Spark plug with alumina-based insulator
US8278809B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 9, 2010 |
| Grant date | Oct 2, 2012 |
| Priority date | — |
| Expiry date | Mar 9, 2030 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC04B2235/96
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A spark plug exhibits a satisfactory withstand voltage characteristic and sufficient mechanical strength in a high temperature environment exceeding 700° C. The spark plug has a center electrode, an insulator, and a ground electrode, characterized in that the insulator is formed of an alumina-based sintered material containing an Si component, a Group 2 element (2A) component, and a rare earth element (RE) component; that the alumina-based sintered material has an RE-β-alumina crystal phase; and that the mean crystal grain size DA(RE) of the RE-β-alumina crystal phase and that of alumina DA(Al) satisfy the following relationship (1):0.2≦DA(RE)/DA(Al)≦3.0.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.