| 摘要 |
PROBLEM TO BE SOLVED: To provide a ceramic heater with which high-temperature strength of a silicon nitride ceramic base is improved and fluctuation in room- temperature strength is minimized. SOLUTION: By forming A1 ingredient thickened layer only on the surface layer of the ceramic base, growth of main-phase particles of silicon nitride is restrained, and so, there will scarcely be any abnormally grown particles generated which can be a starting point of destruction, which means that fluctuation of strength, especially at room temperature, is hardly generated. If rare earth ingredients are included in the A1 ingredients, crystallization of grain boundary phase is promoted and therefore, high-temperature strength is further improved. |
