Process for making ceramic bodies with open channels

A method of making a ceramic body with an open channel comprising the steps of:

• preparing a batch of an extrudable ceramic mix and a batch of an extrudable organic mix;
• forming within an inner chamber of predetermined cross sectional size and shape in an extrusion barrel of a piston type extruder, an outer ceramic tube of the extrudable ceramic mix with an internal bore of predetermined cross sectional size and shape;
• filling and packing the central bore of the ceramic tube with the etrudable organic mix to form an extrudable composite body comprising an inner core of the extrudable organic mix surrounded by the outer tube of extrudable ceramic mix;
• simultaneously extruding the outer tube of ceramic mix and inner core of organic mix through an extrusion die having an inner inclined surface extending and tapering inwardly from an inlet end portion to an outlet end portion of the extrusion die including an outlet aperture of predetermined cross sectional shape and of smaller cross sectional size and area than the inner chamber of the extrusion barrel and thereby producing a continuous single core composite strand of the relatively smaller cross sectional size and area of the aperture;
• cutting the single core composite strand into unfired green single core composite bodies of desired length;
• and
• firing each of the unfired green single core composite bodies at sufficient temperature and period of time to burn out the organic core and bond the ceramic mix into a rigid ceramic body with an open channel therethrough.

A method of making a composite ceramic body with cores extending therethrough comprising the steps of:

• preparing a batch of an extrudable first ceramic mix and a batch of an extrudable second mix of a different composition;
• forming the first ceramic and second mixes into a plurality of single core composite strands of relatively small cross sectional area and of substantially the same length so each composite strand comprises an inner core of the second mix surrounded by an outer layer of the first ceramic mix;
• closely aligning and packing together a number of the single core composite strands into an inner chamber of an extrusion barrel of a conventional extruder sufficient to substantially fill the inner chamber of relatively larger cross sectional area and size than each of the single core composite strands;
• simultaneously extruding and forming the plurality of single core composite strands packed in the inner chamber into a multiple core composite strand of smaller cross sectional size and area than the inner chamber and having a plurality of spaced cores of the second mix surrounded by and spaced from one another by the first ceramic mix by forcing the single core composite strands through an extrusion die having an inner inclined surface extending and tapering inwardly from a large inlet end portion to an outlet end portion of the extrusion die and an extrusion aperture of predetermined cross sectional shape and of smaller cross sectional size and area than the inner chamber of the extrusion barrel;
• cutting the multiple core composite strand into one or more unfired green multiple core composite bodies of desired length;
• and
• firing the unfired green multiple core composite bodies at sufficient temperature and period of time to bond the first ceramic mix and cores of the second mix together into a rigid composite ceramic body with a plurality of spaced cores of the second mix extending therethrough.

A method of making a composite ceramic body with a core of different composition therein comprising the steps of:

• preparing a batch of an extrudable first ceramic mix and a batch of an extrudable second mix of a different composition;
• forming within an inner chamber of predetermined cross sectional size and shape in an extrusion barrel of a piston typ extruder, an outer ceramic tube of the extrudable first ceramic mix with an internal bore of predetermined cross sectional size and shape;
• filling and packing the central bore of the ceramic tube with the extrudable second mix to form an extrudable composite body comprising an inner core of the extrudable second mix surrounded by the outer tube of extrudable first ceramic mix;
• simultaneously extruding the outer tube of the first ceramic mix and inner core of the second mix through an extrusion die having an inner inclined surface extending and tapering inwardly from an inlet end portion to an outlet end portion of the extrusion die including an outlet aperture of predetermined cross sectional shape and of smaller cross sectional size and area than the inner chamber of the extrusion barrel and thereby producing a continuous single core composite strand of the relatively smaller cross sectional size and area of the aperture;
• cutting the single core composite strand into unfired green single core composite bodies of desired length;
• and
• firing each of the unfired green single core composite bodies at sufficient temperature and period of time to bond the first ceramic mix and core of the second mix into a rigid composite ceramic body with a core of the second mix therein.