Abstract: Copper mould spray casting and aging treatment were performed to investigate the microstructure evolution of a Ni-base superalloy. With increasing the cooling rate during solidification, the morphology of primary γ phase changes from coarse dendrite to fine dendritic structure with radial-like feature, accompanied by the inhibition of γ′ phase due to the shortened period during the subsequent solid state transformation process. After aging treatment, both the size and volume fraction of γ′ phase are increased with prolonging the isothermal time, which generate the morphology transition of precipitates from irregular and spherical to ellipse and rectangle due to the competition between the interface energy and strain energy.
Abstract: In this paper, the mechanical properties of glass fiber reinforced unsaturated polyester resin composite panels were investigated. To understand the effect of chopped strand mats on the mechanical properties of the composites, specimens with certain volume fraction of chopped strand mats manufactured by Vacuum Infusion Molding Process (VIMP) and Hand Lay-up techniques were tested under tensile, bending and impact loadings respectively. It was observed that the chopped strand mats enhanced effectively the mechanical properties of the composite panels manufactured by Hand Lay-up method, while the mechanical properties of the composite panels manufactured by VIMP decreased.
Abstract: The effects of 3Z2B addition on the microwave dielectric properties and the microstructures of (1-x)(Mg0.95Co0.05)TiO3-xCa0.6La0.8/3TiO3 ceramics prepared with conventional solid-state route have been investigated. Doping with 3Z2B can effectively promote the densification and the microwave dielectric properties of (1-x)(Mg0.95Co0.05)TiO3-xCa0.6La0.8/3TiO3 ceramics. It was found that (1-x)(Mg0.95Co0.05)TiO3-xCa0.6La0.8/3TiO3 ceramics can be sintered at 1150°C due to the liquid phase effect of 3Z2B additions observed by SEM. The Q×f value of (1-x)(Mg0.95Co0.05)TiO3-xCa0.6La0.8/3TiO3 ceramics decreased with increasing 3Z2B content. At 1150°C, 0.9(Mg0.95Co0.05)TiO3-0.1Ca0.6La0.8/3TiO3 ceramics with 1.0wt% 3Z2B addition possesses a εr value of 22.6, a Qf value of 49,000 (GHz) and a τf value of-10.7 ppm/°C.
Abstract: The electrostatic field distribution of interdigitated electrode piezoceramics (IDEPZT) and piezoelectric fiber composite (IDEPFC) are analyzed by finite element method separately. The impact of the interdigitated electrode asymmetry on the actuation performance of piezoelectric actuators with a certain interlayer thickness is studied. The influence of the interdigitated electrode asymmetry on the actuation performance, stress concentration and electrostatic field concentration with different interlayer thicknesses are also discussed and compared. For piezoceramics, the results show that the actuation performance can be influenced little by increasing the degree of the excursion with a relatively thin interlayer thickness. As the interlayer thickness increases, the actuation performance can be influenced much by increasing the degree of the asymmetry. And it results in the decrease of the longitudinal free strain overall. The electric field becomes increasingly uneven as the degree of the asymmetry increases. The actuated stress can be improved evidently by increasing the degree of the asymmetry with a relatively thin interlayer thickness while the stress concentration is not increased apparently.
Abstract: Unimorph cantilever is widely used in many applications with its bending and tip-deflection. In this paper, a model of the cantilever with the applied voltage and tip-deflection is presented. With the use of this model, a prototype, fabricated by VHB and polycarbonate, is estimated for its bending tip-deflection under a high voltage. And the experiment system is established with a signal generator, high voltage amplifier and laser displacement meter. The experimental results and the theoretical ones are both the same. The conclusions in this paper can be used to make further research on the deformation control of structures.
Abstract: The low-cycle fatigue behaviors of as-extruded and T6 treated Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloys at room temperature have been investigated under those total-strain amplitudes ranged from 0.3% to 1.0%, and the influence of T6 treatment on the low-cycle fatigue properties of Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloy was clarified. The experimental results show that during fatigue deformation, the significant cyclic strain hardening and stable cyclic stress response can be noted for both as-extruded and T6 treated Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloys. The fatigue life of as-extruded Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloy at all strain amplitudes is longer than that of the alloy subjected to T6 aging treatment. The relationship between both elastic and plastic strain amplitudes with reversals to failure shows a monotonic linear behavior, and can be described by the Basquin and Coffin-Manson equations, respectively. The T6 treatment can significantly increase the cyclic strain hardening exponent and cyclic strength coefficient of extruded Al-6Zn-2.5Mg-2Cu-0.1Zr-0.1Sc alloy.
Abstract: Molecular imprinted polymer micrcosheres (MIPMs) were prepared through precipitation polymerization by henriol C using as the template molecule. The morphologies of synthesized MIPMs were characterized by scanning electronmicroscope (SEM). Systematic investigations of the influences of key synthetic conditions, including functional monomers, cross-linkers and porogens, on the morphologies, yields and the recognition properties of the MIPs were conducted. The results indicated that the morphologies of MIPs with DVB as cross-linker was perfect, but their binding affinity is lower than that of MIPs with TRIM or EDMA as cross-linkers. And particle size of MIPs with TRIM as cross-linkers is small but with high binding affinity. Scatchard analysis revealed that the homogeneous binding sites were formed in the polymers. The application of MIPs with high affinity and excellent stereo-selectivity toward henriol C in solid-phase extraction (SPE) column might offer a novel method for the enrichment and determination of sesquiterpenoids in the traditional herbal medicine.
Abstract: Rapid reduction roasting of low grade manganese carbonate ore by coal and biomass fuels from Hunan, China was investigated. Magnetic separation behaviors and magnetic properties of raw manganese ore and roasted manganese ores were analyzed. After reduction by coal and biomass fuels, the manganese ores demonstrate a new Mn-Fe oxide phase, showing obvious mixed magnetic behaviors of ferromagnet and paramagnet, and the magnetic susceptibilities of roasting ores rapidly increase to almost two orders of magnitude in comparison of the raw ores. The results show that magnetizing roasting technology could enhanced the magnetic properties of the manganese ores about two orders of magnitude higher than raw manganese ore at low roasting temperature. Thereby, we deduce that the weak magnetic separation combined with high magnetic separation could be adequate for roasted manganese ore to satisfy the requirement of electrolytic manganese industry. Application of biomass in manganese ore roasting process is promising to the effective use of biomass and for decreasing the consumption of fossil fuels in the manganese industry.
Abstract: A cylinder of Carbon Steel S45C with a ferrite and pearlite structure was analysed to improve the hardness and surface layer as well as the toughness. Accordingly, it is important to undertake a heat treatment process for the hardness and surface layer of this steel. The heat teatment process was carried out using induction heating with five different temperatures of 800°C, 900°C, 1000°C, 1100°C and 1200 °C followed by water quenching with certain cooling speed. The chemical compositions and microstructures of these samples were characterized by spectrometer and optical microscopy. The microhardness of the samples was measured and the surface treatment of the samples was examined using an induction heating furnace. The results showed significant case depth and surface hardness as well as microstructure with martensite and retained austenite that is hard and brittle because of internal stress. Further, to reduce the amount of retained austenite and internal stress, it is necessary to carry out tempering of 300°C, 500°C and 700°C in order to produce toughness of the steel with slightly reduce in hardness.