Yong Jun Hu

The Influence of Heating-Cooling Cycles on the Thermal Storage Performances of Al-17 Wt.% Si Alloy

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

Influence of Annealing Temperature on the Antibacterial Activities and Photoactivity of N-Doped TiO2 Films by Ion Beam Assistance

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.

Study on the Effect of Ultrasonic Waves on the Low Temperature Electroless Ni-P Plating on Copper Substrate

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.

The Influence of Electroless-Silver Coated Cenosphere Powders on the Electromagnetic Shielding Interference Effectiveness and Mechanical Properties of the Silicone Rubber

Silver plating cenosphere powders were developed by electroless plating method. After being mixed with silver plating cenosphere powders and curing agent, silicone rubber composites was obtained. The surface morphology, microstructure and cross-section of Ag-coated cenosphere powders and composites were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influence of different concentration of Ag-coated cenosphere powders on the conductivity, electromagnetic shielding interference effectiveness and mechanical properties of the silicone rubber was discussed from the point of view of condition of Ag-coated cenosphere powders and silicone rubber. The results showed that the smooth and compact silver coating was deposited on the surface of cenosphere powders. The Ag-coated cenosphere powders possessed good oxidation resistance and enough strength to resist being crushed during the preparation of composites. The adhension between the silver film and cenosphere powders was good. There existed the extreme shielding effectiveness (SE) of silicone rubber composites filled with Ag-coated cenosphere powders. The electrical conductivity no longer plays an important role in enhancing the SE of composites when the SE of composites reaches the extremum. When the content of the Ag-coated cenosphere powders was 180 parts per hundred of rubber (phr), the SE values of composites were typically above 80 dB and close to the extremum across the tested frequency range from 2.6 GHz to 3.95 GHz. And the mechanical properties of composites with 180 phr were not degraded obviously.

Phase Transformations and Magnetic Properties of Electroplating Ni-Co on Aluminium

In this paper, Ni-Co coatings on Al foil were prepared by electroplating to obtain Al/Ni-Co composite. Phase transformations and magnetic property of Al/Ni-Co composite heated at 823 K for 80 h were investigated. The results showed that obviously exchanged zone in Al matrix exited and the thickness was about 2.5μm. Ni diffused into the Al easilier than Co. β phase (AlNi and AlCo) and γ phase (Al (Ni, Co) solid solution) of Co-Ni-Al formed during the annealing. The Ms of was decreased significantly when Al diffused into the NiCo alloy film and formed Ni-Al and Co-Al intermetallic compounds.

The Influence of Composition on Morphology, Structure and Magnetic Properties of Ni-Co Films on Aluminum Prepared by Electroplating Method

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.

Microstucture and Mechanical Properties of Semi-Solid Sn–58Bi Alloy

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%.

The Influence of Stirring Time on Mechanical Properties of Sn–58Bi Alloy Treated in the Semi-Solid State by Mechanical Stirring Process

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%.

Investigation into the Electromagnetic Interference Shielding Effectiveness of Silicon Rubber Filled with Carbon Fiber

In this paper, the silicone rubber composed of carbon fibers was prepared. The influence of different concentration of carbon fibers on the conductivity, electromagnetic shielding interference effectiveness property of the silicone rubber was discussed from the point of view of condition of carbon fiber and silicone rubber. The results showed that there existed the extreme conductivity and shielding effectiveness (SE) across the tested frequency range from 2.6 GHz to 3.95 GHz of silicone rubber composites filled with carbon fibers. When the content of the carbon fibbers was 50 parts per hundred of rubber (phr), the SE values of composites were typically above 63 dB and close to the extremum. The compact packing structure of carbon fibers does not play an important role in improved the conductivity of composite. The SE of the composite depends on the conductivity of composite.

Microstructure and Phase Stability of Sintered Hydroxyapatite-Zirconia Composites

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.