GB646003A - Metallurgical processes for producing materials or articles of platinum or allied metals, or their alloys, and materials or articles produced by or from the products of such processes - Google Patents

Abstract

A metallurgical process consists in agglomerating by pressing and sintering metals of the platinum class with or without alloying ingredients, in amounts yielding cold-working alloys with one or more of the oxides of vanadium, niobium and tantalum, the quantity of which oxide is not greater than 10 per cent by weight of the metal, all the ingredients being in a finely divided condition, the sintered body being subsequently swaged, rolled, drawn or otherwise treated to bring it into the form of wire or sheet suitable for use in the production of desired articles. A minor part of the said oxide or oxides may be replaced by one or more other oxides which are stable at the sintering temperature whether or not sintering is carried out in the presence of hydrogen or other reducing gas. The following binary alloys may be used, namely platinum alloyed with up to 30 per cent of rhodium iridium or palladium, or with up to 15 per cent of ruthenium, gold, cobalt or nickel or up to 8 per cent of molybdenum, manganese or tungsten. In an example, 100 c.c.s. of distilled water containing 90 grammes of platinum in the form of a suspension of ammonium choroplatinate is mixed with 50 c.c.s. of an aqueous solution of ammonium hexachlororhodate containing 10 grammes of rhodium and 10 c.c.s. of an aqueous solution of ammonium vanadate containing 0.2 grammes of vanadium pentoxide. The mixture is made up to about 200 c.c.s. with distilled water, dried and heated slowly to about 350 DEG C to decompose the salts to metal and vanadium oxide, which decomposition is completed at about 600 DEG C. The product is crushed, heated to about 850 DEG C in a stream of hydrogen, sieved, pressed in a steel mould under a pressure of about 30 tons per square inch and sintered at about 1400-1500 DEG C and treated to bring it to wire or sheet form. A further example is given of the production, in a similar manner, of a composition containing platinum, tungsten and tantalum oxide. The product may be used in the production of sparking plug electrodes, thermo-couples, electric-furnace heating elements or wire gauze catalysts. Specifications 645,541, 645,681 and 645,682 are referred to.