GB646002A - Metallurgical processes for producing materials or articles of platinum or allied metals, or their alloys, and materials or articles made 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 following oxides, namely, those of lanthanum, neodymium, samarium, praseodymium, scandium, yttrium, terbium, gadolinium, europium, dysprosium, holmium, erbium, thulium, ytterbium and lutecium, the quantity of which oxide or oxides 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 a wire or sheet suitable for use in the production of desired articles. The specified oxides may be partly replaced by one or more other oxides which are stable at the sintering temperature whether or not the sintering is carried out in the presence of hydrogen or other reducing gas, the major portion of the total oxide content being the one or more oxides above specified. The agglomerate may consist mainly of platinum alloyed with rhodium, palladium, iridium, ruthenium or tungsten, e.g. 5-30 per cent of rhodium, the proportion of oxide being 0.01-1.0 per cent of the weight of the metal, or tungsten in the range of 1-8 per cent of the platinum and about 0.2 per cent of oxide. One of the following binary alloys may be used in the agglomerate, namely, platinum alloyed with rhodium, iridium or palladium up to 30 per cent of the alloy, or ruthenium, gold, cobalt or nickel up to 15 per cent, or molybdenum, manganese or tungsten up to 8 per cent of the alloy. The process may be carried out in the following manner. A paste containing 90 grams of platinum in the form of ammonium-chloroplatinate, 10 grams of rhodium in the form ammonium hexachlororhodate, and 10 c.c.s. of an aqueous solution of lanthanum nitrate containing 0.2 grams of lanthanium oxide, is made up to 200 c.c.s. with distilled water. The mass is dried and heated at about 350 DEG C to form platinum, rhodium and lanthanum oxide. The product is heated to 850 DEG C in a stream of hydrogen to reduce any rhodium oxide, pressed at about 30 tons per square inch and sintered at 1400 DEG C in hydrogen for about 1 hour. In another example 96 grams of platinum dissolved in aqua regia, 4 grams of tungsten in the form of ammonium tungstate and a neodymium nitrate solution containing 0.15 grams of neodymium oxide are mixed and treated to form an agglomerate containing platinum, tungsten and neodymium oxide. The agglomerate may be used in the production of sparking plug electrodes, thermo-couples, electric furnace heating elements and wire gauzes or the like for use as catalysts in chemical operations. Specifications 645,541, 645,681 and 645,682 are referred to.