reaction电导 conductance电导率 conductivity电动势的温度系数 temperature coefficient of electromotive force电动电势 zeta potential电功electric work电化学 electrochemistry电化学极化 electrochemical polarization电极电势 electrode potential电极反应 reactions on the electrode电极种类 type of electrodes电解池 electrolytic cell电量计 coulometer电流效率current efficiency电迁移 electro migration电迁移率 electromobility电渗 electroosmosis电渗析 electrodialysis电泳 electrophoresis丁达尔效应 dyndall effect定容摩尔热容 molar heat capacity under constant volume 定容温度计 constant voiume thermometer定压摩尔热容 molar heat capacity under constant pressure 定压温度计 constant pressure thermometer定域子系统 localized particle system动力学方程kinetic equations动力学控制 kinetics control独立子系统 independent particle system对比摩尔体积 reduced mole volume对比体积 reduced volume对比温度 reduced temperature对比压力 reduced pressure对称数 symmetry number对行反应reversible reactions对应状态原理 principle of corresponding state多方过程polytropic process多分子层吸附理论adsorption theory of multi-molecular layers二级反应second order reaction二级相变second order phase change法拉第常数 faraday constant法拉第定律faraday’s law反电动势back e.m.f.反渗透 reverse osmosis反应分子数 molecularity反应级数 reaction orders反应进度 extent of reaction反应热heat of reaction反应速率rate of reaction反应速率常数 constant of reaction rate范德华常数 van der waals constant范德华方程 van der waals equation范德华力 van der waals force范德华气体 van der waals gases范特霍夫方程van’t hoff equation范特霍夫规则van’t hoff rule范特霍夫渗透压公式van’t hoff equation of osmotic pressure非基元反应 non-elementary reactions非体积功 non-volume work非依时计量学反应time independent stoichiometric reactions菲克扩散第一定律fick’s first law of diffusion沸点 boiling point沸点升高 elevation of boiling point费米-狄拉克统计fermi-dirac statistics分布 distribution分布数 distribution numbers分解电压 decomposition voltage分配定律 distribution law分散系统 disperse system分散相 dispersion phase分体积 partial volume分体积定律 partial volume law分压 partial pressure分压定律 partial pressure law分子反应力学 mechanics of molecular reactions分子间力 intermolecular force分子蒸馏molecular distillation封闭系统 closed system附加压力 excess pressure弗罗因德利希吸附经验式freundlich empirical formula of adsorption负极 negative pole负吸附 negative adsorption复合反应composite reaction盖·吕萨克定律 gay-lussac law盖斯定律 hess law甘汞电极 calomel electrode感胶离子序 lyotropic series杠杆规则 lever rule高分子溶液 macromolecular solution高会溶点 upper consolute point隔离法the isolation method格罗塞斯-德雷珀定律 grotthus-draoer’s law隔离系统 isolated system根均方速率 root-mean-square speed功 work功函work content共轭溶液 conjugate solution共沸温度 azeotropic temperature构型熵configurational entropy孤立系统 isolated system固溶胶 solid sol固态混合物 solid solution固相线 solid phase line光反应 photoreaction光化学第二定律 the second law of actinochemistry光化学第一定律 the first law of actinochemistry光敏反应 photosensitized reactions光谱熵 spectrum entropy广度性质 extensive property广延量 extensive quantity广延性质 extensive property规定熵 stipulated entropy过饱和溶液 oversaturated solution过饱和蒸气 oversaturated vapor过程 process过渡状态理论 transition state theory过冷水 super-cooled water过冷液体 overcooled liquid过热液体 overheated liquid亥姆霍兹函数 helmholtz function亥姆霍兹函数判据 helmholtz function criterion亥姆霍兹自由能 helmholtz free energy亥氏函数 helmholtz function焓 enthalpy亨利常数 henry constant亨利定律 henry law恒沸混合物 constant boiling mixture恒容摩尔热容 molar heat capacity at constant volume 恒容热 heat at constant volume恒外压 constant external pressure恒压摩尔热容 molar heat capacity at constant pressure恒压热 heat at constant pressure化学动力学chemical kinetics化学反应计量式stoichiometric equation of chemical reaction化学反应计量系数stoichiometric coefficient of chemical reaction化学反应进度 extent of chemical reaction化学亲合势 chemical affinity化学热力学chemical thermodynamics化学势 chemical potential化学势判据 chemical potential criterion化学吸附 chemisorptions环境 environment环境熵变 entropy change in environment挥发度volatility混合熵 entropy of mixing混合物 mixture活度 activity活化控制 activation control活化络合物理论 activated complex theory活化能activation energy霍根-华森图 hougen-watson chart基态能级 energy level at ground state基希霍夫公式 kirchhoff formula基元反应elementary reactions积分溶解热 integration heat of dissolution吉布斯-杜亥姆方程 gibbs-duhem equation吉布斯-亥姆霍兹方程 gibbs-helmhotz equation吉布斯函数 gibbs function吉布斯函数判据 gibbs function criterion吉布斯吸附公式gibbs adsorption formula吉布斯自由能 gibbs free energy吉氏函数 gibbs function极化电极电势 polarization potential of electrode 极化曲线 polarization curves极化作用 polarization极限摩尔电导率 limiting molar conductivity几率因子 steric factor计量式 stoichiometric equation计量系数 stoichiometric coefficient价数规则 rule of valence简并度 degeneracy键焓bond enthalpy胶冻 broth jelly胶核 colloidal nucleus胶凝作用 demulsification胶束micelle胶体 colloid胶体分散系统 dispersion system of colloid胶体化学 collochemistry胶体粒子 colloidal particles胶团 micelle焦耳joule焦耳-汤姆生实验 joule-thomson experiment焦耳-汤姆生系数 joule-thomson coefficient焦耳-汤姆生效应 joule-thomson effect焦耳定律 joule`s law接触电势contact potential接触角 contact angle节流过程 throttling process节流膨胀 throttling expansion节流膨胀系数 coefficient of throttling expansion结线 tie line结晶热heat of crystallization解离化学吸附 dissociation chemical adsorption界面 interfaces界面张力 surface tension浸湿 immersion wetting浸湿功 immersion wetting work精馏 rectify聚(合)电解质polyelectrolyte聚沉 coagulation聚沉值 coagulation value绝对反应速率理论 absolute reaction rate theory绝对熵 absolute entropy绝对温标absolute temperature scale绝热过程 adiabatic process绝热量热计adiabatic calorimeter绝热指数 adiabatic index卡诺定理 carnot theorem卡诺循环 carnot cycle开尔文公式 kelvin formula柯诺瓦洛夫-吉布斯定律 konovalov-gibbs law科尔劳施离子独立运动定律kohlrausch’s law of independent migration of ions可能的电解质potential electrolyte可逆电池 reversible cell可逆过程 reversible process可逆过程方程 reversible process equation可逆体积功 reversible volume work可逆相变 reversible phase change克拉佩龙方程 clapeyron equation克劳修斯不等式 clausius inequality克劳修斯-克拉佩龙方程 clausius-clapeyron equation控制步骤 control step库仑计 coulometer扩散控制 diffusion controlled拉普拉斯方程laplace’s equation拉乌尔定律 raoult law兰格缪尔-欣谢尔伍德机理langmuir-hinshelwood mechanism兰格缪尔吸附等温式 langmuir adsorption isotherm formula 雷利公式 rayleigh equation冷冻系数coefficient of refrigeration冷却曲线 cooling curve离解热heat of dissociation离解压力dissociation pressure离域子系统 non-localized particle systems离子的标准摩尔生成焓 standard molar formation of ion离子的电迁移率 mobility of ions离子的迁移数transport number of ions离子独立运动定律 law of the independent migration of ions 离子氛 ionic atmosphere离子强度 ionic strength理想混合物 perfect mixture理想气体 ideal gas接触电势contact potential接触角 contact angle节流过程 throttling process节流膨胀 throttling expansion节流膨胀系数 coefficient of throttling expansion结线 tie line结晶热heat of crystallization解离化学吸附 dissociation chemical adsorption界面 interfaces界面张力 surface tension浸湿 immersion wetting浸湿功 immersion wetting work精馏 rectify聚(合)电解质polyelectrolyte聚沉 coagulation聚沉值 coagulation value绝对反应速率理论 absolute reaction rate theory绝对熵 absolute entropy绝对温标absolute temperature scale绝热过程 adiabatic process绝热量热计adiabatic calorimeter绝热指数 adiabatic index卡诺定理 carnot theorem卡诺循环 carnot cycle开尔文公式 kelvin formula柯诺瓦洛夫-吉布斯定律 konovalov-gibbs law科尔劳施离子独立运动定律kohlrausch’s law of independent migration of ions可能的电解质potential electrolyte可逆电池 reversible cell可逆过程 reversible process可逆过程方程 reversible process equation可逆体积功 reversible volume work可逆相变 reversible phase change克拉佩龙方程 clapeyron equation克劳修斯不等式 clausius inequality克劳修斯-克拉佩龙方程 clausius-clapeyron equation控制步骤 control step库仑计 coulometer扩散控制 diffusion controlled拉普拉斯方程laplace’s equation拉乌尔定律 raoult law兰格缪尔-欣谢尔伍德机理langmuir-hinshelwood mechanism兰格缪尔吸附等温式 langmuir adsorption isotherm formula 雷利公式 rayleigh equation冷冻系数coefficient of refrigeration冷却曲线 cooling curve离解热heat of dissociation离解压力dissociation pressure离域子系统 non-localized particle systems离子的标准摩尔生成焓 standard molar formation of ion离子的电迁移率 mobility of ions离子的迁移数transport number of ions离子独立运动定律 law of the independent migration of ions 离子氛 ionic atmosphere离子强度 ionic strength理想混合物 perfect mixture理想气体 ideal gas理想气体的绝热指数 adiabatic index of ideal gases理想气体的微观模型 micro-model of ideal gas理想气体反应的等温方程isothermal equation of ideal gaseous reactions理想气体绝热可逆过程方程adiabatic reversible processequation of ideal gases理想气体状态方程 state equation of ideal gas理想稀溶液 ideal dilute solution理想液态混合物 perfect liquid mixture粒子 particles粒子的配分函数 partition function of particles连串反应consecutive reactions链的传递物 chain carrier链反应 chain reactions量热熵 calorimetric entropy量子统计quantum statistics量子效率 quantum yield临界参数 critical parameter临界常数 critical constant临界点 critical point临界胶束浓度critical micelle concentration临界摩尔体积 critical molar volume临界温度 critical temperature临界压力 critical pressure临界状态 critical state零级反应zero order reaction流动电势 streaming potential流动功 flow work笼罩效应 cage effect路易斯-兰德尔逸度规则 lewis-randall rule of fugacity 露点 dew point露点线 dew point line麦克斯韦关系式 maxwell relations麦克斯韦速率分布 maxwell distribution of speeds麦克斯韦能量分布 maxwelidistribution of energy毛细管凝结 condensation in capillary毛细现象 capillary phenomena米凯利斯常数 michaelis constant摩尔电导率 molar conductivity摩尔反应焓 molar reaction enthalpy摩尔混合熵 mole entropy of mixing摩尔气体常数 molar gas constant摩尔热容 molar heat capacity摩尔溶解焓 mole dissolution enthalpy摩尔稀释焓 mole dilution enthalpy内扩散控制 internal diffusions control内能 internal energy内压力 internal pressure能级 energy levels能级分布 energy level distribution能量均分原理 principle of the equipartition of energy 能斯特方程 nernst equation能斯特热定理 nernst heat theorem凝固点 freezing point凝固点降低 lowering of freezing point凝固点曲线 freezing point curve凝胶 gelatin凝聚态 condensed state凝聚相 condensed phase浓差超电势 concentration over-potential浓差极化 concentration polarization浓差电池 concentration cells帕斯卡pascal泡点 bubble point泡点线 bubble point line配分函数 partition function配分函数的析因子性质 property that partition function to be expressed as a product of the separate partition functions for each kind of state碰撞截面 collision cross section碰撞数 the number of collisions偏摩尔量 partial mole quantities平衡常数(理想气体反应)equilibrium constants for reactions of ideal gases平动配分函数 partition function of translation平衡分布 equilibrium distribution平衡态 equilibrium state平衡态近似法 equilibrium state approximation平衡状态图 equilibrium state diagram平均活度 mean activity平均活度系统 mean activity coefficient平均摩尔热容 mean molar heat capacity平均质量摩尔浓度 mean mass molarity平均自由程mean free path平行反应parallel reactions破乳 demulsification铺展 spreading普遍化范德华方程 universal van der waals equation其它功 the other work气化热heat of vaporization气溶胶 aerosol气体常数 gas constant气体分子运动论 kinetic theory of gases气体分子运动论的基本方程 foundamental equation of kinetic theory of gases气溶胶 aerosol气相线 vapor line迁移数 transport number潜热latent heat强度量 intensive quantity强度性质 intensive property亲液溶胶 hydrophilic sol氢电极 hydrogen electrodes区域熔化zone melting热 heat热爆炸 heat explosion热泵 heat pump热功当量mechanical equivalent of heat热函heat content热化学thermochemistry热化学方程thermochemical equation热机 heat engine热机效率 efficiency of heat engine热力学 thermodynamics热力学第二定律 the second law of thermodynamics热力学第三定律 the third law of thermodynamics热力学第一定律 the first law of thermodynamics热力学基本方程 fundamental equation of thermodynamics 热力学几率 thermodynamic probability热力学能 thermodynamic energy热力学特性函数characteristic thermodynamic function热力学温标thermodynamic scale of temperature热力学温度thermodynamic temperature热熵thermal entropy热效应heat effect熔点曲线 melting point curve熔化热heat of fusion溶胶 colloidal sol溶解焓 dissolution enthalpy溶液 solution溶胀 swelling乳化剂 emulsifier乳状液 emulsion润湿 wetting润湿角 wetting angle萨克尔-泰特洛德方程 sackur-tetrode equation 三相点 triple point三相平衡线 triple-phase line熵 entropy熵判据 entropy criterion熵增原理 principle of entropy increase渗透压 osmotic pressure渗析法 dialytic process生成反应 formation reaction升华热heat of sublimation实际气体 real gas舒尔采-哈迪规则 schulze-hardy rule松驰力relaxation force松驰时间time of relaxation速度常数reaction rate constant速率方程rate equations速率控制步骤rate determining step塔费尔公式 tafel equation态-态反应 state-state reactions唐南平衡 donnan equilibrium淌度 mobility特鲁顿规则 trouton rule特性粘度 intrinsic viscosity体积功 volume work统计权重 statistical weight统计热力学 statistic thermodynamics统计熵 statistic entropy途径 path途径函数 path function外扩散控制 external diffusion control完美晶体 perfect crystalline完全气体 perfect gas微观状态 microstate微态 microstate韦斯顿标准电池 weston standard battery维恩效应wien effect维里方程 virial equation维里系数 virial coefficient稳流过程 steady flow process稳态近似法 stationary state approximation无热溶液athermal solution无限稀溶液 solutions in the limit of extreme dilution 物理化学 physical chemistry物理吸附 physisorptions吸附 adsorption吸附等量线 adsorption isostere吸附等温线 adsorption isotherm吸附等压线 adsorption isobar吸附剂 adsorbent吸附量 extent of adsorption吸附热 heat of adsorption吸附质 adsorbate析出电势 evolution or deposition potential析因子性质 property that partition function to be expressed as a product of the separate partition functions for each kind of state稀溶液的依数性 colligative properties of dilute solutions稀释焓 dilution enthalpy系统 system系统点 system point系统的环境 environment of system相 phase相变 phase change相变焓 enthalpy of phase change相变化 phase change相变热 heat of phase change相点 phase point相对挥发度relative volatility相对粘度 relative viscosity相律 phase rule相平衡热容heat capacity in phase equilibrium相图 phase diagram相倚子系统 system of dependent particles悬浮液 suspension循环过程 cyclic process压力商 pressure quotient压缩因子 compressibility factor压缩因子图 diagram of compressibility factor亚稳状态 metastable state盐桥 salt bridge盐析 salting out阳极 anode杨氏方程young’s equation液体接界电势 liquid junction potential液相线 liquid phase lines一级反应first order reaction一级相变first order phase change依时计量学反应 time dependent stoichiometric reactions 逸度 fugacity逸度系数 coefficient of fugacity阴极 cathode荧光 fluorescence永动机 perpetual motion machine永久气体 permanent gas有效能 available energy原电池 primary cell原盐效应 salt effect增比粘度 specific viscosity憎液溶胶 lyophobic sol沾湿 adhesional wetting沾湿功 the work of adhesional wetting真溶液 true solution真实电解质real electrolyte真实气体 real gas真实迁移数true transference number振动配分函数 partition function of vibration振动特征温度 characteristic temperature of vibration蒸气压下降 depression of vapor pressure正常沸点 normal point正吸附 positive adsorption支链反应 branched chain reactions直链反应 straight chain reactions指前因子 pre-exponential factor质量作用定律mass action law制冷系数coefficient of refrigeration中和热heat of neutralization轴功 shaft work转动配分函数 partition function of rotation转动特征温度 characteristic temperature of vibration 转化率 convert ratio转化温度conversion temperature状态 state状态方程 state equation状态分布 state distribution状态函数 state function准静态过程quasi-static process准一级反应 pseudo first order reaction自动催化作用 auto-catalysis自由度 degree of freedom自由度数 number of degree of freedom自由焓free enthalpy自由能free energy自由膨胀free expansion组分数 component number最低恒沸点 lower azeotropic point最高恒沸点 upper azeotropic point最佳反应温度 optimal reaction temperature最可几分布 most probable distribution最可几速率 most propable speed。
热力学(thermodynamics):研究宏观系统在能量转换过程中所遵循的规律的科学。
系统(system):将一部分物质从其他部分中划分出来,作为研究的对象,这一部分物质就成为系统环境(surroundings):系统之外与系统密切相关的部分成为环境。
敞开系统:系统与环境之间既有物质的交换,又有能量的转换。
封闭系统:无物质交换,只有能量的传递孤立系统(isolated):亦成为隔离系统,无物质交换也无能量的传递广度性质(extensive properties):期数值大小与系统中所含物质的量成正比。
有加和性强度性质(intensive properties):期数值取决于系统的特性而与系统所含物质的量无关状态函数(state function):由系统状态确定的系统的各种热力学性质称为状态函数等温过程(isothermal process):在环境温度恒定下,系统始终态压力相同且等于环境温度的过程。
等压过程(isobaric process):在环境压力恒定下,系统始终态压力相同且等于环境压力的过程等容过程(isochoric process):系统的体积保持不变的过程绝热过程(adiabatic process):系统与环境之间没有热传递的过程循环过程(cyclic process):系统从某一状态出发,经一系列变化,又恢复到原来状态的过程热力学能(thermodynamics energy)也称为内能(internal energy):是系统中物质的所有能量的总和。
标准摩尔生成焓(standard molar enthalpy of formation):在标准压力(100kpa)和指定温度T时,由最稳定的单质生成标准状态下1摩尔化合物的焓变成为该化合物在此温度下的白准摩尔生成焓。
热力学第二定律,克劳休息表述“热量由低温物体传给高温物体而不引起其他变化是不可能的”开尔文表述“从单一热源取出热使之完全变为功,而不发生其他变化时不可能的”也称“第二种永动机不可能造成”。
常用名词1.化学腐蚀chemical corrosion金属在非电化学作用下的腐蚀(氧化)过程。
通常指在非电解质溶液及干燥气体中,纯化学作用引起的腐蚀。
2.双电层electric double layer电极与电解质溶液界面上存在的大小相等符号相反的电荷层。
3.双极性电极bipolar electrode一个不与外电源相连的,浸入阳极与阴极间电解液中的导体。
靠近阳极的那部分导体起着阴极的作用,而靠近阴极的部分起着阳极的作用.4.分散能力throwing power在特定条件下,一定溶液使电极上(通常是阴极)镀层分布比初次电流分布所获得的结果更为均匀的能力。
此名词也可用于阳极过程,其定义与上述者类似。
5。
分解电压decomposition voltage其定义与上述者类似。
能使电化学反应以明显速度持续进行的最小电压(溶液的欧姆电压降不包括在内)。
6.不溶性阳极(惰性阳极)inert anode在电流通过时,不发生阳极溶解反应的阳极。
7.电化学electrochemistry研究电子导体和离子导体的接触界面性质及其所发生变化的科学.8.电化学极化(活化极化)activation polarization由于电化学反应在进行中遇到困难而引起的极化。
9。
电化学腐蚀electrochemical corrosion在卑解质溶掖中或金属表面上的液膜中,服从于电化学反应规律的金属腐蚀(氧化)过程10。
电化当量electrochemical equivalent在电极上通过单位电量(例如1安时,1库仑或1法拉第时),电极反应形成产物之理论重量.通常以克/库仑或克/安时表示。
11 电导率(比电导)conductivity单位截面积和单位长度的导体之电导,通常以S/m表示。
12 电泳electrophoresis液体介质中带电的胶体微粒在外电场作用下相对液体的迁移现象。
13 电动势electromotive force原电池开路时两极间的电势差。
Materials Science and Engineering A 372(2004)180–185Micro-electrochemical polarization studyon 25%Cr duplex stainless steelChan-Jin Park a ,∗,Hyuk-Sang Kwon a ,M.M.Lohrengel baDepartment of Material Science and Engineering,Korea Advanced Institute of Science and Technology (KAIST),373-1Guseong-dong,Yuseong-gu,Daejeon 305701,South KoreabInstitute for Physical Chemistry and Electrochemistry,Heinrich-Heine University Duesseldorf,Duesseldorf 40225,GermanyReceived 5September 2003;received in revised form 3December 2003AbstractMicro-electrochemical characteristics of 25%Cr duplex stainless steel (DSS)were investigated by a new electrochemical technique,a micro-droplet cell.Anodic polarization tests were carried out in pH 5.6acetate buffer solution for annealed DSS solution,for the alloy aged at 850◦C,and for the alloy aged at 475◦C.The anodic peak current density for the ferrite (␣)phase was measured to be higher at slightly lower potential compared with that for austenite (␣)phase in solution annealed DSS,suggesting that ␣was electrochemically more active than ␥,which has a lower Ni content.The polarization curve for the region where the sigma ()phase coexisted with secondary austenite (␥2)phase,(+␥2),in the alloy aged at 850◦C showed two anodic current peaks,which possibly corresponded to those for ␥2and ,respectively.The anodic peak current density and passive current density for the region of (+␥2)in the alloy aged at 850◦C were higher,and the current scattering corresponding to the initiation of metastable pitting corrosion was more evident than those for ␣and ␥in the solution annealed alloy.This indicates that the (+␥2)region was probably electrochemically active,and thus sensitive to active dissolution.The ␥2phase containing lower contents of N,Cr,and Mo compared with the primary austenite (␥)phase as well as the Cr-depleted zone around the phase appeared to be the main cause of the degradation of the stability of the passive film.An anodic current peak was also observed in the polarization curve for the region that had experienced spinodal decomposition of ferrite phase to Fe-rich ␣phase and Cr-rich ␣ phase (␣+␣ ).The anodic current peak for the region of (␣+␣ )in the alloy aged at 475◦C was found at lower potential and the peak current density was higher than those for primary ␣and ␥in a solution annealed alloy.The precipitation of ␣ phase induced the formation of a microscale Cr-depleted region,which is active and hence degrades the stability of passive film.©2004Elsevier B.V .All rights reserved.Keywords:Duplex stainless steel;Micro-droplet cell;Sigma ()phase;Alpha prime (␣ )phase;Passive film1.IntroductionCharacterization of the passive film on a metal surface is traditionally in the domain of electrochemical methods.Because of the low lateral resolution of electrochemical stan-dard methods,however,only macroscopic averaged proper-ties could be obtained.Therefore,important texture or phase depending characteristics of polycrystalline material have rarely been investigated.Except for single crystals,which are specially controlled during solidification,most metals∗Corresponding author.Present address:Stainless Steel Research Group,Technical Research Laboratories,POSCO 1,Goedong-dong,Nam-gu,Pohang 790785,Gyeongbuk,South Korea.Tel.:+82-54-220-7833;fax:+82-54-220-6915.E-mail address:parkcj@posco.co.kr (C.-J.Park).consist of many grains and,sometimes,two or three phases with various crystallographic orientations or phase compo-sitions.Accordingly,the macroscopic electrochemical be-havior is simply the sum of the contributions of the different grains or phases,multiplied by their individual degree of coverage.Sometimes,some special grains or phases showing completely different properties compared with others may dominate the electrochemical response of a macroscopic sample.A new electrochemical device,the capillary-based droplet cell [1,2],as shown in Fig.1,provides facilities for micro-electrochemical investigations at high resolution.Small electrolyte droplets are positioned on the sample sur-face,enabling a spatially resolved surface analysis or modi-fication.The small area of the working electrode determined by the tip size of a capillary with a diameter of 20–600m0921-5093/$–see front matter ©2004Elsevier B.V .All rights reserved.doi:10.1016/j.msea.2003.12.013C.-J.Park et al./Materials Science and Engineering A372(2004)180–185181Fig.1.Typical experimental setup of a micro-droplet cell;the droplet cell contains a micro-reference electrode and a thin gold wire as a counter electrode.enables the investigation of localized corrosion or passiva-tion of small areas within a single grain or phase.In addi-tion,the device has a smaller resolution than some special probe techniques(e.g.STM),but enables a complete range of potentio-static(or dynamic)and galvano-static(or dy-namic)techniques including impedance spectroscopy.This is accomplished by providing a convenient three-electrode system consisting of the working electrode of interest,a thin gold wire as a counter electrode(CE),and a micro-reference electrode(RE).This method has already been applied to the single grains of polycrystalline materials such as Al,Ta,Nb, Hf[3],and Zn[2],and some evidence of texture-depending characteristic of grains were found in those materials.In contrast to pure metals,alloys have rarely been in-vestigated using the micro-droplet cell because of their complexity in structure and chemical composition.Duplex stainless steel(DSS)is potentially a good candidate for micro-electrochemical investigations with the droplet cell, because this alloy is composed of an approximately equal volume fraction of ferrite(␣)and austenite(␥)phase,and, sometimes,secondary phases such as sigma()or alpha prime(␣ )phase[4–6].The excellent resistance to stress corrosion cracking(SCC)of this alloy is attributed to the synergistic effect of␣and␥[7,8].In addition,secondary phases in DSS are known to degrade the corrosion resis-tance of the alloy due to nearby formation of Cr and/or Modepleted zones[4–6].Thus far,single phase alloys with similar chemical com-positions and crystal structures to those of␣,␥orin DSShave been used to investigate the electrochemical behaviorsof each phase.However,these single phase alloys can con-tain grain boundaries and inclusions,and such defects mayunexpectedly affect the experimental results.Therefore,theoptimal method is to directly measure the electrochemicalproperties of a single phase or local area containingfineprecipitates while excluding the effects of other phases ordefects in DSS;the micro-droplet cell enables such an ap-proach.The objective of the present work is to elucidate the in-dividual electrochemical characteristics of␣,␥,and othersecondary phases of duplex stainless steel using the dropletcell.Solution annealed DSS is basically composed of␣and ␥,where␣is relatively richer in Cr and Mo but poorer in Ni and N than␥.This difference in chemical compositionsbetween␣and␥can make a difference in their electrochem-ical behaviors.Generally,␣is considered to be more ac-tive than␥,which has a lower Ni content.With an aging at850◦C,the ferrite phase in DSS is decomposed tophaseand secondary austenite(␥2)phase.Thephase has veryhigh contents of Cr and Mo and induces the depletion ofCr and Mo in the region around the phase and the resultantdegradation of the stability of the passivefilm.In addition,for the DSS aged for a long of time at475◦C,the alloyundergoes the spinodal decomposition of ferrite phase intoa Cr-rich␣ and Fe-rich␣phase.This also can lead to thedegradation of passivefilm.The present work,cover theseinfluences of each phase in DSS on the electrochemical be-haviors and the stability of passivefilm of the alloy.2.ExperimentalThe duplex stainless steel used in the present work wasmelted in a30kW induction furnace.The alloy was castin shell molds,and cylindrical castings with a diameter of27mm and height of130mm were obtained.Table1showsthe chemical composition of the casting.The castings werehomogenized for2h at1250◦C and then solution annealedfor1h at1050◦C.Aging treatment for the specimens wasadditionally performed for10h at850◦C and for300h at475◦C,respectively.The specimens were polished up toTable1Chemical composition of the duplex stainless steel castingCr24.37 Ni 6.76 Mo 1.50 W 3.23 Mn 1.19 Si0.62 N0.26182 C.-J.Park et al./Materials Science and Engineering A 372(2004)180–1851m surface finish,and some specimens were then etched at 5V in 10%KOH solution for metallographic observations.For polarization tests,polished specimens without etching were used,since the chemical composition or roughness of the surface can be changed by the selective dissolution of alloying elements during the etching process.However,␣and ␥could be easily distinguished with optical microscopy,because the hardness of each phase was different;thus re-sulting in small differences in height at phase boundaries during mechanical polishing with diamond suspension.Potentiodynamic anodic polarization tests were carried out in a pH 5.6acetate buffer solution and in a 0.5M H 2SO 4+0.01M KSCN solution using the droplet cell.A capillary with an inner diameter of 30m (area:7.1×10−6cm 2)was used for the measurement.The tip size of the capillary could be estimated from the plateau current in cyclic voltammograms on pure aluminum (Al)in a pH 6ac-etate buffer solution at a scan rate of 100mV/s.A plateau current of 250A corresponds to an specimen exposure area of 1cm 2.Thus,the diameter of the capillary made for the ex-periment in the present work was obtained by measuring the plateau current in the cyclic voltammogram on a Al sample using the droplet cell equipped with the capillary and con-verting the measured plateau current to the capillary area.3.Results3.1.Investigation of solution annealed alloyFig.2shows an optical micrograph of a solution annealed alloy etched in 10%KOH solution.The dark phase indicates ferrite (␣)and the bright phase austenite (␥)in this figure.The volume fraction of ␣and ␥was approximately 50:50,and the grain size was large enough for measurement with a capillary with a diameter of 30m.Fig.2.Optical micrograph of solution annealed alloy etched in 10%KOH solution.1E-81E-71E-61E-51E-4P o t e n t i a l [V v s H g /H g O ]Current density [A/cm 2]Fig.3.Polarization curves of austenite (␥)and ferrite (␣)phase in pH 5.6acetate buffer solution.Fig.3shows the individual polarization curves for ␣and ␥in the pH 5.6acetate buffer solution.In the beginning of po-larization,the current values were scattered.Metastable pit-ting corrosion on surface defects such as micropores formed during solidification or inherent inclusions may have been the cause of this scattering.An anodic current peak was observed near 500mV with increasing potential for both phases.This peak may be attributed to the active dissolution of alloying elements.For the ferrite (␣)phase,the anodic current peak was found at lower potential and the peak cur-rent density was higher than that for the austenite (␥)phase.The lower corrosion potential of ␣compared with that of ␥also confirmed that ␣was electrochemically more active.These results arise from differences in the chemical compo-sitions of each alloy;␣is relatively rich in Cr and Mo while ␥is rich in Ni and N [5,9].3.2.Investigation of σand γ2Precipitates with a size less than 10m are too small for micro-electrochemical measurements using a droplet cell with a capillary diameter of 30m and can only be mea-sured with the surroundings;for example ␣ phase with the surrounding ferrite matrix and phase with the adjacent eu-tectoid secondary austenite (␥2).Fig.4shows an optical micrograph of an alloy aged for 10h at 850◦C.Ferrite (␣)was fully decomposed to and ␥2after the aging.The dark phase indicates and the small bright phase enclosed by phase is ␥2in the figure.Polarization tests on the region where and ␥2coexisted (+␥2)were conducted in a pH 5.6acetate buffer solution using the droplet cell,and the results are shown in Fig.5.The polarization curves for ␣and ␥in the solution annealed alloy are also presented in Fig.5for comparison.In partic-ular,the polarization curve for (+␥2)showed two anodic current peaks,which appeared to be associated with the ac-tive dissolution of ␥2and ,respectively.For (+␥2),theC.-J.Park et al./Materials Science and Engineering A 372(2004)180–185183Fig.4.Optical micrograph of an alloy aged for 10h at 850◦C,etched in10%KOH solution.anodic peak current density and passive current density was higher,and the current scattering in the passive range was more evident than those for ␣and ␥in the solution annealed alloy.It has been established that secondary austenite (␥2)is poorer in N,Cr,and Mo compared with primary austenite,since it originates from the primary ferrite phase and Cr and Mo concentrate in neighboring phase [4].Therefore,␥2and Cr-depleted zones around the phase can degrade the stability of a passive film.The cyclic voltammograms on ␥and (+␥2)regions in 0.5M H 2SO 4+0.01M KSCN so-lution (Fig.6)confirmed that the (+␥2)region was very susceptible to active dissolution.3.3.Investigation of (α+α )␣ Phase can form as a result of spinodal decomposition of ferrite to Fe-rich ␣and Cr-rich ␣ phases,and such phases1E-81E-71E-61E-51E-4P o t e n t i a l [V v s H g /H g O ]Current density [A/cm 2]Fig.5.Polarization curve for the region where and ␥2coexist (+␥2)in an alloy aged for 10h at 850◦C compared with that for ␣and ␥in the solution annealed alloy,in pH 5.6acetate buffer solution.-6-4-20246810C u r r e n t d e n s i t y [m A c m -2]Potential [V vs Hg/HgSO 4/0.5M H 2SO 4]Fig. 6.Cyclic voltammograms of ␥and (+␥2)region in 0.5M H 2SO 4+0.01M KSCN solution.have a very fine size of about 10nm as shown in Fig.7.The symbol ␣in this case may be confused with ␣indicat-ing a primary ferrite phase in other sections.However,␣is currently used in both cases in the literature,thus we have not changed the notation.Polarization tests were conducted on the region where the ferrite phase was decomposed into ␣and ␣ (␣+␣ ).Fig.8shows the polarization curve for (␣+␣ )in an alloy aged for 300h at 475◦C,compared with that for primary ␣and ␥in a solution annealed alloy.An anodic current peak was also observed in the polarization curve for (␣+␣ ).In addition,for the (␣+␣ )region,the anodic current peak was found at a lower potential,and the anodic peak current density and passive current density were higher than those for primary ␣and ␥.The lower corrosion potential of (␣+␣ )region compared with than that of pri-mary ␣and ␥also confirms that the (␣+␣ )region is elec-trochemically active.The precipitation of ␣ phase induces the formation of a Cr-depleted,Fe-rich region (␣)around it,and this region degrades the stability of passive film [6].4.DiscussionThus far,some efforts [8,10,11]have made to investigate the individual electrochemical behaviors of each phase in DSS.In the early stage of the research,single phase alloys with similar chemical compositions and crystal structure to those of ␣and ␥or in DSS was used to estimate the elec-trochemical characteristics of each phase.However,these single phase alloys contain grain boundaries and inclusions,and such defects may unexpectedly affect the experimental results.Especially,phase or grain boundary effects should be taken into account.Perren et al.[11]found the superpo-sition of the two polarization curves of the single phases (␣and ␥)in the active range to a new polarization curve of the phase boundary region,which contains a significant frac-tion of each phase,in their study using their own micro-cell.184 C.-J.Park et al./Materials Science and Engineering A 372(2004)180–185Fig.7.TEM micrographs of an alloy aged for 300h at 475◦C,(a)␥+(␣+␣ )and (b)(␣+␣ ).1E-81E-71E-61E-51E-4P o t e n t i a l [V v s H g /H g O ]Current density [A/cm 2]Fig.8.Polarization curve for the region where ferrite underwent spinodal decomposition to Fe-rich ␣and Cr-rich ␣ in an alloy aged for 300h at 475◦C,compared with that for ␣and ␥in the solution annealed alloy,in pH 5.6acetate buffer solution.Higher fractions of one single phase in the measured area reduced the relative contribution of the other phase to the active region.In addition,it is not usual that two activation peaks corresponding to ␣and ␥,respectively,are obtained in the polarization curve on the solution annealed DSS in the works using traditional three-electrode system with a working electrode area of some cm 2.However,different ac-tivation peak position and peak current density for ␣and ␥were clearly observed in the present work.5.Conclusions1.In the polarization curve for ferrite phase,an anodic cur-rent peak was observed at lower potential and the anodic peak current density was higher compared with those in the curve for the austenite phase in solution annealed du-plex stainless steel,suggesting that ferrite was electro-chemically more active than austenite,which has a lower Ni content.2.The polarization curve for the region where and ␥2coexisted (+␥2)in the alloy aged at 850◦C showed two anodic current peaks,which appeared to be associated with the active dissolution of ␥2and ,respectively.For (+␥2),the anodic peak current density and passive current density were higher,and the current scattering in the passive range was more evident than those for primary ␣and ␥in the solution annealed alloy,indicating that the (+␥2)region was electrochemically active,and thus sensitive to active dissolution.3.An anodic current peak was also observed in the polariza-tion curve for the region where ferrite was decomposed to Fe-rich ␣and Cr-rich ␣ (␣+␣ )in the alloy aged at 475◦C.In addition,for the (␣+␣ )region,the anodic peak was found at a lower potential and the anodic peak current density and passive current density were higher than those for primary ␣and ␥.The precipitation of ␣ phase induces the formation of a Cr-depleted,Fe-rich re-gion,and this area is not only susceptible to active disso-lution,but also degrades the stability of the passive film.References[1]M.M.Lohrengel,A.Moehring,M.Pilaski,Frescenius J.Anal.Chem.367(2000)334.[2]C.J.Park,M.M.Lohrengel,T.Hamelmann,M.Pilaski,H.S.Kwon,Electrochim.Acta 47(2002)3395.[3]A.Moehring,M.M.Lohrengel,in:A.B.Ives,J.L.Luo,J.Rodda(Eds.),Proceedings of the Eighth International Symposium on Pas-sivity of Metals and Semiconductors,vol.PV 99–42,The Electro-chemical Society,Pennington,NJ,2000,p.114.[4]J.O.Nilsson,Mater.Sci.Tech.8(1992)685.[5]J.S.Kim,H.S.Kwon,Corrosion 55(1999)512.[6]C.J.Park,H.S.Kwon,Corros.Sci.44(2002)2817.[7]H.D.Solomon,T.M.Devine Jr.,in:Proceedings of the Conferenceon Duplex Stainless Steels,ASM,Ohio,1983,p.693.C.-J.Park et al./Materials Science and Engineering A372(2004)180–185185[8]J.Hochmannm,A.Desertret,P.Jolly,R.Mayuod,in:Proceedingsof the International Conference on Stress Corrosion Cracking and Hydrogen Embrittlement of Iron Base Alloys,vol.5,NACE,Unieux-Firminy,France,1973,p.956.[9]S.Atamert,J.E.King,Acta Metall.Mater.39(1991)273.[10]C.J.Park,Ph.D.Dissertation,KAIST,2003.[11]R.A.Perren,T.A.Suter,P.J.Uggowitzer,L.Weber,R.Magdowski,H.Boehni,M.O.Speidel,Corros.Sci.43(2001)707.。