Mechanisms of Accelerated Oxidation of Copper in the Presence of Molten Oxides

Accelerated oxidation of copper under the influence of a molten corrosion product is reviewed with an emphasis on the Cu–Bi₂O₃ system. Fast and super-fast stages of the accelerated copper oxidation are considered. Mechanisms of fast and super-fast stages of the accelerated copper oxidation are suggested.     

钛铁混合氧化物短流程直接制备钛铁合金

利用固体透氧膜(SOM)法研究钛铁混合氧化物短流程直接制备钛铁合金。在熔融CaCl2熔盐体系中,以二氧化钛和氧化铁的混合氧化物压片为阴极,氧化钇稳定氧化锆管(YSZ)内的碳饱和铜液为阳极, 在1100 ℃,槽电压3.5 V的条件下电解2~6 h。经SEM、EDS、XRD等分析表明：二氧化钛和氧化铁被电解还原为钛铁合金,直接从氧化物制备钛铁合金是可行且高效的     

过氧化氢水溶液中金属缓蚀剂的试验研究

为降低飞机金属材料在酸性去漆剂中的腐蚀,本文以去漆剂中所用的过氧化氢水溶液体系为研究介质,以20钢、2024．T3铝合金、AIL4130硬铝合金和TCA钛合金等材料为研究对象,通过腐蚀失重法、塔菲尔曲线测试,筛选出对飞机常用金属材料缓蚀效果较好的复配缓蚀剂,即苯骈三氮唑、平平加、笨甲酸钠、多聚磷酸钠的优化组合,并得出20钢、2024-T3铝合金、AIL4130硬铝合金和TCA钛合金在pH为5．0的过氧化氢水溶液体系中的缓蚀效率分别为92．93％、55．56％、92．64％和98．35％。通过添加复配缓蚀剂,金属的腐蚀程度大大降低,符合飞机金属材料腐蚀允许量的相关标准。     

Corrosion Behavior and Mechanism of Irradiated 304 Nuclear Grade Stainless Steel in High-Temperature Water

Corrosion behavior and mechanism of irradiated 304 nuclear grade stainless steel were studied in simulated pressurized water reactor primary water. The microstructure of the oxide formed on the steel irradiated to different doses over an exposure period range of 25–1500 h was analyzed and compared. It was found that the general and intergranular corrosion rates of the steel were increased with irradiation dose, in correspondence with an evolution of the general oxide and the oxide formed at the grain boundary. Correlation of the oxide evolution with the corrosion kinetics and mechanism has been discussed in detail.     

稀土氧化物对贮氢合金电极电化学性能的影响

研究了稀土氧化物La_2O3_,CeO_2,Nd_2O_3和Y_2O_3对AB_5型贮氢电极电化学性能的影响。研究表明,除Y2_O3_外,其余的稀土氧化物可提高贮氢电极的1C放电容量和放电电压,延长贮氢电极的循环寿命,且对贮氢电极性能有利的顺序为:La2_O3_>CeO2_>Nd2_O3_;稀土氧化物添加量越多,贮氢电极的循环稳定性越好,但对贮氢电极的1C放电容量和放电电压的影响存在最佳值。造成这些结果的原因是:稀土氧化物增大贮氢合金颗粒间的接触电阻;稀土氧化物的催化作用;稀土氧化物对镍催化剂的稳定作用及抑制贮氢合金进一步氧化的作用。     

CeO_2对镍基金属陶瓷复合层组织和耐腐蚀性能的影响

利用 5kWCO2 激光器在 5Cr2 1Mn9Ni4N不锈钢基体表面成功熔覆了含不同CeO2 量的镍基金属陶瓷复合层。研究了稀土氧化物CeO2 对激光熔覆金属陶瓷复合层显微组织形态和耐腐蚀性能的影响 ,发现稀土氧化物CeO2 能加速碳化钨颗粒的溶解 ,促使钨与铬形成金属间化合物 ;激光熔覆镍基金属陶瓷复合层的耐硫酸腐蚀能力显著优于 1Cr18Ni9Ti不锈钢 ;且含 0 5 %CeO2 (质量分数 )的激光熔覆层的耐腐蚀能力比含 1 5 %CeO2 (质量分数 )和不含CeO2 的激光熔覆层都要强     

Observations on the structural degradation of silver during simultaneous exposure to oxidizing and reducing environments

The structural stability of silver (Ag) in dual atmosphere exposure conditions, which are representative of solid oxide fuel cell (SOFC) current collector and gas seals, has been examined in the 600–800 °C temperature range. Experiments conducted on Ag tubular sections exposed to flowing H₂-3% H₂O (inside the tube) and air (outside the tube) showed extensive porosity formation along the grain boundaries in the bulk metal. Similar tubular sections, when exposed to air only (both inside and outside the tube), showed no bulk porosity or structural changes. It is postulated that the porosity formation in the bulk metal is related to the formation of gaseous H₂O bubbles due to simultaneous diffusion of hydrogen and oxygen followed by subsequent interaction resulting in the formation of steam. Thermochemical processes that are responsible for structural degradation are presented and discussed. Based on experimental observations, it is concluded that Ag metal may not provide adequate long-term structural stability under a dual-environment condition that is typical of interconnects or gas seals in intermediate temperature SOFCs. This paper was presented at the Fuel Cells: Materials, Processing, and Manufacturing Technologies Symposium sponsored by the Energy/Utilities Industrial Sector & Ground Transportation Industrial Sector and the Specialty Materials Critical Technologies Sector at the ASM International Materials Solutions Conference, October 13–15, 2003, in Pittsburgh, PA. The symposium was organized by P. Singh, Pacific Northwest National Laboratory, S.C. Deevi, Philip Morris USA, T. Armstrong, Oak Ridge National Laboratory, and T. Dubois, U.S. Army CECOM.     

Erratum: Self-Repairing Metal Oxides by G. Hultquist,B. Tveten,E. Hörnlund,M. Limbäck,and R. Haugsrud

Oxidation of Metals -     

Anomalous high-temperature oxidation in the zirconium-copper system

The high-temperature oxidation of the Zr-3 mass% Cu alloy and Zr₂Cu in oxygen is characterized by selective oxidation of zirconium while the excess of copper is accumulated at the alloy-oxide interface forming the Zr₈Cu₅ phase. The oxidation of Zr₂Cu at elevated temperatures shows an anomalous decrease of the oxygen consumption rate in the temperature range 890-975 °C. The oxide layer consists of monoclinic ZrO₂ mainly, with preferentially oriented crystallites in depth region at 900 °C and tetragonal ZrO₂ on the surface below 600 °C, and small amounts of CuO and Cu₂O. The reaction kinetics obeys a parabolic rate law. The activation energy of 117.5 and 54.4 kJ/mol has been estimated for the oxidation of the Zr-3 mass% Cu alloy and Zr₂Cu, respectively.     

金属氢渗透研究综述

综述了氢渗透的研究方法和研究历史,总结了当前对氢损伤机理的研究,以及在易发生氢脆环境下的氢渗透行为规律和影响氢行为的因素。在这些研究的基础上,国内外先后开发了许多氢渗透防护技术,如:阻碍氢原子渗入基体,在材料表面制备涂镀层;消除钢中有害元素的方式,改变中氢原子陷阱的数目;从组织入手,开发高纯度、高抗氢钢,包括一些系列铁素体合金钢等。综述了从传统的电沉积阻氢合金镀层,到新工艺制备阻氢陶瓷层的发展。阻氢涂层具有阻氢性能极佳,兼具保护作用的优点,但容易失效,破损后会加快基体的局部腐蚀;而通过冶金、热处理来净化钢材,改变组织成分开发的纯净钢,其实际抗氢脆性能并不理想,仍然会出现氢引起的力学性能下降,并且具有控制工艺复杂、能耗大的缺点。由此认为,氢一旦进入金属材料内部,造成材料的性能损伤不可避免,防止氢进入金属材料是该领域的关键科学问题。氢渗透过程是氢损伤发生的关键步骤,那么阻碍氢渗透过程的进行就成了氢损伤防护措施的重中之重。抑制氢渗透过程的发生需要从降低氢原子浓度梯度、降低材料内部氢陷阱密度和结合能两方面入手,开发有效的抑氢手段,抑制氢渗透过程,使材料内部的氢原子浓度小于临界氢原子浓度。     

低比例甲醇汽油对金属的腐蚀研究

目的减轻甲醇汽油的腐蚀性。方法以汽车油路系统常用的紫铜、黄铜、钢、铁、铝等金属材质为研究对象,采用金属试片的腐蚀度和颜色变化相结合的方法,分析判断甲醇汽油的腐蚀性,通过考察不同金属试片在不同含量甲醇汽油、含水甲醇汽油以及添加缓蚀剂甲醇汽油中的腐蚀情况,分析甲醇汽油腐蚀的主要原因,并根据缓蚀机理筛选缓蚀剂。结果低比例甲醇汽油对不同金属材质都有明显的腐蚀作用,与93#汽油相比,加入5%(体积分数)的甲醇就能使紫铜、黄铜、钢、铝的腐蚀度增加一倍以上。少量水分可加剧甲醇汽油的腐蚀,但当水含量达到一定程度时,腐蚀度减小。缓蚀剂B对铜系金属材质的腐蚀有较好的抑制作用,缓蚀剂C对铁片腐蚀有较好的抑制作用,复配缓蚀剂H对所选金属材质都有良好的缓蚀效果,可使紫铜、黄铜、铁和铝的缓蚀率分别减小82.1%、81.5%、85.3%和89.5%。结论复配的缓蚀剂能够有效地减缓甲醇汽油对金属的腐蚀。     

Fe/Cr涂层抗热腐蚀性能研究

设计制造出Fe/Cr粉芯丝材,利用电弧喷涂技术制备出耐高温腐蚀的工作涂层。运用光学显微镜、扫描电子显微镜(SEM)、X射线衍射仪(XRD)等研究了电弧喷涂Fe/Cr合金涂层的微观结构、腐蚀动力学和高温下的腐蚀性能。结果表明,该涂层组织致密,涂层中形成Cr2O3或尖晶石型氧化物是其具有优异的抗高温腐蚀性能的主要原因,涂层抗高温腐蚀性能较好。     

金属软管点蚀分析

某炼油厂储油罐底翻油用金属软管发生腐蚀泄漏。通过对腐蚀情况宏观形貌和腐蚀发生区域特点的观察,对金属软管内波纹管进行成分分析、金相分析以及对软管内表面腐蚀坑底形貌和腐蚀产物进行扫描电镜和X射线衍射(XRD)分析,确认了发生腐蚀泄漏的原因是在软管内水溶液里浓缩了Cl~-,导致了腐蚀穿孔。     

换热器波纹管失效分析

某种换热器的主要换热元件波纹管使用后发生严重损坏。采用光学显微镜、扫描电镜和X射线能谱（EDS）等手段对失效波纹管进行断口宏、微观分析、能谱分析、金相检验及化学成分分析,以确定其失效原因。结果表明：该波纹管的失效性质为应力腐蚀,波纹管断口形貌以沿晶断裂为主,断口上可见明显的腐蚀产物,断口内壁有明显的腐蚀坑和由腐蚀坑发展的裂纹,能谱分析结果表明断口腐蚀产物中含有一定量的S和Cl元素;分析认为波纹管在加工过程中的残余应力和使用环境中的Cl-是导致其发生应力腐蚀的主要原因,此外材料中Cr含量偏低也是导致其发生应力腐蚀的另一原因。     

质子交换膜燃料电池金属双极板表面改性研究进展

双极板是质子交换膜燃料电池（Proton exchange membrane fuel cell,PEMFC）的关键部件,对燃料电池的寿命、成本及性能具有重要影响。相比于石墨双极板和碳基复合材料双极板,金属双极板体积小、强度高、导电性能优异,已成为PEMFC双极板的主流材料。然而金属双极板易在PEFMC两极环境中产生腐蚀,且极板表面生成的氧化膜会降低其导电性,严重阻碍了金属双极板的进一步应用。从金属双极板基材选材、涂层结构设计及其性能等方面综述了金属双极板表面改性研究进展,特别探讨了金属双极板金属基涂层（贵金属、金属碳/氮化物、合金等）和碳基涂层（石墨、导电聚合物、无定型碳等）的最新研究成果,从涂层的膜基结合强度、耐蚀性、导电性和疏水性等方面探讨了现有涂层的优劣,涂层结构复合和纳米化有助于提升涂层的致密性,同时可进一步提升涂层导电性和耐蚀性。如何降低金属双极板材料和表面改性成本,提高极板耐蚀性、导电性和可靠性成为双极板研究的趋势,其对PEFMC性能提升和产业化推进具有重大意义。     

不合格金属氧化物的退除方法

总结近年来在金属氧化物退除方面的进展;简略地介绍不锈钢、铝合金、铜合金、镁合金以及铅、锡、锌氧化膜的化学与电化学退除方法,并归结了34种配方.     

Corrosion of superheater steel materials under alkali salt deposits Part 1: The effect of salt deposit composition and temperature

This paper is the first in a series of two reporting on results from an extensive laboratory-scale corrosion study where tailor-made well-characterized synthetic alkali salt deposits were used for corrosion testing of several steel materials used in or aimed for recovery boiler superheater tubing.

The corrosion testing was done in temperatures ranging from 450 to 600 °C. The synthetic alkali salt deposits, containing sodium, potassium sulfates and chlorides, were composed in such a way that their first melting temperature, T₀, and the amount of melt formed at this temperature, varied for each salt mixture.

The results showed on one hand that an increased amount of melt in the salt deposit increased the corrosion of the steel material markedly. The results showed, however also, that corrosion could take place at temperatures clearly below any melting of the salt deposits if the composition was suitable. This took place with salts that contained chlorine. Already a very low amount of chlorine in the salt caused corrosion at temperatures typical for superheaters in the recovery boiler. These effects are qualitatively well-known from earlier but it was surprising that already a very small amount of chlorine caused significant increase in corrosion.

To stress the importance of the deposit layer on the corrosion we introduce two new terms: (1) sub-T₀ corrosion, indicating corrosion taking place below any melting of the deposit and (2) super-T₀ corrosion, indicating corrosion taking place when the deposit contains melt.     

超级电容器氧化锰电极电容特性研究

利用高锰酸钾和硫酸锰溶液之间的化学共沉淀法制备出氧化锰作为超级电容器的活性电极材料。通过循环伏安法和恒流充放电法,研究了不同热处理温度获得的氧化锰电极,不同循环次数以及不同放电电流条件下,在1mol／LNa2SO4水溶液中的电容特性。结果表明,经低温处理的氧化锰在电位窗口为-0．2～ 0．8V(VSSCE)范围内,表现出典型的电容行为。其中经45℃和80℃处理的氧化锰在放电电流为7．32mA／cm^2条件下,比容量分别为147．97F／g和112．26F／g。80℃处理的氧化锰电极循环性能较好。     

碱金属氧化物对陶瓷结合剂性能的影响

研究了Li2O和K2O2种碱金属氧化物对Na2O-B2O3-Al2O3-SiO2基础陶瓷结合剂性能的影响。结果表明：添加Li2O、K2O后，结合剂的玻璃转化温度和耐火度降低，结合剂的高温流动性和玻化程度得到显著改善，结合剂的热膨胀系数有所增大，且含Li2O结合剂的热膨胀系数更小。结合剂的强度随着Li2O、K2O含量的增大先升高后降低，并在添加量为6％和4％（质量分数，下同）时分别达到最大。     

Influence of crystal orientation on cellular growth of a nickel-base single crystal superalloy

The cellular pattern evolution during directional solidification of a nickel-base single crystal superalloy has been studied in different crystallographic orientations using re-oriented seed crystals. Under the same thermal gradient and solidification velocity, the microstructures of differently oriented cellular single crystals are schematically investigated. It is concluded that the cellular growth direction is less affected by the seed orientation and depends on the heat flow, and is usually along heat flow direction. Cellular interface stability and microstructure are greatly influenced by the crystallographic orientation. When increasing the misorientation, the cell spacing increases correspondingly and the cellular growth interface becomes more unstable.