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US 5,626,943 AGranted
Ultra-smooth ceramic substrates and magnetic data storage media prepared therefrom
AssigneeThe Carborundum Company
InventorMichael A. Tenhover
Life of this patent
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Abstract
Layered substrates are disclosed having an ultra-smooth surface finish thereon rendering them useful in making high density magnetic storage media. The layered substrates are comprised of a non-oxide ceramic core coated with a smoothing layer comprised of an amorphous metal, particularly certain amorphous metal alloys based on chromium, molybdenum, tungsten, and mixtures thereof. Also disclosed are magnetic storage media comprising the layered substrates, as well as processes for making the substrates and magnetic media.
Claims50
A layered substrate capable of being adapted for use as a magnetic data storage medium, the substrate comprising:
- a non-oxide ceramic core having a plurality of surfaces;
- and
- a smoothing layer with an inner surface contacting at least one surface of the ceramic core and an outer surface having a surface roughness of less than 100 .ANG. Ra, the smoothing layer comprising a non-magnetic, substantially amorphous metal having a fracture toughness of at least 10 MPa.multidot.m.sup.1/2 ;
- an electrical conductivity or less than about 200 .mu..OMEGA..multidot.cm;
- a crystallization temperature of at least about 400.degree. C.;
- and a coefficient of thermal expansion o between about 2 to about 7 ppm/.degree.C.;
- and wherein the amorphous metal is an alloy which corresponds to the formula:
- M.sup.1.sub.a M.sup.2.sub.b X.sub.c
- wherein
- M.sup.1 is selected from the group consisting of chromium, molybdenum, tungsten, and mixtures thereof;
- M.sup.2 is selected from the group consisting of titanium, zirconium, hafnium, tantalum, vanadium, niobium, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mixtures thereof;
- X is selected from the group consisting of nitrogen, aluminum, boron, silicon, phosphorous, germanium, arsenic, antimony, carbon, tin, and mixtures thereof;
- a is from about 0.5 to about 0.95;
- b is from 0 to about 0.3;
- and
- c is from greater than 0 to about 0.3, and a+b+c is 1.
13 more elements
A magnetic storage medium, comprising:
- a non-oxide ceramic core having a plurality of surfaces;
- a magnetic layer capable of storing data and having an inner surface and an outer surface;
- and
- a smoothing layer with an inner surface contacting at least one surface of the ceramic core and an outer surface having a surface roughness of less than 100 .ANG. Ra, the smoothing layer disposed between the ceramic core and the magnetic layer, the smoothing layer comprising a non-magnetic, substantially amorphous metal having a fracture toughness of at least 10 MPa.multidot.m.sup.1/2 ;
- an electrical conductivity of less than about 200 .mu..OMEGA..multidot.cm;
- a crystallization temperature of at least about 400.degree. C.;
- and a coefficient of thermal expansion of between about 2 to about 7 ppm/.degree.C.;
- and wherein the amorphous metal is an alloy which corresponds to the formula:
- M.sup.1.sub.a M.sup.2.sub.b X.sub.c
- wherein
- M.sup.1 is selected from the group consisting of chromium, molybdenum, tungsten, and mixtures thereof;
- M.sup.2 is selected from the group consisting of titanium, zirconium, hafnium, tantalum, vanadium, niobium, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mixtures thereof;
- X is selected from the group consisting of nitrogen, aluminum, boron, silicon, phosphorous, germanium, arsenic, antimony, carbon, tin, and mixtures thereof;
- a is from about 0.5 to about 0.95;
- b is from 0 to about 0.3;
- and
- c is from greater than 0 to about 0.3, and a+b+c is 1.
14 more elements
The magnetic storage medium of claim 22 wherein the silicon carbide originates from a ceramic green body formed by a tape-casting process.
A process for preparing a layered substrate capable of being adapted into a magnetic storage medium, the processing comprising:
- providing a non-oxide ceramic core having a plurality of surfaces and having a density of at least 90% of theoretical density;
- coating at least one surface of the ceramic core with a smoothing layer comprised of a non-magnetic, substantially amorphous metal having a fracture toughness of at least 10 MPa.multidot.m.sup.1/2 ;
- an electrical conductivity of less than about 200 .mu..OMEGA..multidot.cm;
- a crystallization temperature of at least about 400.degree. C.;
- and a coefficient of thermal expansion of between about 2 to about 7 ppm/.degree.C.;
- and wherein the amorphous metal is an alloy which corresponds to the formula:
- M.sup.1.sub.a M.sup.2.sub.b X.sub.c
- wherein
- M.sup.1 is selected from the group consisting of chromium, molybdenum, tungsten, and mixtures thereof;
- M.sup.2 is selected from the group consisting of titanium, zirconium, hafnium, tantalum, vanadium, niobium, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mixtures thereof;
- X is selected from the group consisting of nitrogen, aluminum, boron, silicon, phosphorous, germanium, arsenic, antimony, carbon, tin, and mixtures thereof;
- a is from about 0.5 to about 0.95;
- b is from 0 to about 0.3;
- and
- c is from greater than 0 to about 0.3, and a+b+c is 1;
- and
- polishing the smoothing layer to a surface roughness of less than 100 .ANG. Ra.
14 more elements
A process for preparing a magnetic storage medium comprising:
- providing a non-oxide ceramic core having plurality of surfaces and having a density of at least 90% of theoretical density;
- coating at least one surface of the ceramic core with a smoothing layer comprised of a non-magnetic, substantially amorphous metal having a fracture toughness of at least 10 MPa.multidot.m.sup.1/2 ;
- an electrical conductivity of less than about 200 .mu..OMEGA..multidot.cm;
- a crystallization temperature of at least about 400.degree. C.;
- and a coefficient of thermal expansion of between about 2 to about 7 ppm/C..degree.;
- and wherein the amorphous metal is an alloy which corresponds to the formula:
- M.sup.1.sub.a M.sup.2.sub.b X.sub.c
- wherein
- M.sup.1 is selected from the group consisting of chromium, molybdenum, tungsten, and mixtures thereof;
- M.sup.2 is selected from the group consisting of titanium, zirconium, hafnium, tantalum, vanadium, niobium, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mixtures thereof;
- X is selected from the group consisting of nitrogen, aluminum, boron, silicon, phosphorous, germanium, arsenic, antimony, carbon, tin, and mixtures thereof;
- a is from about 0.5 to about 0.95;
- b is from 0 to about 0.3;
- and
- c is from greater than 0 to about 0.3, and a+b+c is 1;
- and
- polishing the smoothing layer to a surface roughness of less than 100 .ANG. Ra;
- and
- coating the smoothing layer with a magnetic layer comprised of a material capable of magnetically storing data thereon.
16 more elements
Dependencies are inferred from the claim text.