片状钡铁氧体纳米磁粉的研究及应用

介绍了高密度磁记录媒体用的片状，替代式钡铁氧体纳米磁粉制备方法及其磁特性。分析，讨论了高密度记录对记录媒体磁特性的要求，介绍了最近研制的，先进的钡铁氧体纳米粉磁带及软磁盘的高密度度灵放特性。     

金隆公司300kt/a扩改工程吹炼工艺方案的论证

本文介绍了铜锍吹炼主要工艺方案 ,重点分析并对比了PS转炉、闪速吹炼炉工艺技术的先进性、可靠性、环境保护、操作实践以及运行情况 ,得出了基本结论 ,为金隆扩建改造工程吹炼工艺方案的选择提供了依据。     

The influence of the stabilizing agent SDS on porosity development in alkali-activated fly-ash based foams

Alkali activated foams (known also as “geopolymer foams”) are formed by the adding of a foaming agent, such as Al powder or H₂O₂, to an alkali activated matrix which can be based on, for example, fly ash, slag or meta-kaolin. The foaming agent decomposes and reacts inside the matrix, resulting in the release of gasses which form pores within the structure. Such pores have to be created before the alkali activated foams harden. In order to prevent the escape of these gasses from the foam, a stabilizing agent can be added to the foam mixture. This paper presents the results of tests involving the pore-foaming process in the case of highly porous, alkali activated, fly-ash based foams. Between 0.5 and 1.5 mass % of H₂O₂ was added to the fly ash precursor as a foaming agent, as well as different amounts (varying from 0.1 to 4.0 mass %) of the selected stabilizing agent, which is known as SDS - sodium dodecyl sulfate. The physical, mechanical, and microstructural properties of the hardened alkali-activated foams were determined. Their pore structures were characterised by SEM, as well as by a three-dimensional (3D) technique, X-ray computed micro-tomography. The advantage of the latter method is that a better insight can be obtained into the characteristics of the hardened pore structure, including information about its homogeneity and the pore size distribution. The influence of the amount of the added foaming agent, as well as that of the amount of the stabilization agent, was evaluated, and optimal addition mass percentages were determined. In the case of the best mixtures, the investigated hardened pore structures showed relatively good mechanical properties, and could therefore be used for various applications in the building industry.     

Extraction of aluminium as aluminium sulphate from thermal power plant fly ashes

Valuable metal extraction technology from thermal power plant fly ash is limited. In the present study, aluminium is extracted from fly ash as highly pure aluminium sulphate (>99.0%) by leaching with sulphuric acid, followed by pre-concentration and successive crystallization. Two types of fly ashes from different sources, i.e., Talcher Thermal Power Station (TTPS) and Vedanta Aluminium Company Limited (VAL) were chosen for comparative study on the extraction of aluminium as aluminium sulphate. The product is characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Purity of aluminium sulphate was also investigated by inductively coupled plasma–optical emission spectrometry (ICP–OES). The extraction efficiency of aluminium depends on the varied solid-to-liquid ratio (fly ash : 18 mol/L H₂SO₄, g/mL) and particle size of fly ashes. Physico-chemical analysis indicates that the obtained product is Al₂(SO₄)₃·18H₂O, having low iron content (0.08%).     

Effect of synthesis atmosphere on the proton conductivity of Y-doped barium zirconate solid electrolytes

Yttrium-doped barium zirconate ceramic powders were synthesized by the oxidant peroxide method in air and under controlled atmosphere of nitrogen inside a glove box. The powders were characterized by thermogravimetry, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. After uniaxial cold isostatic pressing, green pellets were sintered at 1600 °C for 4 h. The electrical conductivity behavior was accessed by electrochemical impedance spectroscopy. The results show that specimens synthesized under controlled atmosphere achieved higher electrical conductivity, two orders of magnitude higher than specimens prepared in laboratory air. The enhancement in electrochemical properties and increase in sintering ability is attributed to the less carbonate contamination as a result lower grain boundary density in the samples prepared under controlled atmosphere.     

The impact of porosity,pH2 and pH2O on the polarisation resistance of Ni–BaZr0.85Y0.15O3−δ cermet anodes for Protonic Ceramic Fuel Cells (PCFCs)

The effect of porosity and atmosphere on the polarisation resistance of Ni-BZY cermet anodes for protonic ceramic fuel cells (PCFCs) was investigated using electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The level of porosity was adjusted by the use of differing amounts of starch porogen. The total polarisation resistance of the cermet anode (Rp) generally showed an increase with increasing porosity. The high frequency polarisation resistance (R2) was shown to have low atmosphere dependence but presented a strong correlation to microstructural variations. In contrast, the low frequency polarisation resistance (R3) was shown to have a low dependence on humidity but demonstrated a strong negative dependence on pH₂ with a value of unity. Subsequent discussion relates the lower frequency response to the dissociative adsorption of H₂ on the anode surface. The present study highlights that porogens are not required for peak performance in PCFC anodes under standard operating conditions, a result contrary to that of their oxide-ion conducting cermet counterparts.     

Effective beneficiation of low content nickel ferrous laterite using fluxing agent through Na2SO4 selective reduction

To address the issue of high energy employment and un-green processing in limonitic laterites extraction, selective reduction using Na₂SO₄ additive with the introduction of different fluxes including quicklime, dolomite, and limestone followed by magnetic separation was studied. The objective of the research was to find out the influence of fluxes in optimizing ferronickel product of reduction. The reduction process was carried out at 1400 °C for 6 hours and the obtained product was characterized by scanning electron microscopy (SEM), emission dispersive x-ray (EDX), and x-ray diffraction (XRD) to image the morphology, determine the composition, and examine the mineralogical structure. Result showed that the employment of fluxes exhibited positive effect in improving the product. The highest nickel grade was 21.68 % using limestone flux, while the most promising recovery was 93.73 % utilizing dolomite flux. Meanwhile, mineralogical assessment also proved that the ascending of nickel content is due to the formation of troilite (FeS) as the result of synergy between Na₂SO₄ additives and carbonate minerals from fluxes. This result exhibits a notable performance of fluxes for improving the product of selective reduction.     

Tunable BaxSr1-xTiO3 nanoparticles induced high energy storage density in layer-structured asymmetric polymer-based nanocomposites

In order to solve the problem of low charging and discharging energy density of dielectric capacitors, the structure design of layered polymer matrix composites is carried out in this paper. Ba_0.7Sr_0.3TiO₃, Ba_0.8Sr_0.2TiO₃ and Ba_0.9Sr_0.1TiO₃ nanoparticles were successfully prepared by the oxalate coprecipitation method. The surface of Ba_xSr_1-xTiO₃ was successfully coated with dopamine, which promoted the dispersion of the polymer matrix of the ceramic powder. Monolayer Ba_xSr_1-xTiO₃/PVDF composites containing Ba_xSr_1-xTiO₃ with different Ba/Sr ratios were successfully prepared by the casting method. Three-layer asymmetric composites with different fillers were successfully prepared by layer-by-layer casting. The phase and microstructure of the as-prepared materials were analyzed by XRD and SEM. The dielectric, electrical conductivity, ferroelectric and energy storage properties of the composites were tested. The effects and laws of the design of the three-layer asymmetric structure on the dielectric properties and energy storage properties of the layered composites are mainly studied. When the structure of the three-layer asymmetric composite is 1-2-3, the breakdown field strength reaches 330 kV/mm, the discharge energy density reaches 8.51 J/cm³, and the charge-discharge efficiency is 67%. This work demonstrates that layered composites with asymmetric properties can facilitate the development of electrical energy storage.     

Novel polymer composites of RuO2@nBaTiO3/PVDF with a high dielectric constant

The dielectric properties of a novel polymer dielectric material were investigated. The conductive phase of RuO₂ was synthesized for deposition on the surface of a nanosized BaTiO₃ (nBT). The RuO₂@nBT hybrid particles were incorporated into a poly (vinylidene fluoride) (PVDF) as a three-phase composite (RuO₂@nBT/PVDF). The obtained dielectric constant (ε′) was significantly high (3837.16) for the composite with a volume fraction of $f_{Ru{O}_2@nBT}$ = 0.50. The large interfacial polarization between the RuO₂?nBT and RuO₂?PVDF interfaces considerably increased the value of ε′. Therefore, interfacial polarization is a critical factor in improving the dielectric properties. The dielectric behavior of the RuO₂@nBT/PVDF composites can be described using the effective medium percolation theory model, which indicates the significant contributions of the conductive RuO₂ phase and high-permittivity nBT phase.