Abstract: The invention is a method for improving the flatness of nonmetallic substrates and preferably glass disks. The method comprises the steps of mounting the glass disk on a support. The support preferably comprises a refractory metal having a cooling rate substantially similar to the disk. The disk is then subjected to heating to a temperature in the anneal region for the given material for a period ranging from about 0.5 hours to 12 hours or longer, and then the disk is controllably cooled. The glass disk is preferably cooled at a rate of about 0.25.degree. C./minute to 1.5.degree. C./minute to room temperature. The invention also comprises a hard disk glass memory element and a data storage and retrieval device comprising this element.

Abstract: A rigid magnetic storage media coating composition using a high concentration of magnetic particles includes a dual thermoset binder system. The two polymers forming the dual binder system cure during mutually exclusive temperature ranges to form polymer networks that are interpenetrated and entangled. The thermoset polyurethane-melamine/polyester polymer binder system possesses improved properties including the ability to retain liquid fluorinated polyether lubricant without spin-off. The addition of a small amount of silicone wax to the uncured coating composition enhances composition rheology during spin coating on a rigid substrate.

Abstract: The composition and method of making a magnetic recording media using a polyurethane binder system with high lubricant retention and a high concentration of magnetic particles is described. The use of hydrated alumina with a solvent blocked isocyanate is used to produce an open cell microporosity in the cured coating wherein the individual voids are not greater than the magnetic bit cell size and the alumina particles remain in the coating to improve abrasion resistance. The porosity size is controlled by a surface active agent additive. Also shown is the method of preparing hydrated alumina with small particle size, dispersibility, and compatibility, and wherein the dehydrating temperature has the same range as the isocyanate deblocking temperature whereby the CO.sub.2 formation that creates the porosity occurs as the polyurethane components cure.