微粒团聚的尺度效应及其分形表征

The Scale Dependence of Nano-size Particle Massing and its Fractal Characterization

利用全自动激光粒度分析仪,研究了乙醇分散液中羟基磷灰石微粒团聚过程中粒径分布、微粒的平均团聚粒径和比表面积随微粒团聚时间的变化关系,以及微粒质量分数对平均团聚粒径和比表面积的影响,对微粒团聚平均粒径、比表面积及团聚速率与微粒质量分数及微粒团聚时间的关联性进行了分形表征。结果表明:随微粒团聚时间的延长,所测微纳米微粒的最大分布粒径值、最小分布粒径值逐渐增大,分布曲线有逐渐向正态分布发展的趋势;随团聚时间增加,或微粒质量分数的增大,微粒团聚平均粒径逐渐增大,而比表面积逐渐减小,并都在一定的时间内达到动态平衡;微粒团聚速率分形维数可以客观地描述微粒团聚基本规律,当微粒质量分数一定时,微粒团聚分形维数越大,其团聚速度越大,当微粒团聚分形维数一定时,微粒质量分数越大,团聚速率越大。

The massing rules of hydroxyapatite particles dispersing in alcohol was researched by automatic laser particles tester, the changes of distribution characters of particles, the changing rules of particles average diameters values and particles specific surface areas values following change of time and consistency values were tested, and the rule were expressed by use of fractal geometry. The relationship between massing velocity values of particles and mass consistency values of particles was expressed by use of fractal geometry. The researching results show that following the massing time of particles extents ,the values of maximum particles diameter and minimum particles diameter all increase gradually, the distribution curve has the trend becoming normal distribution ;following the massing time extents or consistency increases, the average particles diameter value increases and the particles specific surface areas value decreases gradually,finally both of the values will get dynamic balance in some time. Fractal geometry dimension of particles massing velocity can describe the massing rules of nano-size particles, when the mass consistency value of particles is certain, the fractal geometry dimension value is more big, the massing velocity value is more quick;when the fractal geometry dimension values of particles is certain, the mass consistency is more big, the massing velocity is more quick.