GB579380A - Improvements in or relating to wrought metal electrical resistance materials - Google Patents

Abstract

579,380. Electrical resistance alloys. COOK, M., ALEXANDER, W. O., and IMPERIAL CHEMICAL INDUSTRIES, Ltd., Sept. 8, 1943, No. 14740. [Classes 72, 82 (i) and 82 (ii)] Wrought electrical resistance materials are made from an alloy containing 1-5 per cent silicon, 1-7 per cent aluminium, the balance being copper. Preferably the silicon content is between 2.5 and 4.5 per cent. Manganese may be present up to 3 per cent. Up to 0.1 per cent of phosphorus, up to 0.5 per cent of zinc or cadmium and up to 0.2 per cent of magnesium may be used to cleanse the molten alloy ; up to 0.2 per cent of nickel may be present but the total of these last mentioned elements should not exceed 0.5 per cent. Iron may be present as an impurity but should not exceed 0.25 per cent. The following elements may be used as grain refining agents; chromium, titanium, tellurium or selenium 0.05-1.0 per cent, zirconium 0.01-0.1 per cent, silver 0.001-0.1 per cent, or cerium 0.03-0.5 per cent. Altematively magnesium oxide, aluminium oxide or cerium oxide may be used in proportions between 0.05 per cent and 1.0 per cent. A suitable heat treatment for such of these alloys as are liable to internal phase transitions is an anneal at about 500‹ C. for 8-24 hours. In processing the alloys pickling and cleaning operations are preferably performed in aqueous solutions of dichromate and sulphuric acid or of sodium bifluoride and sulphuric acid.