Papers by Author: Xiao Ming Du

Abstract: The lost foam casting process of gray cast iron linner was simulated in this paper by using the numerical simulation method to study the properties of the filling and solidification for lost foam casting. And the comparison of the simulated results with the practical casting obtained from foundry was implemented. The results show that the reasonable technical parameters were obtained: pouring temperature of 1400°C, foam density of 13 kg/m³, vacuum of 0.04MPa, coating thickness of 0.5 mm and coating permeability of 9.5×10^-9m²/Pa·s.

Abstract: Filling and solidification for aluminum alloy packing block in die casting were simulated by numerical simulation. Distribution and change of temperature field as well as velocity field were visualized. The desirable processing parameters can be obtained with pouring temperature of 620°C and mould temperature of 180°C as well as shot velocity of 4m/s. The qualified products were obtained on the basis of the optimized die-casting parameters.

Abstract: we give the analytic solution of Ono-Kondo equation based on lattice theory to describe the supercritical high-pressure hydrogen adsorption inside cylindric pores of adsorbents, and predict adsorption isotherms for hydrogen on A and X type zeolite at 77K. It is shown that the model reflects the peculiar features in adsorption isotherms of supercritical hydrogen in particular, a maximum in the adsorption with increasing pressure) .The results from prediction are compared with the experimental data. It shows that the model can elucidate the peculiar features in adsorption isotherms of supercritical hydrogen which are fundamentally different from those of standard (IUPAC) classification, and the results from the equation also qualitatively reflect the experimental results.

Abstract: The influence of the apparent viscosity and pouring temperatures of the semi-solid aluminum alloy on filling and solidification process of the housing cap bearing under the condition of die casting was analyzed using numerical simulation method. The results of simulation show that the mold filling velocity of the semi-solid aluminum alloy decreases markedly with increase of the apparent viscosity. The influence of the pouring temperatures of the semi-solid aluminum alloy on the mold filling velocity is consistent with that of the traditional die casting. The solidification temperatures at the same position of the casting increase with increase of the apparent viscosity of the semi-solid aluminum alloy. There is no casting defect in the casting after complete solidification.

Abstract: We give the analytic solution of Ono-Kondo equation based on lattice theory to describe the supercritical high-pressure hydrogen adsorption inside slit pores of adsorbents, and predict adsorption isotherms for hydrogen on microporous ZSM-5 zeolite at 77K,195K and 293K. The results from prediction are compared with the experimental data. It shows that the model can elucidate the peculiar features in adsorption isotherms of supercritical hydrogen which are fundamentally different from those of standard (IUPAC) classification, and the results from the equation also qualitatively reflect the experimental results.

Abstract: Molecular dynamics (MD) techniques were employed to simulate the diffusion properties of molecular hydrogen on all-silica ZSM-5 zeolite. The results indicated that in the temperature range of 77-293K and the pressure range of 14-3360 kPa, the diffusion coefficients are found to range from 1.2×10^-9 m²/s to 3.8×10^-7 m²/s, and increase with increasing temperature, and decrease with increasing pressure. The activated energy for hydrogen diffusion determined from the simulation is pressure-dependent. The diffusion of the molecular hydrogen in all-silica ZSM-5 zeolite channels is anisotropic duo to the increase of the temperature. The diffusion coefficients in straight channels are higher than that in zigzag channels. The difference results from the structural difference of the two channels and the different loadings of hydrogen. Keywords: Hydrogen; Zeolite; Diffusion; Molecular-dynamics simulation

Abstract: With consideration of the viscosity of semi-solid aluminum alloy slurry and the mold filling characteristics in die casting, the die-casting mould for semi-solid aluminum alloy has been designed and manufactured on the basis of the standard samples. The process of mold filling and solidification of semi-solid aluminum alloy in die casting was simulated by using ProCAST software. With combination of simulation results with die casting experimental data, the results indicate that the influence of heating system of the mould and cross section of ingate for the mould on flowing of semi-solid aluminum alloy in mould cavity is important in this work.