铝合金上锂盐转化层的制备及其性能

研究了在Ｌｉ２ＣＯ３溶液中的电化学行为及实现自钝化的条件，探讨了制备锂盐转化层的优化条件。结果表明，锂离子对铝在碱性碳酸盐溶液中有助钝化作用，通过预先调整转化处理液中相关离子的浓度等可加速自钝化进程，不同的铝合金要采用相应不同的处理工艺，后处理有增强抗蚀作用。     

海洋大气湿度对LY12铝合金初期腐蚀的影响

根据表面带Cl^-的LY12铝合金在模拟海洋大气环境中的腐蚀形貌、增重、最大点蚀深度以及腐蚀体系的自腐蚀电位、交流阻抗等变化,分析相对湿度对其初期腐蚀行为的影响.结果表明,表面含1mg/dm^2Cl^-的LY12铝合金在大气环境的相对湿度＜70%时,几乎不发生腐蚀;在相对湿度＞70%时,发生明显点蚀;在相对湿度＞90%时,腐蚀较严重.腐蚀增重随相对湿度增大而增大,不同相对湿度条件下的腐蚀增重-时间曲线较好地符合Boltz-man模型.相对湿度为90%左右,倾向于出现最深的蚀坑.LY12铝合金腐蚀形貌的变化几乎不会引起其厚水膜高Cl^-自腐蚀体系的电位改变.其厚水膜高Cl^-自腐蚀体系的Nyquist图是实部收缩的单一容抗弧.     

316不锈钢在F-/Cl-酸性溶液中的腐蚀行为

用电化学测量技术，对含F^-和Cl^-稀醋酸介质中316不锈钢的腐蚀行为进行了研究。结果表明，316不锈钢在低浓度F^-/Cl^-稀醋酸溶液中能够钝化，致密钝化膜为双层结构；F^-能加速其均匀腐蚀，但加速作用不显著，浓度不同的含F^-稀醋酸介质中均无点蚀。     

无机成膜型缓蚀剂对铝合金缓蚀作用的研究

通过电化学实验和扫描电子显微镜（SEM）观察,系统地研究了四种无机缓蚀剂对铝合金在3．5％氯化钠溶液中的缓蚀作用。实验结果表明,这些无机缓蚀剂对铝合金具有较好的缓蚀效果。它们主要是通过在铝合金的表面形成一种化学转化膜来实现其缓蚀作用的。同时,由于这层转化膜的存在,明显地提高了铝合金在氯化钠溶注中的抗点蚀的能力。     

渗Al碳钢在高温精制环烷酸介质中的腐蚀行为

研究了固体渗Al碳钢在高温精制环烷酸中的腐蚀行为 ，并评价了渗Al层对碳钢抗环烷酸腐蚀性能的影响.结果表明：腐蚀初期，渗Al碳钢显示出 较好的抗蚀性能；但延长腐蚀时间，其抗蚀性能显著恶化，渗Al层以台阶方式逐层剥落.渗 Al碳钢表面氧化膜及Fe-Al合金层在精制环烷酸介质中的不稳定性是导致涂层抗蚀性能恶化 的主要原因.     

钛合金表面离子束增强沉积膜层的环境适应性和接触相容性

利用离子束增强沉积技术在钛合金表面制备CrN硬质抗磨层和CuNiln固体润滑膜层。通过电化学测试技术对比研究了膜层和钛合金基材在含Cl介质中的抗蚀性能和接触腐蚀敏感性，利用高温静态氧化方法评价了膜层的抗氧化性能。结果表明：(1)CuNiln膜层耐电化学腐蚀性能和抗氧化性能显著优于Cu，在含Cl介质中与钛合金接触相容。(2)在含Cl水溶液中，CrN膜层耐蚀性好，与钛合金接触相容；在HCl HF混合酸中，CrN膜耐蚀性能远优于钛合金；抗氧化性能优于Ti。     

土壤中SRB及Cl^—对1Crl8Ni9Ti不锈钢腐蚀的相互影响

利用交流阻抗测试技术、扫描电镜及表面能谱、失重法、微生物分析等方法，研究了在不同Cl^-含量的土壤中，硫酸盐还原菌对1Crl8Ni9Ti不锈钢腐蚀的影响规律。136d的试验结果表明，不同Cl^-含量土壤中SRB菌量在23000—35000(个／克土)之间，Cl^-的加入并没有显著影响SRB的生长，随着Cl^-的加入土壤中SRB的菌量有增大的趋势；随着土壤中Cl^-含量的增大，不锈钢腐蚀电位负偏移，而且在接菌土壤中的腐蚀电位比在灭菌土壤中负移幅度更大；不锈钢在灭菌土壤中没有发生点蚀现象，而在接菌土壤中发生了严重的点蚀，最大点蚀深度随着土壤中Cl^-含量的增加而增大，这说明在土壤中SRB及Cl^-的共同作用下，增大了不锈钢的点蚀敏感性。不锈钢在灭菌土壤中的阻抗图谱表现为一个半径很大的容抗弧，而在接菌土壤中的阻抗图表现为两个时间常数的双容抗弧。     

稀土在铝合金表面处理中的应用及研究进展

评述了稀土在铝合金表面处理中的应用及研究进展,尤其是铝合金稀土表面转化膜技术和稀土对铝合金阳极氧化的影响两方面.稀土表面转化膜能够提高铝合金的耐蚀性能,工艺以化学浸泡为主;稀土对铝合金阳极氧化是有益的:它使铝合金接受极化的能力增强,同时提高氧化膜的抗蚀性.因此,稀土应用于铝合金表面处理具有良好的发展前景.     

不镀锡钢罐头盒铝盖的点腐蚀

由不镀锡钢制成的带铝合金易开盖的双金属罐头盒,可用来盛装含离子的酒类、果汁等饮料。不镀锡钢罐体的静电位比铝合金点蚀电位的惰性大,会导致铝合金盖的原电池腐蚀。因此,我们研究了两种防止这种腐蚀的方法:(1)使铝合金具有较高的(惰性较大)点蚀电位;(2)选用一种牺牲阳极材料进行覆盖的技术。此外,为了研制抗点蚀的罐盖用铝合金(即具有更大惰性的点蚀电位),研究出了快速测定铝合金点蚀电位的Cu~(2+)离子法,这种方法正在用于研究各种添加元素带来的影响。采用这种方法发展了一种Al-Si-Cu-Mn合金,当罐内Cl~-离子浓度超过1000ppm时,这种合金也不会产生点腐蚀。这些特性使它用作含离子酒类的容器是安全可靠的。当罐内的CI~-离子浓度超过1000ppm时,可以在铝盖上包覆一层牺牲阳极材料。     

N80油管钢C02腐蚀点蚀行为

在模拟油田CO2腐蚀环境下，利用XRD、EDS和SEM研究了N80钢点蚀坑的形成与发展。结果表明，Cl^-会在腐蚀产物膜与金属界面处富积成核，加速该区域的阳极溶解，促使点蚀坑的形核；点蚀坑内也有Cl^-富积，在膜与基体界面处形成厚度为3μm的富积层，加速点蚀坑内基体的腐蚀，使得点蚀坑进一步发展。同时，讨论了阳极反应与点蚀坑形貌之间的关系。     

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).     

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.     

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.     

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。