散热器芯材用Al-Mn合金扁锭的生产

分析了汽车散热器芯材用Al-Mn合金的特性,针对散热器芯材用Al-Mn合金扁锭铸造开头容易出现悬挂和铸锭大面裂纹等问题,进行了铸造工艺的探讨。结果表明,采用铸造速度50 mm/min、铸造温度740℃、冷却水流量150m~3/h、液位高度90 mm的铸造工艺,能生产出性能合格的散热器芯材用Al-Mn合金420 mm×1 420 mm规格的扁锭。铸造开头防止悬挂是生产合格铸锭的关键。     

铜钟艺术品消失模铸造工艺

以铜钟艺术品为例,介绍了消失模铸造工艺过程,并成功铸造了直径550 mm,高620 mm不同部位壁厚8.9.20mm的铜钟,且满足艺术品要求,同时保证了铜钟的声音、色泽等特殊要求。分析了消失模铸造的优越性能。     

铸造参数对半连续铸造7050铝合金板坯质量的影响

从铸造速度、铸造温度、冷却水量、合金成分以及铸造液位高度几个方面着手,系统研究了铸造工艺参数对电磁半连续铸造7050铝合金板坯质量的影响,并深入分析了影响机理,摸索出了行之有效的铸造工艺参数.最佳工艺参数为:铸造速度85mm/min,铸造温度710℃,冷却水流量3m3/h,输入电流2 500A,频率1 700Hz,金属液面高度控制在石墨结晶器高度的1/2处.采用该工艺参数,成功铸造出尺寸为420mm×130mm×1 000mm的7050铝合金板坯.     

基于数值模拟的铝合金薄壁件金属型低压铸造工艺设计

以A356铝合金为研究对象,基于数值模拟方法使用商业铸造软件ProCAST设计了薄壁件金属型低压铸造工艺,并针对铸件表面缺陷进行分析,提出了工艺改进方案,铸造出了截面呈L型,尺寸为长300 mm、宽100 mm、壁厚1.5 mm的完整铸件,铸件表面质量好,无缩松等铸造缺陷.     

托轮的侧压冒口法铸造工艺

介绍了日产5000t干法水泥窑承托部分的托轮的技术要求和侧压冒口法铸造工艺.托轮材质为ZG42CrMo,轮廓尺寸φ2110mm×1050mm,毛重22780kg.在分析了托轮铸造结构工艺性的基础上,比较了顶压冒口法和侧压冒口法两种铸造工艺的优缺点,确定采用侧压冒口法铸造工艺.通过合理选定铸造工艺参数,如造型方法、铸造收缩率、机械加工余量、冒口的形状尺寸和数量、内冷铁的截面尺寸和质量、浇注系统各组元截面积等,严格控制生产工序操作,生产出了合格铸件.     

高强度微细硅铝丝铸造方法和加工工艺的研究

本文研究了Φ0．032mm微细硅铝化的铸造方法和加工工艺，分析比较了不同铸造方法和加工工艺对硅铝丝性能原影响，从其优选出最佳的铸造方法和加工工艺，提高硅铝丝的性能，使其符合要求，满足市场需求。     

锰硅铁合金连续铸造技术研究

作者利用自制的一套带有特殊结晶器的连续铸造实验装置，研究了连续铸造锰硅铁合金的工艺及其制品的外观和内部质量。稳定地连续铸造了直径分别为44mm、52mm、54mm和74mm的锰硅铁合金铸锭。结果表明，所研究的锰硅铁合金连续铸造工艺稳定性良好，连续铸造生产锰硅铁合金产品的外观光洁，内部组织致密、细化，质量明显优于传统模铸生产的锰硅铁合金。     

7055铝合金扁锭铸造工艺研究

利用Almex铸造机,试验研究7055铝合金扁锭的铸造工艺,并对铸锭的化学成分和显微组织进行了分析。试验结果表明:采用高效铝熔体洁净技术,保证了熔体质量;采用软起铸的铸造工艺,可促进铸锭成形,降低开裂倾向;通过多级可控温铝制结晶器进行铸造,浇注温度在700～710℃,结晶器水流量控制为15 m3/h～60 m3/h,铸造速度为30 mm/min～50 mm/min,结晶器液位高度为70 mm～105 mm,获得了外观质量良好、内部成分均匀、高倍组织细小的7055铝合金扁锭。     

球铁铸件罩盖工艺优化与改进

利用有限元模拟软件Pro Cast对球铁铸造工艺进行模拟分析,通过对其凝固过程和缩松缩孔分布趋势的分析,优化改进内浇道尺寸。通过模拟分析后发现,将内浇道的厚度由原先的8 mm增加到10 mm时,铸造缺陷消失。以此工艺生产出合格铸件。     

轧辊挤压铸造关键工艺参数的研究

提出了利用挤压铸造工艺制造轧辊,并根据材料力学和凝固理论导出了轧辊挤压铸造工艺中开始加压时间和保压时间的定量计算模型。同时,结合轧辊挤压铸造工作原理,定义了该零件挤压铸造时的浇注高度,并给出了其计算公式。通过数值模拟软件ProCAST对规格为175mm×480mm的轧辊进行模拟及其缩小样的验证试验,结果表明该轧辊在挤压铸造工艺下无缩孔、缩松等缺陷。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.