Zeta Potentials of Nanoceramic Materials -Measurement and Interpretation

Hydrophobic colloidal Systems, consisting of one phase finely dispersed in another and therefore having an extensive (high energy) interfacial region, are intrinsically unstable. Over a period of time, the suspended particles or droplets in a dispersion will tend to coalesce or adhere upon collision with each other or with another surface thereby reducing the interfacial area and, with it, the potential energy of the system. How rapidly this proceeds is determined to a large extent by the characteristics of the interface, notably the electrical properties of the particle surface and its surrounding double layer. Apart from Suspension stability, these characteristics may also influence, inter alia, adhesion and, in more concentrated Systems, rheological behaviour. Nanoceramic particles, when suspended in a liquid medium, clearly fall into this class and a means of investigating their surface properties and the factors which affect them is highly desirable in order to try to predict and control their behaviour during preparation, processing and application. A valuable parameter in this respect and one which can now be easily determined is the zeta potential which exists at the effective boundary between the particle and its surrounding medium.