Papers by Author: Jia Xiang Liu

Abstract: The turbo air classifier is one of the most widely used equipment in powder classification. The complex flow behaviour inside it, however, prevents material experiments from providing information about its internal separation mechanisms. A study of the interaction of structural variables is therefore undertaken examining air flow behaviour, specifically the air flow between the blades of the rotor cage. The investigation of these flow field characteristics made use of the computational fluid dynamics (CFD) to simulate the air flow in the classifier. It was found that the inlet velocity of the turbo air classifier and the rotary speed of the rotor cage are two of the dominating, non-structural factors that affect velocity distributions in the region between the rotor cage blades. Once the inlet velocity settles, a critical rotary speed must be present to smoothen the flow field between the blades, resulting in an excellent classification performance. Three-dimensional velocity measurements of the region between the blades by laser Doppler velocimeter (LDV) were performed to test the results of the flow field simulation. This revealed that when inlet velocity is invariable, the velocity distributions in the region between the blades are at its most symmetric with the critical rotary speed of the rotor cage making it more favourable for classification. The velocity measurement results are likewise in good agreement with the results of the flow field simulation. Newly structured rotor cages are also simulated and compared with a conventional turbo air classifier, air flow in the newly structured model is smoother. The distributions of radial and tangential velocities are more symmetric and the trend of the rotating vortex between the blades attenuates, particularly when the rotary speed is high. The newly structured rotor cages can therefore achieve higher classification performances.

Abstract: The transparent ITO multi-layers films were fabricated on quartz glass substrate by colloid dip-coating technique from indium metal ingots and stannic chloride. It was systematically studied that the effect of the electrical properties of the ITO on doped Sn in quantitative change, different dip-coating technological conditions such as thermal treatment process, coating number plies by four-probe instrument. From the 5 wt. % Sn to 20 wt. % Sn, with the amount of doped Sn increasing, the sheet resistance of ITO was up to minimum and then increased. Sintering temperature and holding time were the reasons for the electrical properties of the ITO films, when other parameters are unaltered. It is also concluded that coating number plies was play an important role on electrical properties of ITO films by sheet resistance. From the results of research, it can be seen that the multi-layer films has optimum characteristics, whose sheet resistance is 117'/□, when the use level of Sn is 10%wt,heated in 800°C 15min with repeated dip-coating seven times..

Abstract: CaTiO3:Pr3+ was prepared by high temperature solid state reaction and measured by SEM, XRD, excitation and emission spectra. The samples obtained possessed orthorhombic crystal structure of CaTiO3, belonging to Pbnm space group. Excitation spectra of the samples were broad band, their peaks and shoulder peaks were located at about 335nm, 379nm respectively. Emission spectra were single narrow band, emission peaks were located at about 602nm, corresponding to emission of 1D2→3H4 of Pr3+ion. The addition of Eu3+and Dy3+ as co-activator led phosphorescent intensity to greatly enhance, the addition of AgNO3 as ion compensator made the samples material pink and vibrant.

Abstract: Transparent conductive ITO films were fabricated on soda lime float glass substrate by colloid dip-coating technique from indium metal ingots and hydrous tin(IV) chloride. It was systematically studied that the effect of the electrical, the structure and optical properties of the ITO doped Sn in quantitative change and different heat-treating process by XRD, UV-VIS spectrophotometer and four-probe instrument. The results indicated that only cubic In2O3 phase was observed from the X-ray diffraction; with the amount of doped Sn
increasing, the sheet resistance of ITO was up to minimum
and then
increased. The sheet resistance value decreased with the increase of the annealing temperature and holding time; the transmissivity of the ITO films was higher than 80% in 550 nm wavelength. The lowest sheet resistance value of ITO film which was 300nm thick was 153 ohms per square, which was
annealed at 600°C for 1h and doped Sn 10% (wt).