Highly efficient two-stage ring-opening of epichlorohydrin with carboxylic acid in a microreaction system

Ring-opening of epoxides with carboxylic acids has been widely used to prepare many high value intermediates in the polymer and pharmaceutical industries. Most of conventional processes proceeded in batch stirred reactors. As such they always suffer from low productivity and selectivity. Here we developed an advanced technology to perform the ring-opening reaction of epichlorohydrin with neodecanoic acid (NDA) for continuous production of 3-chloro-2-hydroxypropyl neodecanoate in a more efficient and safer way. A microreaction system where a microreactor connected to a stirred reactor was established. When the conversion of NDA rapidly reaching around 90% in a microreactor at 110°C, the reaction solution was transferred to a stirred reactor at 90°C. This two-stage operating mode can reduce the reaction time and improve the selectivity through free switching of temperature in the consecutive two reactors, thus substantially reducing the consumption of energy and materials.     

基于Deform-3D的镍基高温合金残余应力仿真分析

GH4169镍基高温合金应用广泛,但是属于难以加工的材料,而且已加工表面的残余应力很容易导致工件变形,从而影响工件的加工质量。应用Deform 3D软件,研究了不同切削用量下残余应力的变化规律。研究结果表明,切削速度的变化对表面残余应力的影响甚小|背吃刀量和进给量增大,表面残余应力随之增大|随着切削用量的增加,工件内部残余应力亦随之增加。     

钛宝石激光器砂浦（Cr^4＋,Nd^3＋）：YAG晶体的自调Q激光器

用钛宝石激光器泵浦单块（Cr^4 ,Nd^3 ):YAG晶体获得了1．064μm的自调Q激光输出。激光输出的模式是稳定的单纵模,泵浦的阈值功率为63mW,脉冲宽度（FWHM）为8ns,斜率效率高达24％,随着泵浦功率的变化,脉冲宽度保持不变,而重复频率则在变化。这种把激光增益介质和可饱和吸收体结合到一起的自调Q激光晶体的研究将有利于固体激光器的全固化、集成化和实用化。     

Surface integrity in electro-discharge machining, ultrasonic machining, and diamond saw cutting of ceramic composites

Good surface integrity is frequently required for structural ceramic components, since the lifetime of a ceramic component is in most cases determined by its surface features. In this study, the surface integrity of electro-discharge machined, ultrasonic machined, and diamond saw cut ceramic composites has been investigated and compared. The surface roughness, hardness, and topography of the machined surface were examined. Flexural strength and its distributions were used to evaluate the effect of machining process on the surface integrity of the machined specimens. Results show that the machining process had an important effect on the surface quality of the machined ceramics. Electro-discharge machining of ceramics created a heat-affected surface layer with poor surface integrity, such as cracks and craters, and the variable surface damages on the electro-discharge machined specimens resulted in low Weibull modulus. Within most machining conditions, the ultrasonic machined and diamond saw cut specimens behaved fairly consistently, and the flexural strength and Weibull modulus were higher than that of the electro-discharge machined specimens.     

Cationic microparticle based flocculation and retention systems

Two types of microparticles, cationic silica particles (CSP) and cationic polymeric microparticles (CPMP), were used as flocculants and retention aids for solid suspensions in water and pulp, respectively. The solid suspensions used in this study include both positively and negatively charged precipitated calcium carbonate (PCC) and negatively charged polystyrene latex. It was found that CPMP was not an effective retention aid for positively charged PCC suspension in pulp if it was used alone. However, the retention of PCC was improved when negatively charged PCC was used. The combination of cationic microparticle systems (CPMP and CSP) with either cationically or anionically charged water-soluble polyacrylamides could significantly improve the flocculation and retention. The possible mechanisms of flocculation of solid suspensions with different dual-flocculant systems were discussed.     

Novel sol–gel‐derived Ag/SiO2–Al2O3 catalysts for highly selective oxidation of methanol to formaldehyde

Novel Ag/SiO₂–Al₂O₃ catalysts with low silver content prepared by the sol–gel method exhibit excellent catalytic properties in the catalytic oxidation of methanol to formaldehyde. The silver content was as low as 2% and the yield of formaldehyde was achieved as 90.3%, which is 16% higher than that of pumice‐supported silver and even 5–6% higher than that of a commercial electrolytic silver catalyst. XRD, XPS and SEM results reveal that all silver was present as Ag⁺ before catalytic reaction and was partially reduced to the metallic state after the reaction. It was also found that silver was aggregated on the surface after its reduction. This revised version was published online in July 2006 with corrections to the Cover Date.     

年产120吨聚丙烯酸钠絮凝剂的工艺设计与投产

介绍了新开发的生产工艺过程及工艺条件,对120吨/年的工厂设备选型、工厂经济分析及其应用效果作了简要评述。     

大型设备静配合面磨损超差粘接修复技术

1　问题的提出大型设备在重工业(如冶金、矿山、化工等 )企业的生产中具有举足轻重的作用。这些设备的特点是体积大 ,笨重 ,结构复杂。因此 ,在设计、制造过程中 ,为方便今后的加工维修 ,常对其易损部位采用不同材质、不同工艺、分部加工制作 ,再用螺栓连接配合成整体 ,形成一个静态配合面。由于设备在运行过程中长期处于震动、冲击以及工作介质的侵蚀等不利环境中 ,静配合面相互咬合磨损 ,造成配合面磨损超差。久而久之 ,间隙和位移不断加大 ,使螺栓产生松动、串轴 ,设备整体性下降。影响了设备的使用寿命和生产的顺利进行。这种现象在我们…     

紫外线吸收剂UV—9生产新工艺

完善了由三氯甲基苯与间苯二酚缩合成中间体２,４－二羟基二苯甲酮,进而用硫酸二甲酯将对位醚化成标的物２－羟基－４－甲氧基二苯甲酮（ＵＶ－９）的生产工艺。本工艺具生产操作简便、安全、三废排放少并且成本低廉等优点。