Abstract
Strengthening of alpha-alumina-containing porcelain bodies was investigated by lamination with different compositions by two techniques. One was coating technique, in which the test bars were dip-coated with slurry of different batches, containing less amount of alpha-alumina. Coating caused an increase in bending strength of 24% with adequate coating thickness. Nevertheless, a formation of a crack at the surface led to a decrease in strength remarkably if the surface layer exceeded a critical thickness. The other was “double slip casting” technique, laminated bodies were made from two batches designated as surface and internal layers by sequential slip casting. Double slip casting yielded thick surface layer without any crack, thus substitution of zircon for alumina at the surface layer increased the mean bending strength from 38 to 44kgf/mm2 and Weibull modulus from 6 to 17.
