GB1341592A - Composite metallic wire - Google Patents

Abstract

1341592 Electrodepositing tin alloy and magnetic film on wire SOC HONEYWELL BULL 25 May 1971 [26 May 1970] 17043/71 Heading C7B A composite metallic wire substrate, for a cylindrical magnetic memory film having uniaxial anisotropy e.g. Ni-Fe alloy containing 18% Fe, comprises a filamentary conductive core e.g. of 60 micron diameter coated with a layer e.g. between 1 and 5 microns thick of Sn-Ni alloy containing between 29 and 40% Ni. The core may be of Cu-Be, Ag, Cu or Al. The Sn- Ni layer and subsequent magnetic film are preferably formed by electrodeposition followed by rinsing and annealing e.g. at 300‹C. Prior to coating, the core may be treated first in an acetone degreasing bath, then a NaOH-Na 2 CO 3 degreasing bath, then a H 2 SO 4 -HNO 3 cathodic pickling bath, each bath followed by rinsing. The whole fabrication may be effected continuously by pulling the wire (core) through a series of treatment, plating and rinsing baths and annealing ovens. The Sn-Ni plating bath may contain 50 g/ 5nCl 2 .2H 2 O, 250 g/l NiCl 2 .6H 2 O, 40 g/l NH 4 F.HF and 35 m/l aqueous ammonia (35% NH 3 ), and have a pH adjusted to 2À5 by addition of NH 3 or HCl. The subsequent magnetic film may be coated with a protective layer of varnish or synthetic resin, or the Sn-Ni coating described in Specification 1311330.