Applied Mechanics and Materials Vol. 372

Abstract: Nanofluids are considered as promising heat transfer fluids due to enhanced heat transfer ability as compared to the base fluid alone. Knowledge of settling characteristics of nanofluids has great importance towards stability of nanosuspensions. Sedimentation behavior of Alumina nanoparticles due to gravity has been investigated using different proportions of ethanol-water binary mixtures. Nanoparticles of 40 nm and 50 nm are used in this investigation at 23°C. Sediment height with respect to time is measured by visualization method in batch sedimentation. The effect of sonication on the sedimentation behavior is also studied using ultrasonic agitator. The effect of particle diameter, nanoparticle concentration and ethanol-water proportion on sedimentation behavior of nanofluids has been investigated and discussed.

Abstract: We evaluated size controllability and size error occurrence in fabrication of ZnO nanopillar pattern by gel-nanoimprint process. The ZnO nanopillar patterning yielding smaller size error than the conventional nanoimprint process was achieved. The UV-O₃ treatment was also proposed to make precise patterning, but we found that this treatment could not hold the nanostructure patterned, though the clear shape could be obtained just after the treatment.

Abstract: Ferric vanadate (FeVO₄) nanoparticles as visible-light photocatalysts were successfully prepared by microwave irradiation method. The structure and morphology of FeVO₄ nanoparticles were charactered by X-ray diffraction (XRD) and scanning electron microscope (SEM). Absorption ranges, which are responsible for the observed photocatalyst behavior, were investigated. Photocatalytic activities of the synthesized samples were examined by studying the degradation of the model dyes Methylene Blue (MB) under visible-light irradiation (400 nm). Various influence factors such as heat treatment temperature of FeVO₄, and solution pH values as well as the amount of hydrogen peroxide and FeVO₄ catalyst on the photocatalytic degradation of MB were discussed. Results clearly show the degradation ratio can reach 99% under the optimal reaction conditions in dye wastewater treatment in a short photocatalytic reaction time.

Abstract: This paper analysis the process of Al2O3 engineering ceramics grinding and study the mechanism of rotary ultrasonic-vibration grinding. Then setting the model of the material removal rate and grinding force, which is based on Creasing fracture mechanics. Results indicate rotary ultrasonic-vibration grinding can apparently improve the material removal rate and cut down the grinding force.

Abstract: The effects of sintering temperatures on consolidation and mechanical properties of 3 mol% Y-TZP (3Y-TZP) powders were studied in this work. Samples were sintered at 1250°C to 1450°C sintering temperature in air. Throughout the sintering regime, high value of relative bulk density 99.41% of theoretical densities was obtained for the maximum sintering temperature. Maximum Young's modulus of 3Y-TZP was obtained at 1450°C and maximum fracture toughness value of 3Y-TZP was observed at the 1300°C sintering temperature. The Vickers's hardness values of 3Y-TZP also increased gradually with sintering temperature.

Abstract: The effect of ZrB₂ content ranging from 10 to 30 wt% on the mechanical properties and electrical resistivity of sintered Y-TZP/ZrB₂ composite was investigated. While ZrB₂ content showed marginal improvement in elastic modulus, the presence of up to 20 wt% ZrB₂ was beneficial in densification and hardness of the composite when sintered at lower sintering temperatures. Significantly higher fracture toughness of all composites compared to monolithic Y-TZP implied that other toughening mechanisms are at work. In spite of the poor mechanical properties, Y-TZP/30 wt% ZrB₂ showed the lowest electrical resistivity at room temperature.

Abstract: In this study oxygen vacancy concentration on 3Y TZP ceramics was compared for sintered and aged samples in air and argon gas atmosphere. The sintering study was conducted over the temperature range 1250°C - 1500°C. Photoluminescence (PL) spectrums of the sintered samples were taken by laser with excitation wavelength 325nm. Two distinctive sharp and broad peaks were observed for the wavelength ~ 615 nm and ~ 580 600nm. The sample sintered at 1250 °C showed higher oxygen vacancy in both atmospheres. At the same time, argon gas sintered sample showed higher oxygen vacancy than air sintered sample. The emission band blue shifted after 1 h ageing for the sample sintered in 1500 °C in both atmospheres. XRD results on 1 hour aged sample sintered in argon gas atmosphere showed higher monoclinic phase than air sintered sample.

Abstract: Sintered bone is composed predominantly of hydroxyapatite (HA), which is a phase of calcium phosphate. The properties of porous hydroxyapatite (HA) produced by heat treatment of bovine femur bone were evaluated over different temperatures between 400oC and 1200oC. The sintered body was investigated by using a number of physicochemical methods such as scanning electron microscopy (SEM), SEM in combination with energy dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD). The XRD results indicate that the annealing process enhanced the crystalline grade of HA phase in the bone matrices particularly when sintered above 700oC. There was no secondary phase formation in bones sintered between 600oC and 1000oC. However, decomposition of HA to form of β-TCP was observed during heating at high temperature which are 1100°C and 1200°C.

Abstract: The surface of the carbide YG6 milling insert was roughened by using three different pretreatment crafts, the diamond films was deposited on the substrate surface, after deposition, the morphology and quality of the diamond films were detected by using the scanning electron microscopy and the laser Raman spectroscopy, the adhesion strength of the membrane-based was discovered by using the method of indentation test. The results showed that: the surface of the substrate had the lower surface roughening with the hydrochloric acid aqueous solution and methanol solution pretreated, in addition the surface of the films had cracks, obviously, the adhesion strength of the membrane-based was unsatisfactory; However, the surface of the substrate had the higher roughening degree with the sulfuric acid hydrogen peroxide solution pretreated, and with good adhesion strength between the film and substrate.

Abstract: Problems biotic attack facades of prefabricated buildings takes particular with regard to given increasing demands and requirements of thermal technique and energy. In the last twenty years, increased demands on thermal properties of exterior walls, increasing the thickness of thermal insulation, additional insulation contact changes prefabricated walls on multilayer circuit design, but at the same time claddings prefab evident adverse side effects in the form of color change in outer surface rendering locally and globally. In this paper are discussed laboratory tests on the sample confirmed the presence of external plaster façade panel biotic attach building, which is equipped with additional contact system.