Abstract: A ceramic heater 1 includes a silicon nitride ceramic substrate 13 and a resistance-heating member 10 embedded in the silicon nitride ceramic substrate 13 . The silicon nitride ceramic substrate 13 contains oxygen derived from a sintering aid at an average concentration of 0.4–3.2% by weight in a surface layer portion extending from the surface thereof to a depth of 1 mm. The ceramic heater 1 can be manufactured by firing through hot pressing. A firing jig for use in a firing process has an SiC—C composite layer which is formed therein along the surface of cavities thereof while having a predetermined depth as measured from the cavity surface.

Abstract: A ceramic heater 1 includes a silicon nitride ceramic substrate 13 and a resistance-heating member 10 embedded in the silicon nitride ceramic substrate 13. The silicon nitride ceramic substrate 13 contains oxygen derived from a sintering aid at an average concentration of 0.4-3.2% by weight in a surface layer portion extending from the surface thereof to a depth of 1 mm. The ceramic heater 1 can be manufactured by firing through hot pressing. A firing jig for use in a firing process has an SiC—C composite layer which is formed therein along the surface of cavities thereof while having a predetermined depth as measured from the cavity surface.

Abstract: A ceramic heater of required heating properties is made available in that adjusting elements made solid in an electric conductive element are added other than electric conductive elements of an heating resistor in a ceramic heater. Accordingly, resistance temperature coefficient is changed, not largely changing other properties of heating materials.

Abstract: A ceramic heater is composed of an insulating ceramic heater body, a metallic sleeve fitted onto the ceramic heater body, a resistance heating element formed of a metal or a nonmetallic material and embedded in the ceramic heater body, and electrode leads. The length of a portion of the resistance heating element located inside the metallic sleeve is set equal to or greater than the length of a portion of the resistance heating element located outside the metallic sleeve. The resistance heating element has a heating portion which has a resistance per unit length which is twice that of the remaining portion or greater. The heating portion has a length 30 to 100% the length of the portion of the resistance heating element located outside the metallic sleeve.

Abstract: A ceramic heater is formed by embedding a heating element in a ceramic body. A ceramic body is formed from a sintered basic ceramic component containing an adjustment ceramic component in the range of 1 to 3% by weight. The adjustment ceramic component includes at least one component selected from the group consisting of metal silicate, metal carbonate, metal boride, and metal nitride each of which is larger in thermal expansion coefficient than the basic ceramic component.

Abstract: A ceramic heater includes a silicon nitride ceramic and a heating element embedded in the ceramic. The heating element is formed through use of, as a main component, a silicide, carbide, or nitride of at least one element selected from the group consisting of W, Ta, Nb, Ti, Mo, Zr, Hf, V, and Cr. The ceramic includes, as sintering aids, 1 to 20% by weight of at least one rare earth element calculated as an oxide thereof; 0.5 to 8% by weight of V (vanadium) calculated as V.sub.2 O.sub.5, and, 0.5 to 8% by weight of at least one Va/VIa group element selected from the group consisting of Nb, Ta, Cr, Mo, and W calculated as an oxide thereof. The proportion in total of vanadium and the Va/VIa element is 1 to 10% by weight calculated as oxides. The ceramic heater has excellent high-temperature strength and acid resistance.

Abstract: The invention relates to a ceramic heater for use, e.g., as a glow plug for a diesel engine or as an igniter for an oil or gas burner. The ceramic heater has a nonoxide ceramic body having a heating part and a supporting part and a heating resistor embedded in the heating part of the ceramic body. The material of the heating resistor is W, WC, tungsten alloy or a metal nitride such as TiN or TaN. According to the invention the heating part of the ceramic body is formed of aluminum nitride ceramic, which is high in heat conductivity and resistant to oxidation at high temperatures, at least in a core region in contact with the heating resistor, and the supporting part is formed of silicon nitride ceramic which is low in heat conductivity at least in a surface region.