GB620998A - Improvements in the joining of carbon bodies to other bodies - Google Patents

Abstract

A method of making a carbon joint between a carbon body and another carbon or other body having approximately the same coefficient of thermal expansion and the same wettability as the carbon body which method consists in mixing at least 1 cyclic organic compound (having not less than 4 carbon atoms in the ring and a ratio of hydrogen to carbon atoms of about 2 to 1), finely divided carbon and concentrated sulphuric acid with agitation to make a paste, spreading the paste evenly on the joining surfaces, pressing the surfaces together and heating the joint slowly to above 100 DEG C. Furfural may be used as the organic compound in the paste used to form a joint the joint being heated to between 200 DEG C. and 300 DEG C. The paste may be made by mixing furfural with finely divided carbon, mixing concentrated sulphuric acid with finely divided carbon and mixing a minor proportion, about 10 per cent, of the second paste with the first paste with vigorous agitation. After pressing the joined surfaces together the assembly may be allowed to stand at a temperature between 15 DEG C. and 100 DEG C. for a considerable period (e.g. twelve hours or more) before being heated to 200 DEG C. to 300 DEG C. Alternatively the joint may be heated slowly at between 1/2 DEG C. and 3 DEG C. per minute up to a temperature exceeding 100 DEG C. and maintained at that temperature for about half an hour.