中温SOFC阴极材料La0.7Sr0.3Co1-xCuxO3-δ的制备及性能

采用固相反应法制备了La_0.7Sr_0.3Co_1-xCu_xO_3-δ系列中温固体氧化物燃料电池（SOFC）阴极材料粉体.对其进行晶体结构表征,高温电导率和热膨胀曲线测试,并选取其中性能较好的样品进行了单电池实验.结果表明,Cu的掺杂降低了（La,Sr）CoO La₃体系阴极材料的热膨胀系数,在x=0.05时电导率略高于未掺Cu的样品.以La_0.7Sr_0.3Co_0.95Cu _0.05O _3-δ为阴极、Ce_0.8Sm_0.2O_1.9为电解质组成的SOFC单电池,在850℃最大短路电流密度达511mA/cm²,最大输出功率密度约为0.106W/cm².     

含金属元素的常温CO2固体吸附剂研究进展

当今世界环境保护已经成为大家关注的重点问题。随着大量化石燃料的燃烧,过量的CO₂被排放到大气中,在工业生产中如何降低CO₂的排放量成为了众多研究者所探索的对象。利用固体吸附剂对CO₂进行吸附,在众多的减排方式中被认为是一种无腐蚀、无污染、易于操作且吸附性能更高的方式。对含金属元素固体吸附剂的分类、改性方式、吸附原理、吸附效率等不同方面进行了综述,重点介绍了在常温下对CO₂有较高吸附性能的几种改性材料,同时对含金属元素固体吸附剂吸附CO₂的研究方向和前景作出展望。     

Acting mechanism of F,K, and Na in the solid phase sintering reaction of the Baiyunebo iron ore

The effect of F, K, and Na on the solid phase reaction of the Baiyunebo iron ore was investigated by differential thermal analysis (DTA) and X-ray diffraction (XRD). It has been identified that alkaline elements K and Na in the Baiyunebo ore instigate the formation of low melting point compounds Na₂SiO₃ and Na₂O·Fe₂O₃ and the generation of molten state in the solid phase sintering. Element F in the Baiyunebo ore facilitates the formation of cuspidine compound 3CaO·2SiO₂·CaF₂ in the solid phase reaction. The cuspidine compound is kept in solid as one of the final products through the entire sintering process due to its high melting point. In the sintering process, CaF₂ and SiO₂ react with CaO first and form 3CaO·2SiO₂·CaF₂ and 3CaO·2SiO₂, so the formation of ferrites, Na₂O·Fe₂O₃, and 2CaO·Fe₂O₃ is inhibited.     

Structure and photocatalytic properties of TiO<Subscript>2</Subscript>-Graphene Oxide intercalated composite

TiO2-Graphene Oxide intercalated composite (TiO2-Graphene Oxide) has been successfully prepared at low temperature (80°C) with graphite oxide (GO) and titanium sulfate (Ti(SO4)2) as initial reactants.GO was firstly exfoliated by NaOH and formed single and multi-layered graphite oxide mixture which can be defined as graphene oxide,[TiO]2+ induced by the hydrolysis of Ti(SO4)2 diffused into graphene oxide interlayer by electrostatic attraction.The nucleation and growth of TiO2 crystallites took place at low temperature and TiO2-Graphene Oxide composite was successfully synthesized.Furthermore,the photocatalytic properties of TiO2-Graphene Oxide under the irradiation of UV light were also studied.The results show that the degradation rate of methyl orange is 1.16 mg min-1 g-1(refer to the efficiency of the initial 15 min).Compared with P25 powder,this kind of intercalation composite owns much better efficiency.On the other hand,the reusable properties and stable properties of TiO2-Graphene Oxide intercalated composite are also discussed in this paper.At last,crystalline structure,interface status,thermal properties and microscopic structure of TiO2-Graphene Oxide were characterized by X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),thermogravimetric analysis (TGA),field emission scanning electron microscopy (FESEM) and high-resolution Transmission Electron Microscopy (HRTEM).Also,we have analyzed major influencing factors and mechanism of the composite structures which evidently improve the photocatalytic properties.     

Synthesis and luminescence properties of Mn4+-dopant Ca14Zn6Ga10−xAlxO35 solid solution

Mn~(4+)-activated oxide phosphors,owing to their desirable spectral features,eco-friendly and low cost,are emerging as a new class of non-rare-earth red phosphors for warm white LEDs.However,these phosphors possess low photoluminescence quantum efficiency excited by blue chip currently.Herein we report an isostructural solid solution of Ca_(14)Zn_6Ga_(10-x)Al_xO_(35):0.15Mn~(4+)(0≤x≤10)synthesized by a traditional solidstate reaction route.The microstructure and luminescent performance of this red-emitting phosphor are investigated in detail with the aids of X-ray diffraction,diffuse reflection spectra,photoluminescence spectra/decay/QE,and temperature-dependent PL/QE measurements.Blue shift of energy peaks of~4A_2→~4T_1and~4A_2→~4T_2transition is illustrated by the Tanabe–Sugano diagram and the configurational coordinate diagram.The crystal field strength(Dq)and the Racah parameters(B and C)are carefully calculated to estimate the nephelauxetic effectβrespectively.Particularly we achieve external and internal quantum efficiencies as high as26.1%and 40.3%for Ca_(14)Zn_6Ga_6Al_4O_(35):0.15Mn~(4+)excited by 466 nm,the highest one ever reported in Mn~(4+)activated oxide phosphors under the similar condition.     

水热体系下二氧化钛与氧化石墨烯复合纳米晶的合成

 200 ℃下四方结构的二氧化钛(TiO2)与氧化石墨烯(GO)复合纳米晶在一个装有适量钛酸四丁酯、无水乙醇、氧化石墨烯和蒸馏水的密闭的水热釜中加热12 h后被制备。X射线粉末衍射仪（XRD)、扫描电子显微镜（SEM）、透射电子显微镜（TEM）等一系列分析仪器被运用来揭示二氧化钛与氧化石墨烯复合纳米晶是由粒径大约160 nm的四方结构的二氧化钛纳米晶与氧化石墨烯复合而成,通过紫外吸收对其光学性能进行了必要的测试。
     

一步法合成SO42-/TiO2酸位结构及酯化机理研究

 利用高酸值麻疯树油中游离脂肪酸与甲醇酯化反应作为目标反应,通过直接煅烧工业原料偏钛酸,制得高酯化活性的ST(SO₄^2-/TiO₂)固体酸.FTIR研究表明:ST固体酸具有焦硫酸结构酸位,含有高键级高共价特性S=O.S=O强烈的诱导效应提高了与之相连的配位不饱和钛原子的路易斯酸性,吸水后产生质子酸.随着硫含量增加,质子酸性增加.ST固体酸制备过程中,硫酸根与二氧化钛发生固相反应,硫酸根强键合在二氧化钛表面,同时部分硫酸根分解产生三氧化硫并原位吸附,从而形成固体酸位.ST固体酸通过质子化羧酸、甲醇亲核加成、脱水脱质子机理催化酯化反应.对于麻疯树油中游离脂肪酸与甲醇的酯化反应,酸强度H0介于-12.70与-8.2之间的酸中心具有较好的催化活性.     

Scalable synthesis and electrochemical performance of mesoporous graphene from calcium carbonate by magnesiothermic reaction

A novel scalable synthetic method of mesoporous graphene has been developed using the compressed mixture of Mg and excess CaCO₃ in a closed container. The generated solid oxide and unreacted CaCO₃ could act as mesopore-forming agents, and the closed container could prevent the carbon dioxide from CaCO₃ flow away. As a result, the graphenes with a large number of 2–30 ?nm mesopores and high utilization ratio of Mg achieved. The graphenes had high specific surface area and excellent electrochemical performance. In particular, the Mg utilization ratio was up to 53.3% in the preparation of graphene using 2:1 CaCO₃/Mg at 700 ?°C, which is superior to previous researches. The obtained mesoporous graphene exhibited high specific surface area of 743.7 ?m² ?g^-1, large specific capacitance of 140 ?F ?g^-1, and high capacitance retention rate of 64.3%.     

Oxidation behavior of in-situ Al2O3/TiAl composites at 900°C in static air

In-situ Al₂O₃/TiAl composites were successfully synthesized from the starting powders of Ti, Al, TiO₂ and Nb₂O₅. The oxidation behavior of the composites at 900°C in static air was investigated. The results indicate that the composite samples present a much lower oxidation mass gain. Under long-time intensive oxidation exposure, the formed oxide scale is multi-layer. The formation of the outer TiO₂ layer is fine and dense, the internal Al₂O₃ scale has good adhesiveness with the outer TiO₂ scale, and the TiO₂+Al₂O₃ mixed layer forming the protective oxide scale is favorable for the improvement of oxidation resistance. It is believed that the incorporation of Al₂O₃ particulates into the metal matrix decreases the coefficient of thermal expansion of the substrate, and forms a local three-dimensional network structure that can hold the oxide scale. The formation of the oxide scale with finer particle size, stronger adherence, less micro-defects and slower growth rate can contribute to the improvement of oxidation resistance. Nb element plays an important role in reducing the internal oxidation action of the materials, restraining the growth of TiO₂ crystals and promoting the stable formation of the Al₂O₃-riched layer, which is beneficial to improve the oxidation properties.     

Ti3SiC2代替石墨金属基自润滑材料研究进展

Ti₃SiC₂是一种新型的金属陶瓷材料,该材料兼具金属与陶瓷材料的双重性能,具有良好的导电性、导热性、加工性、耐腐蚀性与高温抗氧化性,同时该材料还具有超低的摩擦因数.基于其独特性能,大量科研工作开始投入到使用Ti₃SiC₂代替石墨制备金属基自润滑复合材料中.介绍了近年来石墨及以Ti₃SiC₂作为固体润滑颗粒制备的金属基自润滑复合材料的研究现状及进展.探讨了石墨和Ti₃SiC₂与金属界面结合问题,并对比两种复合材料的力学性能和摩擦学性能.最后指出以Ti₃SiC₂代替石墨制备金属基自润滑材料的可行性以及未来的发展方向.     

Addition of IrO2 to RuO2+TiO2 coated anodes and its effect on electrochemical performance of anodes in acid media

Ternary mixed metal oxide coatings with the nominal composition IrxRu(0.6-x)Ti0.4O2(x=0, 0.1, 0.2, 0.3) on the titanium substrate were prepared by thermal decomposition of a chloride precursor mixture. Surface morphology and microstructure of the coatings were investigated by Scanning electron microscopy(SEM), Field emission scanning electron microscopy(FE-SEM) and X-ray diffraction(XRD) analysis. Systematic study of electrochemical properties of these coatings was performed by cyclic voltammetry(CV) and polarization measurements. The corrosion behavior of the coatings was evaluated under accelerated conditions(j=2 A cm-2) in acidic electrolyte. The role of iridium oxide admixture in the change of electrocatalytic activity and stability of Ru0.6Ti0.4O2coating was discussed. Small addition of IrO2can improve the stability of the RuO2+TiO2mixed oxide, while the electrocatalytic activity for oxygen evolution reaction(OER) is decreased. The shift of redox potentials for Ru0.6Ti0.4O2electrode that is slightly activated with IrO2and improvement in the stability can be attributed to the synergetic effect of mixed oxide formation.     

氨配合法制备活性氧化锌的研究

 以硫酸锌、氨水、碳酸氢铵为原料,采用氨配合法制备出碱式碳酸锌,再经高温煅烧制备活性氧化锌.通过差热-热重分析(DTA-TG)、比表面积测定、X射线衍射(XRD)、扫描电子显微镜(SEM)等测试方法对产物进行了表征.对蒸氨时间、陈化时间、煅烧时间和煅烧温度等因素对活性氧化锌性能的影响进行了详细的研究,得到了制备活性氧化锌的较优条件,在此条件下制得了比表面积高达68.151 m²/g的活性氧化锌.     

Diffusion behavior and distribution regulation of MgO in MgO-bearing pellets

In this paper, the diffusion behavior between MgO and Fe₂O₃ (the main iron oxide in pellets) is investigated using a diffusion couple method. In addition, the distribution regulation of MgO in MgO-bearing pellets is analyzed via pelletizing experiments. The results illustrate that MgO is prone to diffuse into Fe₂O₃ in the form of solid solution; the diffusion rate considered here is 13.64 μm·min-1. Most MgO content distributes in the iron phase instead of the slag phase. The MF phase {(Mg_1-x Fe_x)O·Fe₂O₃, x ≤ 1} is generated in the MgO-bearing pellets. However, the distribution of MgO in the radial direction of the pellets is inconsistent. The solid solution portion of MgO in the MF phase is larger in the outer layer of the pellets than in the inner layer. In this work, the approximate chemical composition of the MF phase in the outer layer of the pellets is {(Mg_0.35-0.77·Fe_0.65-0.23) O·Fe₂O₃} and in the inner layer is {(Mg_0.13-0.45·Fe_0.87-0.55) O·Fe₂O₃}.     

Isothermal oxidation behavior and mechanism of a nickel-based superalloy at 1000℃

The oxidation behavior of a nickel-based superalloy at 1000℃ in air was investigated through X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy analysis. A series of oxides, including external oxide scales (Cr₂O₃, (TiO₂ + MnCr₂O₄)) and internal oxides (Al₂O₃,TiN), were formed on the surface or sub-surface of the substrate at 1000℃ in experimental still air. The oxidation resistance of the alloy was dependent on the stability of the surface oxide layer. The continuity and density of the protective Cr₂O₃ scale were affected by minor alloying elements such as Ti and Mn. The outermost oxide scale was composed of TiO₂ rutile and MnCr₂O₄ spinel, and the growth of TiO₂ particles was controlled by the outer diffusion of Ti ions through the pre-existing oxide layer. Severe internal oxidation occurred beneath the external oxide scale, consuming Al and Ti of the strength phase γ' (Ni₃(Al,Ti)) and thereby severely deteriorating the surface mechanical properties. The depth of the internal oxidation region was approximately 35 μm after exposure to experimental air at 1000℃ for 80 h.     

热压烧结C-SiC-B4C复合材料组织与性能(Ⅱ):氧化行为

以C鳞片,SiC,B4C和TiO2为原料,在2000℃热压合成C-SiC-B4C-TiB2复合材料.研究复合材料在600~1400℃静态空气中的恒温氧化行为,利用TG/DTA研究复合材料氧化机理,利用XRD,SEM研究复合材料恒温氧化后表面相组成和氧化层剖面的显微结构.结果表明不同C鳞片含量的复合材料的氧化动力学曲线均为抛物线,氧化层可分成氧化膜和过渡层,C鳞片质量分数为20%的复合材料在1400℃时有很好的抗氧化自还原能力,表面生成致密的氧化膜,氧化膜的成分为未形成玻璃态的TiO2或SiO2.TiO2固溶体,组织形貌为枝条状.     

The electrical property of MnCo<Subscript>2</Subscript>O<Subscript>4</Subscript> and its application for SUS 430 metallic interconnect

The conductivity of MnCo₂O₄ spinel, the best route to form the MnCo₂O₄ protective coating applied by the sol-gel process, and its effect on the intermediate temperature oxidation behavior of SUS 430 alloy, a typical material for the interconnect of solid oxide fuel cell (SOFC), was investigated. The phase structure and surface morphology of the coating and surface oxides were characterized by XRD, SEM and EDS; the “4-probe” method was employed to determine the conductivity of MnCo₂O₄ spinel and the area specific resistance (ASR) of the surface oxides. The conductivity of MnCo₂O₄ spinel is excellent, which is 2 orders of magnitude better than that of MnCr₂O₄ spinel. Long-term thermally cyclic oxidation at 750°C in SOFC cathode atmosphere and ASR measurement have shown that calcined in reducing atmosphere followed by pre-oxidation in the air is the best technique for forming the MnCo₂O₄ protective coating, which enhances the oxidation resistance, and improves the electrical conductivity and adherence of coated SUS 430 alloy significantly. As a result, the MnCo₂O₄ spinel is the most potential candidate for SOFC metallic interconnect protective coating application.     

Micro-analysis of high-temperature oxidation-resistance of a new kind of heat-resistant grid plate in grate-kiln

To further improve the oxidation-resistance of materials and reduce the cost of grid plates in grate-kiln, a new kind of heat-resistant grid plate was developed. The microstructure of this grid plate with a life more than 18 months was studied by XRD, SEM and EDS techniques. The results show that high hardness, high intensity and good impact property make the new kind of heat-resistant grid plate and its oxide film have a higher resistance to deformation and abrasion at 900-1000℃ Besides, small grain size is beneficial to form a complete protective oxide film. The oxide film composed of SiO₂ layer, Cr₂O₃ layer and Fe₂O₃ layer is rather thin and bonds closely with the backing. The forming of the chemical stable nickel-rich layer increases the density of Cr₂O₃ layer.     

Corrosion behavior of ferritic ODS steel prepared by adding YH_2 nanoparticles in supercritical water at 600 °C

The corrosion behavior of the ferritic oxide dispersion strengthened(ODS)steel(14Cr-3Al-2W-0.1Ti)prepared by adding YH_2nanoparticles(NPs)was investigated in supercritical water(SCW)at 600°C for 1500 h.The mass gain of the ODS steel(215.5 mg/dm~2)was lower than that of SUS430 steel(357.2 mg/dm~2).A dual oxide layer generated on the surface of ODS steel after corrosion in SCW.The outer layer was composed of Fe_2O_3and Fe_3O_4,while the inner layer composed of the spinel-type FeCr_2O_4together with Al_2O_3.The generation of Y_2Ti_2O_7NPs in the ODS steel by adding YH_2NPs prohibits the formation of Y-Al-O particles and leaves more Al available to form a continuous protective oxide scale to improve the corrosion resistance.Moreover,the Y_2Ti_2O_7NPs act as efficient barriers to suppress the outward diffusion of metal atoms.This novel ODS steel shows potential applications in supercritical water.     

Effect of aluminum oxide on the compressive strength of pellets

Analytical-reagent-grade Al₂O₃ was added to magnetite ore during the process of pelletizing, and the methods of mercury intrusion, scanning electron microscopy, and image processing were used to investigate the effect of Al₂O₃ on the compressive strength of the pellets. The results showed that, as the Al₂O₃ content increased, the compressive strength of the pellets increased slightly and then decreased gradually. When a small amount of Al₂O₃ was added to the pellets, the Al₂O₃ combined with fayalite (2FeO·SiO₂) and the aluminosilicate (2FeO·2Al₂O₃·5SiO₂) was generated, which releases some iron oxide and reduces the inhibition of fayalite to the solid phase of consolidation. When Al₂O₃ increased sequentially, high melting point of Al₂O₃ particles hinder the oxidation of Fe₃O₄ and the recrystallization of Fe2O3, making the internal porosity of the pellets increase, which leads to the decrease in compressive strength of the pellets.     

污泥焚烧过程中Cd迁移转化的热力学平衡分析

采用化学热力学平衡方法计算分析了污泥焚烧过程中Cd的迁移转化规律,探讨了S和C1对其转化的影响以及吸附剂的化学吸附效果。研究结果表明,Cd在800 K以下以固体存在,1100 K以上全部以气体形式存在。C1元素对Cd挥发影响不大3元素则会延迟Cd的挥发。Al_2O_3和SiO_2都会与Cd形成固态化合物其都具有一定的化学吸附作用。