ELECTRIC RESISTANCE FURNACES FOR HIGH TEMPERATURE HEATING

摘要

ELECTRIC RESISTANCE FURNACES FOR HIGH TEMPERATURE HEATING An electric resistance furnace adapted for operation at about 1,800.degree.C or higher temperatures even in an oxidizing or neutral atmosphere is disclosed. The furnace has a cylindrical heating chamber defined by a generally cylindrical heating element made of ceramic material, such as zirconium oxide and lanthanum chromide. The heating element has a wall thickness which is very small at its middle section and gradually increases toward each end. The middle section of the heating element defines the useful part of the heating chamber into which the heat generated by the heating element is effectively concentrated. An electrode comprising an annular foil of platinum is provided at each end of the heating element to pass electric current therethrough. A plurality of substantially equally spaced, longitudinally extending, parallel slots are present in the outer peripheral surface of each of the enlarged wall thickness portions of the heating element to provide allowance for thermal expansion of the heating element material. There is also disclosed a method of applying the electrodes to the heating element.