Ceramic igniters

Abstract

New methods are provided or manufacture ceramic resistive igniter elements that include extrusion of one or more layers of the formed element. Ceramic igniters also are provided that are obtainable from fabrication methods of the invention.

1 . A method for producing a resistive igniter, comprising extruding a ceramic element.  
     
     
         2 . The method of  claim 1  wherein the ceramic element comprises two or more regions of differing resistivity.  
     
     
         3 . The method of  claim 1  wherein the ceramic element comprises regions of differing resistivity through a cross-section of the element.  
     
     
         4 . The method of  claim 1  further comprising removing at least a portion a region of a first resistivity to expose a region of a second, distinct resistivity.  
     
     
         5 . The method of  claim 1  wherein the first region has a lower resistivity than the second region.  
     
     
         6 . The method of  claim 1  further comprising applying one or more ceramic compositions to at least a portion of the ceramic element.  
     
     
         7 . The method of  claim 6  wherein a conductive ceramic composition is applied to the ceramic element.  
     
     
         8 . The method of  claim 6  wherein at least two distinct ceramic compositions having differing resistivities are applied to the ceramic element.  
     
     
         9 . The method of  claim 1  further comprising densifying the extruded ceramic element.  
     
     
         10 . The method of  claim 1  wherein a portion of the igniter interior is removed.  
     
     
         11 . The method of  claim 1  wherein a ceramic tile element and the tile element is cut to provide a plurality of igniter elements.  
     
     
         12 . A ceramic igniter element obtainable by extruding a ceramic element.  
     
     
         13 . The ceramic igniter element of  claim 12  wherein the element comprises two or more regions of differing resistivity.  
     
     
         14 . The igniter element of  claim 12  wherein at least a portion of a region of a first resistivity has been exposed to expose a region of a second, distinct resistivity.  
     
     
         15 . The igniter element of  claim 14  wherein the first region has a lower resistivity than the second region.  
     
     
         16 . The igniter element of  claim 12  wherein one or more ceramic compositions are applied to at least a portion of the formed ceramic element.  
     
     
         17 . The igniter element of  claim 12  wherein the igniter element has a substantially rounded cross-sectional shape for at least a portion of the igniter length.  
     
     
         18 . The igniter element of  claim 12  wherein the igniter element has a non-circular cross-sectional shape.  
     
     
         19 . A method of igniting gaseous fuel, comprising applying an electric current across an igniter of  claim 12 .  
     
     
         20 . A method of  claim 19  wherein the current has a nominal voltage of 6, 8, 10, 12, 24, 120, 220, 230 or 240 volts.  
     
     
         21 . A heating apparatus comprising an igniter of  claim 12.