水玻璃有机酯自硬砂旧砂湿法再生技术

讨论了水玻璃有机酯自硬砂旧砂湿法再生技术的机制、关键技术和实施效果,成功的旧砂湿法再生技术可使水玻璃有机酯自硬砂工艺趋于完善。     

3t／h水玻璃砂旧砂再生生产线

３ｔ／ｈ水玻璃砂旧砂再生生产线李伟（铜陵有色金属公司机械总厂安徽铜陵市：２４４０２２）主题词：水玻璃砂，旧砂再生有机酯水玻璃自硬砂（简称ＥＣＳ法）应用至今已有２０多年的历史了，因其具有独特的优点，至今仍被广泛采用。该工艺的水玻璃加入量较其它水玻璃砂加...     

铸钢车间自硬砂工艺设计

大连重型机器厂铸钢车间为新建成项目,现阶段采用呋喃树脂自硬砂,同时在设计上预留了采用水玻璃有机酯自硬砂工艺的可能性。本文对采用的自硬砂工艺进行了分析,同时介绍了进口的可满足两种型砂工艺要求的砂再生系统和混砂设备及车间工艺布置设计。     

有机酯水玻璃自硬砂应用现状及其发展

随着旧砂量再生设备的开发，有机酯水玻璃自硬砂工艺成为一种充满前景的新颖造型铸造方法。本文就国内外该自硬砂应用现状和发展趋势作全面，系统介绍     

国内外旧砂再生技术与设备发展近况及砂种发展展望

本文叙述了国外80年代以来旧砂再生迅速发展的简况,指出已进入了一个崭新的阶段. 文章从粘土砂.树脂砂到水玻璃砂综述了国内外的发展近况.并着重介绍了一些使用中效果较好的典型设备及再生线.对实际生产有现实意义与价值、指出再生已成砂处理系统的一部分。最后.对各砂种的发展作了分析、指出粘土砂湿型最经济,应尽量使用:土型及一般水玻璃砂将逐步为自硬树脂砂和与之竞争的有机酯水玻璃自硬砂及真空吹CO_2硬化取代.并认可有机酯水玻璃自硬砂经济易行、较适合我国国情、今后十年将有更大发展.     

改性水玻璃在有机酯自硬砂中的应用

介绍了改性水玻璃在有机酯自硬砂中的应用，生产实践证明，有机酯自硬砂中改性水玻璃相比普通水玻璃来说，具有加入量低，强度高，溃散性好，有利于旧砂的再生回用等优点。     

有机酯水玻璃自硬砂在大型铸钢件造型（芯）车间应用的分析

有机酯水玻璃自硬砂工艺，是近些年来发展较快的造型（芯）工艺方法之一。它克服了普通水玻璃砂旧砂溃散性差的缺点，具有生产效率高、污染少、经济效益高等优点。通过对几种造型（芯）工艺在大型铸钢件生产应用的对比后认为，用有机酯水玻璃砂工艺更新改造原造型（芯）工艺，是这类铸造车间技术改造的主导方向。     

第四讲 新工艺的发展与旧砂再生

1新工艺发展与旧砂再生的关系砂型铸造方面的新工艺与自硬砂的发展密切相关。众所周知，自硬砂是用特殊粘结剂代替粘土混制的型（芯）砂。这种特殊粘结剂可以有有机的与无机的两大类，前者以各种合成树脂为主，后者则首推水玻璃。六十年代以来发展的自硬树脂砂，不仅可常温自硬，且清散性好，再生容易。由于是化学硬化，型砂易紧实，生产效率较高。七十年代以来由于树脂砂价格昂贵还有有害气体及环境污染，水玻璃砂又有新的突破，发展出有机酯水玻璃自硬砂和真空吹COZ硬化水玻璃砂两种新工艺。水玻璃加入量可减少20～50％，位散性大有改善…     

新型酯硬化水玻璃砂无箱造型生产线

叙述了呋喃树脂自硬砂无箱造型生产线改为新型酯硬化水玻璃砂无箱造型生产线的可行性及优越性，水玻璃砂实现干法再生，回用率＞90%。     

再生砂在铸钢件上的应用及质量控制

旧砂再生循环使用是减少铸造成本的有效途径,合理使用再生砂,减少或避免铸造缺陷产生是再生砂使用的重要环节。文章介绍了热干法联合再生系统,酯硬化水玻璃再生砂的质量检验标准,生产常用的混砂配方,分析了酯硬化水玻璃再生砂的工艺性能。通过酯硬化水玻璃自硬砂工艺使用经验,针对生产过程中容易出现的问题进行分析,并给出了应对措施和解决方案。     

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。