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1.
《Materials Letters》2007,61(8-9):1722-1724
We report on the synthesis of nano-porous silicon oxide (SiO2) layers by gas phase polymerisation reactions of hexamethy disiloxane and oxygen. The SiO2 layers are deposited onto one or more layers of poly(methylmethacrylate) (PMMA) particles spin coated onto the substrate surface. Subsequent annealing of the films to high temperature (500 °C) leads to the pyrolysis of the polymeric particles resulting in a 3D nanoporosity in the film. X-ray Photoelectron (XPS) and Fourier Transform Infra Red Spectroscopy (FTIR) show an SiO2-like surface chemistry and virtually complete removal of the organic components. These materials offer a very high surface area-to-volume ratio suitable for sensing applications. 相似文献
2.
液相化学还原法制备不同形貌的多晶纳米镍 总被引:1,自引:0,他引:1
采用液相化学还原法,在1,2-丙二醇体系中,分别使用吐温-80(Tween-80)、聚乙二醇-6000(PEG-6000)和十二烷基硫酸钠(SDS)与聚乙二醇-6000(PEG-6000)的混合物作为修饰剂,利用1,2-丙二醇还原相同母体醋酸镍,制备形貌分别为海绵体、纤维状、雪花状的多晶纳米镍;在水体系中,使用SDS为修饰剂,利用水合肼还原相同母体醋酸镍,制备球形多晶纳米镍。通过X射线衍射(XRD)、透射电子显微镜(TEM)、选区电子衍射(SAED)对纳米镍进行表征。利用傅立叶红外(FTIR)分析初步解释不同形貌纳米镍的形成机理。 相似文献
3.
《Journal of the European Ceramic Society》2006,26(7):1287-1292
A commercially available Ag–Cu braze alloy foil with Zn was used to join TiC cermet and steel. According to the experimental observations, the interface structure is (Cu, Ni)/Ag (s.s.) + Cu (s.s.)/(Cu, Ni)/(Cu, Ni) + (Fe, Ni) from TiC cermet to steel side. With increased brazing temperature or time, the amounts of (Cu, Ni) near the base metals/Ag–31Cu–23Zn interface and (Cu, Ni) + (Fe, Ni) near the Ag–31Cu–23Zn/steel interface increase, while the amount of Ag (s.s.) + Cu (s.s.) in the middle of the braze alloy decreases. The whole joining process consists of diffusion and solution among atoms of the braze alloy foil and base metals. The maximum shear strength is 120.7 MPa for the joint brazed at 850 °C for 10 min. 相似文献
4.
5.
《Polymer》1986,27(5):742-746
The behaviour of mixtures of iso- and syndiotactic poly(methyl methacrylate) (PMMA) as a function of time and polymer whole concentration in several solvents has been studied by light scattering and laser light scattering. The different solvents investigated in this study are acetonitrile, ethyl acetate, dimethylformamide (DMF), tetrahydrofuran (THF) and 1,4-dioxane. We have found that the last one behaves as a weakly complexing solvent, while the others show a complexing power decreasing from acetonitrile to THF.An increase in polymer whole concentration induces a higher aggregation of the macromolecular coil, while the compaction process of stereocomplex particles is not strongly influenced. The influence of time in stereocomplex behaviour depends on the nature of the solvent employed. In strongly complexing solvents there is initially a strong increase in the aggregation process and a decrease in compaction. However, in weakly complexing solvents these kinetic processes are less important. 相似文献
6.
7.
《Dyes and Pigments》1986,7(3):215-230
The effect of pH on the diazo coupling reaction of some commonly used coupling components (J-acid, Gamma acid, H-acid and S-acid) with monosubstituted diazobenzenes has been investigated. The results demonstrate that, contrary to previous reports, selective diazo coupling ortho to an amino group of an aminohydroxynaphthalenesulfonic acid does not occur in weakly acidic (pH 5–6) media. In fact, such media were found to give nearly exclusive diazo coupling ortho or para to the hydroxyl group. The desired amine coupling reactions required a pH of 3.0–3.5 and occurred only with the more reactive diazonium salts. The structures of the dyes obtained were unambiguously determined with the aid of 1H-NMR spectroscopy. 相似文献
8.
《Solar Energy Materials》1986,13(3):197-202
The thermal oxidative stability of ethylene glycol was investigated over the temperature range of 100–126°C. Aqueous ethylene glycol were heated in sealed tubes in the presence of metallic copper and without metal. Mass spectrometric analysis was used to determine the rates of O2 consumption and CO2 evolution during heating. Copper had a catalytic effect of the glycol degradation. It was found that the rate limiting step in the thermal oxidative process was not related to oxygen consumption, suggesting that the rate limiting step involved the formation of a free radical which subsequently reacts with O2. The evolution of CO2 continued to occur after total consumption of the O2. This suggested that the CO2 is evolved from one of the thermal oxidation products of ethylene glycol. 相似文献
9.
Ti、Ni对ZA27合金组织及力学性能的影响 总被引:1,自引:0,他引:1
采用CMT5205微机控制电子万能拉伸机、扫描电镜、金相显微镜等仪器对ZA27合金的力学性能及微观组织进行测试和分析,研究添加Ni、Ti对ZA27合金的微观组织及力学性能的影响。结果表明:0.4%Ni的加入可以有效细化ZA27合金组织,并在合金非平衡共晶组织中形成富含镍的颗粒,同时使共晶组织变得粗大;添加0.4%Ni和0.3%Ti可进一步细化合金枝晶组织及网状共晶组织,晶界中富镍相和ε相颗粒变小,分布均匀。在150℃时,单独添加0.4%Ni的合金抗拉强度比ZA27合金提高33%,但塑性较差。同时添加0.4%Ni和0.3%Ti的合金抗拉强度比ZA27合金提高50.7%,伸长率比单独添加0.4%Ni时提高38%。 相似文献
10.
The sliding friction and wear behavior of polytetrafluoroethylene (PTFE) composites filled with poly (phenyl p-hydroxybenzoate) (PHBA) and hexagonal boron nitride (h-BN) was investigated with a pin-on-disc tester. The tensile properties, ball indentation hardness, impact strength and thermal diffusivity were measured. The test results in this paper indicate that the tensile strength, elongation at break, and impact strength decreased, however, the ball indentation hardness and thermal diffusivity were increased when the content of h-BN was increased. PTFE composites filled with 20 wt% PHBA and 20 wt% h-BN exhibited a comparative friction coefficient to pure PTFE. Meantime, the wear rate of the composite decreased about 15 times compared to pure PTFE. The synergistic effect of h-BN with low friction and PHBA with high bearing ability promoted the low friction coefficient and wear rate of h-BN/PHBA/PTFE composites. 相似文献