Cruz Robinson C D, Segadães Ana M, Mantas Pedro Q, Oberacker Rainer, Hoffmann Michael J
University of Caxias do Sul, IMC-Instituto de Materiais Cerâmicos, Bom Princípio, Brazil.
University of Aveiro, Department of Materials and Ceramics Engineering, Aveiro, Portugal; University of Aveiro, CICECO-Aveiro Institute of Materials, Aveiro, Portugal.
J Colloid Interface Sci. 2020 Aug 15;574:97-109. doi: 10.1016/j.jcis.2020.04.046. Epub 2020 Apr 11.
The electrical charges that develop on the surface of the ceramic particles upon contact with water, due to the interaction with ions in solution, result in a liquid-solid interface, which utterly modifies the properties of individual particles and the way they interact with each other to form a structure. This work explores a new approach to the relationships between structure and stability of suspensions.
For this purpose, suspensions with a constant 0.35 volume fraction of α-alumina particles, neither spherical nor smooth, and controlled ionic strength (0-90 mM KCl) were prepared and characterized in terms of flow behaviour, electrical conductivity and particle's electrokinetic mobility.
Electrical conductivity (132 µS/cm < conductivity < 5730 µS/cm) and rheology measurements (10 Pa s < viscosity < 10 Pa s) were found to complement each other to produce a more accurate picture of the suspension's structure. Deviations of experimental data from well-accepted behavioural models were elucidated when the surface area equivalent particle size was used. With the electrical double layer thickness obtained from electrical conductivity measurements, this enabled the interpretation of the relationship between the suspension's viscosity and the particles electrical conductivity, which provides a criterion for the stability of concentrated colloidal suspensions.
陶瓷颗粒与水接触时，由于与溶液中的离子相互作用，其表面会产生电荷，从而形成液固界面，这会彻底改变单个颗粒的性质以及它们相互作用形成结构的方式。这项工作探索了一种研究悬浮液结构与稳定性之间关系的新方法。
为此，制备了α - 氧化铝颗粒体积分数恒定为0.35、颗粒既非球形也不光滑且离子强度可控（0 - 90 mM KCl）的悬浮液，并对其流动行为、电导率和颗粒的电动迁移率进行了表征。
发现电导率测量值（132 μS/cm < 电导率 < 5730 μS/cm）和流变学测量值（10 Pa·s < 粘度 < 10 Pa·s）相互补充，能更准确地描绘悬浮液的结构。当使用比表面积等效粒径时，实验数据与公认行为模型的偏差得以阐明。结合通过电导率测量得到的双电层厚度，这使得能够解释悬浮液粘度与颗粒电导率之间的关系，从而为浓胶体悬浮液的稳定性提供了一个判据。
