Papers by Author: Ke Hui Qiu

Abstract: The CeO₂ is prepared directly from bastnaesite as raw material that originated in Dechang, Sichuan province, China. Fully mixed with sodium bicarbonate (NaHCO₃) and roasted at 550 °C, the rare earth element (REE) in bastnaesite transformed into rare earth oxide. And the CeO₂ will be obtained by removing NaF through water washing and leaching the impurity elements including La, Fe, Al, Ca, etc. via hydrochloric acid (HCl). The CeO₂ was characterized by X-ray diffraction (XRD) and X-ray fluorescence (XRF). The XRF results demonstrated that the content of CeO₂ could reach more than 70% in products which can be used as polishing material.

Abstract: The effects of near β heat treatment on the microstructure of TC18 alloy during three temperature stages were studied. The results show that the microstructure of the sample is tri-modal microstructure after near β heat treatment, and the size of α_p does not significantly, but dispersible α_s increases and has a tendency to merge, and then it would not grow up anymore ; β phase would grow up, but the grain boundary has some broken. The experiment result shows that the tri-modal microstructure could obtain high damage tolerance properties of titanium alloy in theory.

Abstract: The preparation of pellets with taking the iron concentrate and titanium concentrate as the raw materials, the pulverized coal as the reducing agent and the CMC as the binder were researched in this paper. It was deduced from the orthogonal experiment results that the impact of quantities of binders on the compressive strength is the greatest, carbon ratio takes the second place, water content takes the third place, and pressure the least; the impact of the water content on the drop numbers is the greatest, pressure takes the second place, carbon ratio takes the third place and quantities of binders the least. Suitable parameters of forming process are ore ratio is 1:1, quantities of binders is 2.5%, carbon ratio is 18%, water content is 8% and pressure is 16 MPa.

Abstract: The preparation and the photocatalytic degradation NO2 - activity of Fe3+-doped TiO2 nano-sized particles is reported in this paper. The TiO2 nano particles were prepared by sol-gel method. The various influence factors about the synthesis process of the Fe3+-doped TiO2 nano photocatalyst were controlled and investigated by XRD (X-ray diffraction), SEM (scanning electron microscopy), and TEM (transmission electron microscopy) etc.. The results show that the phase compositions, crystalline grain size, crystal structure , and photocatalytic activity of the Fe3+-doped TiO2 particles prepared by the method depend on the synthesis technology parameters such as calcination temperature, holding time, Fe3+ ions concentration etc.. The influence factors of the preparation process has been discussed. The photocatalytic decomposition of NO2 - ion into N2 and O2 using Fe3+ and Ce4+-doped TiO2 photocatalysts were investigated under UV irradiation. It was fund that Fe3+-doped TiO2 photocatalysts shows much higher photocatalytic activity than that of the Ce4+-doped TiO2 . The photocatalytic decomposition effect of NO2 - ion is related to the crystalline grain size, irradiation time, and the Fe3+ ions concentration. The Fe3+-doped TiO2 nano powders exhibited the photocatalytic degradation NO2 - activity under UV light irradiation.