ALUMINA SINTERED BODY AND SPARK PLUG

摘要

PROBLEM TO BE SOLVED: To provide an alumina sintered body and a spark plug excellent in alkaline corrosion resistance.SOLUTION: There are provided an alumina sintered body 1 having at least a main phase 2 composed of: alumina crystal 21; a first dispersion phase 3; and a second dispersion phase 4 dispersed in the main phase 2 and a spark plug having an insulation glass composed of the alumina sintered body 1. The first dispersion phase 3 is composed of a MgAlOcrystal and the second dispersion phase contains SiOand/or CaO. The percentage content of the main phase 2 is 90 mass% or more and less than 98 mass%. A highest peak strength Iof X ray diffraction peaks derived from alumina in the alumina sintered body 1 and highest peak strength Iof X ray diffraction peaks derived from MgAlOsatisfy a relationship of 100×I/I≥5.5%. A percentage of existing area of the second dispersion phase 4 in a surface of the alumina sintered body 1 is 15.2% or less.SELECTED DRAWING: Figure 2