| abstract |
An object of the present invention is to provide a spark plug formed of an alumina sintered body produced with excellent workability and high productivity and exhibiting high withstand voltage and high high temperature strength, and a method for producing the spark plug. The present invention is made of a dense alumina-based sintered body in which the insulator (3) has an average crystal grain diameter of 1.50 µm or more, wherein the alumina-based sintered body has a content (S) versus content (S) of a Si component and a group 2 element component. Insulator (3) containing the Si component, Ba and Group 2 element component including one other element except for this, and rare earth element component so that the ratio with respect to the total content of the content (A) is 0.60 or more. A spark plug 1 comprising, and a method of manufacturing the spark plug 1 through a polishing-shaping process of grinding and shaping the insulator 3 prior to combustion. |