Li_2CO_3在含碳球团还原中催化机理的研究

通过在氧化铁中添加碳粉和少量Li2CO3添加剂,考察了碱金属化合物和温度对含碳球团还原过程的影响,探讨了减金属化合物的催化机理,实验结果表明,球团还原车随着碱金属化合物添加量而增大,但增大幅度随添加剂增多、温度升高而减小在球团还原初期,Boudouard反应是还原的限制环节,添加Li2CO3可以降低反应活化能较高温度下球团还原后期,氧化铁的气相还原是反应的限制性环节,添加Li2CO3可以加快Fe／FeO界面上FeO的还原反应,实验条件范围内,温度升高和Li2CO3添加量增加,促进反应限制环节从Boudouard反应向氧化铁还原的转化     

选铁尾矿和钛精矿直接还原-磁选工艺回收铁实验研究

针对铁品位较低的选铁尾矿和钛精矿,探索了直接还原-磁选回收铁的工艺。综合考察了配碳量、焙烧温度、保温时间和冷却方式对直接还原金属化率的影响,找出了实验最优指标。通过XRD和化学分析讨论了不同焙烧温度下还原过程中物相的变化。结果表明:选铁尾矿中二价铁主要存在的物相(Fe,Mg)(Ti,Fe)O3在1300℃下较充分的被还原为金属铁。钛精矿中三价铁主要存在的物相Fe2TiO5在1300℃下较充分的还原为金属铁。在配碳量为6.29%,焙烧温度1300℃,保温时间1.0 h的最优条件下,选铁尾矿铁回收率达到80%,铁品位58%。在配碳量为10.36%,焙烧温度1300℃,保温时间1 h条件下,钛精矿铁回收率达到95%,铁品位78%。     

含碳球团—铁浴熔融还原法关键技术的应用基础研究

系统研究了以非焦煤粉和铁精矿粉为基础的含碳球团－铁浴熔融还原新流程的关键技术。解决了冷固结含碳球团高温强度问题，提出了含碳球团自还原动力学模型，再氧化机理和提高球团预还原速度，抗氧公有力的技术措施和参数，研制出了具有高配碳量，高强度，高自还原速度，高预还原速度，高抗氧化能力的新型含碳球团。同时，研究了含碳球团在铁浴中熔化还原动力学参数，优化得到了控制还原速度，终还原率，熔渣中最低ＦｅＯ含量，泡沫渣     

Li2CO3在含碳球团还原中催化机理的研究

通过在氧化铁中添加碳粉和少量Ｌｉ２ＣＯ３添加剂,考察了碱金属化合物和温度对含碳才还原过程的影响,探讨了碱金属化合物的催化机理,实验结果表明,球团还原率随着碱金属化合物添加量而增大,但增大幅度随添加剂增多,温度升高而减小,在球团还原初期,Ｂｏｕｄｏｕａｒｄ反应是还原的限制环节,添加Ｌｉ２ＣＯ３可以降低反应活化能,较高温度下还原后期,氧化铁的气相还原是反应的限制性环节,添加Ｌｉ２Ｃｏ３可以加快Ｆｅ／Ｆ     

铁铝共生矿碳热预还原过程矿相转变行为

在提出"非高炉提铁-铝酸钙渣提铝"生态化高效利用新工艺的基础上,系统研究预还原温度、时间、钙铝比、碳氧比等对铁铝共生矿预还原过程中金属化率和矿相转变行为的影响。结果表明:矿石金属化率随预还原温度提高而明显增加;随着还原时间的延长和钙铝比的增加,金属化率均先增加后降低,还原时间和钙铝比分别在30 min和0.8时金属化率达到最高;提高碳氧比有利于提高金属化率,但提高幅度不大。预还原条件对预还原矿矿相的种类影响不大,在初期Fe、2CaO·Al_2O_3·SiO_2、12CaO·7Al_2O_3、2CaO·SiO_2和3Ca O·Al_2O_3相均能生成,提高钙铝比、预还原温度和时间有利于促进2CaO·Al_2O_3·SiO_2向12CaO·7Al_2O_3和2CaO·SiO_2转化。预还原过程工艺条件推荐为:预还原温度1300℃,保温时间30 min,钙铝比0.8,碳氧比1.2,此时预还原矿金属化率为63.10%。     

Thermodynamic Analysis and Preparation of Composites in Zr-Si-C-N-O System

为了得到锆英石碳热还原氮化反应时产物相的稳定存在区域,用ΔfG1=A+BT法对Zr-Si-C-N-O系进行了热力学计算和分析,绘制了Zr-Si-C-N-O系优势区相图。结果表明:通过控制配碳量、反应温度、炉内的CO分压和N2分压,可以获得组成分别为ZrO2-Si2N2O、ZrN-Si2N2O或ZrN-Si3N4等的复相材料。根据热力学分析结果,以锆英石、活性炭为原料,N2(99.999%)为氮源,研究了配碳量(10%,20%,22%,30%,质量分数)对锆英石碳热还原氮化反应失重率及产物相组成的影响。结果表明:配碳量不仅显著影响锆英石碳热还原氮化反应产物的物相组成,而且配碳量的增加还会降低锆英石碳热还原氮化反应的开始温度。     

钛精矿碳热还原制备碳氮化钛的研究

以钛精矿和石墨为原料,在氮气气氛下通过碳热还原法制备出碳氮化钛(Ti CN)粉体。结合XRD、SEM、化学成分分析和TG-DSG综合热分析研究了配碳量及反应温度对钛精矿碳热还原进程的影响。研究结果表明,配碳量的增加影响逐级还原反应温度以及反应总失重,当配碳量达到23%时碳氮化钛产物中出现游离碳。钛精矿碳热还原过程中铁氧化物优先还原,钛氧化物经逐级还原形成Ti CN,还原顺序为Ti O2→Ti4O7→Ti3O5→Ti N→Ti(C,N,O)→Ti CN。得到的碳氮化钛粉体呈微米级不规则形状。     

利用铝电解槽废旧阴极碳热还原铬铁矿（英文）

铝电解槽废旧阴极(SPL)是铝电解生产过程中产生的废料,被用作造渣熔剂与碳源来碳热还原铬铁矿。本研究的主要目标是促进碳热还原过程中铬铁合金颗粒的生长,以利于后续过程中合金与渣相的分离。实验证明相对于采用石墨作为还原剂,SPL中的碳组分能够更有效地还原铬铁矿。铬铁矿还原过程中矿物颗粒表面形成惰性的尖晶石层(MgAl_2O_4),从而阻碍反应的进行以及铬铁合金的生长。SPL中的造渣组分(例如霞石及NaF)在较低温度下(约1300℃)形成熔渣,并部分熔解尖晶石以及铬铁矿相。通过破坏铬铁矿颗粒表面的惰性尖晶石层、促进传质过程以及提高还原温度(例如1500℃)实现铬铁合金颗粒的生长。在还原温度为1500℃以及采用SPL作为添加剂条件下,还原得到较为粗大的铬铁合金颗粒,采用淘析法能够实现合金与渣相的有效分离。     

含碳铬团块熔融还原的实验室研究

为预测工业性试验时铬团块的高温还原速度，对含碳铬团块进行了熔融还原的实验室研究，试验了熔池温度，铬团块的预热对还原速度的影响，并与文献数据进行对比，附带对不同预还原度的巴西氧化铁球团进行了高温下碳还原的试验。     

Na2B4O7对再生铝合金除铁效果的影响

采用电感耦合等离子体原子发射光谱仪、金相显微镜等手段研究不同Na2B4O7添加量、反应温度及保温时间对再生铝合金的除铁效果的影响,利用阿基米德原理间接得到在不同温度下Na2B4O7不同的添加量对气孔率的影响.结果表明:在720℃温度下添加0.5％的Na2B4O7、保温30 min除铁率达到最大值7.57％.680℃和760℃温度下随着Na2B4O7添加量的提高导致试样内部气孔的增多而密度均在递减,在720℃下添加量为0.5％时试样密度在增大甚至达到2.69 g/cm3,超出无添加时达到3.46％.适宜的除铁工艺为:Na2B4O7添加量为0.5％,处理温度720℃,保温时间30 min.     

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.