氧化铝生产种分附聚过程的粒度变化模型

通过粒度衡算和质量衡算对氧化铝种分过程附聚段进行种分过程粒度变化模型的构建,选取合适的模型参数和动力学方程,应用模型计算某氧化铝厂种分附聚段出口粒度分布,并与实测值进行对比.结果表明:模型计算粒度分布与实测结果基本吻合,平均粒度的实验值与模型计算值误差在10%以内.     

阳极弧等离子体制备镍纳米粉的机理研究

根据会属结晶的热力学和动力学理论，对采用阳极弧放电等离子体方法制备金属纳米粉的生长过程建立了一个近似的理论模型。研究了等离子体的产生、金属的蒸发、晶核的形成和生长机理。对影响纳米粉性能的各种工艺参数进行了理论分析。并利用X射线衍射（XRD）、透射电子显微镜（TEM）和相应选区电子衍射（ED）对样品的晶体结构、形貌、粒度及其分布进行表征。结果表明：采用阳极弧等离子体法制备的球形镍纳米粒予纯度高，晶格结构与相应的块体物质相同，为fcc结构的晶态，平均粒度为16nm，粒度范围分布在10nm～40nm。电源功率、电弧电流、气体压力及冷却温度是影响晶核的形成和生长的主要因素。通过适当调整各项工艺参数，可有效地控制粒子的粒度。     

冲击破碎粒度分布模型建立与预测

破碎产物粒度精准预测是实现选厂破碎粒度分布调节和控制的关键。基于落重试验和理论分析,对不同矿物破碎特性及其粒度分布预测模型展开研究。结果表明:矿物破碎产物粒度分布与矿物给料粒度、冲击破碎比能耗、破碎参数有关,Boltzmann-Growth方程能够较好地拟合出破碎产物粒度分布与冲击破碎比能耗、t10的回归关系,且在同样破碎比能耗下,破碎产物粒度越小,其累积效应越弱;不同矿物和不同粒度之间矿物破碎特性存在较大差异;在此基础上提出一种综合广义回归模型与粒子群算法的破碎粒度预测与优化模型,并通过试验验证模型的适用性和可靠性,可为矿物破碎粒度智能调控和优化提供理论基础。     

影响流化床反应器中TiO_2氯化反应速率和转化率的参数:实验和模拟方法（英文）

以CO为还原剂,进行中试规模的TiO_2氯化。在CO和Cl_2存在的条件下,对半连续流化床反应器中的TiO_2氯化过程进行实验分析和模拟。通过测量TiCl_4生成量随时间的变化,连续监测氯化过程。系统研究氯化温度、原料粒径和粒度分布、原料量、Cl_2和CO流速等操作参数对转化率的影响。逐渐升高氯化温度导致转化率单调上升。随着原料粒度的增大,转化率降低,负载量的增加导致反应转化率下降。提出一个预测反应过程中转化率、粒径分布和气相组分摩尔分数的模型。在不同的操作条件下,模型预测的转化率与实验数据吻合良好。     

种分法制备超细氢氧化铝过程中的粒度控制

超细氢氧化铝具有许多优点,应用广泛。超细氢氧化铝的粒度分布和颗粒形貌对产品的性能有很大影响。根据湿化学法颗粒成核与生长机理从理论上分析了超细氢氧化铝制备过程中需控制的工艺条件,研究了二段分解工艺中晶种添加量和温度等对分解产品粒度分布的影响,得出了温度和种子添加量对氢氧化铝粒度分布的影响规律。     

镍基合金叶片凝固过程微观组织模拟及工艺优化研究

本文以真空熔模铸造Ｋ４１７镍基高温合金涡轮叶片为研究对象，用宏观传热、传质与微观形核、生长相统一的数学模型，描述了微观组织形成的动态过程。模型考虑了非均质形核的机理及影响因素，用ＣｅｌｕｌａｒＡｕｔｏｍａｔａ法对有效核心的分布作了统计描述，用枝晶尖端生长动力学模型研究了晶粒的生长及〈１００〉择优晶向对生长的影响，确立了由柱状晶到等轴晶转变的判据，并成功地对晶粒生长过程进行了计算机屏幕动态彩色显示。根据计算结果找出了影响叶片微观组织的主要工艺因素是浇注温度、型壳温度、填砂粒度和孕育剂粒度。根据最佳工艺参数组合，制定了优化工艺，用于实际生产后，基本消除了粗大晶粒、缩孔、缩松等缺陷，使叶片铸造合格率比原工艺提高了２２．８３％。     

铝酸钠溶液种分首槽温度控制预报准理论模型的应用

应用铝酸钠溶液种分首槽温度控制预报准理论模型 ,结合实际生产情况 ,在原模型参数的基础上将晶种表面积改设为变量 ,并考虑到反馈比这一重要工艺参数的作用 ,引入小于 45 μm粒子质量分数和二次成核生成的临界粒径的晶核粒径分布值之间的关系 ,应用线性回归原理 ,求出修正后的模型参数 ,根据现场生产数据 ,对首槽控制温度进行预测 ,其结果与稳定生产的首槽控制温度及经验模型 (X模型 )的预测结果基本一致。以C Builder为开发平台 ,成功开发了基于该原理的、运行于Windows系统的应用软件 ,使用效果良好。     

超细尾砂料浆流变参数预测及管输温度分布特征

为探究初始料浆温度变化对超细尾砂料浆流变参数的影响及管道内料浆温度分布特征，开展了超细尾砂料浆流变试验，进行了料浆流动传热仿真试验，推导了流变参数预测模型及管输温度分布计算模型。结果表明：料浆温度与超细尾砂料浆屈服应力、塑性黏度均遵循Exponential Decay 2拟合模型；不同料浆初始温度下管径与管道内料浆温度符合Asym2sig拟合模型，将其模型参数与管径进行深度拟合分析，利用管径表示拟合模型中的变化参量，实现了变量的统一；超细尾砂料浆流动时摩擦生热高于水化产热，依据传热学理论，超细尾砂料浆经管道内摩擦产热传热、水化产热传热以及与外界环境交换传热后达到动态平衡；基于流变参数预测模型及管道内温度分布模型，可在已知管径、料浆初始温度条件下预测管道内料浆屈服应力和塑性黏度。     

砂状氧化铝生产过程首槽温度控制预测的准理论模型

针对砂状氧化铝生产实践，基于热力学与动力学原理以及生产过程稳态运行等假设，推导出了砂状氧化铝生产过程首槽温度控制预测的准理论模型，采用生产现场数据，包括粒度分布值φ（γc),温度（T），苛性比（Rp),苛性钠浓度（c(NaOH))，铝酸钠浓度（c(NaAl(OH)4))等，应用统计回归法求出模型参数，K0,K1,K2,即可根据生产工艺条件要求计算出首槽温度的预报值，用于指导并控制砂状氧化铝生产。     

40Cr钢等温转变曲线与非等温冷却过程数值分析

建立连续冷却过程多相转变模型,并实现了对冷却过程中各相转变量的数值预测。用传统叠加模型和Cahn微分模型分别对40Cr钢连续冷却过程中组织分布进行了模拟计算,结果表明,考虑动力学参数n随温度变化的相变动力学微分方程计算结果与实际结果更为接近。为分析晶粒尺寸对相变过程的影响,结合不同奥氏体化温度下的等温膨胀实验,讨论了考虑晶粒尺寸时的相变动力学模型的应用范围,不同晶粒度下的相变参数n相同时,模型才能准确反应实际相变过程。     

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.