Method for manufacturing a ceramic heater
AssigneeNgk Spark Plug Co., Ltd.
InventorsMasahiro Konishi, Shindo Watanabe
Life of this patent
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Abstract
Ceramic raw powder containing conductive ceramic powder is mixed with a prescribed quantity of a molding assistant containing carbon component. This mixture is molded into a prescribed shape of a resistive heating element to thereby produce a heating element mold. A composite mold is prepared by embedding the heating element mold into molds of a ceramic substrate. The composite mold is sintered at a sintering temperature of 1700.degree. C. or higher. During a process of rising temperature to the sintering temperature, the composite mold is kept in an oxygen containing atmosphere having an oxygen partial pressure of 2.times.10.sup.-4 to 1.0 Torr for 7 minutes or longer at a temperature of 1200.degree. C. or higher.
Claims8
A method for manufacturing a ceramic heater having a structure in which a ceramic resistive heating element is embedded in a ceramic substrate, the ceramic resistive heating element containing a conductive ceramic phase comprising a metallic element component of metallic silicide having at least one element selected from the group consisting of Ta, Nb, Ti, Mo, Zr, Hf, V and Cr, comprising the steps of:
- preparing a composite mold in which a heating element mold is embedded in a substrate mold being a mold of raw powder of said ceramic substrate, said heating element mold being prepared by mixing ceramic raw powder containing conductive ceramic powder to be said conductive ceramic phase with a prescribed quantity of molding assistant containing a carbon component and shaping said heating element mold into a prescribed shape of a resistive heating element;
- sintering said composite mold at a sintering temperature of 1700.degree. C. or higher;
- and
- during a process of rising temperature to said sintering temperature, keeping said composite mold in an oxygen containing atmosphere having an oxygen partial pressure in a range of 2.times.10.sup.-4 to 1.0 Torr for 7 minutes or more at a temperature of 1200.degree. C. or higher.
Dependencies are inferred from the claim text.