Patent ID: 7020952

Claim:
A method for producing a glow plug having a metallic sleeve and a ceramic heater which includes a substrate formed of an insulative ceramic, a heating resistor buried in the substrate, and a pair of power supply leads buried in the substrate, a first end of each power supply lead being connected to a corresponding end of the heating resistor, and the ceramic heater being fixed inside the metallic sleeve, which method comprises: firing a green ceramic heater in a heater forming step; heat treating the resultant ceramic heater obtained in the heater forming step at a temperature of from 900 to 1,600° C. in a heat treatment step; fixing the heat-treated ceramic heater obtained in the heat treatment step inside the metallic sleeve in a brazing step; and polishing the fired ceramic heater after firing in the heater forming step, to expose a second end of each power supply lead at a surface of the substrate, and after the polishing, heat treating the polished ceramic heater in an inert atmosphere wherein the green ceramic heater includes a green substrate which is formed of an insulative ceramic powder and which provides the substrate upon firing; a green heating resistor, which contains an electrically conductive ceramic and an insulative ceramic, and is buried in the green substrate and which provides the heating resistor upon firing; and a pair of power supply leads which are buried in the green substrate, a first end of each power supply lead being connected to a corresponding end of the green heating resistor.