Applied Mechanics and Materials Vols. 675-677

Abstract: BN@BaTiO3 coated Ni nanocapsules were prepared by a two-step method, composed of an arc-discharge and a chemical liquid deposition process. Their microstructure, surface component as well as electromagnetic properties (1-18GHz) were investigated by means of high-resolution transmission electron microscopy, X-ray diffraction, FTIR spectra (FT-IR) and a network analyzer, respectively. The core double-shell Ni@/BN@BaTiO₃ nanocapsules exhibit stronger EM absorption properties and the position of absorb peaks move to the low frequency direction in GHz range in the same thickness, compared to that of Ni@/BN. The microwave absorptive mechanisms of BN@BaTiO₃coated Ni nanocapsule absorbent were discussed.

Abstract: The sol-gel synthesized powder was a single phase Li₂SiO₃. This synthesized powder was reacted with CO₂ at temperatures ranging from the ambient temperature to 511 K, and the products can reverted reversibly to Li₂SiO₃ above 511 K. The degree of absorption was defined as the value obtained by dividing the fractional mass gain of Li₂SiO₃ after absorption by the fractional mass gain corresponding to a 100% reaction. Consequently, the degrees of absorption of the sol-gel synthesized powders were determined to be 9.6%, 13.9%, 16.1% and 20.4% under the absorption condition at 313 K, 333 K, 353 K and 373 K for an exposure time of 115.2 ks, respectively. The specific surface area of synthesized powder was measured as 40 m²/g, higher than that of Li₂SiO₃ synthesized by solid state reaction of 30 m²/g. After CO₂ absorption, the specific surface area of synthesized Li₂SiO₃ was increased with the increase of absorption degree because of the volume expansion. Compared with Li₂SiO₃ synthesized by solid state reaction, Li₂SiO₃ powder synthesized by sol-gel process possessed bigger specific surface areas and higher micro pore volumes. Through the measurement of FE-SEM and BET, the average diameter of micro pores was decreased after CO₂ absorption, because of the generation of Li₂CO₃. The absorption behavior could be best explained by an intraparticle diffusion mechanism, that is, the diffusion of CO₂ gas through the reaction product with an apparent activation energy of 28 kJ∙mol^-1 was a rate-determining step of the absorption reaction.

Abstract: Aluminum alloy A6061 and mild steel Q235 was welded using resistance spot welding with an interlayer of AlCu28. The mechanical properties of the joint were investigated; the effects of various welding parameters on nugget diameter and tensile shear load of the joints were systematically discussed. The results reveal that it is effective to weld aluminum alloy and mild steel using resistance spot welding with an interlayer of AlCu28.

Abstract: Aluminum alloy A6061 and copper coated steel was welded by resistance spot welding with. The mechanical properties of the joint were investigated; the effects of welding parameters on nugget diameter and tensile shear load of the joints were discussed. The results show that the joint strength and nugget diameter increases with the increase of welding current and welding time and decreases with the increase of electrode force. As a result, copper plating as the middle layer of resistance spot welding is suitable for welding of aluminum alloy/steel.

Abstract: Mild steel Q235 and stainless steel SUS304 were welded using resistance spot welding with an interlayer of Ni. The mechanical properties of the joint were examined, the effects of welding parameters on the nugget size and tensile shear strength were investigated. Both the tensile shear strength and nugget diameter increased with the increasing of welding current and welding time, whereas they decreased with the increasing of electrode pressure. The results indicate that the tensile shear strength of joint welded by resistance spot welding with a Ni interplayer is higher in comparison with that obtained by conventional resistance spot weling.

Abstract: Nanocrystalline lead zirconate titanate (PZT) powders have been synthesized by solvothermal method, in which a mixed solvent of ethanol and water was used as reactive medium and Pb (NO₃)₂, ZrOCl₂·8H₂O, C₁₆H₃₆O₄Ti, KOH and NH₃·H₂O were used as raw materials. It was found that PZT particle sizes decreased from 2 μm to 100 nm with the ratio of V_ethanol/V_water increasing from 1/2 to 2/1 under a KOH concentration of 4 mol/L at 200 °C for 4 h. It indicated that the V_ethanol/V_water of mixed solvent played an important role in controlling the morphology and size of PZT crystals, as well as reaction temperature.

Abstract: The unique surface wettability of the silicone rubber can reduce substantially the flashover accidents caused by the dust pollution on the insulator. This paper describes the effects of non-soluble dust, salts component, and natural environment on the surface wettability of the silicone rubber. The structure and composition of the contamination on the silicone rubber surfaces were analyzed. The results indicate that the greater amount of non-soluble dust and salt-like component, the more difficult to restore the hydrophobic property of the sample surface, and even lost hydrophobicity; the natural environment had a more complex influence on silicone hydrophobic property. In short, the property of hydrophobicity and the migration of hydrophobicity of silicone rubber, especially the latter, are important reasons for inhibition of flashover on polluted insulator. However, this special behavior of surface wettability of silicone rubber is affected by many environmental factors.

Abstract: Using the α-SiO2 and conducted by high-energy mechanical milling as the initial material, we investigated the synthesis of coesite under high temperature and high pressure in the condition of adding a certain amount of hard Fe fillings. The synthetic samples are measured by XRD and Raman, and the results show that a small amount of small-sized coesite can be obtained under 2.5 GPa. Based on these results, it is considered that the forming depth of natural coesite under the earth is likely to be obviously shallower than that of plate exhumation in the traditional subduction-exhumation hypothesis.

Abstract: Micro-arc oxidation has become a focus of research on the surface of metal processing. But do not understand the load characteristics of the application of the micro-arc oxidation. In order to get the load characteristics of DC power supply which work in the process of micro-arc oxidation, a muti-waveform frequency sweeping power and DC voltage source series circuit is researched. This method uses the load frequency response can realize the online test load characteristics, load test result is good.