| 摘要 |
PROBLEM TO BE SOLVED: To reduce the deterioration of electric insulation property of the material filled between a heating body and a cover, and prolong the life of sheathed heater. SOLUTION: The sheathed heater comprises a nickel containing metallic heating body 2, a nickel containing metallic pipe 3 sealing the heating body, and an electric insulating material 4 made of oxide filled between the first lead glass 5 and the second lead glass 6. The first lead wire 7 of the heating body 2 penetrates through the first lead glass 5, and the second lead wire 8 of the heating body 2 penetrates through the second lead glass 6. An oxidized layer is formed on the surface of the heating body 2 and the pipe 3.
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