公开(公告)号：US20180272563A1

公开(公告)日：2018-09-27

申请号：US15745208

申请日：2016-07-05

Applicant: DENSO CORPORATION

Inventor： Katsumasa KOEDA ,  Hiroshi ARAKI

IPC: B28B11/24 ,  C01F7/02 ,  H01B19/00 ,  B28B3/02

CPC classification number: B28B11/243 ,  B28B3/02 ,  C01F7/021 ,  C01P2004/61 ,  C01P2006/80 ,  C04B35/111 ,  C04B35/62695 ,  C04B2235/5436 ,  C04B2235/6562 ,  C04B2235/6567 ,  C04B2235/6583 ,  C04B2235/6584 ,  C04B2235/6585 ,  C04B2235/72 ,  C04B2235/96 ,  H01B17/56 ,  H01B19/00 ,  H01T13/20 ,  H01T13/38 ,  H01T21/02

Abstract: Provided are a molding step (A) of preparing an alumina molded body 11 from a molding raw material which contains an alumina raw material powder having an average particle size of 2 μm to 5 μm and a molding additive, and a sintering step (B) of preparing an alumina molded body 12, which becomes a spark plug insulator 1, by sintering the alumina molded body 11. At the sintering step (B), the alumina molded body 11 is conveyed to a continuous furnace 100 provided with a heating zone Z1 which is heated to 700° C. to 1600° C. by a heating means 401, followed by introducing oxygen gas to control the heating zone Z1 to have a high oxygen atmosphere with an oxygen concentration exceeding 20 mol %.