Mesoscale pore structure of a high-performance concrete by coupling focused ion beam/scanning electron microscopy and small angle X-ray scattering

This contribution couples (a) Small angle X-ray scattering (SAXS) experiments of a high-performance concrete (HPC) at the millimetric scale, and (b) Focused ion beam/scanning electron microscopy (FIB/SEM) of the cement paste of the HPC, with 10-20 nm voxel size. The aim is to improve the understanding of the 3D pore network of the HPC at the mesoscale (tens of nm), which is relevant for fluid transport. The mature HPC is an industrial concrete, based on pure Portland CEMI cement, and planned for use as structural elements for deep underground nuclear waste storage. Small angle X-ray scattering patterns are computed from the 3D pore images given by FIB/SEM (volumes of 61-118 μm³). They are positively correlated with SAXS measurements (volumes of 5 mm³). Aside from correlations with FIB/SEM data, experimental SAXS allows to investigate a wider range of effects on the pore structure. These are mainly the HPC drying state, the presence of aggregates (by analyzing data on cement paste alone), and the use of Poly Methyl MethAcrylate resin impregnation.     

Variation of lexan polycarbonate properties by electron beam

The modifications in microstructural, optical, and photoluminescence properties of the Lexan polycarbonate (bisphenol‐A‐polycarbonate) films exposed to different electron doses have been studied using UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), positron annihilation lifetime spectroscopy, photoluminescence spectroscopy, and scanning electron microscopy (SEM). The obtained UV–vis spectroscopy results showed decrease in optical energy gap, optical activation energy, and increase in number of carbon atoms per cluster with increase in electron dose. The chemical changes in electron irradiated polymers due to chain scission and reconstruction have been observed from FTIR spectroscopy. The correlation of positron lifetime study with optical measurement is obtained, and electron irradiation‐induced microstructural modifications within the polymer is understood. SEM result shows the degradation of Lexan polymer after electron irradiation. The mechanical properties and average molecular weight of Lexan decrease after irradiation, whereas average number of chain scissions per original polymer molecule increases. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Controlling surface functional composition and improving the gas-sensing properties of metal oxide sensors by electron beam processing

It has been established that the electron beam processing of the ZnO–SiO₂ and SnO2–SiO₂ thinfilm gas sensors synthesized using the sol-gel method at an electron energy of 900 keV and an absorbed dose of 50 to 200 kGy leads to a significant increase in their sensitivity towards acetone and isopropanol vapors. It is found that the observed effect, which is enhanced with an increase in the absorbed dose, is correlated to an increase in the concentration of the Brønsted acid sites which are formed under the influence of accelerated electrons and capable of reacting to the molecules of the detected substances.     

Characterization of graphite implanted with chlorine ions using combined Raman microspectrometry and transmission electron microscopy on thin sections prepared by focused ion beam

Graphite was modified by 250 keV ³⁷Cl⁺ ion implantation. Combined Raman microspectrometry/transmission electron microscopy (TEM) studies have been used to characterize the multiscale organization of the graphite structure. The penetration depth of ³⁷Cl⁺ into the graphite sample was limited to the surface (∼200 nm) because of the dissipation of the irradiating ion energy as expected by secondary ion mass spectrometry analysis. Raman microspectrometry appears to be an appropriate tool for studying such scales. Spectra showed a strong increase of defect bands after implantation at a fluence of 5 · 10¹³ ions/cm². In order to examine the structural degradation of the graphite versus the depth at the nanometer scale, the focused ion beam technique seems to be a well-suited method for a relevant coupling of Raman and TEM observations.     

Sintering of zirconia ceramics by intense high-energy electron beam

A comparative analysis of the efficiency of zirconia ceramics sintering by thermal method and high-energy electron beam sintering was performed for compacts prepared from commercial TZ-3Y-E grade powder. The electron energy was 1.4 MeV. The samples were sintered in the temperature range of 1200–1400 °C. Sintering of zirconia ceramics by high-energy accelerated electron beam is shown to reduce the firing temperature by about 200 °C compared to that in conventional heating technique. Ceramics sintered by accelerated electron beam at 1200 °C is of high density, microhardness and smaller grain size compared to that produced by thermal firing at 1400 °C. Electron beam sintering at higher temperature causes deterioration of ceramics properties due to radiation-induced acceleration of high-temperature recrystallization at higher temperatures.     

响应面法优化电子束辐照降解土霉素制药废水中COD的研究

为探究电子束辐照技术对土霉素制药废水中COD的去除效果,在单因素试验的基础上,采用Box-Behnken试验设计原理的响应面法,考察了COD初始浓度、pH值和辐照吸收剂量3个因素的影响,并建立了多元线性回归预测模型.结果 表明:在COD初始质量浓度为320 mg/L,pH值为6.8,辐照吸收剂量为261 kGy的条件下...     

Detonation of PETN single crystals initiated by an electron beam

Luminescence in the volume of PETN (tetranitropentaerytrite) single crystals exposed to an electron beam (duration 20 nsec) with an energy density of 15 J/cm², which exceeds the threshold of explosive decomposition, was investigated in real time. Exposure to the ionizing pulse causes radioluminescence and emission related to the critical electron emission from a dielectric which is transformed to a vacuum discharge. The emission zone propagates from the surface into the vacuum at a speed of 5000–6500 m/sec. The absorption of electron beam energy in the irradiated layer (0.25 mm) causes the formation and propagation of a shock wave enhanced by the chemical reaction in the crystal. When the shock wave is reflected from the target on the rear side of the sample, its amplitude increases. This leads to detonation accompanied by emission which propagates from the backside to the irradiated surface of the sample at a speed of 7500–8500 m/sec with the subsequent expansion of the explosive decomposition products into the vacuum.     

Modification of PVC/ENR blends by electron beam irradiation

The effects of electron irradiation, with doses ranging from 20 to 100 kGy on the physical properties of poly(vinyl chloride)/epoxidised natural rubber blends (PVC/ENR50 blends) were investigated. The enhancement in tensile strength, elongation at break, hardness, and aging properties of the blends have confirmed the positive effect of irradiation on the blends. Crosslinking of the ENR50 phase proved to play a major role in the improvement of mechanical properties of blends. The results also revealed that at any blend composition the enhancement in properties depends on the irradiation dose which controls the degree of radiation-induced crosslinking. The single glass transition temperature obtained confirms that the blends remain miscible upon irradiation.     

Crosslinking of cis-1,4-polyisoprene rubber by electron beam irradiation

Various unsaturated polyfunctional monomers were kneaded into cis-1,4-polyisoprene containing fillers under 80°C and then irradiated using an electron beam accelerator to prepare vulcanized rubber with good quality. Results showed that 2G (diethyleneglycol dimethacrylate) is the best sensitizer. The optimal tensile strength of vulcanized IR was obtained by using 14 phr 2G and irradiated to 180 kGy. Compared with the sulfur vulcanizate, greater values of tensile strength, elongation at break, and 100% stress were found with the radiation-cured IR. Their Young's modulus and tan σ were similar. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 113–116, 1997     

高温下电子束辐射交联丁腈橡胶

研究了不同温度下电子束辐照对含和不含多官能团单体的NBR的影响。利用FTIR、动态机械热分析及溶胶-凝胶分析方法分析了经不同剂量辐照后橡胶结构发生的变化。通过Charlesby-Pin-ner公式确定了NBR的断链和交联比。测试了力学性能,发现拉伸强度随多官能单体在高温下的辐照接枝而增大。     

Catalytic graphitization of an amorphous carbon film under focused electron beam irradiation due to the presence of sputtered nickel metal particles

Electron beam irradiation of Ni particles (diameter: ∼500 nm) in a transmission electron microscope (TEM) formed small secondary particles, which moved randomly on an amorphous carbon film. Catalytic graphitization occurred along the path traced by the moving particles. It is generally well known that heat treatment is needed to produce catalytic graphitization of an amorphous carbon. However, we rapidly produced catalytic graphitization in the presence of sputtered Ni particles by focused electron beam irradiation in the TEM although no external heating was employed.     

A new possibility for microstructural investigation of clay-based polymer nanocomposite by focused ion beam tomography

This article describes the focused ion beam (FIB)-tomography as a high-resolution three-dimensional (3D) technique to study the morphology of polymer/clay nanocomposites. To establish the structure-property relationship of such composite material, it is very important to visualize the 3D-structure and distribution of clay particles in the polymer matrix. The sequential two-dimensional sectioning by FIB, followed by imaging of dispersed silicate layers using high-resolution scanning electron microscope, and computer reconstruction can show the degree of dispersion of silicate layers in 3D-space.     

Nature of glowing generated by irradiation of pentaerythrite tetranitrate by an electron beam

Results of studying the nature of glowing generated by pentaerythrite tetranitrate (PETN) excitation by an electron beam with a mean electron energy of ≈250 keV and a current-pulse duration of 15 nsec are presented. The pulse-averaged power density of the beam is varied within 10⁶ ≤ P ≤ 10¹⁰ W/cm². For 10⁶ ≤ P ≤ 10⁸ W/cm², the main type of glowing is demonstrated to be pulsed cathodoluminescence of PETN. In the pre-detonation mode (P ≈ 10⁹ W/cm²), more inertial glowing is formed on the rear front of the luminescence peak, which is identified as the glowing of products of explosive transformation of PETN formed in the region of electron-beam travel. For P ≥ 5 · 10⁹ W/cm², an additional glowing pulse is formed, which is associated with formation and spreading of a dense plasma emerging owing to detonation of the entire mass of the sample. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 87–89, September–October, 2007.     

Properties of barium hexaferrite thick films deposited by electron beam evaporation

This paper presents results obtained on barium ferrite thick films prepared by electron beam evaporation. First of all, we have looked at the influence of substrate temperature on the films properties. Then, we have fixed the substrate temperature to 700 °C and the effects of films thickness on the different properties has been investigated. Indeed for a substrate temperature of 700 °C we have observed that the layers are crystallized in the BaM phase with in-plane preferential orientation. However, a secondary non magnetic phase (BaFe₂O₄), which can modify the magnetic properties, appears on some layers.     

A preparation of polyethylene coatings by pulse laser-assisted electron beam deposition

Polyethylene (PE) coatings were prepared by a method of pulse laser-assisted electron beam deposition, using low-density polyethylene as evaporated target, silicon wafer and polytetrafluoroethylene (PTFE) sublayer as substrates. The as-deposited PE coatings were characterized by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and atomic force microscope. Significant crystallinity increase and root mean square (RMS) roughness decrease of PE coatings were observed in the presence of PTFE sublayer. Laser-assisted deposition increased the crystallinity and mean particle diameter of PE coatings and remarkably, the obtained PE coatings had a relative uniform particle size. These results suggested that pulse laser and PTFE sublayer might contribute to the synthesis of polymer coatings with suitable crystallinity and uniform surface structure.     

Degradation in tensile properties of aromatic polymers by electron beam irradiation

Electron beam irradiation effects of ten kinds of polymers containing various aromatic rings linked by functional groups in the main chain (aromatic polymer) were studied with reference to change in tensile properties. The polymers studied were polyimides ‘Kapton H’, and ‘UPILEX’, polyetherimide ‘ULTEM’, polyamides ‘A-Film’, and ‘APH-50 (nomex type paper)’, poly-ether-ether-ketone ‘PEEK’, polyarylate ‘U-Polymer’, polysulphones ‘Udel-Polysulphone’, and ‘PES’, and modified poly(phenylene oxide) ‘NORYL’. Irradiation was carried out by use of electron beam at a dose rate of 5 × 10³ Gy s^?1 at room temperature. The elongation at break was the most severely influenced by the irradiation and it decreased with increasing dose. The order of radiation resistivity which was evaluated from the dose required for the elongation to become 50% and 20% of the initial value was as follows:Polyimide>PEEK>polyamide>polyetherimide>polyarylate>polysulphone, poly(phenylene oxide)Based on the above experimental results, the following order was proposed as for the radiation stability of the aromatic repeating units composing the main chain:

     

The use of the focused ion beam technique to prepare cross-sectional transmission electron microscopy specimen of polymer solar cells deposited on glass

The use of the focused ion beam (FIB) technique for cross-sectional transmission electron microscopy (TEM) specimen preparation of polymer solar cells deposited on glass substrates is described. Ultra-thin sections were prepared using the ‘lift-out’ technique. Electron microscopy investigations of these specimen resulted in detailed morphological information of the devices (e.g. thickness and interface roughness of the layers). In comparison with standard sample preparation routes for TEM investigations the used technique is well suited for precise sectioning of hybrid structures.     

Structure and morphology of isotactic polypropylene functionalized by electron beam irradiation

The structure and morphology of isotactic polypropylene (iPP), functionalized by electron beam irradiation at room temperature in air, are investigated by elementary analysis, FT‐infrared (FTIR) spectroscopy, electron spectroscopy for chemical analysis (ESCA), polariscope, and static contact angle. Elementary analysis reveals that the element oxygen has been introduced onto iPP chains after electron beam irradiation. In addition, as shown from FTIR spectra, oxygen‐containing groups, such as carbonyl, carboxyl, and ether groups, are introduced onto iPP molecular chains. The dependence of oxygenation extent (as measured by O_1S/C_1S value of ESCA spectra) on electron beam dose is obtained. Under polariscope, it can be observed that the dominant alpha phase appears to become more enhanced, and there is no crystalline phase transition. The static contact angle of iPP decreases with increasing dose. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 75–82, 2000     

Preparation and characterization of modified polypropylene by using electron beam irradiation

The modification by electron beam irradiation was applied to polypropylene (PP). In this process it is tried to add low density polyethylene (LDPE) and talc in the blend to check effects on its rheological property and thermal stability. The decrease in T_m could be the result of chain scissioning which decrease the number of tie molecule in the amorphous regions and consequently weakens the laminar connections. LDPE incorporated sample was comparatively better in shear thinning effect, zero shear viscosity, and thermal stability. Power law index, n, was 0.30 and 0.89 for the modified PP with LDPE and pure PP, respectively.