GB225608A - Improvements in resistors for electric heating - Google Patents

Abstract

225,608. Morgan Crucible Co., Ltd., and Spiers, C. W. Aug. 31, 1923. Resistanee grids; resistance materials.-A resistor for electric heating comprises a solid, coherent ceramic body in which the conducting portion is obtained by the addition of powdered carbon, the conducting portion being entirely surrounded by ceramic material. In the form shown in Fig. 3, a conducting layer which may be formed by mixing flaked graphite with clay is placed upon a thin layer of clay, and interrupted concentric grooves c are made in the conducting layer to form a circuit. The grooves having been filled with clay, a layer of clay is then placed upon the conductor and the whole firmly pressed together. Circular conducting blocks f are worked on to the extreme ends of the conducting circuit and metal terminals g screwed into holes drilled therein. The edge of the element is covered with a layer e of clay. When the resistor is intended for high temperatures, the terminals, which may be water-cooled or provided with gills, are mounted upon graphite rods g', Fig. 5, screwed into raised portions f<1> worked upon the conductor. The portions f<1> have a higher conductivity than the latter, and the rods g<1> are protected by a glazed insulating tube h. The conductor may be made up in layers, each layer being separated from the next by an insulating layer of clay. A clay vessel may be moulded on or around the resistor.