International Business Machines Corporation

Other

Hitachi Global Storage Technologies Netherlands B.v.

John C Shen

James Aloysius Hagan

Douglas Howard Piltingsrud

Dennis Leonard Fox

Brent Ray Den Hartog

Kannimangalam Venkatasubramanyam Viswanathan

John C Ottman

Krishna Gandhi Sachdev

Mitchell S Cohen

Keith S Pennington

Ajay Johary

James J Mayerle

Bruce E Kennedy

The present invention utilizes a combination of chemical and mechanical finishing processes to polish a disk substrate surface to near atomic smoothness. Broadly speaking, the surface of a disk substrate that has been machined (i.e., rough ground) to a predetermined surface roughness is subjected to attack by a chemical formulation (called an attacking agent). The chemical formulation is used to soften the substrate material. Then, the softened material is &ldquo;wiped away&rdquo; via mechanical action.

Substrate independent superpolishing process and slurry

A lubricant film for a thin-film disk is disclosed. The lubricant film comprises a monolayer of fixed lubricant bonded to the surface of the thin-film disk and a mobile lubricant in contact with the layer of fixed lubricant. The monolayer of lubricant film is applied to the thin-film in a method comprising applying a lubricant composition to the surface of a thin-film disk, then heating the thin-film disk at a sufficient temperature for a sufficient time to bond or fix a portion of the lubricant composition to the disk; to evaporate a portion of the lubricant composition from the surface of the disk; and to dispose a portion of the lubricant composition as a mobile lubricant in contact with the fixed lubricant.

Lubricant film for a thin-film disk

Electroerosion recording materials of superior scratch resistance are provided by incorporating a hard, crosslinked polymer film or layer between the support and the removable, thin conductive layer to reduce plastic deformation of the support under stylus writing pressure. The intermediate polymer layer may be unfilled or filled with solid particles, such as silica particles. The materials may be used in various printing processes including making directly readable images, direct negatives, and offset masters.

Scratch resistant recording materials for electroerosion printing

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.

Rigid magnetic recording media

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.

Hydrated alumina binder system

A magnetic recording coating has a high density of magnetic particles uniformly dispersed in a thermoset resin binder with the dispersion applied as a thin coating onto a rigid substrate. The thermoset resin binder comprises a phenolic, an epoxy, and a styrene allylalcohol. The curing action of this coating is initiated by blocked acid catalysts. The material can be cured at a low temperature to produce a smooth, hard coating with an improved orientation ratio and without impairing the properties of the magnetic particles.

Rigid magnetic recording media coating composition

The disclosure is directed to a method and apparatus for superfinishing magnetic disk substrates using a non-friable polishing pad including a high density polyurethane foam binder in which at least 50 per cent by weight of classified hard particles are retained. Polishing occurs by rotating the pad against the surface to be ultrafinished in the presence of a water soluable liquid vehicle maintaining a minimum pressure of 5 pounds per square inch at a rotational speed that achieves the desired aggressiveness of the polishing media. The method and apparatus contemplate both the ultrafinishing of newly prepared substrate disks and the restoring of previously coated disks to a ultrafinished substrate condition without producing substances or conditions toxic to the ecology or the operator.

Fixed abrasive polishing media

The grinding media is formed of a concentration of agglomerate free hard particles exceeding 50 percent by weight of the media, wherein the particles are chelated by a dispersing agent, surface treated with a surfactant, mixed with polyether polyol and polyisocyanate plus a catalyst and water and thereafter rapidly cured in a closed mold which has been preheated to a temperature exceeding 50.degree. C. and a pressure of 60 to 120 PSIG. The water reacts during curing to create a polyurea linkage and release CO.sub.2 as a blowing agent. The resulting media has a low elastic modulus with particles retained in a polyurethane-urea binder system. The media composition may also include an inorganic filler such as glass fibers not exceeding 30 percent by weight of the media.

Fixed abrasive grinding media

The disclosure is directed to a method and apparatus for superfinishing magnetic disk substrates using a non-friable polishing pad including a high density polyurethane foam binder in which at least 50 percent by weight of classified hard particles are retained. Polishing occurs by rotating the pad against the surface to be ultrafinished in the presence of a water soluable liquid vehicle maintaining a minimum pressure of 5 pounds per square inch at a rotational speed that achieves the desired aggressiveness of the polishing media. The method and apparatus contemplate both the ultrafinishing of newly prepared substrate disks and the restoring of previously coated disks to a ultrafinished substrate condition without producing substances or conditions toxic to the ecology or the operator.

Growing community of inventors

Rochester, MN, United States of America

John C Shen