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7A04铝合金在海洋大气环境中初期腐蚀的电化学特性 总被引:5,自引:0,他引:5
通过盐雾腐蚀试验模拟研究7A04铝合金在海洋大气环境中的腐蚀初期规律,采用电化学交流阻抗测试和扫描Kelvin探针技术,研究7A04铝合金在初期腐蚀过程中的电化学行为.结果表明:Cl-对铝合金腐蚀有显著的加速作用,盐雾试验初期表面出现点蚀坑;随盐雾时间增长,点蚀相互连接并扩展,电化学反应阻抗下降.扫描开尔文探针测试结果表明:随腐蚀的不断进行,金属表面阴极区和阳极区不断发生变化,呈现局部腐蚀的特征,表面电位也随时间逐渐升高,阴极区和阳极区逐渐变得明显,腐蚀反应处于不断加速过程. 相似文献
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陈跃良 《稀有金属材料与工程》2021,50(6):2040-2051
对不同周期盐雾腐蚀后38Cr Mo Al钢开展了应变速率为0.001~3000 s-1的准静态和冲击拉伸试验,研究了盐雾腐蚀环境对38Cr Mo Al钢材料在高应变率条件下动态力学性能的影响,借助数字显微镜、FT-IR、SEM、EDS等手段对盐雾腐蚀后的38Cr Mo Al钢表面形貌、腐蚀坑深度、腐蚀产物成分和断口形貌等进行了分析。结果表明,腐蚀速率与盐雾腐蚀时间正相关,腐蚀加速过程遵循幂函数特征,腐蚀产物层对38CrMoAl钢的腐蚀起到促进作用;38Cr Mo Al钢的屈服强度随着应变率的提高而提高,随着腐蚀周期的增加而降低,盐雾腐蚀后的38CrMoAl钢断口呈现多处撕裂状特征,腐蚀时间越长,撕裂状痕迹越多,撕裂状断裂使得试件断口颈缩不再是均匀发展,导致屈服后抗拉强度下降,屈强比升高。对J-C本构模型中的应变率强化项和绝热软化项进行了修正,并加入了腐蚀修正参数,使得新模型可以准确地表征38CrMoAl钢在盐雾腐蚀环境中动态力学行为。 相似文献
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采用盐雾腐蚀试验方法,研究了模拟海洋大气环境下XCS-lode钢与30CrNi3Mo钢的腐蚀性能,通过极化曲线及电化学阻抗谱(EIS)试验研究了两种钢在腐蚀行为上的差异。结果表明:XCS-lode钢相比30CrNi3Mo钢具有更高的自腐蚀电位, XCS-lode钢腐蚀产物膜的阻抗明显大于30CrNi3Mo钢,XCS-lode钢的耐海洋大气腐蚀性能优于30CrNi3Mo钢。 相似文献
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目的 研究40CrNiMo钢在模拟海洋环境中的锈层及电化学性能初期演化规律。方法 采用中性盐雾试验模拟海洋大气环境,通过光学显微镜、EDS、XRD等手段表征40CrNiMo钢内、外锈层微观结构及成分的变化。通过动电位极化、交流阻抗谱及微区电化学技术研究电化学性能的演化规律。结果 40CrNiMo钢在盐雾环境中由点蚀逐渐发展为均匀腐蚀,最大腐蚀坑深度的演化规律为d=87.787t0.325,腐蚀动力学规律为ΔW=6.091t0.738。盐雾4 d后锈层出现分层,7 d后内锈层显著增厚。黄色疏松外锈层主要成分为γ-FeOOH;黑色致密内锈层主要成分为α-FeOOH和Fe3O4,并且在与基体接触界面出现Cr元素富集。极化曲线与EIS测量结果具有较好的相关性,表明40CrNiMo钢的腐蚀速率先增大后减小再增大;而SKP测量结果显示,盐雾环境中试样表面迅速形成阴、阳极区,盐雾7 d后试样表面Volta电位由225 mV持续增大至884 mV,盐雾11 d后降低至609 mV。结论 盐雾1 d后锈层疏松多孔,为... 相似文献
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离子渗氮AISI 420马氏体不锈钢耐蚀行为研究 总被引:4,自引:1,他引:3
采用不同温度对AISI 420马氏体不锈钢进行离子渗氮处理.借助光学显微镜和X射线衍射(XRD)技术分析了渗氮层的微观组织结构,利用显微硬度计测试了渗氮层的硬度分布,通过电化学极化曲线测试和盐雾腐蚀试验研究了离子渗氮AISI 420不锈钢在模拟工业环境中的腐蚀行为.结果表明:AISI 420不锈钢350℃低温离子渗氮层由ε-Fe3N和N过饱和固溶体αN相组成,其化学稳定性高,加之固溶Cr元素的联合作用,明显提高了AISI 420不锈钢基材的腐蚀抗力.AISI 420钢经450℃和550℃渗氮处理,渗氮层中的αN分解成了α相和CrN,造成基体贫Cr,降低了基材的耐蚀性能.马氏体不锈钢低温离子渗氮处理不仅可以提高表面硬度,而且可以获得良好的耐蚀性能. 相似文献
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输电塔杆用热浸镀锌钢在模拟酸雨大气环境中的腐蚀行为 总被引:1,自引:0,他引:1
通过循环盐雾腐蚀实验模拟镀锌钢在酸雨大气环境中的腐蚀过程。采用腐蚀质量损失测试、扫描电镜(SEM)、能谱仪(EDS)和电化学技术分别对腐蚀48,84,132,180和228 h的镀锌钢试样进行测试分析,得到腐蚀动力学规律、腐蚀产物成分、锈层截面形貌以及表面锈层的电化学特性。研究了锈层对镀锌钢在酸雨条件下大气腐蚀的影响。动力学分析表明,腐蚀过程中镀锌钢的表面形成了具有较好保护性的锈层;电化学测试结果表明,锈层的保护性呈现随腐蚀时间的延长先增强后减弱的变化过程。 相似文献
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Deng-Kui Zhang Guo-Qing Wang Ai-Ping Wu Ji-Guo Shan Yue Zhao Tian-Yi Zhao Dan-Yang Meng Jian-Ling Song Zhong-Ping Zhang 《金属学报(英文版)》2019,32(6):684-694
In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone. 相似文献
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After nearly two years'tense construction the first phase of industrialized base of Shenyang Research Institute of Foundry 《中国铸造》2008,5(1):63-64
After nearly two years' tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry (SRIF), located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation. 相似文献
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Z. Sun S.L. Zheng Y. Zhang 《金属学报(英文版)》2007,20(3):187-192
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process. 相似文献
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R. González-Martínez 《金属学报(英文版)》2007,20(4):235-240
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke. 相似文献
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The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C). 相似文献
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The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel. 相似文献
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B.W. Zhang B.W. Li 《金属学报(英文版)》2007,20(2):129-138
On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes' collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process. 相似文献
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R.Z. Wu Z.K. Qu B.D. Sun D. Shu J. Wang 《金属学报(英文版)》2007,20(3):193-198
The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results. 相似文献
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This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before. 相似文献
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Chao Yang He-Fei Huang Massey de los Reyes Long Yan Xing-Tai Zhou Tian Xia De-Liang Zhang 《金属学报(英文版)》2015,28(7):809
Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties. 相似文献