Applied Mechanics and Materials Vols. 395-396

Abstract: Bismuth-based oxides have attractive photocatalytic properties under visible light. Bismuth tungstate(Bi2WO6) particles as a visible light-responsive photocatalyst were prepared by a facile hydrothermal reaction method with the different surfactant assisted using Bi(NO3)3·5H2O and Na2WO4 as raw materials at 180°C for 24h. The as-prepared samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis absorption spectra (UV-vis). The photocatalytic activity of Bi2WO6 crystals was evaluated using the photocatalytic oxidation of rhodamine B (RhB) at room temperature under visible light irradiation. It was found that the morphology and the band gap adsorption edge of Bi2WO6 are different with the different surfactant assisted. The widest band gap energy of Bi2WO6 obtained with SDBS assisted is 2.624eV. In addition, the Bi2WO6 powders exhibit a certain photocatalytic properties to photodegrade RhB and the maximum photocatalytic degradation rate is 32.4% using Bi2WO6 prepared with PVP assisted for 2h.

Abstract: This article will introduce a new type of surface nanotechnology, that is the Surface Nanocrystallization technology by pre-forcing rolling. A nanocrystalline surface layer was fabricated on deposited layer by using pre-forceing rolling technology (PFRT) .The microstructure of treated specimens was characterized by using scanning electron microscopy and transmission electron microscopy. Experimental evidence showed, The technology can form a smooth surface on the parts, so it can be used as the last process of the machining. The equipment has a simple structure, similar to ordinary lathe tool, so can be used in the ordinary lathe or the machining center. Experimental analysis indicated the coars crystal in the surface layer could be refined into nanocrystalline by using the pre-forceing rolling technology, attaining optimizing surface structure of metal parts.

Abstract: Hydroxyapatite coatings with biological activity on magnesium alloy can effectively reduce its degradation rate in the physiological environment. Pre-calcification was applied as the pretreatment in this paper. And then, hydroxyapatite coatings were deposited on the surface of the magnesium alloy in non-magnetic field, near the antarctic and the arctic of a constant magnetic field respectively. The morphology, phase composition and crystal structure of the coatings were analyzed using SEM and XRD. The results show that the crystals of the coatings affected by the magnetic fields are preferential orientation significantly.

Abstract: In this paper, ultrafine Al₂O₃ particles were prepared by mechanical milling, and Ni-P-Al₂O₃ composite coatings were plated on Q235 steel substrates by brush-plating, which plating solutions were containing different concentrations Al₂O₃ particles. The morphology, phase and particle size distribution of the as-prepared Al₂O₃ particles, and the properties of the coatings after heat treatment were investigated. The results show that, the morphology of the as-prepared Al₂O₃ particles were spherical and almost size under 200nm, the coatings were uniformly thickness and the Al₂O₃ particles were uniformly dispersed in the coatings. Heat treatment could improve the performances of the brush-plating Ni-P-Al₂O₃ layers. After 1 hour heat treatment in 400°C, the layer which phosphoric content about 2.3wt% had high rigidity, good abrasion-resistance and adhesion strength, and the layer which phosphoric content about 10.1wt% has good erosion-resistance after 1h heat treatment in 600°C.

Abstract: The photocatalytic waterborne styrene-acrylic coating was prepared by adding different concentrations of homemade TiO₂ transparent emulsion and nanometer TiO₂ powders into styrene-acrylic emulsion. The adhesion, elastic, hardness, impact resistant properties of the film were measured and photocatalytic properties of the film were investigated through the degree of degradation of Rodamine B. The results showed that the photocatalytic properties of coating with homemade TiO₂ transparent emulsion were better than that of nanometer TiO₂ powders, and it does not affect the mechanical properties of the coating.

Abstract: The heat generating mechanism inside the cavity of rolling bearing is analyzed and the convective heat transfer coefficient of bearing raceway surface in different rotational speed is calculated under the oil-air lubrication and the spray lubrication in this paper. The fluid domain geometry model of deep groove ball bearing SKF6208 is established, employing the flow field module in Workbench. The comparing simulations of the temperatures of rolling bearing cavity under the oil-air lubrication to the spray lubrication are done in different rotational speed. The simulation results show that the highest temperature of bearing cavity with the oil-air lubrication is almost the same to the spray lubrication when the bearing rotational speed is lower, and the highest temperature of bearing cavity with the oil-air lubrication is far lower than the spray lubrication when the bearing rotational speed is higher. Those conclusions verify the advantages of the oil-air lubrication in high rotational speed.

Abstract: This paper proposes the third generation wavelet--double tree complex wavelet (DT-CWT) transformation used in nanometer roughness rating, based on the explanation of the shortcomings of the current nanometer roughness rating reference and conventional three dimensional datum evaluations due to the insufficient study. The experiment got porous anodic alumina film as the object of surface roughness of nanotechnology study. Through the comparisons of the three generations of the wavelet reconstruction after the maximum reconstruction error, a conclusion can be made that the superiority of DT-CWT in application is very obvious, a result meeting the16% principle of the surface roughness rating on the bases of DT - CWT extracted datum to compute income parameters, which indicates the feasibility of this application to the extraction of the nano3-D roughness evaluation. Keywords: nanometer roughness;dual-tree complex wavelet;three dimensional datum

Abstract: Experimental research was carried out to analyze the wear patterns of several tools which include high-speed steel (HSS), coated cemented carbide and ceramic tools, and to study the tool wear mechanism in milling resin sand mold materials. The main wear mechanism is abrasive wear and the dominant tool failure mode is flank wear. Different cutting parameters have different influence to the tool wear. In addition, it is essential to select suitable tool material with appropriate hardness. In this paper, the experiment results are contributive to choose proper cutting tool materials and parameters in milling resin sand mold material.

Abstract: The paper presents a failure analysis of tower axle in the water tank wire drawing machine. Material of the tower axle is 40Cr steel. In order to analyze the failure reasons of tower axle in the water tank wire drawing machine, we take experimental means such as morphological analysis, mechanical property testing, micro-metallography and scanning electron microscopy (SEM) of fracture observation, etc. The results show that the fracture of tower axle belongs to brittle fracture. The content of inclusions is more, and the composition is complex in the material. The heat treatment technology is improper. Improper quenched and tempered processing technologies cause more reticular and blocky ferrite in the steel. These are the main reasons for fracture of the tower axle.

Abstract: This paper aims to develop a method to identify the damage location in circumference direction of a pipe using mode transformation of longitudinal guided wave. The corrosion-like damage in bimetal pipe is considered. Case study that damage detection for a bimetal pipe is used to show the validity and advantage of the proposed method. It can be found that the axially symmetric mode guided wave encounter the damage and the three modes were received in reflection. The damage location in circumferential directions could be identified by conversed modes measured at one position. The simulation shows a good performance.