Aerogels are a low-density,porous,non-crystalline,nanometer solid material,whose continuous network structures can be controlled and tialored by varying the amount of reactants,catalyst and *** fragility and brittlene...
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Aerogels are a low-density,porous,non-crystalline,nanometer solid material,whose continuous network structures can be controlled and tialored by varying the amount of reactants,catalyst and *** fragility and brittleness,however,are the major drawbacks,which restrict their application in effective ***,the flexibility of aerogels becomes more attractive in the present *** is the most abundant resource in the world and microfibrillated cellulose can be made from all kinds of plants[1].But cellulose is an insoluble material,which is a main problem in the composite course using cellulose as an adulterant[2].Our work focuses on the preparation of new organic/inorganic hybrid silica-cellulose aerogels by the sol-gel process and supercritical *** sols were prepared by dissolving Methyltrimethoxysilane（MTMS）in acid aqueous solution by using dimethyl sulfoxide（DMSO）as solvent to suppress phase *** nanowhiskers were extracted by the acid hydrolysis of cotton wool in a 64 wt.%aqueous HSO solution and then dispersed into silica sols under the help of *** silica-cellulose aerogels of different cellulose contents were obtained by two-step acid-base sol-gel method and supercritical *** electron microscopy（SEM）,Fourier transform infrared（FT-IR）spectra and X-ray diffraction（XRD）analysis were used to investigate the microstructure and the connection of chemical *** porous structure and specific surface was measured by nitrogen *** action of cellulose in hybrid aerogels was discussed.
The ultrafine WC-Co composite powder was synthesized by a newly developed rapid route based on in situ reactions. By using the as-synthesized composite powder, the granulation processing was then carried out to prepar...
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The ultrafine WC-Co composite powder was synthesized by a newly developed rapid route based on in situ reactions. By using the as-synthesized composite powder, the granulation processing was then carried out to prepare the ultrafine-structured thermal spraying feedstock. The influences of the heat-treatment process on density of the feedstock powder, phase constitution and wear resistance of the resultant WC-Co coatings fabricated by high velocity oxy-fuel （HVOF） were investigated. The results showed that increasing the heating temperature and extending the holding time leaded to remarkable increase in the density and flowability of the feedstock powder. As a result, the decarburization of the in-flight particles could be decreased and the wear resistance of coating was significantly enhanced. The present study demonstrated that the developed techniques for the ultrafine powder and its thermal-sprayed coatings had very promising applications in scaling up to produce ultrafine-structured cermet coatings with excellent performance.
Fine zirconium diboride （ZrB2） powders with high purity were successfully prepared by combustion synthesis through magnesiothermic reduction process in Mg-B2O3-ZrO2 system. The reaction mechanism was investigated by...
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Fine zirconium diboride （ZrB2） powders with high purity were successfully prepared by combustion synthesis through magnesiothermic reduction process in Mg-B2O3-ZrO2 system. The reaction mechanism was investigated by differential thermal analysis and quenching experiment. The results show that the whole magnesio-thermic reduction process includes three stages： first, molten B2O3 and Mg formed above the temperature of 650 ℃, and glassy B2O3 and solid ZrO2 particles were coated on the surface of the molten Mg; thus, the hollow balls can be formed when the molten Mg was exuded under capillary function. Second, ZrO2 particles reacted with molten Mg to form Zr and MgO with dissolution-precip-itation mechanism, which released a large amount of heat to induce the diffusion reaction between B203 and Mg to form B and MgO. Last, Zr reacted with B to form ZrB2 grains. The preparation of ZrB2 by self-propagating syn-thesis in Mg-B2O3-ZrO2 system is a solid-liquid-liquid reaction.
Submicron-sized Ag-polypyrrole/poly（styrene-co-methacrylic acid） （Ag-PPy/P（St-co-MAA）） composite particles were fabricated via a redox reaction between pyrrole and AgNO3 in the presence of P（St-co-MAA） soap-fr...
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Submicron-sized Ag-polypyrrole/poly（styrene-co-methacrylic acid） （Ag-PPy/P（St-co-MAA）） composite particles were fabricated via a redox reaction between pyrrole and AgNO3 in the presence of P（St-co-MAA） soap-free latex. The products are characterized by transmission electron microscopy （TEM）, electron diffraction spectra （EDS）, Raman spectra, thermogravimetric analysis （TGA） and scanning electron microscopy （SEM）. The results showed that Ag-PPy nanocomposites were in situ deposited onto the surface of P（St-co-MAA） latex particles tailored by carboxylic-acid groups. The nanocomposites of Ag-PPy distributed on the surface of polymer particles transformed from discretely dots to continuously coating as the reaction temperature increased from 15℃ to 60℃. Strawberry-like composite particles were obtained at the reaction temperature of 60℃. The TGA characterization confirmed that the Ag-PPy nanocomposites loading onto the P（St-co-MAA） particles were systematically controlled over a range of 6 wt%-42 wt% by changing the reaction temperatures. The fluorescence quenching effect of the Ag-PPy/P（St-co-MAA） composite particles was explored on Rhodamine B as a model molecule with the Stern-Volmer quenching constant Ksv of 5.9 × 104 （g/mL）-1. It is suggested that the fluorescence quenching effect is caused by the resonance energy transfer mechanism.
Polycrystalline BiFeO3 and rare earth substituted ***3 （BRFO, R=Y, Ho and Er） compounds were prepared by rapid solid state sintering technique. Structural phase analysis indicated that all the compounds stabilized i...
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Polycrystalline BiFeO3 and rare earth substituted ***3 （BRFO, R=Y, Ho and Er） compounds were prepared by rapid solid state sintering technique. Structural phase analysis indicated that all the compounds stabilized in rhombohedral structure （R3c space group） and a small orthorhombic phase fraction was observed in BRFO compounds. From the Raman spectra results, the changes in the phonon frequencies （A1） and line widths suggested lattice distortion in the BRFO compounds as was evidenced in the XRD analysis. Compared to the linear variation of magnetization with magnetic field （M-H） shown by BFO, an obvious M-H loop was observed in BRFO compounds which could be due to the suppression of space modulated spin structure and was explained on the basis of weak ferromagnetism and field induced spin reorientation. UV-Vis spectroscopy evidenced a change in local FeO6 envi- ronment due to shift in the 6Alg→4T2g energy transition band. BRFO compounds with improved remnant magnetization and coercive field are applicable for magnetoelectric devices.
A donor-acceptor type conjugated polymer poly（5,6-bis（octyloxy）-4,7-di（thiophen-2-yl）benzo-[c] [1,2,5]- thiadiazole-9,9-dioctylfluorene） （POTBTF） based on octyloxy-containing benzothiadiazole （OTBT） and octy...
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A donor-acceptor type conjugated polymer poly（5,6-bis（octyloxy）-4,7-di（thiophen-2-yl）benzo-[c] [1,2,5]- thiadiazole-9,9-dioctylfluorene） （POTBTF） based on octyloxy-containing benzothiadiazole （OTBT） and octyl- containing fluorine （F） was synthesized by Suzuki coupling reaction. The polymer possesses a narrow bandgap and strong light harvesting ability with excellent thermal stability and reasonable solubility. POTBTF exhibited a broad absorption from 300 to 600 nm with an absorption peak at 543.8 nm. The power conversion efficiency of the polymer solar cell based on POTBTF/PC71BM （1：3, w/w） reached 1.77% with a short-circuit current density of 6.69 mA/cm2, an open-circuit voltage of 0.71 V, and a fill factor of 0.374 under AM 1.5 G irradiation （100 mW/cm2） without annealing or any additives. The results indicate that introducing long alkoxy side chains into benzothiadiazole would not only improve the solubility of the polymers but also maintain the planarity of molecule conformation, and therefore, enhance the performance of photovoltaic devices.
Due to the good physical properties of diamond,diamond/Al composites as a new generation electronic packaging material receive more and more *** is one of the greatest potential for the development of packaging *** on...
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ISBN:
(纸本)9783037859698
Due to the good physical properties of diamond,diamond/Al composites as a new generation electronic packaging material receive more and more *** is one of the greatest potential for the development of packaging *** on the diamond/Al composite materials research at home and abroad was summarized in detail.
Carpet-like zinc films with unique nanowires are fabricated by using a simple physical evaporation *** definite morphologies of the films endow the superhydrophobic material with a contact angle of about 157.9°,a...
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Carpet-like zinc films with unique nanowires are fabricated by using a simple physical evaporation *** definite morphologies of the films endow the superhydrophobic material with a contact angle of about 157.9°,and by additional modification of CF_(3)(CF_(2))_(7)CH_(2)CH_(2)Si(OCH_(3))_(3)the water adhesive force could be tuned from 58.3μN to 14.6μ*** order to analyze the controllable adhesion of superhydrophobic Zn films,we study the microstructure and chemical compositions of the films by x-ray diffraction SEM,TEM,HRTEM and ***,a model based on the balance of micro-surface energy is proposed to illustrate the relationship of the geometry and wettability properties of the *** model provides new insights into how to design-oriented microchannels and micro-protuberance on material surfaces,which is of benefit for controlling their ability of caught-collection in air bubbles and water-pinning collection.
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