INSULATOR FOR SPARK PLUG, METHOD OF MANUFACTURING THE SAME AND SPARK PLUG USING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide an insulator for a spark plug, which has high withstand voltage characteristics even at a high temperature in the vicinity of 700°C, and to provide a spark plug with the same.

SOLUTION: The insulator 2 used for the spark plug 100 and containing alumina (Al2O3) as a main component, is constituted of an alumina-based sintered body which includes at least a silicon (Si) component and one or more rare earth elements (hereinafter expressed as RE.) and has a theoretical density ratio of ≥95%. The insulator 2 for the spark plug has an insulator suppressing the occurrence of dielectric breakdown affected by residual pores existing at an alumina crystal grain boundary and a low-melting point glass phase and having excellent withstand voltage characteristics at a high temperature of about 700°C.

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