Mechanical properties and contact damage behavior in aligned silicon nitride materials

Aligned Si3N4 microstructures were achieved by seeding, extruding, and laminating methods. The degree of grain alignment was determined by microstructural measurements. Mechanical properties, including toughness, strength, hardness, and elastic modulus, as well as the contact damage response, were addressed and discussed as a function of this anisotropic microstructure. K-IC values over 8 MPa.m(1/2) and strengths above 900 MPa were achieved for the most favorable planes in the textured material. Contact damage behavior was influenced by grain orientation in two ways, first, by conferring elliptical shape to the radial surface cracks and second, by the multiple twin/slip formation at the large seeds within the high shear strain region.