GB365081A - Improvements in or relating to non-metallic resistors and methods or making them - Google Patents

Abstract

365,081. Self-supporting resistances; resistance materials ; couplings ; depositing by arc discharge. CARBORUNDUM CO., Ltd., Trafford Park Road, Manchester. -(Assignees of Heyroth, A. H. and Cox, G. C. ; Niagara Falls, New York, U.S.A.) July 15, 1930, No. 21442. Convention date, July 29, 1929. [Classes 37, 38 (i), and 41.] A non-metallic resistance is composed principally of silicon carbide, the contactmaking part or parts being impregnated with silicon, aluminium, nickel or alloys thereof. The contactmaking ends of a rod 5 of silicon carbide which may be preheated is dipped into the crucible 3 of an electric furnace 2 containing molten silicon 4 and the crucible is heated to a temperature (about 2100‹ C.) high enough to cause the boiling silicon to impregnate the end of the non-metallic rod 5. Silicon in granular form slightly in excess of the amount required for impregnation may be introduced into the crucible and heated with the silicon carbide rod, the excess silicon being volatilized in order to remove any particles of silicon adhering to the resistance. Further heating to a higher temperature in the case of silicon impregnation causes the silicon to alloy with the silicon carbide. Alternatively, the resistance may form one electrode of an electric arc, a piece of the substance with which it is to be impregnated being supported on the end of the resistance and an arc struck between it and a carbon rod forming the other electrode. Alternating or direct currents may be used. The Specification as open to public inspection describes a method wherein the resistor forms one electrode of the arc and the impregnating material the other electrode. Specifications 18749/06, [Class 37, Electricity, Measuring &c.], is referred to.