Improvements in or relating to copper clad wire and methods of forming the same

摘要

534,715. Wire: electrolysis. NATIONAL STANDARD CO. Oct. 31, 1939, No. 29069. Convention date, Nov. 1, 1938. Drawings to Specification. [Class 83 (ii)] [Also in Group XXXVI] A copper clad wire consists of a ferrous core with continuous coating of copper, the copper being built up of layers of different crystal sizes. The core blank may consist of a high carbon steel wire containing 0.65 per cent. of carbon, 0.8 per cent. of manganese, 0.015 per cent. of phosphorus, 0.025 per cent. of sulphur, and 0.095 per cent. of silicon and of diameter between 0.09 and 0.15 inches, preferably 0.119 inch. After drawing the coated wire the core should be below 0.06 inches, preferably 0.045 inches diameter and the coating from 1 to 3 thousandths of an inch. The core is first scraped with steel wool &c. then run through a 32 per cent. HCl bath for 1“ minutes and then wiped with rags. washed with water and again dried and then treated for a minute at 180‹F. with an alkaline solution of a prosphate containing two ozs. to the gallon. After washing the core is run into a copper cyanide bath free from hypo and containing 48 grams per litre of copper, and 25 grams per litre of free cyanide. With current at 30 amps per sq. ft. and in 5 minutes at 150‹F. a layer of 0.0008 inches of copper is deposited. After washing in cold water and rinsing in hot water the wire is then washed in sodium cyanide, 3 ozs. to the gallon, at 150‹F. then in water, and is then treated with HCl, washed in water and passed into an acid copper plating bath containing 55-60 grams per litre of copper and 75 of sulphuric acid. At 110‹F. and with current density of 225 amps per sq. ft. in ¥-1“ mins. 0.0005 inch of copper is deposited. The wire is then again submitted to treatment as in the first step but remains in the copper cyanide bath for 1 minute to deposit a layer of 0.0001 inch of copper. It is then again treated as in the second step but remains in the acid copper plating bath for 38 minutes to deposit a layer of 0.0151 inch copper. Copper from a cyanide bath is stated to be normally in fine crystals and from acid solution in large crystals. In the process above described the first acid coating has crystals of smaller size than normal and the second cyanide coating has crystals of larger size than normal so that the crystals in the initial layer are small, those in the outer layer large, and between these layers is a bonding copper zone having crystals of intermediate size. If only two coatings are applied the thickness of the second coating may be 0.000375 to 0.00075 and after coating the wire is drawn in three or four passes through dies of steel or copper or of the material sold under the Registered Trade Mark " Carboloy." It is finally hot tinned at 500‹F. The wire has a tensile strength of between 245,000 and 270,0001bs. per square inch and a resistance of 16.5 to 17.5 ohms per 1,000 feet.