| 摘要 |
<p>A magnetic recording medium comprises an insulating substrate (e.g. of polyester resin) carrying a metal film which provides bonding nuclei for an outer layer of magnetizable metal material having a coercivity greater than 375 Oe and a surface roughness (peak to trough measurement) of less than 4 micro inches. In one example a resin film formed by condensation reaction of terephthalic acid and ethylene glycol is washed in acetone and immersed in boiling water for 15 minutes. It is sensitized in a solution of SnCl2 and HCl at 25 DEG C., rinsed, and immersed in a solution of palladium chloride and HCl at 55-60 DEG C. A nickel coating is then chemically plated on the sheet by immersing in a solu tion of nickelous chloride, sodium hypophosphite, ammonium chloride, sodium citrate and ammonium hydroxide for 70-90 seconds at 90-95 DEG C. giving a film 6-8 m inches thick. A magnetizable metal film of CoNiP alloy is then electroplated on the nickel using a bath containing a nickelous sulphate, cobaltous sulphate, sodium hypophosphite, and ammonium chloride. The bonding metal may alternatively be Al, Cr, Cu, Ag, and Au, and may be provided by vacuum evaporation, cathode sputtering or chemical plating. The magnetizable metal may be Co, CoP alloys, CoS alloys, CoFe alloys, and CoFeNi alloys.</p> |
