共查询到20条相似文献,搜索用时 31 毫秒
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A. AlZahrani Y. Alhamed L. Petrov S. Armyanov E. Valova J. Georgieva J. Dille 《Journal of Solid State Electrochemistry》2014,18(7):1951-1961
Two types of electroless Ni–W–P coatings: nanocrystalline with low P and amorphous with higher P content are investigated. Scanning probe microscopy is applied to study their morphology. Textured nanocrystalline coatings consist of coarse pyramids built of nanometer thick lamellas. The surface morphology of amorphous coatings is much finer and uniform. Nanohardness of all coatings depends on W content. Microhardness is increasing during the heat treatment up to 350 °C due to nickel phosphide precipitation affected by tungsten also. The wear resistance of nanocrystalline Ni–W–P coatings is much higher than that of amorphous in spite of the similar tungsten content in both. Lower corrosion resistance of amorphous Ni–W–P coatings is found by weight loss method during long-term immersion in 5 % NaCl. Electrochemical tests by potentiodynamic polarization curves in two model corrosion media—solutions of 0.5 M H2SO4 and 5 % NaCl—are performed. The corrosion of bi-layered Ni–W–P/Ni–P and Ni–W–P/Ni–Cu–P deposits on mild steel is also investigated. The results prove that an electroless Ni–W–P coating on mild steel extremely improves its mechanical and corrosion behavior. It is demonstrated that in addition to deposit’s structure and composition, the distribution and chemical state of alloy ingredients are also responsible for its properties. 相似文献
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Jacqueline M. Morais Orlando D. H. Santos Júnia R. L. Nunes Cinthia F. Zanatta Pedro A. Rocha‐Filho 《Journal of Dispersion Science and Technology》2013,34(1):63-69
The effects of some composition variables on the development of multiple emulsions by one‐step method were evaluated and their morphology characterized. The formulations that remained stable during the period of the test were submitted to centrifugation and thermal stress tests. The stability and the morphology of multiple droplets were affected not only by the type and concentration of the surfactants employed, but also by the water/oil ratios used. The results suggest that the formation of multiple droplets could involve a combination of transitional and catastrophic phase inversions. The results provide improved knowledge about the one‐step emulsification method, a simplified process to prepare multiple emulsions when compared to the two‐steps method. 相似文献
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Yuanjie Xu Wanxia Huang Qiwu Shi Yang Zhang Linwei Song Yaxin Zhang 《Journal of Sol-Gel Science and Technology》2012,64(2):493-499
Porous nano-structured vanadium dioxide (VO2) films doped with Mo and W ions had been synthesized by sol gel process by employing a sol containing ammonium molybdate and ammonium tungstate with the addition of cetyltrimethyl ammonium bromide (CTAB). The effects of molybdenum and tungsten co-doping and CTAB addition on the structure, morphologies, crystalline and optical properties of VO2 films were investigated systematically in this study. The composition and microstructure were detected by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The Mo and W ions co-doped porous nano-structured VO2 films showed excellent infrared transmittance (nearly 70 %), large transmittance difference (55 %) before and after the phase transition, low transition temperature (35 °C), wide hysteresis width (22 °C) and fast phase transition. The results suggest that such Mo and W ions co-doped porous nano-structured VO2 film is an ideal fundamental material for optical data storage. 相似文献
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《Journal of molecular catalysis. A, Chemical》1999,137(1-3):287-295
The photochemical reaction of W(CO)6 with triphenylphosphine (PPh3) in the presence of γ-Al2O3 and Pd/γ-Al2O3 has been used to prepare W/γ-Al2O3 and Pd–W/γ-Al2O3 catalysts. Adsorbed mono- and disubstituted W species have been identified by FTIR spectroscopy. There is evidence of the adsorption of W(CO)6−x Lx species on both the alumina and the Pd surface. After thermal decomposition and reduction at 573 K the catalysts have been characterized by FTIR spectroscopy of adsorbed NH3, CO and NO. The retention of W and P suppresses the Lewis acidity of the alumina support. On Pd–W/γ-Al2O3, the W is present in a partially reduced state in close association with Pd. This interaction modifies the chemisorptive properties of NO relative to those of the monometallic Pd and W catalysts. In line with these observations the Pd–W/γ-Al2O3 catalyst presents an enhanced activity for NO decomposition at 473 K. 相似文献
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LIU Hui-zhang YUE Bin LI Ming-xing CHEN Zhi-jiang JIN Song-lin XIE Gao-yang 《高等学校化学研究》1996,12(4):393-396
Preparationand~(183)WNMRInvestigationofIridium-containingDawsonDerivativeLIUHui-zhang;YUEBin;LIMing-xing;CHENZhi-jiang;JINSon?.. 相似文献
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Julius Pavlov Washington Braida Adebayo Ogundipe Gregory O’Connor Athula B. Attygalle 《Journal of the American Society for Mass Spectrometry》2009,20(10):1782-1789
The presence of a peak centered near m/z 2862, observed for the first time for the caged dodecatungstate radical-anion, [W12O41]−·, enables distinguishing WO2 from WO3 by Laser Desorption Ionization mass spectrometry (LDI-MS). In addition to WO2, laser irradiation of dry deposits made from aqueous ammonium paratungstate, and calcium and lead orthotungstate also produce
the [W12O41]−·. In contrast, spectra recorded from deposits made from aqueous Na2WO4, sodium metatungstate, and WO3, or non-aqueous calcium and lead orthotungstate, and ammonium paratungstate, failed to show the m/z 2862 peak cluster. These observations support the hypothesis that polycondensation reactions to form [W12O41]−· occur solely in the presence of water. Although dry spots are irradiated for ionization, the solvent used for sample preparation
plays an important role on the chemical composition endowed to ions detected. For example, the m/z 2862 peak seen from deposits made from aqueous ammonium paratungstate, and calcium and lead orthotungstate, is absent in
the spectra recorded either from pristine deposits or those derived from solutions made with organic solvents such as acetonitrile
or ethanol. 相似文献
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J. A. Harker P. Chapuis L. Holborn A. Day H. L. Callendar H. Kamerlingh Onnes Fr. Grützmacher und D. Berthelot 《Fresenius' Journal of Analytical Chemistry》1900,39(7):451-454
Ohne Zusammenfassung 相似文献
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Virginie Comte Olivier Blacque Claude Moïse Marek M. Kubicki 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):721-724
Ring substituted (R=tBu, SiMe3) metallocene dichlorides undergo a nucleophilic substitution on one of the two rings upon the action of LiPPh2M'(CO)x salts with the formation of chloro-hydrido complexes [C5H3(R)PPh2M'(CO)x](C5H4R)M(H)Cl. Their UV irradiation leads to the chloro-bridged M(μ-Cl)M' separable diastereoisomers. Use of the ansa-metal-locene dichlorides [Me2X(C5H4)2MCl2] (X=Si or C) allowed the access to the new bridging system [M(μ-PPh2, μ-Cl)M′] (M=Mo, W ; M'=W). 相似文献
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W/O/W乳液的渗透溶胀与夹带溶胀 总被引:6,自引:0,他引:6
研究了W/O/W乳液的溶胀,实验结果表明,渗透溶胀随内外相溶液间的渗透压差、表面活性剂及载体浓度的增大而增加,但随膜粘度的增加而降低,渗透压差较高时,水渗透的影响大于夹带的影响;膜相中含氧化合物对溶胀的影响大于含氮化合物,采用Span 80作乳化剂时,比采用E 644渗透溶胀约高6倍,夹带溶胀也较高;重复聚结再分散使夹带溶胀急剧增加,因而多级混合澄清槽对液膜操作似不适用。 相似文献
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Analytical and Bioanalytical Chemistry - 相似文献
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Young Rang Uhm Jaewoo Kim Kwang Jae Son Chul Sung Kim 《Research on Chemical Intermediates》2014,40(5):2145-2153
W dispersed mixed polymers of ethylene propylene monomer and high density polyethylene were prepared by means of a twin-screw extruder by the conventional technique using a co-rotated two-roll mill. The W nanoparticles used as filler were prepared by pulse wire evaporation then coated with low-density polyethylene (LDPE) as polymeric surfactant. Surface treatment of the nanoparticles with LDPE was conducted to enhance the wettability and lubrication of the fillers in the polymer matrix. According to SEM images and mechanical properties, dispersion of W/LDPE nanoparticles in the polymer matrix was homogeneous, and adhesion of the nanoparticles to the matrix was strong. The polymer nanocomposites had better mechanical properties than those containing dispersed micro-W powder. The γ-ray attenuation factor of nanofiller-reinforced composites was substantially enhanced compared with that containing micro filler. 相似文献
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Using Fourier transform infrared(FT-IR) spectroscopy technique, the carbonyl stretching vibration bands of AOT in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/water reverse (W/O) microemulsions system have been investigated by least square curve fitting. The results indicate that an asymmetric adsorbed peak of carbonyl stretching vibration of AOT molecule is situated in (1739 ± 1) and (1725 ± 2) cm-1. The two peaks correspond to different carbonyls in gauche conformation and trans conformation of AOT molecules, respectively. With different water contents (W0), the variations of peak intensity ratio (/= l1739/l1725) reflect the change of the ratio for the two conformation populations and the variations of the effective head-group area of AOT molecule have relations to the ratio of two conformation populations. 相似文献