Applied Mechanics and Materials Vols. 651-653

Abstract: The demand for weight reduction in automotive industry has generated great interest in research and development of magnesium applications, especially for powertrain components. Recently, the squeeze casting process is increasingly used on magnesium alloys mainly because of their great ability of eliminating the porosity in the castings. In this study, the effect of hexachloroethane (C₂Cl₆) as a grain refiner added into the squeeze casting AM60 magnesium alloys was investigated. The results of thermal analysis and microstructural analysis indicate the occurrence of heterogeneous nucleation of primary magnesium during solidification. The microstructural analysis suggests that the nucleation behavior of C₂Cl₆-treated AM60 alloy may be attributed to the increase in nuclei and nucleation rate during the solidification of the magnesium alloy.

Abstract: With installed capacity increase of China's coal-fired power plants year by year, the emissions of in flue gas increase year by year, sulfur dioxide pollution of the atmosphere has increased year by year at the same, so strengthen the control of coal-fired power plant emissions of is imperative. Based on the experience of typical coal-fired power plant desulfurization technology and desulfurization, limestone/gypsum wet flue gas desulfurization equipment simulation system has been established. The influence factors of limestone-gypsum wet flue gas desulfurization are once studied.

Abstract: 6005A extruded aluminum with good heat resistance, corrosion resistance, weldability, also has a relatively high strength, good overall performance, designed to meet the speed requirements of the body. Optional 6005A-T5 aluminum alloy sheet be 11 kinds of process parameters laser - arc hybrid welding, by comparison, select standardized test results carried out to optimize weld joints microstructure, mechanical properties of weld performance analysis.

Abstract: Welding at high humidity is frequently needed for the harbor hoisting machinery of steel structures in the coastal port city. A computational procedure is proposed for analyzing residual stress and temperature distributions induced by the T-joint welding in two types of St52-3 high strength low alloy steel plates both 6 mm in thickness. The relative humidity conditions varied from 75 to 90% at constant pressure. The finite element models are employed to evaluate the transient temperature and the residual stress during welding. According to the analysis results, the higher residual stress and the highest concentration of hydrogen are distributed in and surround the heat affected zone (HAZ), and vary with different humidity.

Abstract: A variety of modification approaches such as cross-linking and blending have been explored to prepare efficient membranes based on SPEEK. The addition of inorganic filler is also one of the most widely used approaches to modify the SPEEK because inorganic additives can withstand relatively higher temperatures than virgin polymer. Different inorganic fillers are used to alter the properties of neat polymer.

Abstract: The polysilazane synthesized by aminolysis of dichloromethylviny was coated on kapton by dip-coating method, the AO exposure tests was carried out in a ground-based AO simulator. It is found that the erosion yield of kapton was decreases by about two orders of magnitude. After exposure the coated katpon still have a smooth surface, and its optical properties are still at a high level. The polysilazane coating exhibits a superior AO erosion resistance.

Abstract: Cutting deformation mechanism of hardened steel has been studied. The influences of the cutting parameter for the chip roots have been researched with single factor testes. The influences of the per tooth feed rate and cutting speed for the shear angle and shear strain also have been obtained by lots of trials, choosing more appropriate axial depth of cut and radial depth of cut.

Abstract: Depth of evaluation method of surface crack in laser cladding coating with metal magnetic memory was introduced in this paper. Laser cladding coating specimen were degaussed, placement direction of specimen and detection direction unchanged, detection speed and lift off value of probe were the constant. Results show that gradient value of H_p(y) signal corresponding to surface crack increases as tensile load increases under the same depth of surface crack, gradient value of H_p(y) signal corresponding to surface crack increases as depth of surface crack increases under the same tensile load. Orientation of internal magnetic domain changes as tensile load changes and magnetic leakage field caused by surface crack are seen as two main reasons for above results. Using fitting method with quadratic polynomial, depth of surface crack in laser cladding coating can be evaluated nondestructively in this paper.

Abstract: Wear tester UMT-2 was used to study the friction wear characters of galvanized sheets under dry friction and oil lubrication. Three-dimensional morphology instrument WYKONT11 was used to observe the width and maximum depth of wear scars, surface roughness and surface topography. Energy Dispersive Spectroscopy (EDS) analysis of zinc coating compositions and tests of micro hardness were carried out. Then, the friction wear mechanism of galvanized sheets was preliminary discussed. The experimental results indicate that, under dry friction, galvanized sheets experience three stages: run-in wear, abrasive wear and adhesive wear. Meanwhile, zinc coatings exfoliate until they lose efficacy. Good lubrication is propitious to protect zinc coatings and it can reduce friction wear. The research results can provide guidance for formability analysis and mold design of galvanized sheets.

Abstract: In this paper, multiple-walled carbon nanotubes (MWCNTs) monolayer film and MWCNTs-polyvinylpyrrolidone (PVP) composite films were fabricated on interdigitated electrodes (IDEs) by airbrush technology, respectively. Response performance of all the sensors to various concentrations of vapors including methanol, ethanol, acetone, tetrahydrofuran, water and 1,2-dichloroethane were investigated. The results showed that a larger sensing response was obtained for the composite films compared with the MWCNTs monolayer film. Moreover, the MWCNTs-PVP composite films had a good selectivity for 1,2-dichloroethane vapor.