LAUSR

Abstract Lamellar porous alumina with graded structures was fabricated through a novel method of simultaneous centrifugal casting and directional freeze casting. Alumina particles in ceramic slurry moved outward from the center by centrifugal force and formed stable gradient distribution because of viscous resistance and electrostatic repulsion among particles. The porous and pore-size gradient structure were obtained after freeze drying. With increased rotational speed, the pore size of the lamellar pore channels also gradually increased. However, the sizes of the ice crystals and lamellar pores shrunk at 200 rpm due to the destabilization of laminar flow during ice-crystal growth. Compressive strength obviously improved with increased rotational speed, and that of the resulting porous ceramic was 2.3 times higher than that in the absence of centrifugation at 1000 rpm rotational speed.