GB645541A - 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 suchprocesses - 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 alkaline earth oxides, namely, oxides of calcium, barium, strontium, magnesium and beryllium, the quantity of which oxide is not greater than 10 per cent by weight of the metal, all 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. A minor part of the alkaline oxide constituent 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 8 per cent of tungsten, up to 15 per cent of gold or ruthenium, up to 8 per cent of molybdenum, up to 8 per cent of manganese, up to 15 per cent of cobalt or up to 15 per cent of nickel. In an example, 100 c.cs. of distilled water containing 90 grammes of platinum in the form of a suspension of ammonium chloroplatinate, 50 c.cs. of a solution containing 10 grammes of rhodium in the form of ammonium hexachlororhodate and 10 c.cs. of a solution containing 0.25 grammes of calcium oxide in the form of calcium acetate are mixed, made up to 200 c.cs. wth distilled water, evaporated to dryness and heated slowly to 350 DEG C to decompose the salts to metal and calcium oxide which decomposition is completed at about 600 DEG C. The product is crushed, heated in a stream of hydrogen at about 850 DEG C, pressed in a steel mould at about 30 tons/square inch, sintered in hydrogen at about 1400 DEG C-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 magnesia. The product may be used as sparking plug electrodes, thermo-couples, electric-furnace heating elements or wire gauze catalysts.