Rapid synthesis of DyFeO<Subscript>3</Subscript> nanopowders by auto-combustion of carboxylate-based gels

EDTA and citric acid as two typical chelating reagents with multi-carboxyl groups were used to prepare DyFeO₃ nanopowders, respectively. The experimental results show that all of the carboxylate-based gels exhibited auto-propagating combustion behaviors. The XRD results indicate that DyFeO₃ single phase can be formed directly with CA/MN (citric acid to metal nitrate mole ratio) = 1 when the calcination temperature was above 700 °C. The specimen with EA/MN (EDTA to metal nitrate mole ratio) = 1 had the minimum crystallite size of 33 nm. The SEM images show that the as-burnt powders prepared with EDTA had more excellent dispersibility feature and clearer grain boundaries than that of citric acid. The magnetic measurement results show that DyFeO₃ nanopowders displayed antiferromagnetism characteristics at low temperatures due to the strong exchange interaction between Fe sublattice. As the ambient temperature increased, there was a transition from antiferromagnetism to paramagnetism in DyFeO₃ nanopowders.     

点燃温度对ZnO超细粉体微观形貌和光催化性能的影响

以蔗糖为燃料、硝酸锌为氧化剂/锌源,采用溶液燃烧法合成ZnO超细粉体。采用XRD、SEM、比表面分析仪和分光光度计等检测设备,研究了点燃温度对合成ZnO粉体的物相组成、微观形貌、比表面积和光催化等性能影响,探讨了合成ZnO粉体对甲基橙光催化的作用机理。结果表明:在点燃温度400～700℃,均可合成棒状的ZnO超细粉体、平均径向尺寸小于150 nm;合成ZnO粉体均具有较高光催化性能,并且在点燃温度为500℃时,合成的ZnO粉体具有最大的比表面积(24.83 m2/g)和最佳的光催化性能,在高压汞灯照射60 min条件下,对甲基橙溶液(10 mg/L)的降解率可达98.2%,且反应符合一级动力学规律。     

溶胶-凝胶法8钇稳定氧化锆纤维的制备与表征(英文)

本文以水为溶剂,采用溶胶-凝胶法制备出8钇稳定氧化锆纤维。以氧氯化锆、醋酸锆和硝酸钇为前躯体,聚乙烯醇为粘结剂在含水量30wt%、70℃合成粘度为3～4 Pa.s的可纺性8钇稳定氧化锆溶胶,然后通过离心纺丝法制备出直径为5～10μm的凝胶纤维。最终在1200℃煅烧制备出8钇稳定氧化锆晶体纤维,并通过差热(DTA)、热重(TG)、X射线衍射(XRD)和扫描电镜(SEM)对纤维进行分析和表征。     

Novel layered perovskite GdBaCuFeO5+x as a potential cathode for proton-conducting solid oxide fuel cells

A layered perovskite GdBaCuFeO_5+x (GBCuF) was developed as a cathode material for intermediate-temperature solid oxide fuel cells based on a proton-conducting electrolyte of stable BaZr_0.1Ce_0.7Y_0.2O_3?δ (BZCY). The X-ray diffraction results showed that GBCuF was chemically compatible with BZCY after co-fired at 1,000 °C for 10 h. The thermal expansion coefficient of GBCuF, which showed a reasonably reduced value (15.1?×?10^?6 K^?1), was much closer to that of BZCY than the cobalt-containing conductor. The button cells of Ni–BZCY/BZCY/GBCuF were fabricated and tested from 500 to 700 °C with humidified H₂ (～3 % H₂O) as a fuel and ambient oxygen as the oxidant. A high open-circuit potential of 1.04 V, maximum power density of 414 mW cm^?2, and a low electrode polarization resistance of 0.21 Ω cm² were achieved at 700 °C, with calculated activation energy (E _a) of 128 kJ mol^?1 for the GBCuF cathode. The experimental results indicated that the layered perovskite GBCuF is a good candidate for cathode material.     

考虑不完全检测的冲击模型最优维修策略

针对制造系统中设备检测不完全的情形,研究基于不完全检测的冲击模型的周期检测、维修联合策略．通过定期检测获知系统的劣化状态以进行必要的预防性维修．在假设系统是退化的且有k个不同故障状态的条件下,以最小化系统运行成本为目标,以检测周期T、系统更换前故障次数Ⅳ为联合决策变量,利用更新过程理论建立了系统平均费用率C（T,N）的数学模型,并且给出最优联合策略的数值算法．最后借助数值例子演示了该模型,分析了检测水平对系统运行成本的影响．     

电沉积过程中Cl-对Cu2O晶粒形貌的影响

在酸性溶液中,以透明导电玻璃(ITO)为工作电极,Pt网为对电极,电化学沉积制备了Cu2O颗粒膜。利用了X射线衍射(XRD)研究了Cu2O的结构,扫描电子显微镜(SEM)研究了添加剂对晶粒形貌的影响,并对晶体的生长机制进行了讨论。结果表明,由于Cl-在Cu2O不同晶面的选择吸附作用,随Cl-浓度的增加,Cu2O的形貌由树枝状结构逐渐向立方结构过渡。     

景德镇五代瓷器组成配方的EDXRF分析

景德镇早期制瓷工艺一直是学术界所关注的焦点问题之一。采用能量色散X射线荧光法分析了景德镇五代时期湘湖窑出土白瓷和青瓷样品的胎釉元素组成,并据此探讨其原料和配方。研究表明,五代时期景德镇湘湖窑白瓷胎体所用原料为瓷石,而青瓷瓷胎应是采用瓷石配以紫金土的二元配方;白瓷和青瓷瓷釉皆使用釉果加釉灰的配方,且青瓷瓷釉配方中釉灰的用量高于白瓷瓷釉。     

q移动差分方程亚纯解的一些性质（英文）

主要讨论了q移动差分方程零级亚纯解的一些性质,所得结果推广及改进了先前陈宗煊和郑秀敏,Korhonen等人的结果.     

冷动力喷涂法制备钨和钨合金涂层 及其涂层的计算模拟

采用冷动力喷涂法以纯钨和钨-镍-铁合金为原料在铜合金基体上制备了钨涂层和钨-镍-铁涂层. 研究了冷喷涂过程中钨粉粒径、喷涂距离等因素对涂层性能的影响. 用扫描电子显微镜分析了涂层的表面、断面微观结构, 并用原子力显微镜测量了涂层的粗糙度. 此外, 计算了冷喷涂过程中粉末颗粒的实际速度, 并采用有限元分析软件ANSYS/LS-DYNA模拟了冷喷涂过程中颗粒撞击基体时的变形情况.     

尖晶石型纳米CoAl2O4色料水热合成工艺研究

分别以钴、铝的氯化物、硝酸盐和硫酸盐为起始原料,NaOH为沉淀剂,用水热法合成了纳米尖晶石型钴蓝色料。分别研究了填充度、pH值、nCo/nAl、起始原料种类以及浓度等对合成色料物相组成、颗粒大小与形貌和呈色的影响。用XRD、TEM和色度分析对样品进行了表征。结果表明:以浓度分别为0.15 mol/L和0.3 mol/L的CoCl2.6H2O和AlCl3为起始原料,在填充度为70%、pH值为13、nCo/nAl为1/2的条件下,245℃水热培育20 h制得呈色良好的尖晶石型钴蓝色料,颗粒为八面体型,晶型完整,粒径多为100 nm以下。相同条件下,以钴、铝的硫酸盐为起始原料,产物中除CoAl2O4外,还有Co-Al LDHs、γ-AlO(OH)和β-Al(OH)3;以钴、铝的硝酸盐为起始原料,样品呈绿色,颗粒为八面体型CoAl2O4,粒径多为100 nm以上。