Multylayer Ceramic Composite Formation by Electrophoretic Deposition.

Abstract : Multilayer ceramic composites are of great interest due to prospects for enhancement of fracture toughness. A novel approach to multilayer formation based on electrophoretic deposition is adopted in this work. Alternating layers of ZrO2 and Al2O3 are deposited by alternating immersion in two different suspensions. Deposition rates, green and fired densities and suspensions stability were studied as function of deposition parameters. These parameters are: electric field strength, particle concentration, deposition duration. An extensive study was performed on the effect of additives on the above mentioned criteria. The variation of layer thickness in a constant voltage and constant current regime was studied. Layered structures with up to 300 layers were obtained. Initial microhardness and bending tests were performed indicating crack confinement and significant enhancement of bending strength. The process of scale-up of specimen dimensions needed for fracture toughness measurements encountered difficulties expressed mainly in cracking of green and sintered specimens. Further optimization of deposition parameters was performed in the last stage. Based on these results further work is needed for preparation of the scaled-up specimens and performance of fracture toughness measurements.