THERMOMAGNETIC RECORDING PROCESS

1,224,283. Magnetic recording member. AMPEX CORP. 6 May, 1969 [13 May, 1968], No. 23163/69. Heading HlH. [Also in Division C7] A magnetic record member, as for use in thermomagnetic recording, comprises a substrate (e.g. brass, aluminium or non-conductors, such as plastics materials, having a conductive surface) electroplated with an alloy comprising P 0À05-1À5% and Ni 0-2.5% the balance, apart from impurities, being hexagonal cobalt. To obtain the required form of cobalt the electrolysis is carried out with a pH of 5À5 to 6.6. The basic bath may be sulphate plus chloride, all sulphate, all chloride or sulphamate; the current density may be 5-500 mA/inch2; and the bath preferably contains 0À08-2À3 parts by wt. P (expressed as hypophosphite) and 0-10 parts by wt. Ni per 100 parts by wt. Co.