GB427719A - Improvements in a composite structural material and shaped articles made therefrom, in tended more particularly for electrical purposes - Google Patents

Abstract

A composite structural material for use particularly in electric contacts is prepared by intimately uniting at least two sheets, of which one consists of or contains substantial amounts of the high melting metals tungsten, molybdenum or tantalum, while another consists of or contains substantial amounts of at least one of the lower melting metals silver, gold, aluminium, cobalt, chromium, iron, nickel, copper, platinum or tin, the high melting metal being present in ductile form derived from sintered or molten metal by mechanical working, e.g. by drawing, rolling or hammering. Sheets containing substantial amounts of the high melting metal may be made by mixing it in powder form with a powder of low melting metal, heating until the low melting metal melts allowing the mass to settle and rolling into sheets, or by casting over the powder of ductile high melting metal with liquid low melting metal, or powdered high melting metal introduced into a bath of low melting metal, and allowed to settle. Sheets of the conglomerate so produced are united to sheets of high melting metal produced by rolling, by the application of mechanical pressure at a high temperature and preferably in a reducing atmosphere. In examples, a sheet of tungsten is united to one side of a sheet of copper tungsten conglomerate, and also, if desired, a sheet of copper is attached to the other side. In the former case the conglomerate may be treated with a reagent such as potassium nitrite to remove the tungsten and leave a composite material of tungsten on one side and copper on the other. Specification 395,745 is referred to. The Specification as open to inspection under Sect. 91 comprises also the production of a conglomerate body consisting of at least one metal of high melting point, tungsten, molybdenum, vanadium, zirconium tantalum and titanium in a state of coarser granularity than as usually obtained, in admixture with one or more of the low melting metals specified above. High melting metals in a state of coarser granularity than as usually obtained are produced by a process which comprises obtaining the oxide from the ore in the gaseous state by sublimation, and precipitating the same by condensation, and then obtaining the metal by reduction which is carried out slowly and is said to yield the metal in a coarse state of granulation. The reduction is preferably carried out by means of hydrogen and the retardation is effected by the admixture of steam with the hydrogen. Another method of obtaining coarse granules is to sinter fine grain metal produced in the usual way and then crush the sintered mass until granules of the required size are obtained. Round copper rods may be coated completely with a copper tungsten sheet and drawn. Tubes or wires with an interior of copper and an exterior of copper tungsten may be so produced. This subject-matter does not appear in the Specification as accepted. Reference has been directed by the Comptroller to Specification 198,246, [Class 41].ALSO:The Specification as open to inspection under Sect. 91 describes the production of high melting metals such as tungsten, molybdenum, vanadium, zirconium, tantalum and titanium, in a state of coarser granularity than as usually obtained, by submitting the ore to a sublimation process to extract the oxide in the gaseous state, precipitating the same by condensation and then obtaining the metal from the oxide by a retarded reduction process, which is preferably carried out by the use of hydrogen diluted with steam as the reducing agent. This subject-matter does not appear in the Specification as accepted. Reference has been directed by the Comptroller to Specification 198,246, [Class 41].