Preferred Orientation of Porous Si3N4 Ceramics by Gel‐Casting in a Longitudinal Rotating Magnetic Field.

Abstract: Preferred orientation of porous Si3N4 ceramics with β‐Si3N4 powders as raw material is obtained by gel‐casting in a longitudinal rotating magnetic field and subsequent pressureless sintering. The effects of rotational speed on crystal orientation and properties of porous Si3N4 ceramics are analyzed. The results show that the c‐axis of β‐Si3N4 grains tended to align along the direction of the rotation axis. The degree of orientation in the samples increases with the increasing rotational speed. The textured porous samples show higher bending strength than that of untextured porous samples owing to the integrative effect of the grain orientation and pores. [ABSTRACT FROM AUTHOR]