Simple Rheological Tests and Protocols for SME Ceramic Producers

The rheological behaviour of ceramic suspensions affects the quality of the products and the yield of the processes. Therefore, rheology control is needed to obtain materials with enhanced properties and to reduce energy consumption. The importance of rheology control in slip casting, spray-drying, screen-printing, ink-jet printing, glazing, and so on, either for Quality Control (QC) aims or for system formulation, has been acknowledged from many years. As in these control procedures the determination of the rheological behavior is a critical issue, this work is focused on the assessment of viscosity (flow behavior) and its dependency on time (usually, thixotropic behavior). Most of ceramic factories still use simple and cheap instruments to investigate rheological behaviors (or something related to it). However, the information provided by such instruments is not completely satisfactory. Therefore, optimization of the procedures is important to improve reproducibility and precision. Suggestions about simple tests and protocols applicable to viscometers ordinarily available in ceramic factories are given. Protocols consider besides a precise description of the tests, all other factors that can affect the results, such as the thermo-mechanical history of the samples before testing.