Ceramic igniters

Abstract

New methods are provided or manufacture ceramic resistive igniter elements that include sintering of the elements in the absence of substantially elevated pressures. Ceramic igniters also are provided that are obtainable from fabrication methods of the invention.

1 . A method for producing a resistive igniter, comprising: 
 forming a ceramic igniter element comprising a ceramic composition that comprises one or more sintering aid materials; and    sintering the element at temperature in excess of 1400° C. in the absence of substantially elevated pressures.    
     
     
         2 . The method of  claim 1  wherein the ceramic igniter element is formed by injection molding.  
     
     
         3 . The method of  claim 1  wherein the ceramic igniter element is sintered at a temperature in excess of about 1600° C.  
     
     
         4 . The method of  claim 1  wherein the ceramic igniter element is sintered in an inert atmosphere.  
     
     
         5 . The method of  claim 1  wherein the sintering aid materials comprise one or more rare earth oxides.  
     
     
         6 . The method of  claim 5  wherein the sintering aid materials comprise yttria.  
     
     
         7 . The method of  claim 1  wherein the ceramic igniter element is formed of a composition that does not comprises silicon carbide.  
     
     
         8 . The method of  claim 1  wherein the ceramic element comprises two or more regions of differing resistivity.  
     
     
         9 . The method of  claim 1  wherein the ceramic element comprises-three or more regions of differing resistivity.  
     
     
         10 . A ceramic igniter element obtainable by the method of  claim 1 .  
     
     
         11 . The ceramic igniter element of  claim 10  wherein the element comprises two or more regions of differing resistivity.  
     
     
         12 . The igniter element of  claim 10  wherein the igniter element has a substantially rounded cross-sectional shape for at least a portion of the igniter length.  
     
     
         13 . The igniter element of  claim 10  wherein the igniter element has a non-circular cross-sectional shape.  
     
     
         14 . A method of igniting gaseous fuel, comprising applying an electric current across an igniter an igniter of  claim 10 .  
     
     
         15 . A method of  claim 14  wherein the current has a nominal voltage of 6, 8, 10, 12, 24, 120, 220, 230 or 240 volts.  
     
     
         16 . A heating apparatus comprising an igniter of  claim 10.