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1.
为提高K9光学玻璃在一些特殊应用领域(如高压、温度变化剧烈等)的力学性能,并保证其光学性能符合精密光学仪器要求,对K9光学玻璃进行了化学钢化技术研究。以脆性材料断裂过程微裂纹扩展理论为基础,导出化学钢化玻璃强度应力因子计算模型,分析化学钢化表面应力与表面微裂纹深度、韧性之间的关系,指出化学钢化工艺应注意的事项。通过实验研究,分析化学钢化温度和钢化时间对K9光学玻璃抗弯强度、表面应力及应力层厚度的影响,优化得出K9光学玻璃化学钢化温度为400 ℃、钢化时间为40 h。采用优化工艺,获得了表面应力为500 MPa、应力层厚度为50 μm量级及规格为220 mm×110 mm×22 mm的化学钢化K9光学玻璃样件。钢化后,样件抗弯强度提高了3.5倍以上,且表面疵病、光学鉴别率、透过率等光学性能指标未见明显变化。 相似文献
2.
富氧燃烧烟气喷淋脱水过程数值模拟 总被引:1,自引:0,他引:1
富氧燃烧系统中,脱硫后的高湿烟气需要经过脱水处理才能作为循环烟气利用,喷淋塔是一种常用的脱水设备。本文用CFD(Computational Fluid Dynamics)方法对喷淋塔的烟气脱水过程进行了三维建模模拟,得到了喷淋塔内的温湿度分布并用实验结果进行了验证。通过该模型分析了喷嘴的操作参数和运行特性对液滴平均运动时间和脱水效果的具体影响,讨论了数值模拟中出口烟气"过饱和"现象的成因,研究了不凝气组分对脱水过程的影响,为富氧燃烧脱水系统的设计提供了基础数据和理论方法。 相似文献
3.
近年来,二维层状材料由于其丰富的材料体系和独特的物理化学性质而受到人们的广泛关注.后摩尔时代要求器件高度集成化,大面积、高质量的二维材料可以保证器件中结构和电子性能的连续性.要实现二维材料工业级别的规模化生产,样品的可控制备是其前提.化学气相沉积是满足上述要求的一种强有力的方法,已广泛应用于二维材料及其复合结构的生长制备.但是要实现多种二维材料大尺寸以至晶圆级的批量制备仍然是很困难的,因此,需要进一步建立对各种二维材料生长控制的系统认识.本文基于材料生长机理分析了化学气相沉积反应中的物质运输、成核、产物生长过程对二维材料尺寸的影响,以及如何通过调控这些过程实现二维材料大面积薄膜的可控制备.通过对目前研究成果的总结分析,讨论了如何进一步实现二维材料的高质量大面积制备. 相似文献
4.
大气压非平衡等离子体由于其独特的非平衡特性,可为甲烷和二氧化碳稳定温室气体分子活化和重整提供非热平衡和活化环境.本文采用了零维等离子体化学反应动力学模型,考虑了详细的CH4/CO2等离子体化学反应集,重点研究了反应气体CH4/CO2摩尔分数(5%—95%)对大气压非平衡等离子体甲烷干法重整制合成气和重要含氧化合物的影响.首先,给出了进料气体不同体积比时电子密度和温度随时间的演化规律,结果表明初始甲烷摩尔分数的提高有利于获得较高的电子密度和电子温度.随后,讨论了主要自由基和离子数密度在不同的甲烷摩尔分数下随着时间的变化规律,并给出了反应气体的转化率、合成气体和重要含氧化合物的选择性.此外,还明确了合成气和含氧化合物主要生成和损耗的化学反应路径,发现甲基和羟基是合成含氧化合物的关键中间体.最后,归纳总结给出了主要等离子体粒子之间的总体等离子体化学反应流程图. 相似文献
5.
Barium hexaferrite (BaFe12O19) is a promising candidate for ceramics, microwave devices and numerous applications. Barium hexaferrite was synthesised via the sol-gel auto-combustion technique using glycine fuel. The X-ray diffraction technique confirmed the hexagonal structure of the particles with space group P63/mmc. The morphological analysis was performed using the field-emission scanning microscope, and the images displayed the plate-like particle formation. Transmission electron microscopy was employed to determine the average particle size of the sample, which was estimated to be 155.93 nm. The magnetic studies were taken through the vibrating sample magnetometer (VSM) at 300 K, with which the saturation magnetization (Ms), coercivity (Hc), squareness ratio (Mr/Ms), and energy product (BHmax) was calculated, and the particles were validated to be in single domain arrangement. The dielectric properties were investigated through the LCR meter. Koop and Maxwell-Wagner's model was used to interpret charge conduction and the occurrence of relaxations in the system. 相似文献
6.
《Mendeleev Communications》2022,32(4):467-470
Isomeric forms of indoline spiropyrans show unusual behavior compared with similar compounds, according to experimental data. DFT modeling for gas phase was made to consider the simplest case without environmental effects, which revealed the intramolecular reasons for occurrence of ring opening reaction depending on the particular structure of the compound. The questions of charge redistributions, the changes of geometry and chemical bonds in the structures are also discussed. 相似文献
7.
Candle soot (CS) is a desirable carbon nanomaterial for sensors owing to its highly porous nanostructure and large specific surface area. CS is advantageous in its low-cost and facile preparation compared to graphene and carbon nanotubes, but its pristine nanostructure is susceptible to collapse, hampering its application in electronic devices. This article reports conformal coating of nanoscale crosslinked hydrophilic polymer on CS film using initiated chemical vapor deposition, which well preserved the CS nanostructure and obtained nanoporous CS@polymer composites. Tuning coating thickness enabled composites with different morphologies and specific surface areas. Surprisingly, the humidity sensor made from composite with the lowest filling degree, thus largest specific surface area, showed relatively low sensitivity, which is likely due to its discontinuous structure, thus insufficient conductive channels. Composite sensor with optimum filling degree shows excellent sensing response of more than 103 with the linearity of R2 = 0.9400 within a broad relative humidity range from 11% to 96%. The composite sensor also exhibits outstanding sensing performance compared to literature with low hysteresis (3.00%), a satisfactory response time (28.69 s), and a fast recovery time (0.19 s). The composite sensor is fairly stable and durable even after 24 h soaking in water. Furthermore, embedding a humidity sensor into a face mask realizes real-time monitoring of human breath and cough, suggesting promising applications in respiratory monitoring. 相似文献
8.
Yaoli Wang Yan Liang Huixiang Sheng Jin Wang Junjie Wang Shunhao He Mengdan Guan Yaqi Chen Prof. Gang Lu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(2):e202103709
Surface plasmon can trigger or accelerate many photochemical reactions, especially useful in energy and environmental industries. Recently, molecular adsorption has proven effective in modulating plasmon-mediated photochemistry, however the realized chemical reactions are limited and the underlying mechanism is still unclear. Herein, by using in situ dark-field optical microscopy, the plasmon-mediated oxidative etching of silver nanoparticles (Ag NPs), a typical hot-hole-driven reaction, is monitored continuously and quantitatively. The presence of thiol or thiophenol molecules is found essential in the silver oxidation. In addition, the rate of silver oxidation is modulated by the choice of different thiol or thiophenol molecules. Compared with the molecules having electron donating groups, the ones having electron accepting groups accelerate the silver oxidation dramatically. The thiol/thiophenol modulation is attributed to the modulation of the charge separation between the Ag NPs and the adsorbed thiol or thiophenol molecules. This work demonstrates the great potential of molecular adsorption in modulating the plasmon-mediated photochemistry, which will pave a new way for developing highly efficient plasmonic photocatalysts. 相似文献
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