PURPOSE: To obtain the titled device having excellent insulation between a heat generating part and a metallic base and excellent heat-accumulating and heat-diffusing properties at the time of heat generation, by providing heat generating elements, electrodes and an abrasion-resistant layer on an insulating substrate obtained by providing a predetermined glass ceramic layer on a metallic base.
CONSTITUTION: A glass ceramic layer should at least have a composition comprising not less than 15wt% of at least one alkaline earth metal oxide (BaO, MgO, CaO or ZnO) and not more than 2wt% of an alkali metal oxide (Na2O, K2O or Li2O) and a coefficient of thermal expansion of 60W150×10-7/°C. The material comprising not less than 15wt% of the alkaline earth metal oxide shows a reaction of the oxide with SiO2 and B2O3, which are main constituents of a glass, to form a highly insulating crystalline phase. If the amount of the alkali metal oxide is more than 2wt%, the crystalline phase of the alkaline earth metal oxide with SiO2 and B2O3 is not easily formed, and insulated property and heat resistance will be poor. It is preferable that the coefficient of the glass ceramic layer is slightly lower than that of a metallic base.
NISHINO ATSUSHI
YOSHIDA AKIHIKO
YOSHIIKE NOBUYUKI
| JPS60143585A | 1985-07-29 |