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Magnetorheological devices, including damping devices, rotary devices, and haptic systems constructed with said devices are disclosed. The devices contain dry magnetically-responsive particles, or MR fluids containing the magnetically responsive particles. The magnetically soft particles characteriz

Magnetorheological devices, including damping devices, rotary devices, and haptic systems constructed with said devices are disclosed. The devices contain dry magnetically-responsive particles, or MR fluids containing the magnetically responsive particles. The magnetically soft particles characterized by a single process yield population of atomized particles having a cumulative 10%, 50% and 90% by volume, fraction within specified size, i.e., D10 of from 2 up to and including a D10 of 5 μm, a D50 8 μm up to and including a D50 of 15 μm, a D90 of 25 μm up to and including a D90 of 40 μm, and characterized by a least squares regression of log normal particles size against cumulative volume % fraction of greater than or equal to 0.77.

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1. A controllable magnetorheological damping device comprising a stationary housing, a movable piston and a field generator, and characterized by a design (working) gap of from 0.08 mm to 0.90 mm, said device containing magnetic-responsive particles from a single atomization process population strea

1. A controllable magnetorheological damping device comprising a stationary housing, a movable piston and a field generator, and characterized by a design (working) gap of from 0.08 mm to 0.90 mm, said device containing magnetic-responsive particles from a single atomization process population stream dispersed in a carrier fluid (MR fluid), said particles are characterized by 10% volume (D10) of particles of 2 μm up to and including a D10 of 5 μm; a 50% volume of particles (D50) of 8 μm up to and including a D50 of 15 μm; and 90% volume of particles (D90) of 25 μm, up to and including a D90 of 40 μm; and wherein said single process population exhibits a least squares regression from log normal distribution (R2) of 0.77 and higher.2. The magnetorheological damping device of claim 1 wherein said magnetic-responsive particles are mixed with at least one additive that reduces interparticle friction between the magnetic-responsive particles.3. The magnetorheological damping device of claim 2 wherein the additive is an inorganic molybdenum compound, a fluorocarbon polymer, or mixtures thereof.4. The magnetorheological damping device of claim 2 wherein the additive is present in an amount of 0.1 to 12 weight percent of the magnetic-responsive particles.5. The magnetorheological damping device of claim 1 wherein said MR fluid further comprises a dispersant.6. The magnetorheological damping device of claim 5 wherein the magnetic-responsive particles are iron particles containing less than 1% carbon.7. The magnetorheological damping device of claim 2 wherein the additive is a molybdenum disulfide or a molybdenum phosphate.8. The magnetorheological damping device of claim 2 wherein the additive is molybdenum disulfide.9. The magnetorheological damping device of claim 2 wherein the additive is a fluorocarbon polymer.10. The magnetorheological damping device of claim 2 wherein the additive is polytetrafluoroethylene.11. The magnetorheological damping device of claim 1 wherein said particles are dispersed in a carrier fluid selected from the group consisting of water, glycol, natural fatty oil, mineral oil, polyphenylether, dibasic acid ester, neopentylpolyol ester, phosphate ester, polyester, cycloparaffin oil, paraffin oil, unsaturated hydrocarbon oil, silicone oil, naphthenic oil, monobasic acid ester, glycol ester, glycol ether, poly-α-olefin, perfluorinated polyether and halogenated hydrocarbon.12. The magnetorheological damping device of claim 11 wherein the carrier fluid is mineral oil, paraffin oil, cycloparaffin oil, naphthenic oil or poly-α-olefin.13. The magnetorheological damping device of claim 12 further comprising a molybdenum compound selected from organomolybdenum compound, molybdenum sulfide, molybdenum disulfide, and molybdenum phosphate.14. The magnetorheological damping device of claim 13 wherein the molybdenum compound is molybdenum disulfide.15. The magnetorheological damping device of claim 11, further comprising at least one additive selected from the group consisting of a thixotropic agent, a lubricant, an extreme pressure additive and an antioxidant.16. The magnetorheological damping device of claim 1 which is a linear damper.17. The magnetorheological damping device of claim 1 wherein said carrier fluid has a viscosity between about 1 and about 500 centistokes at 100° C.18. The magnetorheological damping device of claim 17 wherein said carrier fluid has a viscosity of less than about 10 centistokes at 100° C.19. The magnetorheological damping device of claim 1 wherein said carrier fluid is present in an amount of about 50 to about 95 volume percent of said MR fluid and said magnetically responsive particles are present in an amount of about 5 to about 50 volume percent of said magnetorheological fluid.20. The magnetorheological damping device of claim 2 wherein said carrier fluid is selected from the group consisting of water, glycol, natural fatty oil, mineral oil, polyphenylether, dibasic acid ester, neopentylpolyol ester, phosphite ester, synthetic cycloparaffin, synthetic paraffin, unsaturated hydrocarbon oil, monobasic acid ester, glycol ester, glycol ether, fluorinated ester and ether, silicate ester, silicone oil, silicone copolymer, poly-α-olefin, perfluorinated polyether and ester, halogenated hydrocarbon and mixtures and derivatives thereof.21. The magnetorheological damping device of claim 1 wherein said carrier fluid is selected from the group consisting of water, glycol, glycol ester and mixtures thereof.22. The magnetorheological damping device of claim 5 further comprises a thixotropic agent selected from the group consisting of soap, colloidal silica, and organoclay.23. The magnetorheological damping device of claim 22 wherein said thixotropic agent is an organoclay selected from organic modified bentonite.24. The magnetorheological damping device of claim 1 further comprising an extreme pressure additive selected from the group consisting of organophosphorus compound, thiophosphorus compound, thiocarbamate compound.25. The magnetorheological damping device of claim 24 wherein said extreme pressure additive is a thiocarbamate compound having the following structure: wherein R1 and R2 each individually have a structure represented by:Y?((C)(R4)(R5))n?wherein Y is selected from hydrogen, amino, amido, imido, carboxyl, hydroxyl, carbonyl, oxo or aryl group; n is an integer from 2 to 17; R4 and R5 can each individually be hydrogen, alkyl or alkoxy; and R3 is selected from the group consisting of a metal ion, a nonmetallic moiety, and a divalent moiety; a and b are each individually 0 or 1, provided a+b is at least equal to 1, and x is an integer from 1 to 5 depending upon the valence number of R3.26. The magnetorheological damping device of claim 24 wherein said extreme pressure additive is an organophosphorus compound having the following structure: wherein R1 and R2 are each independently hydrogen, an amino group, or an alkyl group having 1 to 22 carbon atoms; X, Y and Z are each independently ?CH2?, a nitrogen heteroatom or an oxygen heteroatom, provided that at least one of X, Y or Z is an oxygen heteroatom; a is 0 or 1; and n is the valence of M; provided that if X, Y and Z are each an oxygen heteroatom, M is a salt moiety formed from an amine having the following structure: wherein R3, R4 and R5 are each independently hydrogen or aliphatic groups having 1 to 18 carbon atoms; and, if at least one of X, Y or Z is not an oxygen heteroatom, M is selected from the group consisting of a metallic ion, a non-metallic moiety and a divalent moiety and with a further proviso that if Z is a nitrogen heteroatom, then M is not an amine.27. The magnetorheological damping device of claim 24 wherein said extreme pressure additive is a thiophosphorus compound having the following structure wherein R1 and R2 each individually have a structure represented by:Y?((C)(R4)(R5))n?(O)W?wherein Y is hydrogen or a functional group?containing moiety such as an amino, amido, imido, carboxyl, hydroxyl, carbonyl, oxo or aryl;n is an integer from 2 to 17 such that C(R4)(R5) is a divalent group having a structure such as a straight-chained aliphatic, branched aliphatic, heterocyclic, or aromatic ring; R4 and R5 can each individually be hydrogen, alkyl or alkoxy; and w is 0 or 1. 28. The magnetorheological damping device of claim 1 wherein said magnetically responsive particles are composed of materials selected from the group consisting of iron, iron manganese, iron boron, iron oxide, iron nitride, iron carbide, iron chromium, low carbon steel, iron silicon, iron nickel, iron cobalt, and a mixture thereof.29. The magnetorheological damping device of claim 28 wherein said magnetically responsive particles are composed of materials selected from the group consisting of iron, iron oxide, iron nickel, iron cobalt, iron manganese, iron silicon, and iron boron.30. The magnetorheological damping device of claim 5 wherein the dispersant is selected from an oleate, naphthenate, sulfonate, phosphate ester, stearic acid, stearate, glycerol monooleate, sorbitan sesquioleate, laurate, fatty acid and fatty alcohol.31. The magnetorheological damping device of claim 30 wherein the dispersant comprises a stearate.32. The magnetorheological damping device of claim 1 wherein said MR fluid further comprises a molybdenum compound.33. The magnetorheological damping device of claim 32 wherein said molybdenum compound is an organomolybdenum.34. The magnetorheological damping device of claim 32 wherein said molybdenum compound is selected from molybdenum thiadiazole; an organomolybdenum made by reacting a fatty oil, diethanolamine and a molybdenum source; and an organomolybdenum made by reacting a diol, diamino-thiol-alcohol and amino-alcohol with a molybdenum source.35. The magnetorheological damping device of claim 32 wherein the molybdenum compound is molybdenum disulfide.36. The magnetorheological damping device of claim 20, wherein the carrier fluid is a poly α-olefin.37. The magnetorheological damping device of claim 1 containing an MR fluid that comprises 50 to 95% volume of a fluid carrier and 5 to 50% volume of a magnetic-responsive particle component characterized by D10 of 2 μm up to and including a D10 of 5 μm, a D50 of 10 μm up to and including a D50 of 13 μm; a D90 of 28 μm to and including a D90 of 35 μm.38. The magnetorheological damping device of claim 1 further comprising at least one additive that reduces interparticle friction between the magnetic-responsive particles, a dispersant, and an extreme pressure additive selected from the group consisting of organophosphorus, thiophosphorus compounds and thiocarbamates.