| 摘要 |
PURPOSE:To improve strength, by so constituting that an insulation layer is provided on the circumference of an exposure part of a blind tip type tubular heating element made of electrically conductive ceramic and a metalized layer of a heat and oxidation proof metal is formed on the external circumference of the insulation layer. CONSTITUTION:One blind end type heating tube 4 made of an electically conductive sinter is fitted in a metal tube 2 for soldering. Then, carbon powder 6 is filled inside the blind end 41 of the heating tube and a core electrode tip side 51 is fitted to the heating tube 4. Then, a gap between the heating tube 4 and the core electrode tip side 51 is filled with an insulation material 7 of powder silicon nitride for insulation and prevention of oxidation of a core electrode. Then, the surface of the blind end 41 of the heating tube is insulated, over which is metalized, while a rear edge side part 52 is soldered to the tip 51 of an electrode and metalized. With this constitution, external force and thermal shock are not actuated directly to a ceramic heating element and strength can be improved. |
