Papers by Author: Min Zhang

Abstract: The compatibilities of polymer blends, Polypropylene (PP) and Polyamide12(PA12) with the quantity ratio 10/90, was simulated by Molecular Dynamics (MD) and Mesoscopic Dynamic simulation (MesoDyn) simulations. Cohesive energy density (CED) and solubility parameters (δ) of pure substances and PP/PA12 blends were got by MD simulations. Flory-Huggins parameter was calculated based on CED values. The mesoscale simulation was related to the molecular simulation through Flory-Huggins parameter. Free energy density and the density profiles were got through MesoDyn simulation. Results showed that solubility parameter difference (Δδ) of PP/PA12 is 4.092 and free energy density value is 0.17 in the equivalent system. And phase separation behavior was observed in the density profiles. All these indicates that PP and PA12 is not miscible which is the same as the experiment results.

Abstract: The mesoscale simulation of polymer blends, Polypropylene (PP) and Polyamide12 (PA12), was calculated by Mesoscopic Dynamic method (MesoDyn). The free energy density, the order parameters and the density profiles were got by the simulation. The evolvement of the phase status was analyzed based on the free energy density and the order parameters. Using density profiles, the kinetics of phase separation was examined and the phase separation behavior was observed. Results showed that mesoscale simulation can be used to determine phase separation of sparingly miscrible polymer blends.

Abstract: Considering the extrudate swell, the polymer extrusion process was calculated by the inversed simulation based on the visco-elastic ecology theory. The fluid characteristics of the polymer melt were described by the Phan-Thien and Tanner (PTT) model. The Finite Element Method was used. Based on the simulation data, the extrusion die lips were analyzed. So it is feasible to design the polymer extrusion die lips using inversed simulation method.

Abstract: WC-TiC-Co cermet and CuZnNi alloy composite coatings were produced on mild steel by a high temperature inside-furnace brazing technique. The microstructure, phase constituents and interfacial diffusion behavior of cermet and Cu-based alloy were investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron probe microanalysis (EPMA) and X-ray diffraction. The tensile strength and wear property of composite coatings were also investigated. The results show that crème particles were not decomposed severely during the inside- furnace brazing process. The microstructure of the matrix is α and β phases. Diffusion occurred at the cermet/Cu-based alloy interface. The tensile strength of the composite coatings reached 240-300MPa, which depended on the brazing temperature and was far higher than that of the flame hardfacing layers. Cermet fracture was basically a brittle fracture in nature and matrix involves ductile fracture.