GB608124A - Improvements in the manufacture of metal bodies - Google Patents

Abstract

608,124. Casting composite articles; powder metallurgy. GENERAL ELECTRIC CO., Ltd., PRICE, G. H. S., and WILLIAMS, F. M., [Representative of WILLIAMS, S. V.]. Jan. 12, 1944, No. 603. [Classes 83 (i) and 83 (iv)] In a process for making a metal body comprising at least one metal of relatively high melting point such as tungsten or molybdenum and at least one metal of relatively low melting point such as copper or silver, a compound of the high melting point metal is first reduced in a container and is then soaked while still in the container with a low melting point metal in molten form. The invention is intended more particularly for making contacts for circuit-breakers or welding electrodes. Tungstic oxide is lightly packed in a recess or recesses in a graphite slab and is heated for approximately two hours at a temperature of 1000‹ C. in an atmosphere of wet hydrogen to reduce the oxide to tungsten. In order to strengthen the porous mass of tungsten produced, the temperature is raised to 1300‹ C. for 30 to 60 minutes to promote sintering, which may be facilitated by the addition to the tungstic oxide of nickel or nickel oxide powder in such quantity that the percentage of nickel does not exceed ¥ per cent of the tungsten content. The tungsten is then saturated with copper or silver while still in the graphite container, either by dropping molten metal on to it or by placing pieces of the metal on the surface of the tungsten and then melting them. Approximately 76 per cent copper or 78 per cent silver may be absorbed. Specification 564,905 is referred to.