To provide a spark plug superior in voltage endurance characteristics under the condition of a high temperature, and having resistance to an acid atmosphere and a basic atmosphere.
A spark plug comprises an insulator including Al components in a proportion of 89 mass% or more in terms of oxides, and Ti components in a proportion of over 0 mass% up to 0.2 mass% in terms of oxides. The insulator is composed of an alumina-based sintered compact which includes, in grain boundary phases located between alumina crystals, a first crystal phase including at least one kind of components selected from La components, Nd components, Pr components, Y components, Er components, Yb components and Lu components, and a second crystal phase including at least one kind of components of Group II elements in the periodic table based on the recommendation by IUPAC in 1990, Al components and Si components.
YOKOYAMA YUTAKA
TANAKA KUNIHARU
MITSUOKA TAKESHI
HONDA TOSHITAKA
KURONO KEIICHI
TAKAOKA KATSUYA
UEGAKI HIRONORI
| JP2011070929A | 2011-04-07 | |||
| JP2001313148A | 2001-11-09 | |||
| JP2001335360A | 2001-12-04 |
Naoki Fukumura