# US 2013/0153816 A1 · Magnetorheological fluids including shape memory alloys > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0153816 A1 - Document ID: US20130153816A1 - Status: Published application - Kind: A1 - Application number: 13/686,847 - Filed: 2012-11-27 - Published: 2013-06-20 - Earliest claimed: 2011-12-15 - Assignees: GM Global Technology Operations LLC - Inventors: Alan L. Browne; Nancy L. Johnson; Peter Maxwell Sarosi; John C. Ulicny - Web page: https://patentgrep.com/patent/US20130153816A1 ## CPC - H01F 1/01: of inorganic materials (H01F1/44 takes precedence) - H01F 1/0308: {with magnetic shape memory [MSM], i.e. with lattice transformations driven by a magnetic field, e.g. Heusler alloys} - H01F 1/442: {the magnetic component being a metal or alloy, e.g. Fe (H01F1/447 takes precedence)} - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract Magnetorheological (MR) fluids are disclosed herein. An example of the MR fluid includes a carrier fluid, magnetic particles disposed in the carrier fluid, and non-magnetic particles disposed in the carrier fluid. The non-magnetic particles are particles of a shape memory alloy having an Austenite finish temperature (Af) that is lower than a temperature encountered in an application in which the MR fluid is used so that the shape memory alloy exhibits stress-induced superelasticity. ## Claims ### Claim 1 A magnetorheological (MR) fluid, comprising: a carrier fluid; magnetic particles disposed in the carrier fluid; and non-magnetic particles disposed in the carrier fluid, the non-magnetic particles being particles of a shape memory alloy having an Austenite finish temperature (Af) that is lower than a temperature encountered in an application in which the MR fluid is used so that the shape memory alloy exhibits stress-induced superelasticity. ### Claim 2 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the carrier fluid is chosen from water, mineral oils, synthetic oils, hydrocarbons, silicone oils, elastomers, fats, gels, greases, esters, polyethers, fluorinated polyethers, polyglycols, fluorinated hydrocarbons, halogenated hydrocarbons, fluorinated silicones, organically modified silicones, copolymers thereof, and combinations thereof. ### Claim 3 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the magnetic particles are chosen from a metal, a metal alloy, a magnetic oxide ceramic, a mixed ferrite, and combinations thereof. ### Claim 4 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the shape memory alloy is chosen from a copper-zinc-aluminum-nickel alloy, a copper-aluminum-nickel alloy, a nickel-titanium alloy, a zinc-copper-gold-iron alloy, a gold-cadmium alloy, an iron-platinum alloy, a titanium-niobium alloy, a gold-copper-zinc alloy, an iron-manganese alloy, a zirconium-cobalt alloy, a zinc-copper alloy, and a titanium-vanadium-palladium alloy. ### Claim 5 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the magnetic particles are present in an amount ranging from about 10 vol % to about 45 vol % of the magnetorheological fluid. ### Claim 6 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the non-magnetic particles are present in an amount ranging from about 1 vol % to about 35 vol % of the magnetorheological fluid. ### Claim 7 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the magnetic particles and the non-magnetic particles, together, are present in an amount ranging from about 45 vol % to about 53 vol % of the magnetorheological fluid. ### Claim 8 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the non-magnetic particles of the shape memory alloy are hollow particles. ### Claim 9 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the non-magnetic particles of the shape memory alloy are solid particles. ### Claim 10 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the non-magnetic particles of the shape memory alloy include a combination of hollow particles and solid particles. ### Claim 11 (depends on 1) The magnetorheological fluid as defined in claim 1 wherein the non-magnetic particles of the shape memory alloy are spherical, randomly shaped, or combinations thereof. ### Claim 12 A method for making a magnetorheological (MR) fluid, the method comprising: selecting a carrier fluid; introducing magnetic particles into the carrier fluid; and introducing non-magnetic particles into the carrier fluid, the non-magnetic particles being particles of a shape memory alloy having an Austenite finish temperature (Af) that is lower than a temperature encountered in an application in which the MR fluid is used so that the shape memory alloy exhibits stress-induced superelasticity. ### Claim 13 (depends on 12) The method as defined in claim 12, further comprising selecting the carrier fluid from water, mineral oils, synthetic oils, hydrocarbons, silicone oils, elastomers, fats, gels, greases, esters, polyethers, fluorinated polyethers, polyglycols, fluorinated hydrocarbons, halogenated hydrocarbons, fluorinated silicones, organically modified silicones, copolymers thereof, and combinations thereof. ### Claim 14 (depends on 12) The method as defined in claim 12, further comprising selecting the magnetic particles from a metal, a metal alloy, a magnetic oxide ceramic, a mixed ferrite, and combinations thereof. ### Claim 15 (depends on 12) The method as defined as in claim 12, further comprising selecting the shape memory alloy from a copper-zinc-aluminum-nickel alloy, a copper-aluminum-nickel alloy, a nickel-titanium alloy, a zinc-copper-gold-iron alloy, a gold-cadmium alloy, an iron-platinum alloy, a titanium-niobium alloy, a gold-copper-zinc alloy, an iron-manganese alloy, a zirconium-cobalt alloy, a zinc-copper alloy, and a titanium-vanadium-palladium alloy. ### Claim 16 (depends on 12) The method as defined in claim 12 wherein: the introducing of the magnetic particles includes adding from about 10 vol % to about 45 vol % of the magnetic particles to the carrier fluid; and the introducing of the non-magnetic particles includes adding from about 1 vol % to about 35 vol % of the non-magnetic particles to the carrier fluid ### Claim 17 (depends on 12) The method as defined in claim 12, further comprising selecting hollow particles, solid particles, or combinations of hollow and solid particles for the non-magnetic particles of the shape memory alloy.