Applied Mechanics and Materials Vols. 117-119

Abstract: Using metallographic observation and mechanical measurement, metallurgical saw blade made of 8CrV steel was continuously tempered at 300 °C-460 °C.The experimental results demonstrated that: with the increasing tempered temperature, the quenched martensite will transform into the tempered martensite, tempered martensite+tempered sorbite and tempered sorbite; the strength of samples declined continuously but yield ratio increased a little. At about 420°C, the temper brittleness occurred and obvious properties change happened of the samples, such as impact value, reduction area and elongation percent. However, the hardness values enhanced at this temperature.

Abstract: Recently, the forming of thermoplastic composite (TPC) sheets has been receiving the attention of researchers. Woven fabric TPCs have been successfully utilized in automotive, aerospace and defense industries, due to their high formability and strength. Hence, to optimize the forming process, it is essential to understand the mechanical behavior of the woven fabric and accordingly, various appropriate numerical methods are developed. A reliable simulation tool for forming is needed to obtain the optimum processing parameters, in which parts can be formed without defects, such as wrinkles. This paper explores the experimental, numerical and theoretical works conducted by many researchers to investigate the formability of TPC sheets.

Abstract: Use the Monoclinic phase of nano-scale ZrO₂ , Li₂ZrO₃ and MgO as raw materials, with high temperature solid state reaction, we synthesized the Lithium zirconate materials which can directly absorb CO₂ at high temperatures of 450~550°C. Then use the scanning electron microscopy (SEM) and X-ray diffraction (XRD) for the morphology and structure analysis. The CO₂ absorption properties were tested by thermal analyzer (TG). The experimental results showed that the amount of MgO addition affected the Lithium zirconate’s CO₂ absorption properties, but to the pH and surface area, there is on influence.

Abstract: The electrodeposition of cobalt nanoparticles from mixture of 1-butyl-3- methylimidazolium chloride (BMIC) ionic liquid and urea was investigated. The results from the cyclic voltammetry (CV) show that the reduction of Co(II) to cobalt is an irreversible process and controlled by the diffusion of Co(II) on Pt working electrode. The cobalt nanoparticles prepared by direct current (DC) electrodeposition method at 70 °C were characterized by scanning electron microscope (SEM). Test results indicate that the Co nanoparticles are grain-like arrays and link together because of their magnetic property. The average length of these particles is about 100 nm.

Abstract: The wettability between ceramic particles and metal play an important role in fabrication of ceramic particles reinforced metal matrix composites(PRMMCs). In present paper, Al₂O₃ particles were coated with nickel by chemical plating to modify the preparation and properties of Al₂O₃ particles reinforced steel matrix composites. Using the Al₂O₃ particles treated by chemical nickel-plating, Al₂O₃ particles reinforced steel matrix composites were fabricated by powder metallurgy process(PM). And the wear resistance of the composites was investigated. The results show that: the nickel coating can fully and tightly cover on the surface of Al₂O₃ particles, and the nickel coating thickness is uniform about 2~3 micron; The nickel coating can effectively improve the uniform distribution of Al₂O₃ particles in the composites. And the treated Al₂O₃ particles can be tightly bonded with steel matrix,which improve the wear resistance of composites. The wear resistance of composites reinforced treated and untreated Al₂O₃ particles each is 2.5 and 1.6 times of Hadfield steel.

Abstract: Porous alumina containing hydrothermal derived hydroxyapatite (HA) composite were successfully fabricated via protein foaming-consolidation method. Alumina and HA powders were mixed with yolk, starch and darvan 821 A at an adjusted mass ratio to make slurry. The slurries were cast into cylindrical shaped molds and then dried for foaming and consolidation process. Subsequently, the dried bodies were burned at 600°C for 1 h, followed by sintering at temperatures of 1300 - 1400°C for 2 h. The porous alumina-HA composites with pore size in the range of 95-300 µm and density of 2.7 – 2.9 g cm-3 were obtained. Porosity of bodies decreased from 31.7 to 27.6% when sintering temperatures increased from 1300 to 1400°C. The increasing HA-to-alumina mass ratio from 0.2 to 0.8 w/w increased compressive strength of sintered bodies from 2.3 to 10.0 MPa. XRD pattern results show intensity of tricalcium phosphate (TCP) phase increased with sintering temperatures and also found that the sintering process did not alter phases in the porous bodies.

Abstract: Titanate nanotubes were synthesized at various hydrothermal temperatures and reaction times by the hydrothermal process and used as photocatalyst. BET analysis was conducted in order to find out the surface area of these as-prepared samples and it was found that the surface area increases with rise in temperature till 130 oC. Synthesized as-prepared titanate nanotubes were applied on methylene blue degradation from aqueous media by UV irradiation. It was observed that dye removes ~99% from the aqueous media at a titanate nanotubes dose of 2 g/L.

Abstract: Pd nanoparticles have been prepared on the surface of glassy carbon electrode (GCE) by electrochemical deposition method and applied for the nonenzymatic detection of H₂O₂. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were employed to investigate the as-prepared Pd nanoparticles on the surface of GCE. The electrochemical properties of Pd nanoparticles modified GCE were also characterized by cyclic voltammetry and chronoamperometry. The results showed that Pd nanoparticles modified GCE had a favorable catalytic ability for the reduction of H₂O₂ in PBS medium (pH=7.6). At an applied potential of -0.06 V, the nonenzymatic H₂O₂ sensors produce high and reproducible sensitivity to H₂O₂ with 52.45 μA/mmol۰dm–3. Linear responses were obtained over a concentration range from 0.15 mmol۰dm^–3 to 18 mmol۰dm^–3 with a detection limit of 25 μmol۰dm^–3 (S/N=3). Additionally, it exhibited a rapid response time (within 1s), which was much faster than some nonenzymatic H₂O₂ sensors.

Abstract: Pre-tension of filament is critical to the characteristics of solo-sirofil composite yarn. In this paper, solo-sirofil yarns under filament pre-tension of 5-25cN were produced by modified EJM-128K ring spinning frame. The hairiness, breaking strength, breaking work and yarn evenness were tested under standard test conditions. It’s explored that when the pre-tension of filament is 15cN, perform of solo-sirofil achieve the best level with lower hairiness, higher breaking strength and breaking work, and better yarn evenness.

Abstract: Coenzyme Q10 (CoQ10) is a poorly water-soluble active ingredient with intrinsic chemical instability, but holds strongly antioxidative capacity. The CoQ10-NLC aqueous dispersion has been prepared, the antioxidative activity between CoQ10-NLC and CoQ10 cosmetic have been investigated, and several employed methods such as scavenging efficiency on DPPH radical and inhibition of superoxide anion and hydroxyl radical generation illustrated its potentially antioxidative activity. The test results displayed that CoQ10-NLC aqueous dispersion indicated higher antioxidative activity than commercially available CoQ10 cosmetic.