| 摘要 |
PROBLEM TO BE SOLVED: To improve the heating efficiency of a ceramic heater to be used as an impregnation type electric heater for molten metal. SOLUTION: This ceramic heater is a sintered body formed by integrally laminating an intermediate layer (3) as a heating wire made of ceramic or high melting-point metal and a base layer (2) made of silicon nitride group ceramic and for coating the intermediate layer for protection. The base layer (2) is desirably formed at 90% or more of relative density, and the intermediate layer (3) is desirably formed at about 10μm or less of particle diameter and at 50% or more of relative density. A surface of a green compact layer (21) of silicon nitride group ceramic is formed with a groove (g) so as to obtain a compact (S1 ), and thereafter, a green compact layer (30) of ceramic or high melting point metal powder as the heating wire forming raw material is provided in the groove (g) so as to obtain a compact (S2 ), and a green compact layer (22) of silicon nitride group ceramic for coating the green compact layer (30) is laminated on the surface of the compact (S2 ) so as to obtain a compact (S3 ), and the compact (S3 ) is sintered so as to manufacture a ceramic heater.
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