9712773 Shih The objective of the research is to obtain fundamental understanding on the gelation, consolidation, and rheology of coated ceramic suspensions and establish their structure-property relationships. The approach that will be taken includes both experimental and theoretical work. The experimental system that will be studied is aluminum oxide-coated silicon carbide suspensions. There are several practical benefits of selecting this system for study. The yielding properties of aluminum oxide- coated silicon carbide gel network will be measured by dynamic and static rheological tests. The same yielding properties will be calculated based on a recently developed network yielding theory. The zeta potential needed for the calculation of interparticle interaction will be measured, and will be compared to the predictions of numerical simulation of ceramic coating on particle surface. The consolidation behavior of the aluminum oxide-coated particle suspensions will be investigated with sedimentation, centrifugation, and pressure filtration. The structural information about the coated particulate network will be characterized by light scattering. It is expected that by making the connection between theory and experiment, a systematic picture of structure-property relationship can be established for the coated ceramic suspensions. %%% Ceramic powders coated with another ceramic material have been used in many applications in colloidal ceramic processing. The ceramic coating can protect the core particles from dissolution. The coating may modify the interaction between the core particles, thereby improve the rheological properties of suspensions. Although the applications of ceramic-coated particles are many, the understanding of the suspension properties of coated particles is very limited. Intuitively, one might think that the property of the coated powder would be similar to that of the coating material. However, as shown by the results from rec ent studies, the consolidation and rheological properties of coated-powder suspensions can be quite complex. There is a need to perform a systematic study on the colloidal properties of coated powders so that their full potential benefits can be harvested. The research will have a significant impact on the applications of silicon carbide and alumina ceramics. ***
