electrokinetic properties of ceramic powders

The electrokinetic behaviour of compact ceramic surfaces is mainly characterised by streaming-potential measurement using flow parallel to the surface. For these measurements the electrokinetic analyser (EKA) is commercially available. Often this method shows experimental difficulties. In view of filtration-membranes characterisation the process determining effect derives not only from the surface. The open porosity of the membrane as a whole also influences the interaction with charged species to be filtrated. A new method was developed closely related to real filtration: A ‘flow-through’ potential measurement. Suspensions are nowadays characterised using an electroacoustic method. To link the electrokinetic results measured on suspensions to measurements on compact surfaces a new ‘electroacoustic-surface-potential’ measurement was tested. It is obvious that the electrokinetic behaviour of compact ceramic cannot be derived from suspension measurement. The properties of the electrically chargeable M–OH groups on the surface is changed during thermal treatment.