Abstract: A multi-layer rod shaped ceramic igniter includes an elongated tapered electrode having a central core of resistant material and two annular segments. One of the segments in on one side of the core and the other on an opposite side and connected to two slightly converging facets extending along the core. The multi-layered rod shaped ceramic igniters disclosed herein may be manufactured by slip-casting, injection molding or extruding a green annular body and removing material from opposite sides of the green body to form two almost parallel but slightly converging facets that extend over the heater igniter between the back surface and the tip of the igniter. After removing material between the annular segments the igniter is air dried and then heated in a vacuum at atmospheric pressure to approximately 900° C. in order to burn off the organic binder. The ceramic is then held in an inert atmosphere and heated to a temperature of 1600° C.

Abstract: A multi-layer rod shaped ceramic igniter includes an elongated tapered electrode having a central core of resistant material and two annular segments. One of the segments in on one side of the core and the other on an opposite side and connected to two slightly converging facets extending along the core. The multi-layered rod shaped ceramic igniters disclosed herein may be manufactured by slip-casting, injection molding or extruding a green annular body and removing material from opposite sides of the green body to form two almost parallel but slightly converging facets that extend over the heater igniter between the back surface and the tip of the igniter. After removing material between the annular segments the igniter is air dried and then heated in a vacuum at atmospheric pressure to approximately 900° C. in order to burn off the organic binder. The ceramic is then held in an inert atmosphere and heated to a temperature of 1600° C.

Abstract: An improved ceramic heater to be incorporated in a glow plug is described. The heater is made up of a ceramic core enclosed by two layers sintered together to form a unitary ceramic heater. All three component elements of the heater are composed of silicon nitride containing different concentrations of an electrically conductive ceramic substance, such as titanium nitride, titanium carbonitride or molybdenum disilicide. Each component additionally contains low amounts of sintering additives. The core of the heater has the highest concentration (46-75 vol. %) of the electrically conductive substance. The core enclosed in a ceramic layer which is an electrical insulator and is composed of silicon nitride, less than 28 vol. % of the electrically conductive ceramic substance and sintering additives. An outer layer over the core contains the electrically conductive ceramic substance in a concentration (33-50 vol. %) which is in between that in the core and that in the insulator layer.