Spray-drying was used to produce the high emissivity NiCr2O4 powders with a spinel structure. Preliminary investigations focused on fabricating the high emissivity powders for infrared radiation coatings and finding t...
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Spray-drying was used to produce the high emissivity NiCr2O4 powders with a spinel structure. Preliminary investigations focused on fabricating the high emissivity powders for infrared radiation coatings and finding the relationship between microstructure and emissivity. The NiCr2O4 powders were characterized for composition, microstructure, and infrared emissivity by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, infrared radiant instrument, and Fourier transform infrared spectra （FT-IR）. Thermogravimetry and differential thermal analysis show that the appropriate baking temperature for NiCr2O4 powder preparation is about 1200？C. The emissivity measurement and FT-IR spectra show that, because of the special spinel structure, the NiCr2O4 powders have a high emissivity about 0.91. Spray-drying is a suitable method to produce the high emissivity ceramic powders.
Ag modified ZnO （Ag/ZnO） nanocrystals were prepared by a facile and low temperature wet chemical method. The phase structures, morphologies, and optical properties of the as-prepared samples were characterized by X-...
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Ag modified ZnO （Ag/ZnO） nanocrystals were prepared by a facile and low temperature wet chemical method. The phase structures, morphologies, and optical properties of the as-prepared samples were characterized by X-ray powder diffraction （XRD）, field-emission scanning electron microscopy （FESEM）, high-resolution transmission electron microscopy （HRTEM）, the Brumauer-Emmett-Teller （BET） surface area, UV-vis diffuse reflectance spectroscopy and photoluminescence （PL） spectra, respectively. The photocatalytic performance of Ag/ZnO with diffent Ag contents was measured with the degradation of methyl orange （MO） at room temperature under UV light irradiation. The experimental results indicated that the well-crystalline ZnO nanopaticles with a size of ca. 4.5 nm exhibited a high photocatalytic activity for the degradation of MO with the apparent rate constant （k） of 1.57 ×10-2 min-1, and the photocatalytic activities of ZnO were further enhanced by modification with silver. When the Ag loading was 3mol%, Ag/ZnO showed the highest photocatalytic acitivity with a k value of 5.452×10-2 min-1, which is 3.5 and 2.5 time more than that of ZnO and commercial P25, respectively.
Air plasma spraying （APS） was used to produce high emissivity coatings with a NiCr204 spinel structure. The relationship between the emissivity and the crystal structure was investigated. X-ray diffraction （XRD） a...
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Air plasma spraying （APS） was used to produce high emissivity coatings with a NiCr204 spinel structure. The relationship between the emissivity and the crystal structure was investigated. X-ray diffraction （XRD） analyses show that NiCr204 spinel has been fabri- cated with the space group Fd3m. Scanning electron microscope （SEM） photographs show that the coating consists of a laminated structure with homogeneous grains and high porosity because of the unique feature of plasma spraying. The emissivity measurement and Fourier transformation infrared radiation （FT-IR） spectra show that NiCr204 has a high emissivity of about 0.91 because of its special spinel structure APS is a suitable method to produce high emissivity coatings.
Crystalline microporous zeolites with pore sizes typically at 0.4-1.5 nra are one of the most useful catalysts in industrial processes such as oil refining and organic synthesis owing to their strong catalytic perform...
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Crystalline microporous zeolites with pore sizes typically at 0.4-1.5 nra are one of the most useful catalysts in industrial processes such as oil refining and organic synthesis owing to their strong catalytic performance,high thermal and hydrothermal stabilities,and well-defined micropores with excellent shape-selectivity in ***,one disadvantage of these zeolitic catalysts is that their pores are too small to be accessed by bulky reactants hindering their use in the fine chemical and petroleum processing industries. To overcome
An ultra-fast densification method based on high heating rate from the combustion reaction for producing carbon nanotubes （CNTs） reinforced alumina ceramics is reported. The heat generated by combustion reaction is ...
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An ultra-fast densification method based on high heating rate from the combustion reaction for producing carbon nanotubes （CNTs） reinforced alumina ceramics is reported. The heat generated by combustion reaction is adopted to act as a high temperature source to the sample, which results in a heating rate of 1660℃/min of the sample. Then a great mechanical pressure is applied to the sample when the sample gets the expected temperature. The densification process is finished in several minutes. The results indicate that the densification method is beneficial to protect the CNTs from destruction and creates good interracial combination between the nanotubes and the matrix. With the addition of 1 wt% CNTs, the fracture toughness of the ceramics prepared increases about 50%.
The effects of microwave sintering on the properties, phases and microstructure of W-2OCu alloy, using composite powder fabricated by spray pyrolysis-continuous reduction technology, were investigated. Compared with t...
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The effects of microwave sintering on the properties, phases and microstructure of W-2OCu alloy, using composite powder fabricated by spray pyrolysis-continuous reduction technology, were investigated. Compared with the conventional hot-press sintering, microwave sintering to W-2OCu composites could be achieved with lower sintering temperature and shorter sintering time. Furthermore, microwave sintered W-Cu composites with high densification, homogenous microstructure and excellent properties were obtained. Microwave sintering could also result in finer microstructures. ：~
Mg-Al bonded composite materials expand Mg and Al alloys' applications by combining their unique performances together. However, the formation of Mg-Al intermetallic compounds in interface zone of Mg/Al directly-b...
Mg-Al bonded composite materials expand Mg and Al alloys' applications by combining their unique performances together. However, the formation of Mg-Al intermetallic compounds in interface zone of Mg/Al directly-bonded joint seriously obstructs its further development. To solve this problem, Mg-Ag-Al multilayer composite materials have been successfully prepared by diffusion bonding technology. The effect of key process parameter (bonding temperature) on microstructure of this material has been mainly investigated. The results show that Mg and Al were well bonded by using silver interlayer when the bonding temperature exceeded 370°C. But Mg17Al12 and Mg2Al3 compounds were formed in the interface zone at temperatures higher than 420°C. By means of controlling the bonding temperature (380 °C–420 °C), silver interlayer effectively restrained the generation of Mg-Al intermetallic compounds, and Mg-Ag intermetallic compounds (Mg3Ag, MgAg) were formed in the interface zone instead.
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