| 摘要 |
<p>This invention has for its object to provide a ceramic heater wherein, even when a direct current is applied to the heater for many hours, the resistance heating element is not easily oxidized so that the resistance change of the resistance heating element due to such oxidation and heater degradation due to aging can be successfully prevented. The present invention is directed to a ceramic heater which comprises an insulation sheet comprising 88 to 95 weight % of Al2O3 supplemented with, as sintering aids, 3 to 10 weight % of SiO2, 0.4 to 1.0 weight % of MgO and 1.0 to 2.5 weight % of CaO, a core covered with said insulation sheet, a resistance heating element of high-melting metal as interposed between said insulation sheet and core, and an intermediate layer of an alumina ceramic body having a thickness of 5 to 50 mu m, said alumina ceramic body containing 0.05 to 4 weight % of SiO2, 0.01 to 0.5 weight % of MgO and 0.01 to 1.2 weight % of CaO as interposed between at least a part of said resistance heating element and said core, etc. <IMAGE></p> |
