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排序方式: 共有157条查询结果,搜索用时 31 毫秒
31.
多孔阳极氧化铝的微观结构与气压的关系 总被引:1,自引:1,他引:0
为验证氧气析出对PAA孔道产生和发展的作用,深入探讨PAA的形成机理,本文分别研究了在真空下和常压下,铝在磷酸溶液中的阳极氧化过程,用SEM表征了不同气压下PAA孔道的微观结构.在低气压下制备PAA膜,因为氧气析出速度快,所以同样条件下得到的PAA的孔道比常压下的孔径大、孔壁薄.结果表明,"酸性溶解腐蚀孔洞"只发生在氧化膜的表层,而表层下方是规则的"氧气析出孔道";PAA孔道的生成和发展是内部氧气析出孔道和酸性溶解腐蚀孔洞贯通的过程,但起决定作用的是"氧气气泡模具效应". 相似文献
32.
Guodong Tang Yuan Cao Jinfang Zhang Yu Zhang Yinglin Song Fengli Bei Lude Lu Chi Zhang 《Synthetic Metals》2008
A series of new candidates as nonlinear optical materials, tetra-nuclear heterobimetallic clusters [MOS3M3′Y(PPh3)3] (M = Mo, M′ = Ag, Y = Br 1; M = W, M′ = Ag, Y = I 2; M = Mo, M′ = Cu, Y = I 3; M = W, M′ = Cu, Y = I 4), have been synthesized by newly developed ligand-redistribution reaction for third-order nonlinear optical (NLO) studies. Single-crystal X-ray diffraction shows that clusters [MoX(μ3-S)3(μ3-Br)(AgPPh3)3] 1 and [WX(μ3-S)3(μ3-I)(CuPPh3)3] 4 (X = O0.5S0.51, O 4) adopt an isomorphous neutral cubane-like skeleton. Their optical nonlinearities were measured by Z-scan technique with an 8 ns pulsed laser at 532 nm. These clusters were found to exhibit effective nonlinear absorption, self-focusing effects and large optical limiting capabilities. The effective NLO susceptibilities χ(3) and the corresponding second-order hyperpolarizabilities γ of these clusters are also reported. The influence of cluster composition on NLO properties has been discussed accordingly. 相似文献
33.
Qiaofeng Han Shuang Feng Yan Sun Xin Wang Xuejie Yang Lude Lu 《Materials Letters》2009,63(18-19):1611-1613
Bi2S3 hierarchical columniform structures assembled by nanorod-built lamellae have been first synthesized by a simple wet chemical method through the reaction between Bi(NO3)3?5H2O and CS2 at 80 °C for 14 h using DMSO as solvent without any surfactants. These new Bi2S3 structures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Compared to ethylene glycol and DMF, DMSO supplied an excellent chemical environment favorable to the generation of Bi2S3 quickly in heterogeneous condition. The influences of the synthetic parameters were discussed and a possible growth mechanism for the formation of these complex structures was proposed. 相似文献
34.
Peanut-shaped Sb2S3 superstructures have been synthesized via a hydrothermal process at 120 °C for 8 h using hydrochloric acid and antimony O-benzyl dithiocarbonate (benzylxanthate, Sb(S2COC7H7)3) as starting materials. The powder X-ray diffraction (XRD) pattern shows the product corresponds to the pure orthorhombic phase of Sb2S3, the purity and composition of which are further confirmed by X-ray photoelectron spectroscopy (XPS). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) studies reveal that the peanut-shaped Sb2S3 superstructures are aggregated by nanorods. The possible mechanistic pathways in the formation of the structures are discussed. 相似文献
35.
蓄冰系统设备管道保冷厚度的确定 总被引:1,自引:0,他引:1
对蓄冰系统的设备及管道的防结露保冷厚度、经济保冷厚度及冷损失进行了算法研究,并对蓄冰系统常用保冷材料作了计算和分析,给出了蓄冰系统的小保冷厚度。 相似文献
36.
合成皂石为前驱物制备高稳定性含镍介孔分子筛 总被引:4,自引:2,他引:2
以无机盐为原料通过控制pH值,用水热法合成含Ni皂石,并以此皂石为前驱物、十六烷基三甲基溴化铵为模板剂,制备含Ni介孔分子筛.用X射线粉末衍射、Fourier变换红外光谱、程序升温还原、透射电子显微镜、比表面积和孔径测定等仪器和方法表征样品的物化性能.结果表明:制得了有序性好的含Ni介孔分子筛,其比表面积为811.2m2/g,平均孔径为3.64nm.所制备的含Ni介孔分子筛经850℃焙烧3h或100℃水热处理10d后仍然具有介孔结构,说明样品具有高的(水)热稳定性. 相似文献
37.
38.
Yao Xiao Nasir Mahmood Abbasi Yan‐Fang Zhu Shi Li Shuang‐Jie Tan Wei Ling Ling Peng Tingqiang Yang Lude Wang Xiao‐Dong Guo Ya‐Xia Yin Han Zhang Yu‐Guo Guo 《Advanced functional materials》2020,30(30)
Considering the ever‐growing climatic degeneration, sustainable and renewable energy sources are needed to be effectively integrated into the grid through large‐scale electrochemical energy storage and conversion (EESC) technologies. With regard to their competent benefit in cost and sustainable supply of resource, room‐temperature sodium‐ion batteries (SIBs) have shown great promise in EESC, triumphing over other battery systems on the market. As one of the most fascinating cathode materials due to the simple synthesis process, large specific capacity, and high ionic conductivity, Na‐based layered transition metal oxide cathodes commonly suffer from the sluggish kinetics, multiphase evolution, poor air stability, and insufficient comprehensive performance, restricting their commercialization application. Here, this review summarizes the recent advances in layered oxide cathode materials for SIBs through different optimal structure modulation technologies, with an emphasis placed on strategies to boost Na+ kinetics and reduce the irreversible phase transition as well as enhance the store stability. Meanwhile, a thorough and in‐depth systematical investigation of the structure–function–property relationship is also discussed, and the challenges as well as opportunities for practical application electrode materials are sketched. The insights brought forward in this review can be considered as a guide for SIBs in next‐generation EESC. 相似文献
39.
新型酚醛树脂固化过程的表征研究 总被引:9,自引:0,他引:9
主要利用DSC、TG及IR技术研究了新型S157酚醛树脂体系的固化反应及其动力学、树脂体系中改性剂含量对固化反应的影响及固化过程中树脂体系结构变化规律,为确定新型S157酚醛树脂体系的固化工艺提供依据。新型S157酚醛树脂体系的固化反应表观活化能约为82kJ/mol,固化反应级数为0.91;有机硅改性剂的加入及其含量对树脂基体固化反应表现活化能、固化反应级数和热分解温度基本无影响,但失重率有所降低;在树脂基体等温固化过程中,活性羟甲基指数逐渐降低,树脂在高温固化过程中由于受到氧化而产生羰基吸收。 相似文献
40.
High‐impact polystyrene (HIPS)/nano‐TiO2 nanocomposites were prepared by surface pretreatment of nano‐TiO2 with special structure dispersing agent (TAS) and master batch manufacturing technology. The results show that when the nano‐TiO2 content is 2%, the notched impact strength, tensile strength, and elastic modulus of HIPS/nano‐TiO2 nanocomposites increased to a maximum. This result indicates that nano‐TiO2 has both toughening and reinforcing effects on HIPS. The heat‐deflection temperature and flame‐retardance of HIPS/nano‐TiO2 nanocomposites are also obviously improved as the nano‐TiO2 content is increased. The nanocomposites manufactured by the two‐step method have better mechanical properties than that made by a one‐step method. HIPS/nano‐TiO2 nanocomposites are also non‐Newtonian and pseudoplastic fluids. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 381–385, 2003 相似文献