GB513728A - Improvements in or relating to articles comprising silicon carbide - Google Patents

Abstract

513,728. Electric resistances. TENNANT, W. J. (Carborundum Co.) April 11, 1938, No. 11100. [Class 37] [Also in Group. III] Articles such as electrical resistances are formed of a plurality of silicon-carbide-containing parts by integrally uniting the parts by means of welds containing silicon carbide. The silicon-carbide-containing parts may be formed by placing a part preformed from carbonaceous material adjacent one containing silicon carbide with a layer of carbonaceous welding material between them and heating the article in the presence of silicon so that silicon permeates the joint to weld the parts together and permeates the carbonaceous part to convert it into a siliconized silicon-carbide body. A suitable carbonizable welding material is a paste formed of casein and water, another comprises a paste of cereal flour, carbon and charcoal of a consistency of thick mortar for large and robust bodies or of a consistency of paint for smaller articles. The surfaces to be joined should be generously wetted with casein' glue and the excess wiped off. When the parts are joined together by the paste they are dusted with silicon powder and on heating to over 1800‹C. the joint is permeated by the silicon while if one of the parts is of carbonaceous matter it also is permeated by silicon and since it is of lower specific resistance than parts formed of recrystallized silicon carbide it is suitable as a terminal, and where the latter is used as a heating element. Examples of assemblies according to the process are shown in Figs. 1 and 2. In Fig. 1, 10 denotes recrystallized sillicon carbide parts, 11 denotes the terminal ends produced according to the process and 12 the welds. In Fig. 2 parts 13, 14 and 15 are welded together at 16. Specifications 366,605 and 513,265 are referred to.