| 摘要 |
A mini-floppy disk or like information storage device is comprised of a circle of data storage medium having a central metal hub. In use, the hub is contacted with and driven by a magnetized spindle. The hub comprises a ferromagnetic substrate and a metal coating. The coating has magnetization Bs which is less than the magnetization of the substrate. The coating is harder than the substrate, preferably greater than 400 DPH hardness number. The coating is deposited with an amorphous microstructure while the substrate is crystalline. The coating has a nodular surface texture and surface oxide film which provides improved adhesive bond strength, where the medium is joined to the hub. The coating preferably is an electroless plating deposit, comprised of nickel or cobalt base metal, with phosphorous or boron additive; most preferably it is nickel-11% phosphorous.
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