Apparatus and method for forming a sealed outer ring for ceramic regenerator

Apparatus for forming a gas-impervious ceramic seal within a predetermined number of the peripheral cells of a ceramic honeycomb structure having first and second opposing surfaces defining the cell openings and having an outer wall surrounding the cells, while simultaneously forming a ceramic layer on the outer wall, the apparatus comprising:

• a. a first reservoir adapted to receive the structure and a castable ceramic composition, the reservoir having a bottom portion defining an opening corresponding in shape to the cross section of the structure and having an area at least equal to the area of the first surface, and having side walls of a height at least equal to the height of the outer wall of the structure;
• b. first removable gas-impervious slurry-impervious contact means adapted for gas-impervious contact with a central portion of the second surface, for forming a temporary vacuum seal of the central portion cells, and leaving the peripheral cells exposed;
• c. a second reservoir adapted for positioning atop the structure and having outer walls adapted for contact with the outer walls of the structure, for maintaining a ceramic slurry composition in contact with the exposed cells of the second surface;
• d. second removable gas-pervious slurry-impervious contact means adapted for contact with at least the cell openings of the first surface corresponding to the exposed cell openings of the second surface;
• e. vacuum means positioned below the second contact means in contact therewith, adapted for evacuating the exposed peripheral cells through the second contact means, to promote flow of slurry into the evacuated cells, thereby to at least partly impregnate and seal these cells against gas flow;
• and
• f. vibrator means positioned below the vacuum means and in contact therewith for vibrating the apparatus to promote flow of the casting and slurry compositions.