| 摘要 |
PROBLEM TO BE SOLVED: To provide a spark plug having a glazing layer which has small content of Pb (lead) and is capable of firing at relatively low temperature and excellent in insulation and easy to achieve a smooth glazing face. SOLUTION: The glazing layer 2d of the spark plug 100 contains 25-45 mol% of Si component in the oxide conversion of SiO2, 20-40 mol% of B component in the oxide conversion of B2O3, 5-25 mol% of Zn in the oxide conversion of ZnO, and 0.5-15 mol% in total of Ba and/or Sr component in the oxide conversion of BaO or SrO. As an alkaline metal component, it contains 5-10 mol% in total of one or two or more kinds of K as an essential component, Na in the oxide conversion of Na2O, K in K2O, and Li in LiO2, and further, it contains 0.5-5 mol% of one or two or more kinds of Mo, W, Ni, Co, Fe and Mn component in the oxide conversion of Mo in MoO3, W in WO3, Ni in Ni3O4, Co in Co3O4, Fe in Fe2O3 and Mn in MnO2 respectively.
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