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本文针对α-Al2O3有序介孔材料的导热特性开展分子动力学模拟分析.提出了一种保证电中性的孔道结构构造方法;采用逆非平衡分子动力学方法(muller-plathe法),选取Matsui势为作用势,模拟计算了Al2O3介孔晶体材料在不同环境温度下沿孔道轴向方向的热导率;并借助全面实验分析法,设计了模拟条件,以考察孔径和孔隙率对热导率的影响.模拟结果显示:介孔Al2O3热导率先随温度的升高呈上升趋势,并在200—400 K之间取得极值;而后在400—1400 K范围内,热导率随温度的升高几乎呈线性下降.孔隙率一定时,随孔径增大,介孔Al2O3材料比表面积降低,界面散射的抑制作用减弱,使材料热导率略有上升;孔径一定时,随孔隙率上升,孔道壁面声子数减少,材料热导率下降明显;相对于孔径因素,材料孔隙率对声子导热影响更大.
In this paper, the molecular dynamics simulations of the thermal conductivity of α-Al2O3 ordered mesoporous materials are carried out. A new method for constructing the pore structure is proposed to ensure the charge neutrality. By using the inverse non-equilibrium molecular dynamics method (muller-plathe method) Matsui potential is the potential of the simulated thermal conductivity of Al2O3 mesoporous materials along the axial direction of the tunnel at different ambient temperatures. By means of comprehensive experimental analysis, the simulation conditions were designed to investigate the effect of pore size and porosity on thermal conductivity The simulation results show that the thermal conductivity of mesoporous Al2O3 firstly increases with increasing temperature and reaches the extreme value between 200-400 K. In the range of 400-1400 K, the thermal conductivity increases with the increase of temperature When the porosity increases, the specific surface area of mesoporous Al2O3 decreases and the inhibition of interfacial scattering decreases, which leads to a slight increase of the thermal conductivity of the material.With the increase of porosity, The number of phonons in the cell wall decreases and the thermal conductivity of the material decreases obviously. Compared with the pore size, the porosity of the material has a greater influence on the thermal conductivity of the phonon.