Advanced Materials Research Vols. 291-294

Abstract: Presented paper deals with investigation of selected ternary oxidic system with high content of silicates from the viewpoint of surface properties. Research was focused not only on experimental investigation, but mostly on theoretical modelling of surface tension. This approach was chosen due to absence of compact set of information from the area of heterogeneous processes at high temperatures. It is moreover very often difficult to access appropriate data. Surface properties were investigated by sessile drop method. Afterwards calculation was made with use of selected semi-empirical models and obtained outputs were confronted with experimentally obtained data. Modelling comprised also temperature dependence of surface tension and influence of SiO₂ on its values.

Abstract: In order to optimize rolling process of AM50 Mg alloy, numerical simulation method is adopted to find reasonable process parameters. And then, the metallograph was viewed to find the microstructure evolution during hot rolling process. Through numerical simulation it is found that while the heating temperature is 420 and the train less than 0.33 each time. Through 10 times rolling, a 10mm thickness plate was rolled to 0.5mm, and its grain size also decreases to 10μm, which indicates that AM50 Mg alloy can be formed by hot rolling method.

Abstract: With the 3D thermal mechanical coupled elastic-plastic finite element method and by simulating the whole rolling process of 1250mm×20mm C-Mn hot strips, this paper obtains the temperature field and deformation result of the rolling process. By comparing the temperature drop curve with the measured data in the field, it shows that the simulation result is close to the real situation. Based on the thermal mechanical coupled simulation of the whole rolling process, this paper completes the computational simulation of the prediction of the 3D microstructure and property of hot strips by using the relevant microstructure evolution and property prediction models and advanced C language programming, thus providing reference for the property prediction of new products and processes.

Abstract: In this paper, we propose a novel material- amorphous silicon germanium(a-SiGe). The a-SiGe film was formed by PECVD at a low temperature and a low frequency. By adjusting the fraction x of Ge in Si_1-xGe_x, optimal SiGe bandgap was achieved. We used amorphous silicon germanium alloy as MOSFET source/drain. The parameter of MOSFET shows that, as the fraction increases, the drain-to-source breakdown voltage increases. With reduction of the minority carrier inject ratio, the current gain β of parasitic BJT in MOSFET was reduced greatly, which eliminates the limit of the breakdown voltage of the device.

Abstract: Taken hot tandem mill as research object, based on complete flatness control theary, in order to improve flatness control technology, an advanced strip flatness forecast and simulation system for hot tandem mill is developed through theoretical analysis, mathematical modeling, computer simulation and industrial validation. The simulation system’s outputs include flatness, on-load roll gap, rolling force distribution, contact pressure between rolls, strip’s temperature evolution, thermal roll shape and roll wear shape, which can be applied to mill type selection, flatness control performance analysis, preset control, roll shape optimization, virtual rolling, and so on. The simulation system can provide research and development platform for flatness control technology’ improvement and independent innovation, and has important significance to improve the flatness control level of hot tandem mill.

Abstract: This paper proposes an efficient method to the lowest cost tool sequence for semi-finishing of mold cavity on a 3-axis mill machine. Suppose that the rough machining has completed, so the redundant slice is thin enough and can be removed with a single pass of the semi-finishing cutter. To guarantee the cutting operations do not gouge the desired surface, there is a largest cutter which can be used at any part of the surface. On the other hand, to improve efficiency, large cutter should be priority selected. Dynamic programming finds a near optimal tool sequence based on the approximate evaluation of machining cost.

Abstract: The precise prediction of extrudate swell is significant to the control of melt flow and the quality of final products. A mathematical model of power law flow for polymer extrusion is investigated. The penalty function formulation is introduced to the finite element model and the free surface is updated with streamline equation in a decoupled method. A proper penalty constant is determined by comparison of numerical results with different penalty constants. The velocity field is obtained and the distribution of velocity on different cross sections is compared. The effects of volumetric flow rate and die shape on extrudate swell ratio are discussed. The simulation results are very important for the process and die design of the polymer extrusion.

Abstract: The combustion of pulverized coal in supercritical pressure W-shaped flame boiler is efficient.To decrease the formation of NOx in the furnace some reasonable measures are supposed to be taken to obtain low NOx combustion. In light of a 600MW supercritical pressure W-flame boiler, the combustion of low-quality anthracite coal and the formation of NO in the furnace are numerical simulated. The influence of concentration of pulverized coal, velocity of the primary air and the air distribution on the front and rear wall to the formation of NO is studied. The results indicate that NO emission at furnace exit can be effectively decreased by increasing the concentration of pulverized coal. Compared with the conventional concentration, NO emission can be decreased by 42%. The NO formation in the furnace can be controlled by selecting a reasonable primary air velocity on the front and rear arch, and there is a best primary air velocity. The study of supercritical W-flame boiler has great reference significance for the combustion adjustment and operation of large capacity W-shape flame boiler.

Abstract: In this paper, methane adsorption in single-walled carbon nanotube (SWNT) has been simulated by using the grand canonical ensemble Monte Carlo (GCMC) method. Lennard-Jones (LJ) potential is used to represent the fluid-fluid interaction, Lennard-Jones potential and integral method are used to calculation of the potential between fluid molecules and carbon atoms, respectively. In the simulation, two methods of calculation of potential between fluid molecules and SWNT are compared. The potential calculated by the two methods are almost the same. Then the influence of diameter of SWNT on the usable capacity ratio (UCR) is analyzed, and the parameters of the SWNT which has the best adsorption performance at 300K is recommended under certain pressure.

Abstract: A thermo-mechanical coupled finite element model for warm forming of dual-phase steel (DP) laser tailor-welded blanks (TWBs) was established based on ABAQUS software. The isothermal deep drawing of rectangular cups at elevated temperatures and the non-isothermal deep drawing at the temperature of 400°C were simulated. The distributions of temperature and differences between the isothermal and non-isothermal conditions were discussed. The results show that the temperature has great effect on the warm forming of DP-TWBs, and it achieves the best formability at the forming temperature of 400°C, and the non-isothermal deep drawing can further improve the warm formability.