| 摘要 |
A smooth recording surface is formed on a record medium such as aluminium or a ferrous material by soaking the surface for two to forty hours at room temperature in a polyhalo lower alkane, drying, treating in an alkaline bath, rinsing in water and electroless plating. The polyhalo lower alkanes have no more than three carbon atoms per molecule such as methyl chloride, trichloroethylene, dichloroethylene, perchloroethylene, propylenedichloride, bromotrichloromethane and dichlorodifluoromethane. In an example, an aluminium disc is soaked for 16 hours in trichloroethylene, air dried, and treated in an alkaline bath with a pH of 8 at 71 DEG C. After rinsing and dipping in an inhibited acid bath (H2SO4: H3PO4: H2O in 1 : 2 : 3 volume ratio) followed by rinsing, the disc is plated in an electroless nickel phosphorus plating bath. A steel disc is similarly plated but is first treated with a reversing current of 70 to 100 amps. per ft.2 in the alkaline bath. |
