Solid State Phenomena Vol. 319

Abstract: Thermal conductivities of silicone rubber filled with Al₂O₃ were prepared. Thermal conductivity experimental results obtained were analyzed using the Nielsen and Agari models to explain the effect of Al₂O₃ filler on the formation of thermal conductive networks. Thermal conductivities increased with the adding of mixed Al₂O₃ of large and small sizes fillers. The scanning electron microscopy (SEM) showed that it is the optimum particle sizes and quantities that made the filler packing closer, which thus leads to formation of more thermal conductive chains.

Abstract: This paper investigates the post necking phenomenon in mild steel using six different hardening laws (Hollomon, Swift, Ludwik, Ghosh, Voce and Hockett-Sherby) by extrapolation method. This is carried out through the finite element simulation on tensile deformation of a mild steel specimen under quasi-static condition. Reference flow curves are obtained analytically and found helpful for the numerical simulation. The material parameters of the above hardening laws are evaluated by curve fitting method based on the pre necking experimental data and their suitability is examined before and after necking.

Abstract: Tensile, compressive and flexural (3-point bending) tests are performed on electromechanical universal testing machine (Zwick/Roell 250kN) to determine mechanical characteristics of an aluminium hybrid composite fabricated through stir casting process at different rates of quasi-static loadings in room temperature 25°C. Influence of heat treatment (annealing) is observed on the material properties. After annealing, the tensile, compressive and flexural strengths decrease while ductility, malleability and bending capability of the composite increase. Bending tests are conducted at different crosshead speeds (1-100mm/min) to study its effects on flexural stresses. It is found that the specimen geometry affects the stress-strain behaviour of the composite.

Abstract: Taguchi method is applied to optimize the compositions of Al-Mg-Ti-Cu-SiC hybrid composites for maximum wear resistance. Wear tests are performed on a pin-on-disc machine under a constant load of 3 kg on specimens of above composites prepared using Taguchi L9 orthogonal array through stir casting route. Each test is conducted for 30 minutes at disc rotational speed of 600 rpm. The contribution of each constituent is evaluated using ANOVA. Linear and quadratic regression models are also developed. The predicted results by these models are very close to the experimental results. It is found that Taguchi method is very successful in the optimization of particulate reinforcements (Mg, Ti, Cu and SiC) in the composites for maximum wear resistance.

Abstract: Radiological characterization of tuff of Ciglio area in Ischia Island was performed to assess the potential radiological hazard associated with its use. For this purpose, high resolution gamma-ray spectroscopy was used. In five green tuff samples was measured the activity concentration of natural gamma-ray emitting radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K so, the mean gamma index was calculated. The mean value of the gamma index resulted lower than the reference level and it meets the dose criterion for the safety use of green tuff as building material.

Abstract: LiFePO₄ (LFPO)-based composite cathode was deposited on Li_0.35La_0.55TiO₃ (LLTO) solid electrolyte via slurry coating method. A composite cathode comprising of LiFePO₄, LLTO, and carbon black (CB) were mixed together in a slurry and deposited on a dense LLTO pellet substrate. The effects of heat treatment temperature and hot-pressing in the structure and densification of the deposited composite cathode were investigated. Cathode component precursors were analyzed for its particle size distribution using particle size analyzer and revealed a bimodal particle size distribution for each component materials. Structural characterization using X-ray powder diffraction (XRD) analysis revealed that distinct XRD peaks were observed which can be attributed to LFPO and LLTO for the deposited as-dried and heat treated (450 °C ) composite cathodes. Surface and cross-sectional SEM images revealed that hot-pressing provided denser morphology with smaller thickness as compared to the just as-dried and heat treated samples without the application of temperature with pressure.

Abstract: This paper presents a study of parameters that effect to width of chocolate line based on additive manufacturing and screw based extrusion. In order control a width of chocolate extruded lines for constructing chocolate model, three pitch of lead screw, three distances between nozzle and workspace, and three extrusion rates are assigned as independent variables. The result was showed that those three independent parameters were affects to width of extruded chocolate line. When the pitch of lead screw and the chocolate extrusion rate were increased, the width of the chocolate width had been expended. Moreover, if the distances between nozzle and workspace was increase, the chocolate width had been narrow.

Abstract: One component room temperature vulcanized (RTV) silicone resin was prepared by combination of a kind of polydimethylsiloxane-b-phenylsilsesquioxane copolymer with crosslinker and catalyst. The effects of feeding order on properties of cured silicone resin were studied in detail. When hydroxyl terminated polydimethylsiloxane was added in three times and the D/T ratio was 2.0~2.3 during synthesis, the cured resin with the hardness over 20Shore D had the better elastic-plastic properties and heat resistance than the other two feeding orders. The tensile strength was over 3MPa and the elongation at break was above 75%. The T_d5% was 416.6°C.The silicone resin also had good radiation resistance. At the radiation dose of 1500kGy, there was no obvious defect observed in the material, and the tensile strength increased to 6.83MPa, while elongation at break decreased to 26%.

Abstract: The global warming phenomenon has led to world climate change caused by high concentrations of greenhouse gases (GHG) especially carbon dioxide (CO₂) in the atmosphere. Carbon dioxide is produced in large quantities from fuel combustions, gas sweetening processes, etc. Since its emission rises annually, some efforts to reduce the emission are, therefore, required. Monoethanolamine (MEA), a primary amine, has been widely used for many years for acid gas removal. To get a better column performance, an accurate physical properties measurement, such as density, needs to be conducted. This study aims to measure the densities of 10 wt.% MEA aqueous solutions at temperatures from 10 to 90 °C and CO₂ loadings up to 0.417 mol CO₂/mol MEA. The results show that the higher the concentration of CO₂ the higher the density at a constant temperature, while the densities decrease as temperatures increase due to volumetric expansion. Besides, an expression to correlate the densities of 10 wt.% MEA aqueous solutions was also developed based on the pure-component molar volumes together with the excess molar volumes. The average error of the measurement was found to be 0.18%.