Static and Cyclic Fatigue of Alumina at High Temperatures: II, Failure Analysis

Failure mechanisms of an alumina, tested at 1200°C under static and various cyclic loading conditions, were examined. Slow crack growth of a single crack is the dominant mechanism for the failure in specimens under cyclic loading with a short duration of maximum stress at all applied stress levels, as well as at high applied loads for static loading and cyclic loading with a longer hold time at maximum stress. At low stress levels, failure of static loading and cyclic loading with a longer hold time at maximum stress might occur by formation and/or growth of multiple macrocracks. More importantly, for all the given loading conditions. The viscous glassy phase behind the crack tip could have a bridging effect on the crack surfaces. A simplified model for calculating effective stress intensity factor at the crack tip under static and various cyclic loading demonstrated a trend consistent with the stress–life data.     

Local orders,lattice distortions,and electronic structure dominated mechanical properties of (ZrHfTaM1M2)C (M = Nb,Ti, V)

High-entropy carbides (HECs) are regarded as potential candidate structural materials with attractive mechanical properties due to their ultra-high hardness. It is essential to reveal the atomic and electronic basis for strengthening mechanism in order to develop the advanced HECs. In the present work, C (M = Nb, Ti, V) are selected as case studies. The effects of transition metals (M) on the lattice parameters, bulk modulus, enthalpy of formation, electron work function (EWF), and bonding morphology/strength of HECs are comprehensively studied by first-principles calculations. It is found that the lattice parameters, equilibrium volumes, and bulk modulus of HECs are improved with the increase of M atomic volumes. The atomic-size differences among various groups of elements not only result in the lattice mismatch/distortion but also contribute to the formation of weak spots. In the view of bonding charge density, the electron redistributions caused by the coupling effect of the lattice distortion and valance electron differences can be revealed obviously, which identify the different bonding strength. Moreover, in terms of EWF, the proposed power-law-scaled hardness of HECs is validated and matches well with those reported theoretical and experimental results, providing a strategy to design advanced HECs with excellent mechanical properties.     

纳米香精在棉织物上的应用研究

本文探讨了纳米玫瑰香精在棉织物上的加香整理工艺,并对加香棉织物的香气缓释性能作了初步评价.结果表明纳米香精在棉织物上的加香整理后效果较为理想,加香织物经50次洗涤后仍有大量的香精残留,香气质量无明显变化.     

能源、物料在线监测系统的开发与应用

通过对自贡鸿鹤化工(集团)有限责任公司的能源、物料计量和现状的分析,详细阐述了利用计算机的在线监测技术对化工生产中的能源、物料的监控、计量、管理的实际应用情况和取得的经济效果。     

Application of membrane reactor for dehydrogenation of ethylbenzene

Two types of membrane reactors have been constructed in order to evaluate the influence of membrane reactor configuration on the performance of the dehydrogenation of ethylbenzene in a porous alumina membrane reactor. The type I construction combine reaction and separation in the same space. The type II configuration is comprised of three parts, i.e., reaction prior to separation, reaction and separation, and reaction after separation. The results showed that the overall yield of styrene in Type I is only 4% higher than that of the fixed bed reactor at 893 K, while 11 % enhancement in yield to styrene was obtained with Type II through optimizing the reaction conditions.     

用ATR-FTIR快速检验蔬菜表面残留抑虫琳

运用傅立叶变换衰减全反射红外光谱法(ATR-FTIR)技术对青菜表面残留的抑虫琳进行了分析。通过对蔬菜表面残留的不同浓度抑虫琳的红外光谱图的分析得出,运用ATR-FTIR技术所能检测到的抑虫琳的最低检出限为0.06 mg/cm2菜叶。并且分别采用了峰高和峰面积定量的方法进行了定量分析,两种方法的线性相关系数分别为0.9971和0.9694。实验结果表明,该分析方法能够快速检验出能引起急性中毒的药品量,并且测定过程简便,无需预处理。     

高效乙烯聚合催化剂的制备——I．催化剂的制备规律

研究了新型含镁络合物的结构、性质及其用于制备高效乙烯聚合催化剂的制备规律。结果表明：将镁、有机醇以及不与镁发生“格式反应”的卤代烷相互作用可迅速发生反应形成新型含镁络合物溶液。该络合物在溶液中可析出结晶。具有特定的化学结构．可以均匀承载于多孔硅胶的孔隙中，负载TiCl4后制备出形态良好的球形高效乙烯集合催化剂。     

溶胶-凝胶法制备负载型钨磷酸催化剂

为改善浸渍法制备的负载型钨磷酸催化剂HPWA/SiO2,在有水参与的反应中活性中心Keggin结构钨磷酸(HPWA)的流失,换用溶胶-凝胶法制备了一系列w(HPWA)=11.1%~40%的负载型钨磷酸催化剂HPWA-SiO2。通过红外光谱和紫外漫反射光谱联合表征,证明溶胶-凝胶法制备的HPWA-SiO2催化剂中,钨磷酸依然保持Keggin结构,没有转变为钨硅盐等而失去酸催化功能。在此基础上对溶胶-凝胶法制备的HPWA-SiO2和浸渍法制备的HPWA/SiO2进行了水相中钨磷酸流失率考察,结果表明,溶胶-凝胶法制备的HPWA-SiO2催化剂的流失率基本保持在0.71%~0.84%,而浸渍法制备的HPWA/SiO2催化剂的流失率为2.4%,是前者的3倍多,从而证明溶胶-凝胶法制备的负载型钨磷酸催化剂,能够更好地防止钨磷酸活性中心在水相反应中的流失。     

树脂相分光光度法测定人发中痕量铜

研究了铜与钛铁试剂在pH=9．00的碱性介质中反应生成有色络合物，与717#强碱性阴离子交换树脂交换吸附，在树脂相下进行光度分析的方法。铜树脂相络合物的最大吸收波长为375um；表观摩尔吸光系数ε为6．4×104L·mol(-1)·cm(-1)；符合Beer定律的范围为0～1．6mg·L(-1)。此法用于人发中痕量钢的测定，结果令人满意。     

转盘反应器固定米根霉的L－乳酸发酵

研究了米根霉的固定化方法，研制了用吸附法固定米根霉的生物转盘反应器，考察了在该反应器中培养基组成及其它操作条件对Ｌ－乳酸发酵的影响。实验结果表明，应用吸附法固定化的米根霉及生物转盘反应器进行Ｌ－乳酸发酵具有发酵速率快，Ｌ－乳酸得率高及既能用于连续发酵又能用于间歇发酵等优点