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AssigneeThe Dow Chemical Company
InventorsAleksander J. Pyzik, Chan Han, Uday V. Deshmukh, Kevin J. Nilsen, Donald J. Perettie, Arthur R. Prunier, Jr.
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A hard drive disk substrate is formed of a multi-phase ceramic-based material having at least two phases with amorphous phases being present in an amount less than about 1 volume percent based on the volume of the ceramic-based material or at least one phase being free metal. A process for producing the ceramic-based disk substrate is produced by forming a flat disk of a porous ceramic and then infiltrating the porous ceramic with a metal whereby a multi-phase ceramic-based computer hard drive disk is produced. Additionally, a step of passivating the porous ceramic by elevating it to a temperature of about 1300.degree. to about 1800.degree. C. before the infiltrating step may be performed, such that the surfaces are passivated and the reaction kinetics can be controlled during the infiltrating step. A preferred composite material is made of a multi-phase boron carbide composite material including grains having peaks with an average roughness value, Ra, of between about 1 to about 200.ANG., the roughness value being formed in situ by causing a micro hardness gradient of between about 19 and about 3200 Kg/mm.sup.2 in the various phases of the multi-phase boron carbide composite material.
A hard drive disk substrate comprised of an aluminum-boron-carbon composite, the composite having from about four volume percent to about thirty volume percent of free aluminum metal, the composite having a density greater than ninety eight percent of theoretical density wherein the substrate is formed by a process that melts the aluminum.
A hard drive disk substrate comprised of an aluminum-boron-carbon composite, the composite having from about four volume percent to about fifteen volume percent of free aluminum metal, the composite having a density greater than ninety eight percent of theoretical density wherein the substrate is formed by a process that melts the aluminum.
Dependencies are inferred from the claim text.