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研究了纳米SiO2悬浮体系的流变特性、沉降过程以及分维特性。从悬浮体系应力随剪切速率的变化曲线,我们发现其流变曲线随着体积分数的变化而改变。通过对不同流型悬浮体系流变曲线的拟合,得出屈服应力值和塑性粘度均随浓度的增加而增加。沉降过程的研究表明,对NH4Cl浓度为1.8mol/L的SiO2悬浮体系,存在两个临界体积分数,重力作用下形成凝胶的临界体积分数为0.1,而上限临界体积分数约为0.54～0.6左右。另外,我们由沉降速度和体积分数的关系计算了该体系较高体积分数下的分维数为D=2.35±0.05。
The rheological properties, sedimentation process and fractal dimension of the nano-SiO2 suspension system were studied. From the curve of the stress of the suspension system with the shear rate, we find that the rheological curve changes with the volume fraction. Through the fitting of the rheological curves of the suspension systems with different flow patterns, it is concluded that the yield stress and the plastic viscosity all increase with the increase of the concentration. The sedimentation process shows that there are two critical volume fractions of SiO2 suspension with NH4Cl concentration of 1.8mol / L, the critical volume fraction of gel formed by gravity is 0.1 and the upper critical volume fraction is about 0.54 ~ 0.6 . In addition, we calculated the fractal dimension of the system at a high volume fraction of D = 2.35 ± 0.05 from the relationship between sedimentation rate and volume fraction.