초록

An element-modified ferrofluid comprising a base oil, a plurality of magnetic particles covered with at least one surfactant, and an elemental modifier. The elemental modifier is a metal, a metal mixture, an alloy, or a nonmetal.

대표청구항 ▼

What is claimed is: 1. A magnetic fluid composition comprising: an oil-based, low vapor pressure carrier liquid; a plurality of magnetic particles coated with at least one surfactant, said plurality of magnetic particles dispersed within said carrier liquid forming a ferrofluid; and at least one el

What is claimed is: 1. A magnetic fluid composition comprising: an oil-based, low vapor pressure carrier liquid; a plurality of magnetic particles coated with at least one surfactant, said plurality of magnetic particles dispersed within said carrier liquid forming a ferrofluid; and at least one elemental modifier disposed without dispersant within said ferrofluid, said at least one elemental modifier being present in said ferrofluid in an amount greater than zero percent and equal to or less than ten percent by weight to the weight of said ferrofluid and wherein said magnetic fluid is aged at room temperature or higher and at an elevated relative humidity for a sufficient time to provide said ferrofluid with a longer useful life than said ferrofluid would have without the addition of said at least one elemental modifier. 2. The composition of claim 1 wherein said elemental modifier is one of a metal, a metal mixture, a metal alloy, and a nonmetal. 3. The composition of claim 2 wherein said elemental modifier is at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, gold, boron, dysprosium, erbium, gadolinium, germanium, holmium, indium, iridium, palladium, lead, molybdenum, neodymium, niobium, osmium, rhodium, samarium, tantalum, tin, tungsten, yttrium, zirconium, ytterbium, carbon, thulium, terbium, and praseodymium. 4. The composition of claim 3 wherein said elemental modifier is at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, gold, dysprosium, erbium, gadolinium, samarium, yttrium, ytterbium, thulium, holmium, praseocymium, and terbium. 5. The composition of claim 4 wherein said metal is at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, and gold. 6. The composition of claim 2 wherein said elemental modifier is one of bronze, cupro nickel, nickel chromium, nickel silver, palladium silver, zirconium nickel, titanium nickel, brass, a mix of chromium, nickel, manganese, silicon, and iron, and a mix of chromium, nickel, manganese, silicon, molybdenum, and iron. 7. The composition of claim 1 wherein said elemental modifier has a purity of about 99%. 8. The composition of claim 1 wherein said elemental modifier has a plurality of elemental modifier particles, said elemental modifier particles having a size of about one micrometer to about 170 micrometers. 9. The composition of claim 2 wherein said metal mixture has a least a first metal component and a second metal component, said first metal component and said second metal component each make up from about 10% to about 90% of said metal mixture. 10. The composition of claim 9 wherein said metal mixture has a least a first metal component and a second metal component, said first metal component and said second metal component each make up about 50% of said metal mixture. 11. A magnetic fluid composition comprising: an oil-based, low vapor pressure carrier liquid; a plurality of magnetic particles coated with at least one surfactant, said plurality of magnetic particles dispersed within said carrier liquid forming a ferrofluid; and at least one elemental modifier disposed without dispersant within said ferrofluid wherein said elemental modifier is at least one of a metal, a metal mixture, a metal alloy, and a nonmetal, said at least one elemental modifier being present in said ferrofluid in an amount greater than zero percent and equal to or less than ten percent by weight to the weight of said ferrofluid and wherein said magnetic fluid is aged at room temperature or higher and at an elevated relative humidity for a sufficient time to provide said ferrofluid with a longer useful life than said ferrofluid would have without the addition of said at least one elemental modifier. 12. The composition of claim 11 wherein said carrier liquid is a polar or a nonpolar liquid. 13. The composition of claim 12 wherein said carrier liquid is selected from the group consisting of a hydrocarbon-based oil, an ester-based oil and a silicone-based oil having low volatility and low viscosity. 14. The composition of claim 11 wherein said elemental modifier is at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron cobalt, copper, zinc, silver, platinum, gold, boron, dysprosium, erbium, gadolinium, germanium, holmium, indium, iridium, palladium, lead, molybdenum, neodymium, niobium, osmium, rhodium, samarium, tantalum, tin, tungsten, yttrium, zirconium, ytterbium, carbon, thulium, terbium, and praseodymium. 15. The composition of claim 14 wherein said elemental modifier is at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, gold, dysprosium, erbium, gadolinium, samarium, yttrium, ytterbium, thulium, holmium, praseocymium, and terbium. 16. The composition of claim 15 wherein said elemental modifier is at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, and gold. 17. The composition of claim 11 wherein said elemental modifier is one of bronze, cupro nickel, nickel chromium, nickel silver, palladium silver, zirconium nickel, titanium nickel, brass, a mix of chromium, nickel, manganese, silicon, and iron, and a mix of chromium, nickel, manganese, silicon, molybdenum, and iron. 18. An element-modified magnetic fluid with a longer useful life obtained by the process comprising: adding a quantity of elemental modifier without dispersant to an oil-based, low vapor pressure magnetic fluid forming a mixture; aging said mixture at room temperature or higher and at an elevated relative humidity for a sufficient time to provide a ferrofluid with a longer useful life than said ferrofluid would have without the addition of said quantity of elemental modifier; and removing an excess of said elemental modifier from said magnetic fluid. 19. The magnetic fluid of claim 18 wherein said aging step includes aging at a temperature of at least 60째 C. 20. The magnetic fluid of claim 18 wherein said aging step includes aging at a relative humidity of about 80% or higher. 21. The magnetic fluid of claim 18 wherein said aging step includes aging at a temperature of about 80째 C. and relative humidity of about 90%. 22. The magnetic fluid of claim 18 wherein said aging step include aging at a temperature of about 90째 C. and relative humidity of about 90%. 23. The magnetic fluid of claim 18 wherein said aging step includes aging for a period of about 2 days to about 80 days. 24. The magnetic fluid of claim 18 wherein said elemental modifier adding a step further includes adding a quantity greater than zero percent and equal to or less than ten percent by weight of said quantity of elemental modifier to said weight of said magnetic fluid. 25. A method of making an improved magnetic fluid, said method comprising: obtaining a quantity of an oil-based, low vapor pressure magnetic fluid; adding an amount of elemental modifier without dispersant to said quantity of magnetic fluid; mixing said elemental modifier and said quantity of magnetic fluid forming a mixture; aging said mixture at room temperature or higher and at an elevated relative humidity for a sufficient time to provide said magnetic fluid with a longer useful life than said magnetic fluid would have without the addition of said amount of elemental modifier; and removing excess elemental modifier from said mixture. 26. The method of claim 25 wherein said adding step includes adding a elemental modifier having a plurality of particles sized from about 1 micrometer to about 170 micrometers. 27. The method of claim 25 wherein said adding step includes selecting said elemental modifier wherein said elemental modifier is one of a metal, a metal mixture, a metal alloy, and a nonmetal. 28. The method of claim 25 wherein said adding step includes selecting said elemental modifier wherein said elemental modifier comprising at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, gold, boron, dysprosium, erbium, gadolinium, germanium, holmium, indium, iridium, palladium, lead, molybdenum, neodymium, niobium, osmium, rhodium, samarium, tantalum, tin, tungsten, yttrium, zirconium, ytterbium, carbon, thulium, terbium, and praseodymium. 29. The method of claim 25 wherein said adding step includes selecting said elemental modifier wherein said elemental modifier comprising at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, gold, boron, dysprosium, erbium, gadolinium, samarium, yttrium, ytterbium, thulium, holmium, praseocymium, and terbium. 30. The method of claim 25 wherein said adding step includes selecting said elemental modifier wherein said elemental modifier comprising at least one of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, and gold. 31. The method of claim 25 wherein said aging step includes aging at a temperature of about 60째 C. or higher. 32. The method of claim 25 wherein said aging step includes aging at a relative humidity of about 80% or higher. 33. The method of claim 25 wherein said aging step includes aging at a temperature of about 80째 C. and relative humidity of about 90%. 34. The method of claim 25 wherein said aging step includes aging for a period of about 2 days to about 80 days. 35. The method of claim 25 wherein said elemental modifier adding step further includes adding an amount greater than zero percent and equal to or less than ten percent by weight of said amount of said elemental modifier to said weight of said magnetic fluid. 36. A magnetic fluid composition comprising: an oil-based, low vapor pressure carrier liquid; a plurality of magnetic particles coated with at least one surfactant, said plurality of magnetic particles dispersed within said carrier liquid forming a ferrofluid; and at least one elemental modifier selected from the group consisting of a metal, a metal mixture, a metal alloy, and a nonmetal, wherein said metal, metal mixture, metal alloy and nonmetal is one or more of nickel, aluminum, silicon, titanium, vanadium, chromium, manganese, iron, cobalt, copper, zinc, silver, platinum, gold, boron, dysprosium, erbium, gadolinium, germanium, holmium, indium, iridium, palladium, lead, molybdenum, neodymium, niobium, osmium, rhodium, samarium, tantalum, tin, tungsten, yttrium, zirconium, ytterbium, thulium, terbium, praseodymium, bronze, cupra nickel, nickel chromium, nickel silver, palladium silver, zirconium nickel, titanium nickel, brass, a mix of chromium, nickel, manganese, silicon, and iron, and a mix of chromium, nickel, manganese, silicon, molybdenum, and iron; said at least one elemental modifier being disposed within said ferrofluid forming a treated ferrofluid wherein said at least one elemental modifier being present in said ferrofluid in an amount greater than zero percent and equal to or less than ten percent by weight to the weight of said ferrofluid and wherein said treated ferrofluid is aged at room temperature or higher and at an elevated relative humidity for a sufficient time to provide said ferrofluid with a longer useful life than said ferrofluid would have without the addition of said at least one elemental modifier.