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Abstract

A process for producing a high density magnetic storage device such as a rigid memory disc having improved magnetic recording properties including high coercivity, high remanence and improved hysteresis loop squareness. The device is prepared by initially cleaning the surface of a substrate, such as an aluminum disc, zincating that cleaned surface, when applicable electrolessly depositing a non-magnetic, nickel-phosphorus layer thereon which is substantially free of pits and other surface imperfections and which has a nickel content of from approximately 88 to 92 percent and a phosphorus content of from 12 to 8 percent, by weight. The non-magnetic, nickel-phosphorus layer is then polished and a magnetic, cobalt-phosphorus layer electrolessly deposited thereon. The cobalt-phosphorus deposition is performed in a highly stable, ammonia-free bath containing a source of cobalt ions, a source of hypophosphite ions, a source of citrate ions, and a low molecular weight, bath soluble amino acid. Preferably, a buffering agent such as, for example, a borate is employed in the bath. Thereafter, if desired, a protective coating in the form of a fluorocarbon, graphite or an electroless nickel-boron layer may be applied as an overlayer to the cobalt-phosphorus layer.

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First Claim