Oxidative dehydrogenation of ethane over Co–BaCO3 catalysts using CO2 as oxidant: effects of Co promoter

Co–BaCO₃ catalysts exhibited high catalytic performance for oxidative dehydrogenation of ethane (ODE) using CO₂ as oxidant. The maximal formation rate of C₂H₄ was 0.264 mmol · min⁻¹ · (g · cat.)⁻¹ (48.0% C₂H₆ conversion, 92.2% C₂H₄ selectivity, 44.3% C₂H₄ yield) on 7 wt% Co–BaCO₃ catalyst at 650 °C and 6000 ml. (g · cat.)⁻¹. h⁻¹. Co–BaCO₃ catalysts were comparatively characterized by XRF, N₂ isotherm adsorption-desorption, XRD, H₂-TPR and LRs. It was found that Co⁴⁺–O species were active sites on these catalysts in ODE with CO₂. The redox cycle of Co–O species played an important role on the catalytic performance of Co–BaCO₃ catalysts. On the other hand, the co-operation of BaCO₃ and BaCoO₃ was considered to be one of possible reasons for the high catalytic activity of these catalysts.     

涂层转移法精密铸造技术在子午线轮胎模具制造中的应用

子午线轮胎模具计算机辅助快速制造系统是由ＣＡＤ技术、快速成型技术、涂层转移法精密铸造技术、材料技术等多项高新技术组合而成的一项独特的先进制造技术。该系统充分利用液态材料成型任意性和高再现性的特点，具有适应性强、重复性好、加工周期短、制造成本低的特点。     

压挤成形--固化法制备0-3型压电复合材料的性能研究

详细地叙述了室温压挤成形———固化工艺制备 0 -3型压电复合材料工艺 ,使用XRD、SEM和HP42 94测试并分析了样品的结构和性能 ,并与压电陶瓷性能参数进行了对比 ;同时用这种工艺制备可以获得介电损耗小、机电耦合系数为 2 5 .11%、压电应变常数为 3 2PC N和机电品质因数可达到 3 0 2的 0— 3型压电复合材料。     

Synthesis, isolation, spectroscopic and electrochemical characterization of some calcium-containing metallofullerenes

A few Ca-containing mono-metallofullerenes, i.e. Ca@C₇₆, Ca@C₈₈, Ca@C₉₀ (I, II), were synthesized by an improved DC arc discharge method and isolated by a multi-stage HPLC method for the first time. These isomer-separated metallofullerenes were characterized by LD-TOF MS and UV-vis-NIR spectrometry. Their HOMO-LUMO band gaps and possible molecular geometries are discussed according to the absorption spectra in this report. In addition, the cyclic and differential pulse voltammetry of Ca@C₇₆ was conducted in MeCN/C₆H₅CH₃ (1:4 v/v). The voltammograms of Ca@C₈₂ (II, III) and Ca@C₈₄ (II) were also recorded. Their electrochemical behaviors are discussed compared with those of corresponding ytterbium metallofullerenes. The features of the Ca metallofullerenes’ electronic structures are also discussed.     

加成型液体乙烯基硅橡胶的研制Ⅱ.白炭黑表面处理对硅橡胶性能的影响

以六甲基二硅氮烷为主要表面处理剂，考察了表面处理剂、处理助剂、水的用量等对白炭黑增强效果的影响。结果表明，处理100份白炭黑时，用25份六甲基二硅氮烷，5份二甲基二乙氧基硅烷，5份水，所得白炭黑对加成型液体硅橡胶增强效果较好。     

Na_2O－ZnO－CaO－Al_2O_3－SiO_2烧结微晶玻璃的试制

Ｎａ＿２Ｏ－ＺｎＯ－ＣａＯ－Ａｌ＿２Ｏ＿３－ＳｉＯ＿２烧结微晶玻璃的试制刘世权，许淑惠，袁怡松，杨晓晶（西北轻工业学院７１２０８１）ＳｉｎｔｅｒｅｄＮａ＿２Ｏ－ＺｎＯ－ＣａＯ－Ａｌ＿２Ｏ＿３－ＳｉＯ＿２ＧｌａｓｓＣｅｒａｍｉｃｓ￥ＬｉｕＳｈｉｑｕａｎ...     

用聚丙烯酸酯乳液提高轮胎帘线储存稳定性

研究了一种自交联型五元共聚聚丙烯酸酯乳液的单体种类和配比、加料顺序、表面活性剂的种类和用量、引发剂用量等合成工艺因素与乳液稳定性及其增粘和防紫外线、臭氧老化的关系。用这种乳液改性的ＲＦＬ浸渍液处理锦纶６６轮胎帘线，可以显著改善帘线的储存稳定性。     

One-Step Synthesis of Luminescent Nanoparticles of Complex Oxide, Strontium Aluminate

An organic aqueous solution of metal acetylacetonate precursors was subjected to spray pyrolysis in order to fabricate SrAl₂O₄:Eu (SAO) nanoparticles. Non-agglomerated luminescent SAO nanoparticles, having a spherical shape with a size of 10–30 nm, were achieved in a single step, while only submicrometer-sized SAO particles were obtained from the conventional ultrasonic pyrolysis of the metal nitrates. Without any post-annealing process, the as-prepared SAO nanoparticles were observed to exhibit a strong photoluminescence, which is comparable with that of the submicrometer-sized SAO particles. A mechanism for the formation of the nanoparticles is also discussed.     

Effect of Microstructure on Material-Removal Mechanisms and Damage Tolerance in Abrasive Machining of Silicon Carbide

Effects of microstructural heterogeneity on material-removal mechanisms and damage-formation processes in the abrasive machining of silicon carbide are investigated. It is shown that the process of material removal in a conventional silicon carbide material with equiaxed-grain micro-structure and strong grain boundaries consists of the formation and propagation of transgranular cracks which results in macroscopic chipping. However, in a silicon carbide material, containing 20 vol% yttrium aluminum garnet (YAG) second phase, with elongated-grain micro-structure and weak grain boundaries, intergranular micro-cracks are formed at the interphase boundaries, leading to dislodgment of individual grains. These different mechanisms of material-removal affect the nature of machining-induced damage. While in the conventional silicon carbide material the machining damage consists of transgranular median/radial cracks, in the heterogeneous silicon carbide material, abrasive machining produces interfacial micro-cracks distributed within a thin surface layer. These two distinct types of machining damage result in a different strength response in the two forms of silicon carbide materials. In the case of the conventional silicon carbide, grinding damage results in a dramatic decrease in strength relative to the as-polished specimens. In contrast, the ground heterogeneous silicon carbide specimens show no strength loss at all.     

KC型第三代推动篦冷机的开发设计及其特点

前言 从我国水泥生产技术的发展来看，由于第二代以及不带热端固定床的第三代推动篦式冷却机均存在高温端部容易漏料、篦饭寿命短、篦板结构形式的缺陷使得其冷却效率差、易出现“红河”、二三次风温低、冷却风量偏大、动力消耗大、热回收效率低等一系列不尽人意之处。我院存对同外有关技术的消化吸收和实验研究的基础上，通过不断开发、优化，