Sintered corundum body of closed cell structure used as e.g. grinding disc.

Abstract
NOVELTY - The sintered corundum body has a closed cell structure, specified macroporosity, cell size, structural porosity and sintered crystallite size values and low glass-forming impurity and dopant contents. DETAILED DESCRIPTION - A sintered corundum body has a closed cell structure, a macroporosity of 5-50 vol.%, a cell size of less than 250 mu m, a structural porosity of less than 2.5%, a sintered structure mean crystallite size of less than 5 mu m and a glass-forming impurity and dopant content of less than 3 wt.%. An INDEPENDENT CLAIM is also included for the production of the above sintered body by: (a) preparing a ceramic slip of 35-50 vol.% solids content and 0.1-0.5 Pas viscosity (measured by a rotary viscometer with a shear rate of 100 second-1); (b) impregnating the slip into an open porous pyrolyzable organic body of 30-300 pores/cm pore frequency to fill all the macropores; (c) removing 0-50 vol.% of the impregnated slip for achieving the desired macroporosity in the sin tered body; (d) drying at 60-80 deg. C; and (e) firing in flowing air at 1000-1200 deg. C; and sintering the resulting ceramic skeleton. USE - As a grinding body (claimed), e.g. a grinding disc. ADVANTAGE - The binder-free sintered body has a high strength (e.g. a mean compressive strength of greater than or equal to 100 MPa at less than 35 % macroporosity or greater than or equal to 20 MPa at 50 % macroporosity) and a high hardness of greater than or equal to 1700 HV1.