Minnesota Mining and Manufacturing Company

Richard N Gardner

Kenneth Robert Dillon

Thomas A Rinehart

Robert P Freese

Leslie H Johnson

A magneto optical thin film recording medium is disclosed having very high carrier-to-noise ratios and high rotation angles. A transmission electron microscope photomicrograph (at 200,000 X) of one such medium is shown in FIG. 1. These are multi-phase amorphous materials having magnetic anisotropy perpendicular to the plane of the thin film. They are produced in a triode vacuum sputtering process at vacuums in the range of 4.times.10.sup.-3 to 6.times.10.sup.-4 Torr. By adjusting process parameters such as substrate temperature, anode bias and deposition rate, the properties of the thin film can be altered.

Amorphous magneto optical recording medium

A magneto optical thin film recording medium is disclosed having very high carrier-to-noise ratios and high rotation angles. A transmission electron microscope photomicrograph (at 200,000.times.) of one such medium is shown in FIG. 1. These are multi-phase amorphous materials having magnetic anisotropy perpendicular to the plane of the thin film. They are produced in a triode vacuum sputtering process at vacuums in the range of 4.times.10.sup.-3 to 6.times.10.sup.-4 Torr. By adjusting process parameters such as substrate temperature, anode bias and deposition rate, the properties of the thin film can be altered.

A triode vacuum sputtering process, and vacuums in the range of 4.times.10.sup.-3 to 6.times.10.sup.-4 Torr are used to obtain amorphous rate earth/transition metal alloy thin films useful as magneto optic media. By adjusting process parameters such as substrate temperature, anode bias and deposition rate, the properties of the thin film can be altered.

Sputtering process for making magneto optic alloy

A multi-layer magneto optical thin film recording medium is disclosed having very high carrier-to-noise ratios (at least 47 decibels) and high rotation angles. A transmission electron microscope photomicrograph (at 200,000 X) of one such medium is shown in FIG. 1. The magneto optic layer is a multi-phase amorphous material having magnetic anisotropy perpendicular to the plane of the thin film produced in a triode vacuum sputtering process at vacuums in the range of 4.times.10.sup.-3 to 6.times.10.sup.-4 Torr. Various transparent layers, such as dielectric intermediate and anti-reflective layers and a protective covering layer, are combined with the magneto optic layer and a reflective surface to yield media having enhanced carrier-to-noise ratio and magnetic optic angle of rotation.

Multi-layer amorphous magneto optical recording medium

A precision molded article, such as a die cavity, is made by combining granules of a first metal or alloy and a second metal or alloy, the second metal or alloy having a homogeneous appearance at some temperature below its melting point, and a higher Rockwell Hardness than the first metal or alloy, mixing the granules with a heat fugitive organic binder, molding the granule-binder mixture into a green molded preform, thermally degrading and removing essentially all the binder to form a skeletal preform, and infiltrating the preform with a third metal or alloy which will wet the second metal or alloy and has a lower Rockwell Hardness than the second metal or alloy, thereby forming a molded article having granules of first metal or alloy the majority of which are fully enveloped within a single skeleton of the second metal or alloy, the skeleton of second metal or alloy being surrounded by layers or matrices of softer metals.

Infiltrated powered metal composite article

A precision molded article, such as a die cavity, is made by combining iron powder granules and optional manganese granules with a heat fugutive organic binder, molding the granule-binder mixture into a green molded preform, thermally degrading and removing essentially all the binder to form a skeletal preform, and infiltrating the preform with an infiltrant which has a lower melting point than the iron powder granules and which optionally contains manganese, with the proviso that either the above decribed manganese granules are employed or manganese-containing infiltrant is employed, thereby forming a molded article having a skeleton of ferroalloy granules having a martensitic or perlitic core and an outer layer of austenitic manganese steel, the skeleton being surrounded by infiltrant.

Austenitic manganese steel-containing composite article

A precision molded article, such as a die cavity, is made by combining granules of a refractory and granules of a first metal or alloy which has a homogeneous crystalline appearance at a temperature below its melting point and has a lower Rockwell Hardness than the refractory, mixing the granules with a heat fugitive organic binder, molding the granule-binder mixture into a green molded preform, thermally degrading and removing essentially all the binder to form a skeletal preform, and infiltrating the preform with a second metal or alloy which will wet the first metal or alloy and has a lower Rockwell Hardness than the first metal or alloy, thereby forming a molded article having refractory granules fully enveloped within a single skeleton of the first metal or alloy, the refractory granules and skeleton of first metal being surrounded by layers or matrices of softer metals.

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Grant Township, MN, United States of America

Richard N Gardner