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应用电化学阻抗技术并结合物相分析技术研究了合金元素Cr对Fe在 650℃ (Li,K) 2 CO3 共晶熔盐中的腐蚀行为的影响 .结果表明 ,加入 5 %和 1 0 %Cr不能改善Fe的耐腐蚀性能 ,而加入 2 0 %和 2 5 %Cr则能显著提高其耐腐蚀性能 ;Fe及Fe Cr合金腐蚀电化学阻抗谱呈双容抗弧特征 ,合金腐蚀受荷电粒子在氧化膜中的迁移控制 .提出将合金表面形成的氧化膜理想化为一电容器 ,并建立了氧化物电容与双电层电容相串联的等效电路来描述合金腐蚀的阻抗特征 .此外 ,根据所提等效电路对合金腐蚀电化学阻抗谱进行了解析 . 相似文献
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熔融盐热腐蚀的电化学阻抗模型 总被引:6,自引:0,他引:6
研究了Ni3A,FeAl合金及溅射CoCrAlY涂层在熔融盐腐蚀过程中的阻抗谱特征,根据合金在熔融盐腐蚀过程进行了表面氧化膜形成的特点,并结合阻抗实验结果,提出金属材料在熔融盐腐蚀过程中的电化学阻抗模型,当合金表面形成完整,致密的氧化膜时,其阻抗谱呈双容抗弧特征;反之,当氧化膜疏松,多孔时,则表现为受氧化剂扩散控制;当合金表面氧化膜不完整的涂层遭受局部较快腐蚀时,则通常表现为双容抗弧特征。 相似文献
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发展高性能核燃料组件是提高核电经济性的必由之路,改善核燃料元件包壳锆合金的性能是其中关键问题之一。本文概述了我们近几年研究改善锆合金耐腐蚀性能的结果:控制Zr4合金成材时的热加工制度,可以明显改善它的耐腐蚀性能,尤其是耐疖状腐蚀性能。其主要原因是αZr中Fe+Cr的固溶含量变化,而不是析出相微粒的大小。由于Zr4合金中析出相Zr(Fe,Cr)2微粒的氧化比αZr基体慢,并与成分中的Fe/Cr比有关,当嵌镶在氧化膜中的Zr(Fe,Cr)2微粒继续氧化形成单斜结构ZrO2和立方结构(Fe,Cr)3O4后,由于体积膨胀会造成氧化膜中的局部张应力。从这一角度出发,热处理对析出相细化、均匀分布以及Fe/Cr比的变化等也是应考虑的问题。发展ZrSnNb(Fe+Cr)新合金,对改善锆合金的耐腐蚀性能有更大的潜力,成分(%,质量分数,下同)的选择应为Sn1~12,Nb~1,Fe+Cr可保持或略高于Zr4的水平。 相似文献
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采用电化学阻抗谱研究了FeAl金属间化合物在650℃熔融(Li,K)2CO3中的腐蚀行为,结果表明,在腐蚀初期,合金腐蚀电化学阻抗谱表现为典型的扩散控制的特征;随着腐蚀的进行,其电化学阻抗谱则由两个容抗弧组成。提出了相应的等效电路,解析了电化学阻抗谱,并讨论了合金腐蚀机制。 相似文献
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Fe—Cr合金在650℃熔融(Li—K)2CO3中的腐蚀行为 总被引:5,自引:0,他引:5
研究了纯铁,Fe-5Cr,Fe-10Cr,Fe-20Cr、Fe-25Cr合金在650℃熔融(0.062Li-0.38K)2CO3(摩尔分数)中和空气气氛下的腐蚀行为,结果表明,纯铁,Fe-5Cr及Fe-10Cr合金均遭受较快腐蚀,Cr的加和量在10以下无助于改善Fe的耐蚀性能,而Cr的加入量为20和25则能显著改善Fe的耐腐蚀性能,讨论了纯铁及Fe-Cr合金的腐蚀机制。 相似文献
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Ni在熔融(Li,K)_2CO_3中的腐蚀行为 总被引:1,自引:0,他引:1
采用电化学阻抗谱技术研究了Ni在650℃熔融(Li,K)2CO3中的腐蚀行为.在自腐蚀电位下,Ni的腐蚀电化学阻抗谱呈典型的扩散控制特征,表面形成疏松的氧化膜,腐蚀速度较快.提出了相应的等效电路,求得相关电化学参数 相似文献
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采用电化学阻抗技术研究了涂有Na2SO4-K2SO4盐膜的纯Ni和Ni基高温合金M38G在900℃,空气气氛中的热腐蚀行为.结果表明,纯Ni发生快速腐蚀,其腐蚀电化学阻抗谱 呈典型的扩散控制反应的特征;M38G合金在热腐蚀过程中由于形成了具有较好保护性的腐蚀产物层,其腐蚀电化学阻抗谱呈双容抗弧特征.提出了等效电路来解析电化学阻抗谱,并探讨了材料的腐蚀过程. 相似文献
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利用电容测试法和电化学阻抗谱技术研究了稀土Ce对Fe-3Cr合金在1 mol/L NaHCO3+0.5 mol/L Na2CO3缓冲溶液中所形成的钝化膜电化学腐蚀行为的影响.结果表明:稀土Ce能大大降低钝化膜内的施主密度,使膜电阻和离子在膜内的传递电阻增大,导致离子在膜内的扩散能力降低.稀土的加入可以增强基体合金在含有Cl-缓冲溶液中的耐腐蚀性能. 相似文献
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采用电化学阻抗谱技术研究了Ni在650 C熔融(Li,K)2CO3中的腐蚀行为.在自腐蚀电位下,Ni的腐蚀电化学阻抗谱呈典型的扩散控制特征,表面形成疏松的氧化膜,腐蚀速度较快.提出了相应的等效电路,求得相关电化学参数, 相似文献
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The corrosion behavior of pure Fe and Fe–Cr alloys with different Cr content in the presence of a solid NaCl deposit and water vapor at 600°C was studied. Results indicated that the corrosion of pure Fe was severe even in air at 600°C and the scale formed on the surface was compact and uniform. However, with a solid NaCl deposit on its surface, the corrosion of pure iron in air was suppressed to some extent, but the presence of water vapor in the atmosphere causes accelerated corrosion. Under the synergistic effect of NaCl and water vapor, the corrosion of pure iron is accelerated more significantly. In contrast with the known effect of Cr content on the oxidation of Fe–Cr alloys, an increasing Cr content in Fe–Cr alloys increases the corrosion rate of the alloys under the synergistic effect of solid NaCl and water vapor. A mechanism to explain the effect of water vapor and NaCl on the corrosion of pure iron and Fe–Cr alloy is proposed. 相似文献
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研制了4种Mn含量不同的Fe-Cr-Mn三元合金,并系统研究和分析了其在450℃熔融锌液中的腐蚀行为及组织变化规律。结果表明,4种不同锰含量的Fe-Cr-Mn三元合金腐蚀层的形貌基本相似,但与纯铁在液锌中的腐蚀形貌差别很大,其主要是由致密的δ相层和分布于η相中稀疏的ζ相颗粒组成,且δ相层厚度随锰含量的提高先增加后减少,其中属含Mn量为9.55%的Fe-Cr-Mn三元合金腐蚀层中致密的δ相层厚度最厚,表现出较好的耐锌蚀能力,同时,此三元合金基体与腐蚀层界面处存在Cr的富集区,此区约含27.48%的Cr,厚度在1μm左右。连续完整的富Cr抑制层的形成,能够减缓铁锌反应的速度,减慢对基体的腐蚀速度,提高了耐锌蚀能力。 相似文献
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The corrosion behaviour of pure iron, pure chromium, and aluminium/silicon alloyed Fe-Cr materials was investigated at 650 °C in air accompanied by gaseous or solid KCl salt. The corrosion rates of these materials with KCl salt are high and they are strongly affected by the salt amount, the types of the alloying elements and the concentration of chromium. The dominant degradation mechanism for the chromia-forming alloys by KCl attack is the preferential formation of potassium chromate over the conventionally protective chromia, characterized by typical features of bubbles, cracks, volatility and severe spallation for the corrosion products. A detrimental effect of chromium is confirmed. Al-alloying addition to Fe-Cr alloys is beneficial by enhancing the corrosion resistance. Silicon is more effective in promoting the corrosion resistance of Fe-Cr alloys by forming a stable and dense oxide layer in the inner zone which suppresses the rapid growth of iron oxides. 相似文献
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Pure Fe, Cr and Fe-Cr binary alloys were corroded in O2 containing 298 ppm KCl vapour at 750 °C. The corrosion kinetics were determined, and the microstructure and the composition of oxide scales were examined. During corrosion process, KCl vapour reacted with the formed oxide scales and generated Cl2 gas. As Cl2 gas introduced the active oxidation, a multilayer oxide scales consisted of an outmost Fe2O3 layer and an inner Cr2O3 layer formed on the Fe-Cr alloys with lower Cr concentration. In the case of Fe-60Cr or Fe-80Cr alloys, monolayer Cr2O3 formed as the healing oxidation process. However, multilayer Cr2O3 formed on pure Cr. 相似文献
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The corrosion behavior of Fe-Cr and Fe-Ni-Base commercial alloys has been investigated in an argon-42.6% oxygen-14.7% bromine gas mixture at 700 °C which was one of the environments encountered in the UT-3 thermochemical water decomposition reaction process to produce hydrogen. The test alloys were type 304 and 310 stainless steels, Incoloy 800, and Incoloy 825. Two-dimensional thermodynamic phase stability diagrams were constructed for iron, chromium, nickel, and titanium to predict the condensed corrosion products that are stable with respect to the representative alloying elements when the alloy is exposed to the argon-42.6% oxygen-14.7% bromine gas mixture at 700 °C. The oxides were thermodynamically stable phases with respect to the corresponding metals. Post-reaction treatment of test alloys included discontinuous mass-change measurements, scanning electron microscopy (SEM), electron probe micro-analysis (EPMA) for morphological and compositional investigation of the corrosion products, and the X-ray diffraction (XRD) for phase identification. XRD identified oxides and spinels as corrosion products but low-melting metal bromides were detected for all alloys with deleterious effects on high-temperature properties of these alloys during exposure to the environment. The poor corrosion resistance of the test alloys was mainly caused by the cracking and spalling of iron and chromium-rich oxides and further growth of various metal bromides beneath the oxide scale following prolonged exposure. The high iron content of the test alloys had deleterious effects on the performance of these alloys in the environment. 相似文献
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Electron microscopy investigations have been conducted on the oxides formed on Fe and Fe-Cr alloys at elevated temperatures (700–800?C) and at low oxygen partial pressures (~10?3Pa). Oxide nucleation and growth on chromium-rich iron alloys are significantly different from that for pure iron. On pure Fe and on Fe-3%Cr, wustite and magnetite particles nucleate and grow out of the surface, while on the higher Cr-containing alloys (≥9 wt. % Cr) the spinel oxide (Fe, Cr)3O4 nucleates and grows into the metal. The differences in oxide formation in the early stages of oxidation are explained in terms of the diffusion of different species being rate-controlling and in terms of rapid diffusion, for example, at the metal-oxide interface. 相似文献
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本文以电化学方法(动电位极化曲线测量)和全浸法考察了不同状态(无定形态、无定形合金退火态以及晶态)FeCr8P13B5和FeCr8P13C7合金在氯离子介质中的耐蚀性能,结果表明(1)无定形FeCr8 P13 B5和FeCr8P13C7合金都具有优异的耐蚀性能。它们的动电位极化曲线十分相似,当极代电压为+1.5伏(SCE)以下时。试样不出现破裂电位Eb,钝态电流维持在10微安/厘米~2以下;这两种无定形耐蚀合金在30℃的0.5N-2.5NHCl、40和60℃的10%,FeCl_3、6H_2O、60℃的3.5%NaCl以及30℃的1MH_2SO_4+0.5MNaCl中全浸168小时其腐蚀速率为10~(-3)-10~(-4)毫米/年。(2)无定形FeCr8P1385和FeCr8P13C7合金经500℃1小时真空退火(晶化)处理后,后者的耐蚀性能急剧恶化,而前者仍保持无定形状态的优异耐腐蚀性能。电化学测量与全浸试验所得的结果是一致的。 相似文献