Heating resistor for ceramic heaters, ceramic heaters and method of manufacturing ceramic heaters
AssigneeNgk Spark Plug Co., Ltd.
InventorsKazuho Tatematsu, Shindo Watanabe
Life of this patent
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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. The heating resistor may be used to a double frame ceramic heater, whereby deviations of baking conditions may be made little to heighten adherence and avoid breakage at grain boundaries
Claims7
A heating resistor for a ceramic heater comprising:
- an electrically conductive element containing materials including at least one of a silicide, carbide and nitride of at least one metallic element selected from W, Ta, Nb, Ti, Mo, Zr, Hf, V and Cr;
- an adjusting element made at least with the materials of the electrically conductive element for changing a resistance temperature coefficient of the heating resistor for the ceramic heater;
- and
- a sintered body wherein when a total of the electrically conductive element and the adjusting element is 100 wt %, the adjusting element is 0.1 to 5.0 wt %, and average diameter of crystal grains of the electrically conductive element is 11 μm or less.
A ceramic heater comprising:
- a ceramic base;
- a heating part to be buried in the ceramic base, comprising a heating resistor having an electrically conductive element containing materials including at least one of a silicide, carbide, and nitride of at least one metallic element selected from W, Ta, Nb, Ti, Mo, Zr, Hf, V and Cr;
- and an adjusting element made at least with the materials of the electrically conductive element for changing a resistance temperature coefficient of the heating resistor for the ceramic heater, wherein the heating resistor comprises a sinter ed body;
- and when a total of the electrically conductive clement and the adjusting element is 100 wt %, the adjusting clement is 0.1 to 5.0 wt %, and average diameter of crystal grains of the electrically conductive clement is 11 μm or less.
A method of manufacturing a ceramic heater, comprising the steps of:
- mixing raw materials for an electrically conductive element composed of at least one of a silicide, carbide, and nitride of one or more metallic elements selected from W, Ta, Nb, Ti, Mo, Zr, Hf, V, and Cr and raw materials for an adjusting element;
- molding the mixture;
- burying the molded body in ceramic powdered materials;
- and
- baking the molded body buried in the ceramic powdered materials, wherein when a total of the electrically conductive clement and the adjusting element is 100 wt %, the adjusting element is 0.1 to 5.0 wt %, and average diameter of crystal grains of the electrically conductive element is 11 μm or less.
Dependencies are inferred from the claim text.