Applied Mechanics and Materials Vols. 268-270

Abstract: In this study, we conducted experiments to investigate the electrical and optical characteristics of a non-equilibrium Ar-N2 plasma discharge at atmospheric pressure. To obtain the plasma discharge we used our indigenously designed plasma generating device named CAPPLAT (Cold Atmospheric Pressure Plasma Torch) which was manufactured by Cresur Corporation. The plasma discharge obtained with only Ar gas was quite filamentary. So, to achieve a homogeneous discharge N2 gas was admixed. The effects of different volumes of admixed N2 gas were also studied. The optical emission spectroscopy was used to study the active charged species in the plasma discharges. The further increased volume of N2 gas further suppressed the emission intensity of Ar metastables but at the same time the emission intensity of the second positive system of nitrogen molecules (N2(C3Πu) enhanced significantly. It can be concluded that in Ar- plasma discharge, argon metastables are the main energy carriers but when N2 gas is added to the feeding gas (Ar) for plasma generation, the second positive system of nitrogen molecules (N2(C3Πu) become the main energy carriers. On the other hand the addition of the N2 gas doesn’t change the electrical characteristics of plasma discharge significantly. To identify the effectiveness of the CAPPLAT as a tool for sterilization, highly environmental stress resistant bacterial (Bacillus subtilis) endospores were treated for different durations. We could successfully deactivate the population of 1.0X107 to 4.0X107 Bacillus endospores/ml. The details of this experiment are discussed in our next paper.

Abstract: Using finite element method, the residual stress distribution of TIG dressed welded toe followed by chilling treatment with different temperature of steel and aluminum alloy T-joint was calculated. And the residual stresses of welded toe were also measured by using the blind-hole method. The results indicate that with the increase of initial temperature of chilling treatment, the longitudinal residual stresses in welded toe of steel joint are gradually transited from tensile residual stresses to compressive ones, and there is no significant change for transverse residual stresses; and the longitudinal residual stresses in welded toe of aluminum alloy joint are compressive stress and gradually increased, no significant change for transverse residual stresses.

Abstract: The paper focuses on the high-temperature oxidation of a crude oil in a forward in-situ combustion process. The reaction conforms to Arrhenius prescription. Based on Semenov’s definition of ignition, equations for calculating the ignition temperature and stable combustion temperature are derived from the heat balance of the high-temperature oxidation. With previous experimental data, an average empirical parameter of the equations is calculated and two predictive equations are got. It’s concluded from the equations that these two temperatures of the reaction are only dependent on crude properties, and other factors in the reservoir have little influence on them.

Abstract: The effects of alkali charge on the activity and stability of copper-based mixed oxides catalyst for the water-gas shift reaction (WGSR) were investigated. Activity tests showed that the copper-based mixed oxides catalyst while the 2[NaOH]/[Cu²⁺+Mn²⁺] is above 1.2 displayed higher activity and better stability than that of others catalysts. The BET , XRD and TPR results revealed that the Cu-Mn catalyst while the 2[NaOH]/[Cu²⁺+Mn²⁺] is above 1.2 led to higher surface area, a more stable catalyst structure and suitable reduction performance, in turn leading to better catalytic behavior for the Cu-Mn catalyst.

Abstract: The paper studied the time depended crystallinity in a PE cast during the cooling process in mold. According to the competition theory between crystallization and its decomposition in HDPE polymer, a thermodynamic model and the differential equation for crystallization by cooling HDPE polymer was set up. A deference method was applied to solve the differential equation. The temperature and crystallinity were given in form of contour lines for an axial symmetric thick workpeace, and criterion based on the surface crystallization was proposed to determine the correct stripping time in a casting process. The model and the method are capable of calculating temperature and crystal concentration at any time and any mass point in a cast body, and are helpful for the choice of appropriate casting technology.

Abstract: Liaohe oil field block 58 for Huancai, the efficiency of production of thickened oil is low, and the efficiency of displacement is worse, likely to cause other issues. Researching and developing an type of Heavy Oil Viscosity Reducer for exploiting. The high viscosity of W/O emulsion changed into low viscosity O/W emulsion to facilitate recovery, enhanced oil recovery. Through the experiment determine the viscosity properties of Heavy Oil Viscosity Reducer. The oil/water interfacial tension is lower than 0.0031mN•m-1, salt-resisting is good. The efficiency of viscosity reduction is higher than 90%, and also good at 180°C.

Abstract: We have developed a new, simple, green and very reproducible aqueous synthesis method for the preparation of different sizes CdTe QDs without the use of any pyrophoric organometallic precursors. Transmission electron microscope image demonstrates the shape, monodispersity, average size and size distribution. Two different sizes CdTe QDs are mixed and standing for three months in aqueous solution. Through UV-Vis absorption spectroscopy and fluorescence spectrum detection, we confirm Ostwald ripening process can also occur in CdTe QDs mixed solution for a long time at room temperature.

Abstract: In the presence of alkaline catalyst NaOH,the cationic corn starches bearing quaternary amino group with high degree of substitution are prepared by the reaction of the starch with 2, 3- epoxy propyl trimethylammonium chloride (ETA) in aqueous solutions.Under the conditions of molar ratio anhydroglucose/ETA/alkali =1: 4.0: 0.2025, reaction temperature 60°C and reaction time 6h, degree of substitution of the product is 1.0959. Structure of the product is characterized by FTIR and 13C NMR spectroscopy.X-ray diffraction indicates that the crystal structure of the native starch is destroyed and disordered structure of cationic starch is formed.

Abstract: In order to enforce explosion energy and mechanical strength of energetic material. we use physics and chemistry property of aluminum fire to improve the performance of energetic material. Before explosion the physics property of mechanical property can reinforce the mechanical strength; when explosion the reaction heat of aluminum can increase the energy of explosive. The air blast experimental results indicated that Al fibre can increase the energy of energetic material.. And the same time mechanical strength experimental results indicated that aluminum can enhance the strength of energetic material.

Abstract: Dry machining is an eco-friendly machining process and its importance in the manufacturing industries should be taken seriously. Machining without the use of any cutting fluid is becoming increasingly more popular due to concerns regarding the safety of the environment and reducing cost. Dry and wet turning of T6061 aluminium alloy was performed on a lathe by using Silicon Nitride (Si3N4) inserts as the cutting tool. Tool wear behaviour of Si3N4 cutting tool were studied with the aim of finding the optimum cutting conditions for both dry and wet machining. Machining was performed at four different cutting speeds; 292, 388, 518 and 689 m/min using two different cutting parameters (feed rate, f = 0.2 mm/rev, depth of cut, d = 0.1 mm and f = 0.4 mm/rev, d = 0.2 mm). Material removal rate (MRR) was also obtained and the temperature at the tool-chip interface were measured using an infrared (IR) thermometer as to see the effect of temperature rise during machining. Dry machining with smaller cutting parameters resulted in lower wear rates by 37 to 48% for all four cutting speeds. Nevertheless, reduction of wear rate by 38 to 57% was found from wet machining. The optimum cutting speed for both dry and wet machining of T6061 aluminium alloy using Si3N4 cutting tool was found to be 518 m/min for both cutting parameters. However, the optimum cutting parameters are apparently with the feed rate of 0.4 mm/rev and depth of cut of 0.2 mm. At the optimum cutting speed, the tool tip temperature for dry machining was higher than wet machining by 40 and 51% for f = 0.2 mm/rev and f = 0.4 mm/rev respectively. Dry machining of T6061 Aluminium alloy can be more suitable particularly at higher cutting speed with interrupted cutting operations.