钢包渣线用超低碳MgO-MA-C砖的研制与应用

以高纯电熔镁砂、镁铝尖晶石微粉和纳米炭素为主要原料,分别加入总量为4%(质量分数)的硅粉、铝粉和硅粉-铝粉复合粉为防氧化剂,加入清洁的自来水混练均匀后,在500 t 摩擦压砖机上成型为碳质量分数小于1%的超低碳MgO-MA-C 标型砖试样.在对比各试样(包括普通MgO-C砖试样)的抗氧化性能、高温抗折强度、体积稳定性和抗渣性的基础上,对配方和生产工艺进行了优化,研制出了性能较好的超低碳(碳质量分数小于1%)MgO-MA-C砖.所研制砖在武钢200 t转炉钢包渣线区使用,平均使用次数达75次.     

One-stage synthesis of (Y0,5Bi0,5)3(Fe0,5Ga0,5)5O12 garnet using the organometallic gel auto-combustion approach

Nanosized powder of (Y_0.5Bi_0.5)₃(Fe_0.5Ga_0.5)₅O₁₂ ferrite garnet with a narrow particle size distribution was prepared via the gel auto-combustion approach based on polyvinyl alcohol (PVA) and metal nitrates. The peculiarities of garnet phase formation were studied by infrared spectroscopy (IR spectroscopy), simultaneous thermal analysis (TGA/DSC), C, H and N-elemental analysis, and powder X-ray diffraction (XRD). The final powdery product was characterized using powder XRD, IR spectroscopy, X-ray fluorescence (XRF) and scanning electron microscopy (SEM). We established that the use of PVA provides one-stage crystallization of a single-phase ferrite-garnet due to the formation of a thermally stable PVA-salt complex. Crystallization of the (Y_0.5Bi_0.5)₃(Fe_0.5Ga_0.5)₅O₁₂ powder occurred at 700?°C, without intermediate and impurity phases.     

微米级和纳米级颗粒的检测

介绍小于0．1μm空气悬浮粒子的检测。     

Temperature- and electric-field-dependent electrical properties and nanoscale domain structures in PIN-0.49PMN-0.27 PT single crystal

The effect of temperature and electric field on phase transitions, dielectric relaxation behavior, and macroscopic electrical performances of Pb(In_1/2Nb_1/2)O₃-0.49 Pb(Mg_1/3Nb_2/3)O₃-0.27PbTiO₃ (PIMNT27) single crystals were studied. The nanosized domains of unpoled crystals and the engineered domains of DC electric field poled crystals were intuitively recorded by piezoresponse force microscopy (PFM). The distribution of nanosized domains with different sizes and patterns induced by domain switching and domain wall motion under different poling fields and temperatures were also studied to understand the effect of nanosized domains on phase transitions, piezoelectric, and electromechanical properties.     

Ultrasonic wave aided selective epoxidation of mixed styrene and α-pinene with air over nanosized Co3O4

Catalytic selective epoxidation of mixed biolefins with air over nanosized Co₃O₄ catalyst under mild ultrasonic conditions has been first reported. When the styrene/α-pinene molar ratio was 1:5, the highest conversions were, respectively, reached 81.8 mol% for styrene and 76.1 mol% for α-pinene, with the epoxidation selectivity of 84.1% (styrene oxide) and 94.6% (α-pinene oxide), notably higher than those of the conventional reactions under magnetic stirring. An intermolecular electron-transfer phenomenon between conjugated styrene and electron-rich α-pinene was revealed by UV–vis spectra, which was considerably important for the enhancement of reactivities of both olefinic molecules observed experimentally.     

Effects of the co-addition of Zn and sodium dodecylbenzenesulfonate on photocatalytic activity and wetting performance of anatase TiO2 nanoparticle films

In this paper, doped and undoped anatase TiO₂ nanoparticle films on indium tin oxide glasses have been fabricated by spin coating sols containing Zn²⁺ or Zn²⁺ and sodium dodecylbenzenesulfonate (DBS), respectively. The effects of the co-addition of Zn²⁺ and DBS on the photocatalysis performance and wetting properties of the resulting TiO₂ nanoparticle films were investigated. The results showed that the addition of Zn²⁺ improved both the photocatalytic activity and the hydrophilicity, which was attributed to surface oxygen vacancies. The co-addition of Zn²⁺ and DBS resulted in an important increase of the surface roughness, resulting in films showing a superhydrophilic behavior. However, the photocatalytic activity was slightly decreased by co-adding Zn²⁺ and DBS. The DBS addition resulted in changes in the surface microstructure of the TiO₂ films, changing the photocatalytic activity and wetting performance.     

Nanosized Ni-Mn Oxides Prepared by the Citrate Gel Process and Performances for Electrochemical Capacitors

Nanosized Ni-Mn oxide powders have been successfully citrate gel precursors. The powder materials derived from prepared by thermal decomposition of the Ni-Mn calcination of the gel precursors with various molar ratios of nickel and manganese at different temperatures and time were characterized using thermal analysis （TG-DSC）, scanning electron microscopy （SEM）, X-ray diffraction （XRD） and Brunauer-Emmet-Teller （BET）. The optimized processing conditions of calcination at 400℃ for 1 h with Ni/Mn molar ratio 6 were proved to produce the nanosized Ni-Mn oxide powders with a high specific surface area of 109.62 m^2/g and nanometer particle sizes of 15-30 nm. The capacitance characteristics of the nanosized Ni-Mn oxide electrode in various concentrations of KOH solutions were studied by the cyclic voltammetry （CV） and exhibited both a doublelayer capacitance and a Faradaic capacitance which could be attributed to the electrode consisting of Ni-Mn oxides and residual carbons from the organic gel thermal decomposition. A specific capacitance of 194.8 F/g was obtained for the electrode at the sweep rate of 10 mV/s in 4 mol/L KOH electrolyte and the capacitor showed quite high cyclic stability and is promising for advanced electrochemical capacitors.     

硅钨酸/TiO_2复合光催化材料光解水催化性能研究

采用浸渍法制备了复合杂多酸H4SiW12O40/TiO2光催化材料,并用XRD、FT-IR和UV-Vis-DRS研究了其结构形态,同时考察了H4SiW12O40/TiO2光催化剂对光解水制氧的应用研究。结果表明,H4SiW12O40/TiO2仍然保留Keggin结构,TiO2均匀固载在H4SiW12O40中,H4SiW12O40与TiO2之间仅仅是简单的物理吸附。在紫外光辐射下光催化分解水制氧的实验中,H4SiW12O40/TiO2的光催化析氧速率高达231.37μmol/(L.h),为纯H4SiW12O40的1.37倍。     

Chemical reduction of nitrate by nanosized iron: kinetics and pathways

This study was conducted to investigate chemical reduction of nitrate by nanoscale zero-valent iron (ZVI) in aqueous solution and related kinetics and pathways. In the last decade, employment of micro-scale ZVI has gained its popularity in nitrate reduction. To further study chemical reduction of nitrate, nanosized iron was synthesized and tested in this work. It has a size in the range of 50-80 nm and a BET surface area of 37.83 m(2)g(-1). Chemical reduction of nitrate by nanosized iron under various pHs was carried out in batch experiments. Experimental results suggest that nitrate reduction by nanosized ZVI primarily is an acid-driven surface-mediated process. A stronger acidic condition is more favorable for nitrate reduction. Results of the kinetics study have indicated that a higher initial concentration of nitrate would yield a greater reaction rate constant. Additional test results also showed that the reduction rate of nitrate increased as the dose of nanosized ZVI increased. In all tests, reaction rate equations developed do not obey the first- or pseudo-first-order reaction kinetics with respect to the nitrate concentration. Based on the research findings obtained, two possible reaction pathways for nitrate reduction by nanoscale iron particles have been proposed in this work.     

水热法制备纳米TiO2粉体工艺条件研究

系统研究了如何应用水热法来制备TiO2纳米粉体。通过实验确定了较佳工艺技术参数:浓度为5%,pH值等于9,保温的温度为220℃。用三乙醇胺作为分散剂,用Tween80和Span80作为表面改性剂研究分析其对TiO2纳米粉体团聚的作用。