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61.
《Fusion Engineering and Design》2014,89(11):2635-2641
Deuterium recovery from water–isotopes mixture using thermal diffusion can be improved by employing the branch column device, instead of single column devices, with the same total column length. The remixing effect due to convection currents in a thermal diffusion column for heavy water enrichment is thus reduced and separation improvement increases when the flow rate or the total column length increases. The improvement in separation can reach about 50% for the numerical example given. 相似文献
62.
《Materials and Manufacturing Processes》2012,27(3):309-314
ABSTRACT In the present paper the influence of solution temperature 450–550°C on microstructure and mechanical properties of cast Al-12%-0.3% Mg and Al-16%-0.3% Mg alloys has been reported. It was observed that an increase in solution temperature increased the tensile strength of all alloys under investigation. Ductility was adversely affected. Higher solution temperature produced better refinement and distribution of eutectic silicon crystals than a low temperature. Heat treatment of all alloys showed spheroidization of eutectic silicon crystals. Scanning electron microscopy (SEM) of tensile-fractured surfaces was carried out to investigate the influence of solution temperature on the mode of fracture. 相似文献
63.
《Materials and Manufacturing Processes》2012,27(3):366-369
The size of nano particles of ferrites synthesized using low-temperature procedures is sensitive to the chemical reactions. At times, the intermediary stages of chemical reactions remain subtle. It is because of the rate of reactions being fast. Some chemicals which take part in the reaction are playing an autocatalytic role. The understanding of the role played by such reactants is essential for having the control on the reaction and growth size of the particles of the product. FTIR spectroscopic analysis along with DTA can play still a substantial role in the synthesis of nano particles. In this article, the successful use of sol-gel technique with citric acid as the catalysis is analyzed using FTIR and TGA. The individual stages of reaction are explained. 相似文献
64.
《Materials and Manufacturing Processes》2012,27(2):168-173
Laser beam welding of C–Mn steel plates with Ni powder filler metal has been performed. Metallography samples of the welded cross-section have been observed by scanning electron microscopy (SEM) and submitted to energy dispersive spectroscopy to obtain Ni concentration profiles. On the basis of the experimental results, neural networks have been carried out. These networks were first validated and then utilized to foresee Ni concentration along the welded thickness. The objective of obtaining the best Ni penetration and minimizing powder loss was reached optimizing, by numerical simulation, process parameters, such as powder rate and joint geometry. 相似文献
65.
《Materials and Manufacturing Processes》2012,27(4):497-503
This article deals with an experimental investigation into the different cutting factors which influence the machinability factors such as cutting force, cutting temperature, and tool life during high speed turning of superalloy Inconel 718. Also the article aims to study the relationship of cutting parameters with respect to the tool–chip contact length and chip microstructure. A standard K-type (alumel/chromel) thermocouple was embedded in to the top shim of the tool holder to measure temperature during turning. The test results show that there exist a close relationship between the cutting parameters and tool–chip contact length, thermal loading equivalent, and chip microstructure. In particular, it was observed that by the proper selection of cutting parameters the cutting force, cutting temperature and tool life can be controlled to the great extent. Also by selecting the proper cutting parameters, the tool–chip contact length can be controlled effectively so as to reduce the temperature which is responsible for rapid tool wear (flank wear) and plastic deformation of the cutting edge. The cutting parameters greatly affect the microstructure grain orientation of the chip. 相似文献
66.
《Materials and Manufacturing Processes》2012,27(6):637-643
The current work presents a detailed study on the high temperature processing of solution treated Al–Mg–Si alloy in the temperature range of 623 K to 773 K and at different strain rates in the range of 5 × 10−5 to 6 × 10−2 s−1. A constitutive relation that can be used in modeling the forming process of this alloy under similar hot working conditions is established. Also, the prevailing deformation mechanism was investigated through relations of the steady state stress dependence on strain rate which revealed a stress exponent of 8.5 (strain rate sensitivity; m ∼ 0.12). This stress exponent is higher than what is usually observed in Al and Al–Mg alloys under similar experimental conditions. This high stress exponent may arise from the presence of threshold stress that results from dislocation interaction with second phase particles (Mg2Si), precipitating during the deformation at high temperatures. The values of threshold stress showed an exponential increase with decreasing temperature and a dependence with an energy term Qo = 38 kJmol−1. The apparent activation energy for solution treated condition was calculated to be about 320 kJmol−1, which is higher than the activation energy for self-diffusion in Al (Qd = 143 kJmol−1) and for the diffusion of Mg in Al (115–130 kJmol−1). By incorporating the threshold stress in the analysis, the true activation energy was calculated to have a value of 111 kJmol−1, and the normalized strain rates can be represented by a power function of the effective stress with stress exponent of ∼3. Ductility was documented to reveal the best working condition for this alloy in solution treated condition. The ductility exhibited a maximum value of about 120% at 773 K at a strain rate of 0.064 s−1. The results of the current work is, also, compared to the results of another heat treatment condition (T4-naturally aged) to reveal which ever condition holds better hot forming characteristics. 相似文献
67.
《Materials and Manufacturing Processes》2012,27(5):489-493
Powders of K0.5Na0.5NbO3 (KNN) were prepared by the Polymerized Complex Method (PC method), based on the Pechini-type reaction route. The crystallization process of KNN during the calcination of an amorphous precursor was observed, using TG-DSC analysis and X-ray powder diffraction. After calcination the powders were ball milled, pressed into pellets, and sintered at 1100°C, which is lower than the sintered temperature of the conventional solid-state method. Using this procedure, we achieved relatively high-density and very homogeneous KNN ceramics. The electric properties of the ceramics were investigated. The results showed that these values are superior to those of sintered KNN ceramic counterparts made by the conventional solid-state method. 相似文献
68.
《Materials and Manufacturing Processes》2012,27(1):31-37
A genetic algorithm-based analysis for the primary microstructural requirements of optimal transformation induced plasticity (TRIP) behavior of the multiphase steel is attempted. Design of primary multiphase microstructure of steel for maximum TRIP effect is perhaps the most important job in TRIP-aided steel design. The quantitative and qualitative control over the complex composite behavior of the different constituent phases present in these steels such as polygonal ferrite, bainitic ferrite, and martensite–austenite constituent is still a challenging task. In this work, the tensile behavior of the steel has been simulated using pertinent models proposed earlier. Necessary assumptions are made using domain knowledge to generalize the tensile model for the considered realm of the problem. Based upon the conflicting nature of the tensile strength and ductility of the steel, the problem is considered here as multiobjective optimization problem. The optimization constraints are inherently taken care by the typical formulation of the problem. The Pareto front results are found quite convincing for TRIP-aided steel design. 相似文献
69.
《International Journal of Pavement Engineering》2012,13(4):229-240
This paper documents and discusses an investigation into the time–temperature superposition principle as it relates to ductile failure in asphalt. Seven binders of approximately the same low and intermediate temperature and varying high temperature Superpave® grades were tested in a dynamic shear rheometer (DSR) and double-edge-notched tension test to determine their rheological and failure energy master curves. Master curves typically permit the prediction of rheological properties at very long or short timescales from measurements at higher or lower test temperatures over more accessible testing timescales. It has been suggested in the Strategic Highway Research Program final report A-369 that rheological shift factors obtained from a DSR experiment can be used to predict failure master curves from experimentally accessible data at various temperatures. The findings of this study suggest that this substitution is not generally accurate. For straight asphalt binders the difference can be relatively small but for more highly modified materials serious errors would be introduced. 相似文献
70.
《International Journal of Pavement Engineering》2012,13(1):19-31
The reliability issues in bituminous pavement design, based on mechanistic–empirical approach, have been discussed in this paper. Variabilities of pavement design input parameters are considered and reliability, for various proposed failure definitions, of a given pavement is estimated by simulation as well as by analytical (first order second moment) method. A methodology has been suggested for designing a bituminous pavement for a given level of overall reliability by mechanistic–empirical pavement design approach. 相似文献