Title:
スパークプラグ
Document Type and Number:
Japanese Patent JP6369837
Kind Code:
B2
Abstract:
A spark plug 1 includes an insulator 3, a center electrode 4, a metallic shell 7, and a ground electrode 8. The insulator contains not less than 90.0 mass% and not greater than 98.1 mass% of Al 2 O 3 with respect to a total mass of elements, as reduced to oxides, contained in the insulator, and has a porosity not greater than 5%. Assuming that a porosity of the insulator after a heat treatment is B, a difference (B-A) of the porosities before and after the heat treatment is not greater than 3.5%. In the heat treatment, the insulator is placed in a furnace, and a temperature in the furnace is increased from a room temperature to 1400°C at a temperature increase rate of 7°C/min and is held at 1400°C for 30 minutes, and thereafter, the temperature is decreased from 1400°C to 400°C at a temperature decrease rate of 10°C or less per 5 minutes and is decreased to the room temperature.
Inventors:
Yoshida Haruki
Junpei Isasa
Toshiki Honda
You Yokoyama
Kuniji Tanaka
Araki Nobuyoshi
Toshiki Ima
Junpei Isasa
Toshiki Honda
You Yokoyama
Kuniji Tanaka
Araki Nobuyoshi
Toshiki Ima
Application Number:
JP2015186376A
Publication Date:
August 08, 2018
Filing Date:
September 24, 2015
Export Citation:
Assignee:
Nippon Special Ceramics Co., Ltd.
International Classes:
H01T13/38; C04B35/111
Domestic Patent References:
| JP2011070929A | ||||
| JP2011070928A | ||||
| JP63190753A | ||||
| JP2013529355A | ||||
| JP2011154908A |
Foreign References:
| WO2014034055A1 |
Attorney, Agent or Firm:
Naoki Fukumura