We present a systematic rheological study on the fumed silica suspensions to understand the effect of particle and fluid parameters on the critical shear rate and shear thickening ratio. It was observed that removal of air bubbles and water contamination is crucial to prepare good shear thickening fluids. A careful sample preparation method was adopted to properly disperse the fumed silica particles in polyethylene glycol solution, and we achieved discontinuous shear thickening at low particle concentration. It was observed that the critical shear rate in shear thickening suspension is strongly influenced by both carrier fluid and particle concentration. However, the shear thickening ratio is mainly influenced by the particle parameters and the frictional forces between the particles. Increasing the amount of smaller particles in the suspension significantly decreases the maximum viscosity and shifts the onset of shear thickening to higher values of critical shear rates with much smaller shear thickening ratio. Further, a possible mechanism has been proposed based on the influence of carrier fluid and particle size distribution to explain the rheological behaviour of shear thickening suspension. Our study supports the theory of particle-particle frictional contacts as the main reason for the discontinuous shear thickening.

中文翻译：

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载液和粒度分布对剪切增稠悬浮液流变学的影响

我们对气相二氧化硅悬浮液进行了系统的流变学研究，以了解颗粒和流体参数对临界剪切速率和剪切增稠比的影响。据观察，去除气泡和水污染对于制备良好的剪切增稠液至关重要。采用仔细的样品制备方法将气相二氧化硅颗粒适当分散在聚乙二醇溶液中，我们在低颗粒浓度下实现了不连续剪切增稠。据观察，剪切增稠悬浮液中的临界剪切速率受载液和颗粒浓度的强烈影响。然而，剪切增稠率主要受颗粒参数和颗粒间摩擦力的影响。增加悬浮液中较小颗粒的数量会显着降低最大粘度，并将剪切增稠的开始转移到更高的临界剪切速率值，而剪切增稠比要小得多。此外，基于载液和粒度分布的影响提出了一种可能的机制来解释剪切增稠悬浮液的流变行为。我们的研究支持粒子-粒子摩擦接触理论是不连续剪切增稠的主要原因。基于载液和粒度分布的影响，提出了一种可能的机制来解释剪切增稠悬浮液的流变行为。我们的研究支持粒子-粒子摩擦接触理论是不连续剪切增稠的主要原因。基于载液和粒度分布的影响，提出了一种可能的机制来解释剪切增稠悬浮液的流变行为。我们的研究支持粒子-粒子摩擦接触理论是不连续剪切增稠的主要原因。