Injection molding of ceramic elements
The invention provides new methods for manufacture ceramic resistive heating elements that include forming a heating element body comprising comprises two or more regions of differing resistivity, and processing a portion of the element body to form a heating element. Heating elements such as igniters and glow plugs also are provided obtainable from fabrication methods of the invention.
1 . A method for producing a resistive ceramic heating element, comprising:
forming a heating element body comprising comprises two or more regions of differing resistivity; and
processing a portion of the element body to form a heating element.
2 . The method of claim 1 wherein processing defines an electrical pathway of the heating element.
3 . The method of claim 1 or 2 wherein processing comprising removing one or more portions of the element body.
4 . The method of claim 1 or 2 wherein processing comprises removing one or more protruding sections of the heating element body.
5 . The method of claim 4 wherein removing comprises removing two opposed sections of the heating element body.
6 . The method of claim 1 wherein the element body comprises three or more regions of differing resisitivity.
7 . The method of claim 6 wherein the heating element body comprises insulator, conductive and resistive (ignition) zones.
8 . The method of claim 6 wherein the heating element body comprises insulator, conductive, booster and resistive (ignition) zones.
9 . The method of claim 1 wherein the heating element body comprises regions of differing resistivity through a cross-section of the heating element.
10 . The method of claim 1 wherein the heating element body comprises an inner insulator region and outer conductive region.
11 . The method of claim 1 wherein the heating element body is formed at least is part by slip casting.
12 . The method claim 1 wherein the heating element body is formed at least is part by dip coating.
13 . The method of claim 1 the heating element has a substantially rounded cross-sectional shape for at least a portion of the heating element length.
14 . The method of claim 1 wherein the heating element is an integral element.
15 . A method for producing a resistive ceramic heating element, comprising:
slip casting ceramic material to form a heating element body;
processing a portion of the element body to form a heating element.
16 . The method of claim 15 wherein slip casting comprises deposition of at least two distinct ceramic materials to form a heating element body.
17 . The method of claim 15 or 16 wherein processing defines an electrical pathway of the heating element.
18 . The method of claim 15 wherein processing comprising removing one or more portions of the element body.
19 . A ceramic heating element obtainable by a method of claim 1 or claim 15 .
20 . A heating element body comprising comprises (i) two or more regions of differing resistivity and (ii) one or more protruding sections.
21 . The heating element body of claim 20 wherein the heating element body comprises an inner insulator region and outer conductive region.
22 . A method of igniting gaseous fuel, comprising applying an electric current across a heating element of claim 19 .
23 . A method of claim 22 wherein the current has a nominal voltage of 6, 8, 10, 12, 24, 120, 220, 230 or 240 volts.
24 . A heating apparatus comprising a heating element of claim 19 .