| 摘要 |
PURPOSE:To improve the durability and uniform exothermic characteristic in a high temp. by a method wherein the outer surface of a graphite-made substrate on the outer surface of which a spiral groove is cut at the tip side of the substance is covered with a silicon-based ceramic lower layer formed by a vapor phase method and in the spiral grooves heating elements are placed and the tops of the lower layer and the heating elements are covered with a silicon-based ceramic upper layer applied by the vapor phase method. CONSTITUTION:On the outer surface of a rod-shaped graphite-made substrate 6 at its tip side a spiral groove 7 is cut with a uniform depth and from one end of the groove 7 a longitudinal groove 8 is cut to the tip end surface of the substance 6 and from the other end of the groove 7 a longitudinal groove 10 is cut to reach halfway the other end of the substrate 6. The outer surface of the substance 6 is covered with a silicon carbide lower layer 11 formed by a vapor phase method and in the groove 7 and respective longitudinal grooves 8, 10 tungsten heating elements 12, 13, 14 are placed on the layer 11 to be on a level with the edge surfaces of the grooves. The tungsten heating elements 12, 13, 14, 13A and the lower layer 11 are covered with a silicon carbide upper layer 15 applied by the vapor phase method.
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