摘要
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。
We discuss the rheological properties, sedimentation process and fractal trait of nano-SiO_2 suspensions. From the curves of stress as a function of shear rate for varying SiO_2 volume fractions, we find that the rheological curves vary as the suspension volume fractions change. After fitting the curve of different volume fraction, yield stress and plastic viscosity were given respectively. Results show that they both increased with the increase of volume fraction. The study of the sedimentation indicates that there exist two critical volume fractions for the SiO_2 suspensions when NH_4Cl concentration is 1.8mol/L. The critical volume fraction for gelation in the presence of gravity is 0.1,and the upper critical volume fraction was about 0.54～0.6. Also the variations of the settling velocity along with the volume fractions show a fractal distribution, and the fractal dimension was _D_=2.35±0.05.
出处
《功能材料》
EI
CAS
CSCD
北大核心
2003年第6期721-722,727,共3页
Journal of Functional Materials
基金
国家自然科学基金资助项目(20043002)
