Heating resistor, heating resistor for use in ceramic heater, and ceramic heater using the same
AssigneeNgk Spark Plug Co., Ltd.
InventorsSindo Watanabe, Masahiro Konishi
Life of this patent
Estimating the term…
Abstract
A heating resistor containing RE2O3 (where RE represents a rare earth element) in a predetermined amount. The mole ratio of residual oxygen to RE2O3, the amount of residual oxygen being expressed on an SiO2 basis and being obtained by subtracting the amount of oxygen contained in RE2O3 from the total amount of oxygen, falls within a predetermined range. A crystal phase of disilicate or melilite serves as a predominant phase of grain boundaries. The heating resistor contains a conductive component, such as WC or TiN, which contains one or more elements selected from among Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. The heating resistor is embedded in a substrate, yielding a ceramic heater.
Claims13
A ceramic heater comprising a substrate and a heating resistor embedded in the substrate, said heating resistor is formed of a silicon nitride ceramic containing silicon nitride in a predominant amount, a conductive component, and a rare earth element (RE), wherein
- the rare earth element is contained in an amount of 1-6 mol % as reduced to RE2O3;
- the mole ratio of residual oxygen to RE2O3 is 1-5, the amount of residual oxygen being expressed on a silicon oxide (SiO2) basis and being obtained by subtracting the amount of oxygen contained in a rare earth element oxide from the total amount of oxygen contained in the heating resistor;
- and
- a predominant phase of the heating resistor other than conductive component and the silicon nitride is melilite (RE2O3.Si3N4).
A ceramic heater comprising a substrate and a heating resistor embedded in the substrate, said heating resistor is formed of a silicon nitride ceramic containing silicon nitride in a predominant amount, a conductive component, and a rare earth element (RE), wherein
- the rare earth element is contained in an amount of 1-6 mol % as reduced to RE2O3;
- the mole ratio of residual oxygen to RE2O3 is 2-5, the amount of residual oxygen being expressed on a silicon oxide (SiO2) basis and being obtained by subtracting the amount of oxygen contained in a rare earth element oxide from the total amount of oxygen contained in the heating resistor;
- and
- a predominant phase of the heating resistor other than conductive component and the silicon nitride is disilicate (RE2Si2O7).
A ceramic heater comprising a substrate and a heating resistor embedded in the substrate, said heating resistor is formed of a conductive silicon nitride ceramic which contains silicon nitride in a predominant amount and a conductive component, wherein a predominant phase of the conductive silicon nitride ceramic other than the conductive component and the silicon nitride assumes a crystal phase having a melting point of not lower than 1600° C.
A ceramic heater comprising a substrate and a heating resistor embedded in the substrate, said heating resistor is formed of a conductive silicon nitride ceramic which contains silicon nitride in a predominant amount and a conductive component, wherein
- the silicon nitride ceramic contains 1-6 mol % of RE2O3, where RE is a rare earth element;
- the mole ratio of residual oxygen to RE2O3 is 2-5, the amount of residual oxygen being expressed on a silicon oxide (SiO2) basis and being obtained by subtracting the amount of oxygen contained in the rare earth element oxide from the total amount of oxygen contained in the heating resistor;
- and
- a predominant phase of the conductive silicon nitride ceramic other than the conductive component and the silicon nitride is disilicate (RE2Si2O7).
A ceramic heater comprising a substrate and a heating resistor embedded in the substrate, said heating resistor is formed of a conductive silicon nitride ceramic which contains silicon nitride in a predominant amount and a conductive component, wherein
- the silicon nitride ceramic contains 1-6 mol % of RE2O3, where RE is a rare earth element;
- the mole ratio of residual oxygen to RE2O3 is 1-5, the amount of residual oxygen being expressed on a silicon oxide (SiO2) basis and being obtained by subtracting the amount of oxygen contained in the rare earth element oxide from the total amount of oxygen contained in the heating resistor;
- and
- a predominant phase of the conductive silicon nitride ceramic other than the conductive component and the silicon nitride is melilite (RE2O3.Si3N4).
Dependencies are inferred from the claim text.