Papers by Author: Hong Hua Cai

Abstract: Multilayer SiO2 crystals modified by alkoxysilanes were fabricated by the vertical deposition technique combined with self-assembly method. The SiO2 colloidal crystallization was prepared by the traditional Stöber-Fink-Bohn method, and modified by different alkoxysilanes to investigate the properties of the films. The films fabricated by the ordering of SiO2 spheres were investigated by infrared spectrometer, X-ray diffraction, scanning electron microscope, UV-visible spectrophotometer. The results showed that thin film is the face-centered cubic structures and the spheres are [111]-oriented.

Abstract: Nanosized barium ferrite spinel particles were prepared with the aid of ultrasound radiation by a precursor approach. A precursor was got by sonicating an aqueous solution of BaCl2, Fe (NO3)3·9H2O and urea firstly. Nanosized BaFe2O4 particles with a size of ca.40nm were prepared after the precursor was heated at 950 °C for 15 h. The nanosized barium ferrite particles and the precursor were characterized by powder X-ray diffraction, scanning electron microscopy, FT-IR and differential scanning calorimetry.

Abstract: Copper ferrite powders were successfully synthesized by sonochemical method. The resultant powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR, differential thermal analysis-thermal gravimetric (DTA-TG), differential scanning calorimetry (DSC) and VSM. The particle saturation magnetization (Ms) is 66 emu/g and an intrinsic coercive force (iHc) is 2100 Oe when the precursor calcined at 950 °C for 15 h.

Abstract: WO3 sol was prepared through the sol-gel process. Ethanol, acetone and SiO2 sol were added to the WO3 sol. The WO3 thin films on glass substrate were obtained with the hybrid sol by the dip-coating technique, and then were heat-treated at different temperatures for a certain time. X-ray diffractometer and scanning electron microscope were used to characterize the crystal structure and surface morphology of these coatings. Visible light transmittance changes of the thin films irradiated under UV light were measured with UV spectrometer. The experimental results demonstrated that photochromic effect, hardness and uniformity of thin films were improved when the thin films are obtained with the hybrid sol.

Abstract: TiO2 coatings on ceramic substrate were prepared using TiOSO4 and silica sol. Coatings were then heat-treated respectively at 300°C, 400°C or 500°C for 30mins. Degradation of the solution of chlorinated methane by UV light and TiO2 coating were investigated. It can be concluded from the results that the coating with composition of 80wt%TiO2-20wt%SiO2 heated at 500°C display better degradation effect than the other coatings. As the initial concentration of chloromethane goes up, the degradation rate increases; while as the degree of substitution by chlorine goes up, the catalytic effects decreases.

Abstract: Sol-gel coatings of mixed TiO2-SiO2 had been deposited on ceramic substrates by spraycoating technique to study their hydrophilic and photocatalytic behavior on exposure to sunlight or ultraviolet illumination. The range of the films heat-treatment temperature is from 300°C to 500°C. AFM and XRD analysis were used to characterize the crystal structure and surface morphology of these coatings. Hydrophilic property was evaluated by water contact angle measurement under sunlight illumination condition, and photocatalytic activity by decomposition rate of aniline blue under ultraviolet illumination. Attrition resistance experiment was also carried out to test the hardness and adherence strength of these films. The experimental results demonstrate that this coating possesses high photo-activity and excellent adhesion to ceramic substrates.

Abstract: The precursor solution of titanium oxide coating was prepared by using titanium-oxygen sulfide. Solution with PH value of 8.5 was used to for coating on the surface of glass through dipping. The coatings were analyzed with DSC, AFM and XRD. The hydrophilic results of titanium oxide coating were obtained according the water contact angle measurement in the sunlight irradiation condition. The experimental results demonstrate that this solution is a good precursor for coating of titanium oxide, and the coatings treated at a higher temperature have shown good hydrophilic property.