The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 14, 2001
Filed:
May. 18, 1999
Makoto Sugimoto, Nagoya, JP;
Hiroaki Masuda, Nisshin, JP;
NGK Spark Plug Co., Ltd., , JP;
Abstract
A glaze layer formed on the surface an alumina-based insulator of a resistor spark plug contains SiO,(18 to 35% by weight), B,O,(25 to 40% by weight), ZnO (10 to 25% by weight), BaO (7 to 20% by weight), Na,O (3 to 9% by weight), and K,O (3 to 9% by weight). Since the difference between the coefficients of linear expansion of the glaze and that of the alumina-based insulating material is relatively small, the glaze layer is less susceptible to cracks and the like. Also, since the glaze has a softening point lower than that of conventional lead-silicate-glass-based glaze, the glost-firing temperature can be as low as 800° to 950° C. Therefore, even in the case where glost firing is performed concurrently with a glass sealing step, a center electrode and a terminal metal piece are less susceptible to oxidation. Further, even though the content of the alkali metal component is high, a good insulating performance is obtained so that excellent flashover resistance is attained.