SPINEL POWDER AND MANUFACTURING PROCESS THEREFOR, AND PROCESSES FOR PRODUCING THERMAL SPRAYING FILM AND GAS SENSOR ELEMENTS

摘要

A spinel powder which is obtained by mixing electrofused alumina with a raw material for magnesia and firing the resulting mixture and which is characterized in that the powder particles are covered with granular spinel particles. Thus, a spinel powder which exhibits excellent thermal sprayability and has a unique particle shape and a simple manufacturing process therefor are provided. Further, a process for producing gas sensor elements which comprises using the spinel powder as the thermal spray powder for forming a protective film and which contributes to the minimization of unevenness of characteristics of the sensors is provided.