Papers by Author: Yong Jun Hu

Abstract: In this paper, Ni-Co alloy films with different composition were obtained by means of electroplating method. The morphology, structure and magnetic properties of Ni-Co alloy films with different Cobalt content are evaluated. The effect of the crystal orientation on the morphology of Ni-Co deposits with different compositon was discussed. The results showed that Ni–Co alloy films with Cobalt content decrease is composed of pyramidal, spindly, mixed pyramidal and spindly, and cellular particles respectively. To the deposits with similar composition, change of morphology is related to the preferential orientation. With the increase of the Nickel content, the saturation magnetization (Ms) value of the Ni–Co alloy films increases and then decreases sharply. The coercivety (Hc) value of the Ni–Co alloy films decreases with the Nickel content increase.

Abstract: In this paper, the technology of semi-solid casting was to used are produced Sn-Bi alloy. The influence of agitating time at 125 °C on the microstructure and mechanical properties of of Sn-58Bi casting alloy were discussed. The eutectic Sn-Bi alloy was mechanically agitated during the casting solidification process. The results indicated that non-lamellar Sn-Bi structure with long plate shape, short strip, small size block and suborbicular block shape Sn phase was obtained for different stirring time. The elongation of Sn-Bi alloy with non-lamellar eutectic structure is improved prominently. Compared with the elongation of lamellar eutectic Sn-Bi alloy prepared by conventional die casting, the elongation of semi-solid Sn-Bi alloy with suborbicular block shape Sn phase is enhanced up to 45%.

Abstract: Preparation of semi-solid Sn–58Bi alloys by mechanical stirring casting method was investigated. The effect of temperature below the melting temperature on the microstructures and mechanical properties of semi-solid Sn–58Bi alloys was discussed. The experimental results showed that long plate shape, block shape and suborbicular Sn phases were formed by mechanical agitation during the casting solidification process. The non-lamellar Sn-Bi Microstructure improves prominently the elongation of Sn-Bi alloy. The elongation of semi-solid Sn-Bi alloy with suborbicular Sn phase is enhanced up to 37% compared with the elongation of lamellar eutectic Sn-Bi alloy prepared by conventional die casting. After the agigation above 130 °C, non-lamellar Sn-Bi eutectic structure is formed and lamellar Sn-Bi eutectic precipitates. When the agitating temperature was 135 °C, the elongation of semi-solid Sn-Bi alloy mixed with non-lamellar and lamellar Sn-Bi alloy microstructure is enhanced up to 24%.

Abstract: The change of thermal properties of Al-17 wt.% Si alloys in different heating-cooling cycles was studied by differential scanning calorimetry (DSC). The influence of heating-cooling cycles on the latent heat of melting was discussed in the view of microstructure of Al-Si alloy. The results showed the latent heat of as-cast Al–13 wt%Si alloy is 548.6 J/g, which Al-Si alloy possesses good thermal energy storage property. The onset of melting point of Al-Si alloy increases indistinctively and is about 577 °C. When the heating-cooling cycle was 1200 times, the latent heat increased to 526.0 J/g. With heating-cooling times increase, the grain size and shape of the primary Si decrease. The shape of eutectic Si is changed into stripe

Abstract: In this paper, the influence of different sintering temperatures on the microstructure, density, shrinkage and final phase content of hydroxyapatite-zirconia (HA-ZrO₂) composites was studied. Composites of hydroxyapatite with 3 mol% Y₂O₃ stabilized zirconia with MgO were sintered between 1100 °C and 1400 °C. The reaction and the transformation of phases were investigated by X-ray diffraction and FTIR spectroscopic measurements. Those results indicated that the processes of HA dehydroxylation were found, the mean grain size of the sample sintered was varied from 1.2 µm to 5.3 µm. Dimension shrinkage increased to 0.24% as the sintered temperature increased from 1100 °C to 1400 °C, the bulk density increased monotonically to 95.6% with increasing temperature up to 1400 °C.

Abstract: In this paper，electroless Ni-P plating on copper substrate at 50 °C in ultrasonic field was carried out. The frequency of ultrasonic waves was 40 kHz. The effect of ultrasonic on the composition, plating rate and morphology of Ni-P deposite was investigated at the ultrasonic power of 40, 70 and 100 W. The experimental results showed Ni-P deposit could not be obtained without ultrasonic field at 50 °C. The content of nickel and the thickness of Ni-P deposit increased with the ultrasonic waves power increase. Ultrasonic irradiation power remarkably refines the nodule size of Ni-P particles. The collapse of cavities in solution seems to suppress the Z-direction growth of the nodule.

Abstract: The N-doped TiO₂ films were prepared by cathode vacuum arc deposition with ion beam assisted. Influence of annealing temperature on the microstructure, optical property, photocatalytic activity and antibacterial activities of the N-doped TiO₂ films was studied. The experimental results indicate that annealing treatment significantly affects both microstructure and photoactivity. All the as deposited N-doped TiO₂ films retained an amorphous structure, the crystalline structure of N-doped TiO₂ films annealed in the range 400°C- 600°C were examined to be of anatase structure with a (101) preferential orientation，photocatalytic activity of the N-doped TiO₂ film annealed at 500°C was best under visible light, The N-doped TiO₂ films against E. coli and S. aureus had more than 99% antibacterial rate, and the antibacterial activity of the N-doped TiO₂ films stronger slightly with the increase of the annealing temperature.

Abstract: The titania films codoped by aluminum and nitrogen have been prepared by cathodic vacuum arc with titanium aluminum alloy target in an O2/N2 gas mixture. The films were characterized by X-ray diffraction (XRD), X-rayphotoelectron spectra (XPS) and ultraviolet-visible spectra (UV–vis). The results showed that all films annealled were crystalline anatase structure with a (101) preferential orientation, XPS revealed that Al and N were successfully doped into the lattice of TiO2. The optical properties of the films revealed that the spectrum response of the Al, N-codoped TiO2 films extended from the UV region to the visible region. The absorption of the Al, N-codoped TiO2 film in the visible region(>400 nm) was enhanced, compared with the pure TiO2 film and N-doped TiO2 film. The Al, N-codoped TiO2 film showed the best photocatalytic activities for the oxidative destruction of Acid Fuchsin (AF) under visible light irradiation.