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排序方式: 共有156条查询结果,搜索用时 31 毫秒
41.
Titanium/chromium interfaces produced by titanium thin film deposition on chromium substrates have been reactively mixed using ion-beams of 2 and 3 keV at room temperature (RT). The ion-beam mixing (IBM) has been analysed using X-ray photoelectron spectroscopy (XPS), angle-resolved X-ray photoelectron spectroscopy (ARXPS) and Monte Carlo TRIDYN simulations. Below ∼2 × 1016 ions/cm2, the IBM kinetic is characterised by a strong decrease of the Ti concentration along with a fast nitrogen incorporation, that can be explained mainly by Ti sputtering and nitrogen implantation. Above that ion dose, the Ti/Cr ratio can be varied in a broad range maintaining nearly constant the nitrogen concentration (∼50%), as a consequence of sputtering, nitruration and mixing effects taking place simultaneously. ARXPS results show that the composition of the ternary films formed by reactive IBM is rather uniform in the near surface region. The comparison of experimental results with those obtained from TRIDYN, that uses pure ballistic mechanisms, suggests that the chemical reaction with the nitrogen partial pressure and processes driven by residual defects are the rate-controlling mechanisms during the reactive IBM of Ti/Cr interfaces. 相似文献
42.
S. Sapieha C. A. Ferguson R. P. Beatson M. R. Wertheimer 《Plasma Chemistry and Plasma Processing》1989,9(2):225-234
The deposition of organosilicone plasma polymers on the surface of paper has been examined by scanning and transmission electron microscopy. Plasma polymer was deposited on fibers and fibrils near the surface of the sheet, the coating thickness being highest in those regions which were directly exposed to the plasma. As the coating thickness was increased, pores in the paper surface closed. 相似文献
43.
H. Cao R. Zhang H. M. Chen P. Mallon C. -M. Huang Y. He T. C. Sandreczki Y. C. Jean B. Nielsen T. Friessnegg R. Suzuki T. Ohdaira 《Radiation Physics and Chemistry》2000,58(5-6):645-648
Photodegradation of a polyurethane-based topcoat induced by accelerated UV irradiation is studied using Doppler broadened energy spectra (DBES) and positron annihilation lifetime (PAL) spectroscopies coupled with slow positron technique. Significant and similar variations of S-parameter and ortho-positronium intensity (I3) in coatings are observed as functions of depth and of exposure time. The decrease of S is interpreted as a result of an increase of crosslink density and a reduction of free-volume and hole fraction during the degradation process. 相似文献
44.
Elastic properties of a thermal barrier ceramic coating composed of an NiCoCrAIY bond coat and a ZrO2(Y2O3) top coat were measured by a four-point bending rig in the temperature range 20°C–900°C. Different types of specimens (i.e., with bond coat only or with bond coat and top coat, on one side or on both sides) were employed. Test procedures were based on the theory discussed in Part 1 to enhance accuracy and to estimate confidence intervals. In particular, the method employed at high temperature was calibrated at room temperature by comparing the results with those obtained by methods with low sensitivity to layer thicknesses. For the bond coat, Young's modulus was found to be temperature independent up to about 500°C; a decreasing trend was observed above this temperature. For the top coat, a slightly temperature range examined. A possible explanation is given on the basis of phase transformation and the microstructure of the two layers. At room temperature, Poisson's ratio for the bond coat was found to be near 0.3, whereas a near zero value was measured for the top coat. 相似文献
45.
Johann Cho Silke Schaab Judith A. Roether Aldo R. Boccaccini 《Journal of nanoparticle research》2008,10(1):99-105
Electrophoretic deposition (EPD) has been used to combine multi-walled carbon nanotubes of diameter in the range 20–30 nm
and commercially available TiO2 nanoparticles (23 nm particle size) in composite films. Laminate coatings with up to four layers were produced by sequential
EPD, while composite coatings were obtained by electrophoretic co-deposition of carbon nanotubes and TiO2 nanoparticles, respectively. Scanning electron microscopy was used to characterize the resultant microstructures. The mechanism
of EPD of carbon nanotube/TiO2 nanoparticle composites is discussed. 相似文献
46.
The synthesis of allyl ether functionalized siloxane monomers under ultrasonic irradiation at ambient conditions 总被引:1,自引:0,他引:1
The novel class of cationic UV-curable allyl ether functionalized siloxane monomers type CH2=CH---CH2---O---R---O---Si(CH3)3 and type CH2=CH---CH2---O---R---O---Si(CH3)2---O---R---CH2---CH=CH2 have been synthesized in excellent yields in short times at ambient temperature conditions in the absence of any added catalyst by the classical silylation reactions of homoallyloxyalcohols with chlorosilanes under ultrasonic irradiation. 相似文献
47.
Amel?Ben Slimane Mohamed?M.?ChehimiEmail author Marie-Josèphe?Vaulay 《Colloid and polymer science》2004,282(4):314-323
Polypyrrole (PPy)-coated poly(vinyl chloride) (PVC) powder particles were prepared by the in situ chemical polymerisation of pyrrole in aqueous solutions in the presence of PVC powder particles. The PVC particles in suspension served as a hydrophobic substrate for the in situ polymerisation of pyrrole using iron chloride as the oxidising agent and sodium p-toluene sulfonate. In these conditions, tosylate-doped PPy (PPyTS) was obtained and chlorides were inserted as minor codoping species. In some cases, the pyrrole was polymerised after incubating the PVC particles with poly(N-vinyl pyrrolidone). Scanning electron microscope (SEM) micrographs showed that the PVC particles retained their initial, quasispherical shape after coating by PPy. At low magnification, the coated PVC particles appeared smooth, but at high magnification, they exhibited a decoration by elementary nanoparticles of about 200-nm size due to PPy bulk powder grains. Elemental analysis indicated a mass loading of PPy in the range 1–58% w/w. Specific surface analysis by X-ray photoelectron spectroscopy (XPS) resulted in the spectra of the PPy-coated PVC particles resembling those of bulk powder PPyTS even for low PPy mass loading. The surface fraction of PPy repeat units was found to vary in the 55–91% range. This result is consistent with the SEM observation of the PPy nanoparticles at the surface of PVC powder grains. However, despite the important loading of PPy, the XPS estimation of the overlayer thickness is in favour of a patchy coating rather than continuous coatings of PPy. 相似文献
48.
49.
This paper reviews the progress of two-dimensional mesoporous materials including their synthesis strategy,mesostructure,composition,surface property,flexibility,and potential applications.During the past two decades,research on two-dimensional mesoporous materials has experienced an evolution from fragile coatings to flexible membranes.Aiming at practical applications,it is significant to support mesoporous materials with proper matrices for example porous membranes especially flexible ones to form mesoporous composite membranes with designed pore size and chemistry. 相似文献
50.
Novel heat-resistance UV curable waterborne polyurethane coatings modified by melamine 总被引:2,自引:0,他引:2
Z.H. Fang H.Y. Duan Z.H. ZhangJ. Wang D.Q. Li Y.X. Huang J.J. Shang Z.Y. Liu 《Applied Surface Science》2011,257(11):4765-4768
Novel UV curable waterborne polyurethane coatings (UVWPU) modified by melamine was prepared using isophorone diisocyanate (IPDI), polyethylene glycol (PEG), α,α-dimethylol propionic acid (DMPA), hydroxyethyl acrylate (HEA) as main materials. Copolymer structure was verified using Fourier transform infrared spectroscopy (FT-IR). Performance of the coatings was evaluated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), and mechanical tests such as pencil hardness and resistance to water. The results showed that the modified UVWPU film had the good thermal resistance, water resistance and mechanical properties. The optimum melamine dosage was 4.70 wt.%, the glass transition temperature (Tg) of the modified film increased by 20.4 °C and 5% weight-loss temperature (253 °C) increased by 105 °C. No change color, crinkle, desquamate, dehisce and frothy were found after the modified film dried at 130 °C for 2 h. 相似文献