5083 aluminum Alloy was prepared by cryomilling method. The microstructure, microstructural evolution and thermal stability and of sample powder were investigated by XRD, SEM and DSC. The results showed that the parti...
详细信息
5083 aluminum Alloy was prepared by cryomilling method. The microstructure, microstructural evolution and thermal stability and of sample powder were investigated by XRD, SEM and DSC. The results showed that the particles size of 5083 alloy powder during cryomilling was gradually reduced, Mg phase was gradually disappeared and super-saturated to Al;Milling time and milling speed were the main factors of affected alloy structure and performance, and high speed cryomilling could result in more uniform nanometer grains. Energy spectrum analysis and DSC suggest that the thermal stability of the cryomilling 5083 alloy powder was improved at certain extent, it may be attributed to the presence of nano-scale Al2O3 particles.
Boron carbide ceramics were synthesized and desificated in one step by spark plasma sintering (SPS) technique using boron and graphite powders as raw materials. The impact of sintering temperature, sintering pressure,...
详细信息
Boron carbide ceramics were synthesized and desificated in one step by spark plasma sintering (SPS) technique using boron and graphite powders as raw materials. The impact of sintering temperature, sintering pressure, holding time and heating program, on sintering performance of boron carbide ceramics was studied. The results indicated that the starting temperature of synthesis was at 1100°C;higher temperature and pressure, appropriate holding time and heating-up rate, as well as two holding steps were beneficial to densification of boron carbide ceramics. The suitable SPS process conditions were optimized as: sintering temperature of 1800°C, pressure of 40 MPa, holding time of 6 min, heating-up rate of 100°C/min, and two holding steps, on which boron carbide ceramics of higher density were obtained.
Using boron carbide (B4C), zirconium oxide (ZrO2) and graphite (C) as starting materials, ZrB2-B4C composites were prepared by Spark Plasma Sintering-Reaction synthesis. The reaction process was studied by theoretical...
详细信息
Using boron carbide (B4C), zirconium oxide (ZrO2) and graphite (C) as starting materials, ZrB2-B4C composites were prepared by Spark Plasma Sintering-Reaction synthesis. The reaction process was studied by theoretical calculation, DSC and XRD of the specimens sintered at different temperatures. And the sintering mechanism was analyzed through the shrinkage ratio curve during the sintering. The results showed that the start temperature of the reaction among ZrO2, B4C and C accords with the theoretical temperature. At the initial stage of the sintering of ZrB2-B4C, the kinetic equation of the shrinkage showed that the sintering mechanism was a surface melting sintering mechanism.
The precursors of CIS and CIGS thin films were prepared by one-step electrodeposition in alcohol solution and then annealed in Ar atmosphere at 550°C for 30min. The influences of deposition potentials and salt co...
Al12Si3.75Ge0.25O26 ceramic powder was prepared by sol-gel method using Al（NO3）3,Si（OC2H5）4 and Cl3GeCH2-CH2COOH as *** structural formation of Al12Si3.75Ge0.25O26 ceramic powder was analyzed by *** reduction by f...
详细信息
Al12Si3.75Ge0.25O26 ceramic powder was prepared by sol-gel method using Al（NO3）3,Si（OC2H5）4 and Cl3GeCH2-CH2COOH as *** structural formation of Al12Si3.75Ge0.25O26 ceramic powder was analyzed by *** reduction by flowing H2/Ar mixture gas,strong room temperature photoluminescence （PL） can be observed at 565 nm,613 nm,682 nm,731 nm and 777 nm,*** PL intensity scarcely depends on the reduction temperature and duration,while the sample reduced at 500 ℃ for A^3 hours has the highest PL *** and after reduction at 500 ℃,the volume of unit cell of mullite solid solution decreases to 0.4699 *** on the analysis of XPS and Raman spectra,it can be approved that the PL phenomenon at room temperature is caused by the embedded Ge nanoparticles with the average size of about 1.95 nm.
Hierarchically organized γ-AlOOH hollow spheres with nanoflake-like porous surface textures were fabricated by chemically induced self-transformation of metastable solid particles of amorphous aluminium oxyhydroxide ...
详细信息
Hierarchically organized γ-AlOOH hollow spheres with nanoflake-like porous surface textures were fabricated by chemically induced self-transformation of metastable solid particles of amorphous aluminium oxyhydroxide produced in situ within hydrothermal reaction mixtures containing aluminium sulfate and urea. Thermal treatment of the γ-AlOOH product at 600 °C produced intact hollow spheres of γ-Al 2 O 3 . Formation of the hollow γ-AlOOH structures was strongly dependent on the reaction temperature and time, as well as the concentration and molar ratio of the reactants. Hollow γ-AlOOH spheres were not obtained using mixtures of urea and aluminium nitrate or aluminium chloride, as metastable precursor particles were not produced under these conditions. In general, the described method is efficient and environmentally benign, and has significant advantages over traditional template approaches to the large-scale production of hollow inorganic materials. The prepared hierarchically organized γ-AlOOH and γ-Al 2 O 3 hollow spheres should have important applications in areas of catalysis, separation science, biomedical engineering and nanotechnology.
Raw Mg,Si powder were used to fabricate Mg2Si bulk thermoelectric generator by spark plasma sintering （SPS）.The optimum parameters to synthesize pure Mg2Si powder were found to be 823 K,0 MPa,10 min with excessive c...
详细信息
Raw Mg,Si powder were used to fabricate Mg2Si bulk thermoelectric generator by spark plasma sintering （SPS）.The optimum parameters to synthesize pure Mg2Si powder were found to be 823 K,0 MPa,10 min with excessive content of 10wt% Mg from the stoichiometric ***2Si bulk was synthesized and densified simultaneously at low temperature （823 K） and high pressure （higher than 100 MPa） from the raw powder,but Mg,Si could not react completely,and the sample was not very dense with some microcracks on the ***,Mg,Si powder reacted at 823 K,0 MPa,10 min in SPS chamber to form Mg2Si green compact,again sintered by SPS at 1023 K,20 MPa,5 *** fabricated sample only contained Mg2Si phase with fully relative density.
Iridium thin films have been deposited on Si3N4（100 nm）/Si（100） substrates by magnetron sputtering. And then iridium film micro-patterns were fabricated by ion milling technique. The atomic force microscopy （AFM...
详细信息
Iridium thin films have been deposited on Si3N4（100 nm）/Si（100） substrates by magnetron sputtering. And then iridium film micro-patterns were fabricated by ion milling technique. The atomic force microscopy （AFM） measurements reveal that there is a very fiat and smooth surface with an average roughness of 0.64 nm for the iridium films. The X-ray diffraction also reveals that the deposited iridium films have a polycrystalline microstructure with （111） plane preferential orientation. The electrical resistivity of the iridium films was also measured and discussed.
Skutterudite CoAs3 is a potentially important thermoelectric material. Morse potential is employed here to carry out molecular dynamics simulations of nanobulk CoAs3 at the temperature of 0 K. The stress-strain relati...
详细信息
Skutterudite CoAs3 is a potentially important thermoelectric material. Morse potential is employed here to carry out molecular dynamics simulations of nanobulk CoAs3 at the temperature of 0 K. The stress-strain relationships under uniaxial tensile and/or compressive strain are obtained. The elastic modulus, extreme strength and deformation mechanism are studied. The simulation results indicate that nanobulk CoAs3 abruptly ruptures at much higher strain level under tension than conventional bulk CoAs3. Both the extreme stresses under tension and compression are much higher than those of conventional bulk CoAs3.
A series of samples of hexagonal boron nitride-aluminum nitride ceramic composites with different amounts of CaF2 as sintering aid were prepared by spark plasma sintered at 1700-1850 ℃ for 5 *** addition of CaF2 effe...
详细信息
A series of samples of hexagonal boron nitride-aluminum nitride ceramic composites with different amounts of CaF2 as sintering aid were prepared by spark plasma sintered at 1700-1850 ℃ for 5 *** addition of CaF2 effectively lowered the sintering temperature and promoted the densification of AlN-BN *** the increase of sintering temperature,the density increased,and the contiguity of AlN grains enhanced in AlN-BN *** conductivity of AlN-BN composites increased with the increase in CaF2 content and sintering temperature,and there is a maximum value of 78.6 W·m^-1·K^-1 when the sample with 3wt% CaF2 sintered at 1800 ℃.
暂无评论