Abstract: Disclosed herein is a dual density disc comprising a dense outer tube comprising alumina having a purity of greater than 99%; and a porous core comprising alumina of a lower density than a density of the dense outer tube; wherein the porous core has an alumina purity of greater than 99%. Disclosed herein too is method comprising disposing in a dense outer tube a slurry comprising alumina powder and a pore former; heating the dense outer tube with the slurry disposed therein to a temperature of 300 to 600° C. to activate the pore former; creating a porous core in the dense outer tube; and sintering the dense outer tube with the porous core at a temperature of 800 to 2000° C. in one or more stages.

Abstract: Disclosed herein is a dual density disc comprising a dense outer tube comprising alumina having a purity of greater than 99%; and a porous core comprising alumina of a lower density than a density of the dense outer tube; wherein the porous core has an alumina purity of greater than 99%. Disclosed herein too is method comprising disposing in a dense outer tube a slurry comprising alumina powder and a pore former; heating the dense outer tube with the slurry disposed therein to a temperature of 300 to 600° C. to activate the pore former; creating a porous core in the dense outer tube; and sintering the dense outer tube with the porous core at a temperature of 800 to 2000° C. in one or more stages.