Forming of Ceramic Laminates Comprising Thin Layers of a Few Particles

In this paper, a water-based colloidal processing method for manufacturing multilayers with very thin zirconia layers between thick alumina-based layers is presented. The procedure involves the dip coating of green tapes in binder-containing slurries and further lamination and sintering. Dipping studies show that thickness increases with soaking time until a higher limit is achieved, indicating the existence of interaction between slurry and substrate. After sintering, homogeneous, dense, and continuous zirconia layers with thicknesses between 3 and 0.8 lm alternated with 350 lm layers of alumina are obtained, thus meaning that the cross section of these thin layers range from four or five to only one or two grains. Although the residual stresses are estimated to be around 2 GPa, indentation cracks
do not shown any interaction when passing through the compressive layers, indicating the existence of a lower thickness limit to achieve a threshold stress.