Multilayer Al2O3/Mo composites

The present study was concerned with multilayer composites of the .../Al2O3/Al2O3 + x vol. % Mo/Al2O3 type produced by tape casting. Molybdenum content in individual layers of the composites varied from 4 to 28 vol. %. The densities, porosities, Young moduli, bending strengths, and fracture toughnessess of the composites were measured. The residual stress in the layers was analysed by FEM. Investigations of the composite microstructures revealed: α-Al2O3, Mo, and Mo2C. After sintering, the composites had a high relative density (the porosity Pc did not exceed 10%). As the volumetric content of molybdenum increased, the densities of the composites increased, whereas their Young moduli E decreased. The highest values of the bending strength σb (819 MPa), stress intensity factor KIC (7.75MPa·m1/2), and cracking energy γ (102 J/m2 ) were obtained in the composite with the 14 vol. % molybdenum content. The strength σb and fracture toughness of this composite were more than two times higher than those of Al2O3, and the cracking energy – six times. These values can be partly explained in terms of the compressive residual stress in the composite layers.