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81.
《Optical Materials》2014,36(12):2418-2424
Sol–gel dip-coating was used to grow ZnO thin films doped with various concentrations of B ranging from 0 to 2.5 at.% on quartz substrates. The effects of B doping on the absorption coefficient (α), optical band gap (Eg), Urbach energy (EU), refractive index (n), refractive index at infinite wavelength (n∞), extinction coefficient (k), single-oscillator energy (Eo), dispersion energy (Ed), average oscillator strength (So), average oscillator wavelength (λo), moments M−1 and M−3, dielectric constant (ε), optical conductivity (σ), and electrical resistivity (ρ) of the BZO thin films were investigated. The transmittance spectra of the ZnO and BZO thin films show that the transmittance of the BZO thin films was significantly higher than that of the ZnO thin films in the visible region of the spectrum and that the absorption edge of the BZO thin films was blue-shifted. The BZO thin films exhibited higher Eg, EU, and Eo and lower Ed, λo, M−1 and M−3 moments, So, n∞, and ρ than the ZnO thin films. 相似文献
82.
Based on much of the importance of RTV on the field of self-cleaning application for its nontoxic, tasteless, and thermal stability, the effects of D4-SiO2 on mechanical properties, Al(OH)3 and decabromodiphenyl oxide ethyl(DBDPE) on flame retardant property of RTV matrix were investigated firstly. Then, a new kind of complex fire retardants was compounded. The morphology of additives and fracture appearance of composites were demonstrated by SEM. The hot property of RTV-based composites was outlined by TG. It is found that D4-SiO2/Al(OH)3/DBDPE/Sb2O3/RTV composites were of better comprehensive performances in mechanical property, hot property, fire resistance property, and insulating property, which presented tear 26.73 kN/m of strength, 279.8% of elongation at break, 2.81 MPa of tensile strength, FV-0 at the level of flame retardant property, 46 of Oxygen index (OI) 3.03 × 1015 Ωm of Volume electric resistivity, the range of decomposition temperature was 370°C to 650°C, and the percentage of remain weight was 26.4%. Those properties was acquired on the condition of 11 wt % D4-SiO2 + 20 wt % Al(OH)3 + 15 wt % DBDPE+ Sb2O3 at the amount of 3.0 wt % to 3.7 wt %. This investigation leads the authors to a conclusion that D4-SiO2/Al(OH)3/DBDPE/Sb2O3 is a kind of better combination modifier than anyone kind of which in comprehensive properties for RTV. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
83.
Low‐Energy Electron Beam Induced Charging and Secondary Electron Emission Properties of FEP Film Used on Satellite Surfaces 下载免费PDF全文
Many kinds of insulating materials are used outside a spacecraft. They include FEP films, polyimide films, and so on, and are used as thermal control materials. These materials are exposed to a charged‐particle environment around the spacecraft. Thus then become charged due to charged particles, especially electrons. It has been pointed out that charging of these materials is likely to cause discharges on the surfaces. From this viewpoint, we investigated the charging potential characteristics of 127‐μm‐thick FEP film, a typical thermal control material, by exposing it to electron irradiation at various energies below 20 keV. In the dependence of the charging potential on the electron energy, we found that the electron energy at which no charge‐up occurs is about 2.7 keV. This appears to be the energy at the which secondary electron emission yield becomes unity. This indicates that electron irradiation of FEP film with energies lower than 2.7 keV induces positive charging. From the charge decay characteristics after electron irradiation, the volume resistivity of the film was also obtained as a function of the electric fields in the bulk of the FEP film. 相似文献
84.
Discontinuities are one of the most harmful damage to the durability of concrete structures. Currents approaches are limited to assessments of surface damages, even if non-destructive methods appear to be effective for the detection and the location of cracks. That is why, these methods might be unsuitable for investigation of massive concrete body as dams and locks. Present works aim at the presentation of new results with electrical resistivity to study damages within concrete structures. In this article, the electrical resistivity focused on the study of cracks and discontinuities (concrete joints, interfaces…) in massive concrete structures by measurements done in preexisting boreholes. The used array is the normal dc resistivity logging. The study presents numerical and experimental results. First, modeling allows correcting experimental data. Then, development shows the sensitivity relatively to the discontinuity characteristics (aperture and the resistivity contrast between the discontinuity and the concrete). The tests on a real structure are carried out to define the methodology for on-site measurement. Results support the modeling. 相似文献
85.
《国际聚合物材料杂志》2012,61(7):557-574
ABSTRACT The present work investigates the effect of various filling levels (FLs) of FeCl3 on the structure and physical properties of polystyrene (PS) films. X-ray diffraction scans revealed two main peaks, the amorphous and the polymerization peaks. The infrared transmission spectra depicted the main PS characterizing peaks. The direct current (dc) electrical conduction was attributed to the interpolaron charge carrier hopping. The temperature dependence of dc magnetic susceptibility exhibited Curie–Weiss behavior. The positive values of the paramagnetic Curie temperature (θp) indicate the predominance of a ferromagnetic exchange interaction between the magnetic centers at low temperatures, whereas the negative value of θp at 9% FL suggests the existence of an antiferromagnetic exchange interaction. The electron spin resonance (ESR) investigations imply the presence of isolated and aggregated Fe+3 ions at intermediate and higher FLs, respectively, in the polymeric matrix. 相似文献
86.
《Ceramics International》2022,48(16):22672-22680
Cu–Ni/Al2O3 nanocomposite powders were manufactured using an in situ chemical reaction technique. This technique provides improved wettability and adhesion between the matrix and reinforcement phases. Aluminum nitrate, copper nitrate and nickel nitrate were used as start materials for the production of the composites. The powders were sintered in a hydrogen environment at 900 °C for 2 h after being cold pressed at 700 MPa. To determine the effect of Al2O3 on electrical and thermal conductivities and thermal expansion behaviors, the Cu–Ni matrix was supplemented with 3, 5, and 8 wt% Al2O3. The findings revealed that Al2O3 nanoparticles (20 nm) were dispersed uniformly throughout the copper-nickel matrix. Microhardness was improved from 53.3 HV for Cu–Ni matrix to 92.7 HV for Cu–Ni/8%Al2O3 nanocomposites. The electrical and thermal conductivities and thermal expansion coefficient were reduced as the amount of Al2O3 in the Cu–Ni matrix increased. The electrical conductivity was reduced by 38.7% by addition 5% Al2O3 nanoparticles to Cu–Ni matrix. The high interfacial bonding between Cu–Ni and Al2O3 nanoparticles was the main reason of the hardness improvement and maintaining relatively good electrical and thermal properties. 相似文献
87.
采用原子转移自由基(ATRP)活性聚合方法在多壁碳纳米管(MWNT)表面接枝丙烯酸丁酯聚合物(PBA),并以此对聚丙烯(PP)进行改性。红外光谱(FT-IR)及透射电子显微镜(TEM)测试结果表明,采用ATRP法成功地将PBA接枝到多壁碳纳米管(MWNT)表面。对PP/MWNT复合材料电性能研究表明,MWNT-PBA的添加比MWNT-COOH更能降低复合材料的电阻率。MWNT-PBA的加入可使PP从绝缘材料转变为抗静电材料。MWNT-PBA和MWNT-COOH加入PP都能提高材料的电性能,而MWNT-PBA比MWNT-COOH的作用更加明显。 相似文献
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90.
目前高密度电阻率法所采用的数据资料处理方法主要是把地质结构体视为二度体进行二维处理,而实际的地质结构体大都为三度体或似二度体,从而二维数据资料处理结果只是一种近似解释,其计算精度与反演效果都不佳,对测区多条断面进行综合解释的难度大。然而在实际勘探工作中,受自然条件和工作成本的影响,三维勘探原始数据的获得一般较少,数据勘探仍以二维为主,这样利用二维勘探数据进行三维反演显得尤为重要。本文结合了广东某地高密度电阻率法对岩层划分的工程勘察实例,利用二维勘探的数据进行三维反演,并对二、三维反演结果进行对比,结果表明三维反演在岩层划分中更能凸显岩层分界面区域及岩层的空间分布,而岩层与覆盖层的整体连续性也得以更真实的体现,与钻探结果吻合更好。 相似文献