Abstract: An aqueous conversion coating composition for treating metal substrates such as aluminum, aluminum alloys, zinc, zinc alloys, magnesium, magnesium alloys and steel to provide a conversion coating thereon. The conversion coating composition comprises a) a source of aluminum ions; b) a fluoro compound; c) at least one pH adjuster; d) a source of Group VIB metal ions selected from the group consisting of tungstate ions and trivalent chromium ions; and e) optionally, a preservative. The conversion coating composition provides a corrosion resistant coating on the metal surface and improves the adhesion of subsequently applied layers.

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.