The present work explores the application of microwave heating for the melting of powdered tin. The mor- phology and particle size of powdered tin prepared by the centrifugal atomization method were charac- terized. T...The present work explores the application of microwave heating for the melting of powdered tin. The mor- phology and particle size of powdered tin prepared by the centrifugal atomization method were charac- terized. The tin particles were uniform and spherical in shape, with 90% of the particles in the size range of 38-75μm. The microwave absorption characteristic of the tin powder was assessed by an estimation of the dielectric properties. Microwave penetration was found to have good volumetric heating on powdered tin. Conduction losses were the main loss mechanisms for powdered tin by microwave heating at temperatures above 150 ℃. A 20 kW commercial-scale microwave tin-melting unit was designed, developed, and utilized for production. This unit achieved a heating rate that was at least 10 times higher than those of conventional methods, as well as a far shorter melting duration. The results suggest that microwave heating accelerates the heating rate and shortens the melting time. Tin recovery rate was 97.79%, with a slag ratio of only 1.65% and other losses accounting for less than 0.56%. The unit energy consumption was only 0.17 （kW·h）·kg-1- far lower than the energy required by conventional melting methods. Thus, the microwave melting process improved heating efficiency and reduced energy consumption.展开更多
Bismuth-doped tin dioxide nanometer powders were prepared by co-precipitation method using SnCl4 and Bi（NO3）3 as raw materials. The effects of calcining temperature and doping ratio on the particle size, composition...Bismuth-doped tin dioxide nanometer powders were prepared by co-precipitation method using SnCl4 and Bi（NO3）3 as raw materials. The effects of calcining temperature and doping ratio on the particle size, composition, spectrum selectivity of bismuth-doped tin dioxide and the phase transition of Bi-Sn precursor at different temperatures were studied by means of X-ray diffraction, transmission electron microscopy, ultraviolet-visual-near infrared diffuse reflection spectrum and the thermogravimetric-differential scanning calorimetry. The results show that prepared bismuth-doped tin dioxide powders have excellent characteristics with a single-phase tetragonal structure, good dispersibility, good absorbency for ultraviolet ray and average particle size less than 10 nm. The optimum conditions for preparing bismuth-doped tin dioxide nanometer powders are as follows: calcining temperature of 600℃, ratio of bismuth-doped in a range of 0.10-0.30, and Bi-Sn precursor being dispersed by ultrasonic wave and refluxed azeotropic and distillated with mixture of n-butanol and benzene. The mechanism of phase transition of Bi-Sn precursor is that Bi 3+ enters Sn-vacancy and then forms Sn—O—Bi bond.展开更多
This paper reports that indium tin oxide （ITO） crystalline powders are prepared by coprecipitation method. Fabrication conditions mainly as sintering temperature and Sn doping content are correlated with the phase, ...This paper reports that indium tin oxide （ITO） crystalline powders are prepared by coprecipitation method. Fabrication conditions mainly as sintering temperature and Sn doping content are correlated with the phase, microstructure, infrared emissivity c and powder resistivity of indium tin oxides by means of x-ray diffraction, Fourier transform infrared, and transmission electron microscope. The optimum sintering temperature of 1350℃ and Sn doping content 6～8wt% are determined. The application of ITO in the military camouflage field is proposed.展开更多
hemical co-precipitation method was used to prepare indium tin hydroxide. Indium tin hydroxide has the structure of cubic crystal. The cubic crystal structure transformed to amorphous after heat treatment at 250℃ for...hemical co-precipitation method was used to prepare indium tin hydroxide. Indium tin hydroxide has the structure of cubic crystal. The cubic crystal structure transformed to amorphous after heat treatment at 250℃ for 1 h. When the heat treatment temperature was higher than 280℃, the amorphous transformed to cubic crystal structure. After heat treatment at 600℃ for 1 h, the particle size of indium tin oxide is 8～20 nm. The weight ratio of In∶Sn is near 9∶1. Its granule has spherical shape. The dispersity is good.展开更多
文摘The present work explores the application of microwave heating for the melting of powdered tin. The mor- phology and particle size of powdered tin prepared by the centrifugal atomization method were charac- terized. The tin particles were uniform and spherical in shape, with 90% of the particles in the size range of 38-75μm. The microwave absorption characteristic of the tin powder was assessed by an estimation of the dielectric properties. Microwave penetration was found to have good volumetric heating on powdered tin. Conduction losses were the main loss mechanisms for powdered tin by microwave heating at temperatures above 150 ℃. A 20 kW commercial-scale microwave tin-melting unit was designed, developed, and utilized for production. This unit achieved a heating rate that was at least 10 times higher than those of conventional methods, as well as a far shorter melting duration. The results suggest that microwave heating accelerates the heating rate and shortens the melting time. Tin recovery rate was 97.79%, with a slag ratio of only 1.65% and other losses accounting for less than 0.56%. The unit energy consumption was only 0.17 （kW·h）·kg-1- far lower than the energy required by conventional melting methods. Thus, the microwave melting process improved heating efficiency and reduced energy consumption.
基金Project(GC200603) supported by the Open Fund of Guangdong Provincial Key Laboratory for Green Chemicals projectsupported by the Key Laboratory of Enhanced Heat Transfer and Energy Conservation of Ministry of Education of China
文摘Bismuth-doped tin dioxide nanometer powders were prepared by co-precipitation method using SnCl4 and Bi（NO3）3 as raw materials. The effects of calcining temperature and doping ratio on the particle size, composition, spectrum selectivity of bismuth-doped tin dioxide and the phase transition of Bi-Sn precursor at different temperatures were studied by means of X-ray diffraction, transmission electron microscopy, ultraviolet-visual-near infrared diffuse reflection spectrum and the thermogravimetric-differential scanning calorimetry. The results show that prepared bismuth-doped tin dioxide powders have excellent characteristics with a single-phase tetragonal structure, good dispersibility, good absorbency for ultraviolet ray and average particle size less than 10 nm. The optimum conditions for preparing bismuth-doped tin dioxide nanometer powders are as follows: calcining temperature of 600℃, ratio of bismuth-doped in a range of 0.10-0.30, and Bi-Sn precursor being dispersed by ultrasonic wave and refluxed azeotropic and distillated with mixture of n-butanol and benzene. The mechanism of phase transition of Bi-Sn precursor is that Bi 3+ enters Sn-vacancy and then forms Sn—O—Bi bond.
文摘This paper reports that indium tin oxide （ITO） crystalline powders are prepared by coprecipitation method. Fabrication conditions mainly as sintering temperature and Sn doping content are correlated with the phase, microstructure, infrared emissivity c and powder resistivity of indium tin oxides by means of x-ray diffraction, Fourier transform infrared, and transmission electron microscope. The optimum sintering temperature of 1350℃ and Sn doping content 6～8wt% are determined. The application of ITO in the military camouflage field is proposed.
文摘hemical co-precipitation method was used to prepare indium tin hydroxide. Indium tin hydroxide has the structure of cubic crystal. The cubic crystal structure transformed to amorphous after heat treatment at 250℃ for 1 h. When the heat treatment temperature was higher than 280℃, the amorphous transformed to cubic crystal structure. After heat treatment at 600℃ for 1 h, the particle size of indium tin oxide is 8～20 nm. The weight ratio of In∶Sn is near 9∶1. Its granule has spherical shape. The dispersity is good.
