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为了从理论上探讨纳米粒子在基体材料中的分布规律,以纳米SiC质量分数为3%、5%、7%、9%的SiC/PTFE(聚四氟乙烯)复合材料为例,根据纳米SiC的半径(25nm)、密度(3.2g/cm3)、质量分数和基体材料的密度(2.2g/cm3),以10-12 g为质量单位、25nm∶1像素为比例尺,建立了纳米粒子在基体中均匀/偏聚分布的三维仿真模型,基于其盒维数定量表征了不同团聚/偏聚程度的纳米粒子的分散度,并进行了力学实验验证。结果表明:均匀分布下随着纳米SiC粒子半径的不断增加,或体积分数的不断减小,其盒维数也逐渐减小;当SiC粒子半径超过100nm时,不再具有分形特性。偏聚分布下随着纳米SiC粒子(半径为50nm)间距的不断加大,或体积分数的不断减小,或层状、线状、团状分布的依次改变,其盒维数也逐渐减小;相同体积分数下偏聚分布的盒维数低于均匀分布;当粒子间距超过450nm时,不再具有分形特性。均匀分布下纳米SiC/PTFE复合材料的力学性能测试结果与其三维仿真模型的盒维数线性相关(|R|>0.9)。盒维数可定量表征纳米粒子的分散度,并可用于预测纳米复合材料的宏观性能。
In order to theoretically investigate the distribution of nanoparticles in the matrix material, taking the SiC / PTFE (polytetrafluoroethylene) composites with 3%, 5%, 7% and 9% (25nm), density (3.2g / cm3), the mass fraction and the density of the matrix material (2.2g / cm3), 10-12g mass units, 25nm: The three-dimensional simulation model of uniform / segregation distribution was used to quantitatively characterize the dispersion degree of nanoparticles with different agglomeration / segregation degree based on the box dimension. The mechanical experiment was also conducted. The results show that the box dimension decreases with the increase of the radius of nano-SiC particles or the decrease of the volume fraction of nano-SiC particles under uniform distribution. When the radius of SiC particles exceeds 100 nm, the fractal dimension of SiC particles no longer exists. With the increasing segregation of nano-SiC particles (radius of 50nm) increasing spacing, or the volume fraction of decreasing, or stratification, linear, slug-like distribution of the order of change, the box dimension is also gradually reduced ; The box dimension of segregation distribution under the same volume fraction is lower than the uniform distribution; when the distance between particles is over 450nm, the fractal dimension no longer has the same fractal characteristic. The test results of the mechanical properties of nano-SiC / PTFE composites with uniform distribution are linearly related to the box dimension of the 3D simulation model (| R |> 0.9). The box dimension quantitatively characterizes the dispersion of the nanoparticles and can be used to predict the macroscopic properties of the nanocomposites.