| 摘要 |
An insulator for spark plug with a main constituent of alumina and containing silicon includes a grain boundary phase positioned between alumina particles. The grain boundary phase contains: a group 2A element; a rare earth element; and at least one kind of zirconium, titanium, chrome, niobium, manganese, and iron (a first element). Assuming that a total amount of the rare earth element is X (mass %), a total amount of the group 2A element is Y (mass %), and a total amount of the first element is Z (mass %), the following are met:;0.40≦Y/X≦2.00;0.10≦Z/X≦0.40. |
| 主权项 |
1. An insulator for spark plug with a main constituent of alumina and containing silicon, comprising
a grain boundary phase positioned between alumina particles, wherein the grain boundary phase contains:
at least one kind of elements selected from a group of group 2A elements consisting of a magnesium, calcium, strontium, and barium;at least one kind of elements selected from a group of rare earth elements consisting of lanthanum, neodymium, praseodymium, yttrium, ytterbium, and cerium; andat least one kind of elements selected from a first element group consisting of zirconium, titanium, chrome, niobium, manganese, and iron, wherein assuming that element determination is performed in a visual field of 180 μm×250 μm at any given cross section in terms of oxide with an electron probe microanalyzer (EPMA), and assuming that a total amount of an element selected from the group of rare earth elements is X (mass %), a total amount of an element selected from the group of group 2A elements is Y (mass %), and a total amount of an element selected from the first element group is Z (mass %), the following are met:
0.40≦Y/X≦2.000.10≦Z/X≦0.40. |
