| 摘要 |
<p>A spark plug comprising: a center electrode; a met shell; and an alumina ceramic insulator disposed between the center electrode and the metal shell, wherein at leastpart of the surface of the insulator is covered with a glaze layer comprising oxides, wherein the glaze layer comprises: 1 mol% or less of a Pb component in terms of PbO; 30 to 60 mol% of a si component in terms of SiO2; 20 to 50 mol% of a B component in terms of B2O3; 0.5 to 25 mol% of a Zn component in terms of ZnO; 0.5 to 15 mol% in total of at least one of Ba and Sr components in terms of BaO and SrO, respectively; 2 to 12 mol% in total of at least two alkaline metal components of Na, K and Li, in terms of Na2O, K2O, and Li2O, respectively, wherein K and Li is essential; and 0.1 to 10 mol% of a F component in terms of F2. <IMAGE></p> |
