滇润楠叶提取物在H_3PO_4中对钢的缓蚀性能研究

采用失重法、动电位极化曲线和电化学阻抗谱(EIS)研究了滇润楠(Machilus yunnanensis)叶提取物(MYLE)在1.0 mol/L H3PO4中对冷轧钢缓蚀作用。结果表明:MYLE在1.0mol/L H3PO4溶液中对冷轧钢具有良好的缓蚀作用,缓蚀率随缓蚀剂浓度的增加而增大,但随温度的升高而降低。MYLE在钢表面的吸附符合Temkin吸附等温式。MYLE为混合抑制型缓蚀剂;EIS谱在高频区呈容抗弧,在低频区出现小段感抗弧,电荷转移电阻随缓蚀剂浓度的增加而增大。     

滇润楠叶提取物在H_2SO_4中对钢的缓蚀作用

滇润楠(Machilus yunnancnsis)叶的提取物(简称为MYLE)可作为绿色缓蚀剂。用失重法、动电位极化曲线和电化学阻抗谱(EIS)研究了MYLE在0.5mol/L H_2SO_4中对冷轧钢的缓蚀作用。结果表明,MYLE对冷轧钢具有良好的缓蚀作用,且在钢表面的吸附符合Langmuir吸附校正模型;MYLE为混合抑制型绥蚀剂;EIS谱在高频区呈容抗弧,在低频区出现感抗弧,电荷转移电阻随缓蚀剂浓度的增加而增大。     

木薯淀粉接枝共聚物在盐酸介质中对冷轧钢的缓蚀作用

采用氧化还原引发体系引发木薯淀粉与丙烯酰胺接枝共聚反应制备的天然木薯淀粉接枝共聚物(SGA),可以作为一种环境友好型绿色缓蚀剂。本文用失重法、动电位极化曲线、电化学阻抗(EIS)和扫描电子显微镜(SEM)首次研究了SGA在1.0mol/L HCl溶液中对冷轧钢的缓蚀作用。结果表明,SGA对冷轧钢具有良好的缓蚀作用,在钢表面的吸附符合Langmuir吸附等温式,为混合抑制型缓蚀剂;EIS谱呈半圆容抗弧,电荷转移电阻随缓蚀剂浓度的增加而增大。SEM表明SGA在钢表面吸附形成了致密的缓蚀剂膜层。     

2-巯基嘧啶对冷轧钢在柠檬酸中的缓蚀性能

采用失重法、动电位极化曲线和电化学阻抗谱(EIS)研究了2-巯基嘧啶(MP)对冷轧钢在0.2 mol/L柠檬酸(H_3C_6H_5O_7)溶液中的缓蚀性能。结果表明,MP具有优良的缓蚀作用,缓蚀率随缓蚀剂浓度及温度的升高而增大。MP在钢表面的吸附符合Langmuir吸附等温式,且为伴随熵增加的吸热过程。MP的电化学作用机理为"几何覆盖效应"的混合抑制型缓蚀剂,EIS谱呈单时间常数的弥散容抗弧,电荷转移电阻随MP浓度的增加而增大。     

2,4-二氨基嘧啶对冷轧钢在HCl溶液中的缓蚀作用

通过浸泡试验、电化学试验和扫描电子显微镜(SEM)观察研究了2,4-二氨基嘧啶(DAP)在1.0mol/L HCl溶液中对冷轧钢的缓蚀作用。结果表明:DAP在HCl溶液中对冷轧钢具有良好的缓蚀作用;缓蚀率随缓蚀剂含量的增大而增大,DAP浓度为10.0mmol/L时缓蚀率最大,可达94.8%;DAP为混合型抑制型缓蚀剂,DAP在冷轧钢表面的吸附符合Langmuir吸附等温式,缓蚀率随温度的升高而下降。     

土霉素在含氯离子的醋酸介质中对冷轧钢的缓蚀作用

采用失重法、电导率测试、电化学方法研究了过期药土霉素在含氯离子的20%醋酸溶液中对冷轧钢的缓蚀作用。结果表明,土霉素在含氯离子的20%醋酸溶液中对冷轧钢有较好的缓蚀效果,且缓蚀率随着缓蚀剂浓度的增加而增大。当土霉素质量浓度为7.0g·L-1时,缓蚀率达到88.6%,该缓蚀剂是一种混合型缓蚀剂;且在冷轧钢表面的吸附符合Langmuir吸附等温式,其吸附是物理和化学吸附过程。     

元宝枫叶提取物在硫酸中对钢的缓蚀作用

采用失重法、动电位极化曲线和电化学阻抗谱(EIS)研究了元宝枫叶提取物在0.5 mol/L H28O4溶液中对冷轧钢腐蚀的影响.结果表明:元宝枫叶提取物对冷轧钢具有良好的缓蚀作用,且在钢表面的吸附符合Langmuir吸附等温式;元宝枫提取物为混合抑制型缓蚀剂;EIS谱在高频区呈容抗弧,在低频区出现感抗弧,电荷转移电阻随...     

冷轧钢表面木薯淀粉接枝共聚物自组装膜的缓蚀性能

目的合成出木薯淀粉-苯乙烯-甲基丙烯酸甲酯接枝共聚物(CS-PE-MMA)及运用自组装技术形成在柠檬酸中对钢具有良好缓蚀性能的CS-PE-MMA分子膜。方法用扫描电子显微镜(SEM)、红外光谱(IR)表征了自组装分子膜的形貌和组成;采用动电位极化曲线、电化学阻抗谱(EIS)研究缓蚀性能。结果CS-PE-MMA在冷轧钢表面形成球斑状稳定有序而致密的分子膜。动电位极化曲线表明工作电极阴阳极反应同时被抑制,EIS谱主要呈半圆容抗弧,电荷转移电阻随CS-PE-MMA自组装温度升高,时间增大而增大,缓蚀率最高达73.04%。结论 CS-PE-MMA属于混合抑制型缓蚀剂,自组装分子膜在H3C6H5O7溶液中对冷轧钢有良好的缓蚀作用。     

H_3PO_4溶液中吐温-80在冷轧钢表面上的吸附及缓蚀性能

采用失重法、动电位极化曲线、电化学阻抗谱(EIS)研究H_3PO_4溶液中非离子表面活性剂吐温-80在冷轧钢表面上的吸附行为及其缓蚀性能,并用扫描电子显微镜(SEM)和接触角测量仪分别表征了钢表面的微观形貌和疏水性。结果表明,吐温-80有效抑制了冷轧钢在H_3PO_4溶液中的腐蚀,其最大缓蚀率在30℃时可达90%以上。缓蚀性能随吐温-80浓度的增加而增强,但同一缓蚀剂浓度下,随温度的上升呈下降趋势;随H_3PO_4浓度的增大先增加后下降,在3.0 mol/L处达到极大值。在H_3PO_4中添加吐温-80主要抑制了钢的阴极腐蚀反应,使电荷转移电阻和界面双电层电容值均显著增大;同时从微观形貌可看出钢表面的腐蚀程度显著减弱,但疏水性增强。     

云南甜龙竹竹叶提取物在盐酸中对钢的缓蚀作用

云南甜龙竹竹叶提取物（DBLE）可作为一种环境友好型植物缓蚀剂,用红外光谱（FTIR）表征了DBLE的主要官能团。采用失重法、动电位极化曲线、EIS和SEM研究了 DBLE在1.0 mol/L HCl溶液中对冷轧钢的缓蚀作用。结果表明：DBLE具有良好的缓蚀作用,最大缓蚀率达93%,且在钢表面的吸附符合Langmuir吸附等温式。通过Van't Hoff方程和Arrhenius公式分别求出了吸附热 Δ H_ads和表观活化能E_a,并据此讨论了缓蚀作用机理。DBLE为混合抑制型缓蚀剂;EIS谱呈半圆容抗弧,电荷转移电阻随缓蚀剂浓度的增加而增大。SEM再次表明DBLE 对钢具有好的缓蚀作用。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

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.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

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.     

Thermodynamics Study on the Decomposition of Chromite with KOH

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.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

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.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

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).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

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.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

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.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

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.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。