Ceramic laminates with improved mechanical reliability by tailoring the porosity of the constituting layers

Two different ceramic laminates composed of porous alumina and alumina/zirconia layers were designed and produced in the present work. The two symmetrical architectures were selected whose fundamental difference is the presence on the surface of a porous layer in the first and a compact alumina/zirconia composite layer in the second. The residual stress profile and corresponding fracture toughness were tailored to promote the stable growth of surface defects prior to final failure to increase the mechanical reliability of the material. The laminates were realized by stacking together different green laminae (containing specific pore former content) in a specific order, thermo-compression and co-sintering. The results point out an important reduction of the strength scatter and a clear insensitivity to surface damage. It is also shown that the mechanical performances are strictly related to the specific architecture of the laminate, this allowing to tailor a priori the mechanical performances of the composite.