Et3NHCl/AlCl3离子液体物性的研究

C4烷基化是生产高辛烷值清洁汽油调合组分的重要工艺。Et3NHCl/AlCl3离子液体催化烷基化工艺,中试试验表明其具有较好的催化活性和选择性。因此探索Et3NHCl/AlCl3系列的离子液体的基础物性对研究复合离子液体的物性提供参考。本论文合成了6种不同摩尔比的Et3NHCl/AlCl3离子液体,测定这6种离子液体的密度、粘度、熔点和溶解度,并且考察了温度对物性的影响。     

TMPAC-AlCl3离子液体中恒电流电沉积铝

合成了不同TMPAC和AlCl₃摩尔比的TMPAC-AlCl₃离子液体,并测定了其在不同温度下的电导率。在摩尔比为1:2的TMPAC-AlCl₃离子液体中进行了恒电流电沉积实验,研究了温度、电流密度、搅拌速度和添加剂甲苯等对沉积层的影响。结果表明:在相同条件下摩尔比为1:2的TMPAC-AlCl₃离子液体电导率最大,当温度为80℃,电流密度为20 mA·cm^-2,搅拌速度为500 r·min^-1时,沉积层质量较好且电流效率较高;甲苯的加入,增大了TMPAC-2AlCl₃离子液体的电导率,降低了槽电压,当添加甲苯的体积分数为50%,电流密度为23 mA·cm^-2时,可以得到较为致密、色泽良好、平整而均匀的沉积层。     

氯铝酸离子液体催化异丁烷/丁烯烷基化反应

合成含有不同阴离子和阳离子的AlCla／Et3NHCl类离子液体,通过加入过渡金属氯化物对2AlCl3／Et3NHCl进行改性。用快速原子轰击质谱仪考察了这些离子液体的阴离子结构,并在高压釜中考察了不同离子液体对异丁烷／丁烯烷基化反应的催化能力。结果表明,氯铝酸类离子液体中的阴离子Al2Cl7^-是影响烷基化反应催化活性的主要原因;不同AlCla／Et3NHCl摩尔比能够改变离子液体的酸强度,并影响烷基化的选择性。加入CuCl2的2AlCl3／Et3NHCl产生了新的阴离子,使烷基化油中C8含量明显提高。改性后的2AlCl3／Et3NHCl离子液体是异丁烷／丁烯烷基化反应的良好催化剂。     

氯化胆碱添加剂对[Bmim]Cl-AlCl3离子液体体系电解精炼铝的影响

研究了AlCl3摩尔分数为0.667的[Bmim]Cl-AlCl3离子液体体系中氯化胆碱(ChCl)添加剂对体系电导率及电解精炼铝的影响. 结果表明,当ChCl浓度小于8 mmol/L时,体系的电导率随ChCl浓度增加而显著提高,但ChCl浓度进一步增加体系的电导率逐渐降低. 添加少量ChCl后,阴极还原峰电位正移,还原峰电流逐渐降低. 在温度373 K和电流密度50 A/m2条件下添加5 mmol/L ChCl进行恒电流电解,电解过程的槽电压显著降低,阴极电流效率显著提高(接近100%),直流电耗仅为0.611 kW×h/kg,只有纯离子液体体系电解铝的50%,且在低碳钢基体上得到的铝沉积层光滑致密、晶粒细化.     

氯化胆碱-丙二酸离子液体电沉积锌-镍合金

采用恒电位法在氯化胆碱-丙二酸类离子液体中电沉积制备了Zn-Ni合金镀层.重点研究了沉积电位对Zn-Ni合金镀层孔隙率、耐蚀性、结合力和表面形貌的影响.结果表明,在-1.2 V下电沉积所得Zn-Ni合金镀层的孔隙率较低,表面平整致密,耐蚀性最好.     

复合搅拌电沉积Ni-Al2O3的研究

施加空气-磁力复合搅拌电沉积制备Ni-Al2O3复合镀层,并研究了电流密度对共沉积速率、电流效率及所得复合镀层形貌的影响。结果表明:复合搅拌状态下,共沉积速率随电流密度的增加而加快,而电流效率随电流密度的增加先升后降;采用适宜的电流密度,可制得形貌状况良好的Ni-Al2O3复合镀层。     

盐酸三乙胺-三氯化铝离子液体催化甲苯与氯代叔丁烷烷基化反应

用盐酸三乙胺和无水三氯化铝合成了不同配比的Et3NHCl-AlCl3离子液体,研究了反应时间、反应温度、离子液体的用量、甲苯与氯代叔丁烷摩尔比对烷基化反应的影响。结果表明,Et3NHCl-AlCl3酸性离子液体具有较高的催化活性,良好的低温反应活性和对位选择性。得到了该反应优化反应条件:离子液体中AlCl3与Et3NHCl的摩尔比1.6,反应温度20℃,离子液体的用量为甲苯质量的10%,甲苯与氯代叔丁烷摩尔比2,反应10 min。该条件下,氯代叔丁烷的转化率为98%,对叔丁基甲苯的选择性为82.5%。离子液体重复使用5次,其催化活性不变,离子液体再生后可循环使用。     

Ni-SiC复合电镀工艺的优化及镀层结构表征

利用电沉积法制备出Ni-SiC复合镀层,研究了阴极电流密度、温度、pH、搅拌速率、表面活性剂等工艺参数对镀层显微硬度和沉积速率的影响,通过正交试验得出了最佳工艺参数:阴极电流密度4A/dm2,SiC微粒悬浮量60g/L,温度40℃,pH 2.5,搅拌速率300 r/min.用SEM、XRD和TEM分析了镀层的表面形貌、组织结构及镀层中粒子的分布,结果表明:SiC微粒均匀分布于复合镀层中,镀层表面平整光滑,显微组织均匀、致密,其显微硬度也较纯镍镀层有显著提高.     

铜铝双金属复合离子液体的电化学行为及电沉积铜机理

铜铝双金属复合离子液体是新型碳四烷基化技术所用的绿色催化剂,电化学处理是回收工业应用过程外排复合离子液体中金属铜的有效途径之一,为此需要深入研究其电化学行为和电沉积铜机理。循环伏安研究发现,铜铝双金属复合离子液体在Pt盘电极、W盘电极和玻碳电极上的还原过程均包括铜的欠电势沉积、Cu(Ⅰ)的还原和铜的超电势沉积,氧化过程均包括Cu→Cu(Ⅰ)、Cu(Ⅰ)→Cu(Ⅱ)。计时安培研究表明,铜的成核方式为三维瞬时成核。长周期实验结果显示Cu(Ⅰ)的浓度随着时间下降的趋势变缓,表明电沉积铜速率逐步下降。电沉积电势对沉积产物的形貌影响较大,-2.60 V下的产物形貌更平整致密。XRD结果表明在-1.20~-2.60 V电势下阴极电沉积只生成金属铜。     

铜铝双金属复合离子液体的电化学行为及电沉积铜机理

铜铝双金属复合离子液体是新型碳四烷基化技术所用的绿色催化剂,电化学处理是回收工业应用过程外排复合离子液体中金属铜的有效途径之一,为此需要深入研究其电化学行为和电沉积铜机理。循环伏安研究发现,铜铝双金属复合离子液体在Pt盘电极、W盘电极和玻碳电极上的还原过程均包括铜的欠电势沉积、Cu(Ⅰ)的还原和铜的超电势沉积,氧化过程均包括Cu→Cu(Ⅰ)、Cu(Ⅰ)→Cu(Ⅱ)。计时安培研究表明,铜的成核方式为三维瞬时成核。长周期实验结果显示Cu(Ⅰ)的浓度随着时间下降的趋势变缓,表明电沉积铜速率逐步下降。电沉积电势对沉积产物的形貌影响较大,-2.60 V下的产物形貌更平整致密。XRD结果表明在-1.20~-2.60 V电势下阴极电沉积只生成金属铜。     

QF-J3-2型汽轮发电机的负序电流保护

针对云浮硫铁矿化工厂QF-J3-2型汽轮发电机由于电网缺相运行导致发电机转子轴瓦烧毁的事故,设计安装了发电机负序过电流保护装置,避免了类似原因造成的事故和损失,确保了发电机的安全。     

纳米碳酸钙的合成理论及其应用进展

详细介绍了纳米级碳酸钙合成中涉及到的4个化学过程（即石灰石煅烧、生石灰消化、碳化、陈化）的有关理论研究近况；综述了目前碳酸钙通过颗粒尺寸的细微化、晶形复杂化和表面改性处理技术的采用，纳米级活性碳酸钙在橡胶、造纸、塑料等工业中的应用现状，并预测了纳米级碳酸钙的发展前景。     

Study of Mn doped multiferroic DyFeO3 ceramics

Structural, Raman, room temperature and temperature dependent leakage current density, dielectric, magnetization and room temperature Mossbauer studies of Mn doped DyFeO₃ (i.e., DyFe_1−xMn_xO₃; x=0 to 0.5) polycrystalline materials prepared through sol-gel route are reported in this paper. From Rietveld refinement of x-ray diffraction (XRD) patterns it is found that all the samples are formed in single phase without any detectable impurity. The Raman modes with doping are consistent with literature of such doped orthoferrites. From the room temperature (RT) leakage current density (J-E) measurements, it is observed that leakage current density increases with Mn doping concentration, which is explained in terms of microstructure. The leakage current density is found to decrease with the decrease of temperature in each sample as observed from low temperature leakage current density (J-E) measurements. Further, activation energy is calculated from the temperature dependent J-E data. The dielectric loss data is observed to exhibit frequency dependence and the activation energy obtained indicate the contribution from space charges. From temperature dependent magnetization data, it is found that with the increase of Mn content, the spin reorientation (SR) transition temperature (T_SR) moves towards higher temperature. From M-H curves at 10 K and 300 K with different Mn doping concentrations, it is found that saturation Magnetization (M_S) decreases with increase of Mn doping. Room temperature Mossbauer data shows the presence of Fe³⁺ state and the gradual decrease of internal hyperfine filed with increase of Mn content.     

Influence of Cr2O3 on highly nonlinear properties and low leakage current of ZnO–Bi2O3 varistor ceramics

ZnO–Bi₂O₃–Sb₂O₃–Co₂O₃–MnO₂–xCr₂O₃ (ZBSCM–xCr₂O₃, 0≤x≤0.6 mol%) varistors were fabricated through the conventional solid state method, and the effects of Cr₂O₃ on the microstructures and electrical properties were investigated. Results showed that the secondary phases CrBi₁₈O₃₀ and Co₂Cr_0.5Sb_0.5O₄ emerged when x ranges from 0.2 to 0.4. In these compositions, Cr₂O₃ acted as a donor and decreased the electrical properties of ZBSCM. For samples with x=0.5, the secondary phases transformed to MnCr₂O₄ and the electrical properties increased significantly: the nonlinear coefficient α sharply increased up to 80.71 and the barrier height ϕ_b reached 3.88 eV. This indicates that the donor effect of Cr₂O₃ disappeared. In addition, with the increase of Cr₂O₃, the average grain size of ZnO decreased from 7.48 μm to 5.46 μm, which in turn resulted in an increase of breakdown voltage E_1mA from 216.17 V/mm to 362.50 V/mm. Besides, all the samples showed the low value of leakage current of lower than 0.1 μA. This varistor might be a promising candidate for highly effective applications.     

Enhanced insulating and piezoelectric properties of BiFeO3-BaTiO3-Bi0.5Na0.5TiO3 ceramics with high Curie temperature

BiFeO₃-BaTiO₃ ceramics are promising lead-free piezoelectric ceramics due to their high piezoelectric properties and high Curie temperature, but their high leakage current density makes the poling difficult. In this study, a decreased leakage current density by three orders of magnitude was obtained in Bi_0.5Na_0.5TiO₃ (BNT) added 0.67BiFeO₃-0.33BaTiO₃ (BF-BT) ceramics. It was found that the largely improved insulating properties benefit from the reduced oxygen vacancies and weak reduction of Fe³⁺ to Fe²⁺ as confirmed by photoluminescence and X-ray photoelectron spectroscopy measurements, thereby contributing to high-temperature and high-field poling. In addition, the introduction of BNT leaded to increased grain size. Due to the grown grains as well as reduced oxygen vacancies and Fe²⁺, enhanced insulating and optimal piezoelectric properties with P_r = 24.2 µC/cm², d₃₃ = 183 pC/N, k_p = 0.28, and T_C = 467°C were achieved in BF-BT-0.05BNT ceramics.     

RoDip-3输送系统电泳不良浅析

结合RoDip-3输送系统特点,分析了该系统电泳不良形成原因,并针对各个形成原因,制定了相应的预防和处理措施。     

Pulsed current-driven wetting of 3YSZ by liquid Cu and its mechanisms

The wettability of 3 mol% Y₂O₃-stabilized ZrO₂ (3YSZ) by molten Cu can be greatly improved by applying pulsed currents at 1373 K. The improvement was closely related to current polarity and influenced by duty cycle and frequency. When the Cu/3YSZ interface was under cathodic condition, the wettability was mainly improved by the formation of substoichiometric ZrO_2-δ and metallic Zr at the interface. Increasing duty cycle caused the interface to change from forming protrusions to creating depression. Decreasing frequency further deepened the depression. In the opposite polarity, the adsorption and enrichment of oxygen reduced the solid-liquid and liquid-vacuum interfacial energies, thus improving the wettability. Only bubbles formed at the interface. The larger the duty cycle, the more rapidly bubbles formed and escaped. The effect of frequency at this polarity was weak. Overall, this work provides a novel and effective strategy for tailoring the wettability and interfacial chemistry between zirconia and metals.     

Lead-free 0.7BiFeO3-0.3BaTiO3 high-temperature piezoelectric ceramics: Nano-BaTiO3 raw powder leading to a distinct reaction path and enhanced electrical properties

Herein, nano-BaTiO₃/Bi₂O₃/Fe₂O₃ and BaCO₃/TiO₂/Bi₂O₃/Fe₂O₃ were respectively used to prepare 0.7BiFeO₃-0.3BaTiO₃ (0.7BF-0.3BT) ceramics by conventional solid-state method and clarify the reaction path, phase structure, microstructure, ferroelectric, and piezoelectric properties. 0.7BF-0.3BT ceramic using nano-BaTiO₃ with cubic phase (C_BT) undergoes the formation of rhombohedral α-phase (R_α) and the transition from R_α and C_BT to rhombohedral β-phase (R_β) and pseudo-cubic (PC) phases, while the counterpart using BaCO₃/TiO₂ directly generates R_β and PC. Nano-BaTiO₃ can decrease pores and oxygen vacancies in the resultant ceramics comparing to BaCO₃/TiO₂, which is due to an inhibited decomposition of R_α and a weaker reduction of Fe³⁺ to Fe²⁺, leading to increased density and reduced leakage current density. Benefitting from a proper phase ratio, increased density and reduced leakage current density, the enhanced piezoelectric properties d₃₃?=?210?pC/N, k_p?=?0.34, P_r?=?31.2?μC/cm² and T_C?=?514?°C are obtained in 0.7BF-0.3BT ceramic using nano-BaTiO₃. Our work reveals the importance of raw materials and the potential of BF-BT as a high-temperature lead-free piezoelectric ceramic material.     

Analytical performance of 3?m and 3?m +1 armchair graphene nanoribbons under uniaxial strain

The electronic band structure and carrier density of strained armchair graphene nanoribbons (AGNRs) with widths of n =3 m and n =3 m +1 were examined using tight-binding approximation. The current-voltage (I-V) model of uniaxial strained n =3 m AGNRs incorporating quantum confinement effects is also presented in this paper. The derivation originates from energy dispersion throughout the entire Brillouin zone of uniaxial strained AGNRs based on a tight-binding approximation. Our results reveal the modification of the energy bandgap, carrier density, and drain current upon strain. Unlike the two-dimensional graphene, whose bandgap remains near to zero even when a large strain is applied, the bandgap and carrier density of AGNRs are shown to be sensitive to the magnitude of uniaxial strain. Discrepancies between the classical calculation and quantum calculation were also measured. It has been found that as much as 19% of the drive current loss is due to the quantum confinement. These analytical models which agree well with the experimental and numerical results provide physical insights into the characterizations of uniaxial strained AGNRs.     

Enhanced photovoltaic properties of PbTiO3-based ferroelectric thin films prepared by a sol-gel process

PbTiO₃ (PTO), Pb(Mn_0.1Ti_0.9)O₃ (PMTO), Pb(Sr_0.1Ti_0.9)O₃ (PSTO), and Pb(Zr_0.1Ti_0.9)O₃ (PZTO) were prepared on an indium tin oxide (ITO)/glass substrate by a sol-gel method. PTO, PMTO, PSTO, and PZTO films exhibited energy band gaps of 3.55 eV, 3.63 eV, 3.59 eV, and 3.66 eV, respectively. All these films generated high photocurrents due to high shift currents, because carrier migration channels were successfully introduced by a lattice mismatch between the films and ITO substrates. The PMTO thin film exhibited the best ferroelectric and photovoltaic properties, with a photovoltage of 0.74 V, a photocurrent density of 70 μA/cm², and a fill factor of 43.34%, which confirms that shift current and ferroelectric polarization are two main factors that affect the ferroelectric photovoltaic properties. The PSTO, PZTO, and PTO thin films displayed space-charge-limited current (SCLC) when the electric field strength was below 10 kV/cm, and these three films broke down when the electric field strength was above 10 kV/cm. Analysis of the shift current mechanism confirmed that the breakdown of the PZTO and PSTO thin films resulted from Pool Frenkel emission current. The PMTO thin film displayed SCLC in the test range, which indicates that doping with Mn could inhibit defect formation in ferroelectric thin films.