| 摘要 |
PURPOSE: To provide a spark plug having a glaze layer in which the content of Pb component is less, and further which is superior in fluidity in glost firing, and which is superior in an anti-flashover property with a high insulation resistance. CONSTITUTION: As for the glaze layer 2d of the spark plug 100, the content of Pb component is made to be 1 mol% or less by PbO conversion, and further, 30 to 60 mol% of SiO2 is contained, 20 to 50 mol% of B2O3, 0.5 to 25 mol% of ZnO, and 0.5 to 15 mol% of BaO and/or SrO in the total are contained. Furthermore, oxides of alkali metal components are contained in the range of 2 to 12 mol% in the total as the form that K and Li are indispensable. Further, F is contained by 0.1 to 10 mol% as the value in which F is calculated as F2.
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