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Fabrication of Practical Magnetorheological Fluids and Their Properties

Author: ZhuHong
Tutor: JiangWanQuan
School: University of Science and Technology of China
Course: Analytical Chemistry
Keywords: Carbonyl iron particles CI-PMMA composite magnetic particles CI-CoFe2O4 composite magnetic particles Magnetorheological fluid Additive
CLC: TB381
Type: Master's thesis
Year: 2010
Downloads: 222
Quote: 1
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Abstract


The magnetorheological fluid as an intelligent material, is made of soft magnetic particles uniformly dispersed in a dispersion medium to form a concentrated suspension system. The system performance in the absence of a magnetic field is applied to a fluid state; Once the external magnetic field is applied by the liquid can occur in the millisecond time change to the class in a solid state, along with the shear yield stress and viscosity rapidly increases exponentially, and its The value increases with the strength of the external magnetic field; After the removal of the applied magnetic field, the magneto-rheological fluid system and quick to respond to the fluid state. Based on the characteristics of the magnetorheological fluid can be applied to engineering practical fields, has been developed based on magneto-rheological fluid devices: shock absorbers, brake valve, clutch, magneto-rheological dampers, etc.. This thesis focuses on the basic part of the magnetorheological fluid - a soft magnetic particles, additives and non-magnetic dispersion medium, from the preparation of the composite magnetic particles, characterization, magneto-rheological properties as well as multi-component additive mixed magnetic rheological fluid Preparation magnetorheological performance assessment aspects of the study, specific studies are as follows: 1. brief introduction to the basic nature of the magnetic material, magnetic nanomaterials research progress and magnetorheological materials research progress. Overview of the the magnetic nanomaterials excellent performance, typical synthetic methods and the surface modification technology. The highlight the magnetorheological materials composition, classification, rheological mechanism, research progress, the magnetorheological materials defects and problems to be solved at this stage. 2 to improve the sedimentation stability of the material of the magneto-rheological fluid, in order to prepare a polymer layer coated carbonyl iron particles as the starting point, and methyl methacrylate (Methyl Methacrylate, MMA) in situ in the surface of the carbonyl iron particles prepared by emulsion polymerization, the composite magnetic particles of iron carbonyl - poly methyl methacrylate (CI-PMMA). The experimental methods used polymer materials, good chemical stability, low toxicity, and experimental operation is simple. Product of CI-PMMA composite magnetic particles through a series of test methods to characterize particle morphology, surface elements, crystal structure, and thermal stability. Silicone oil-based magnetorheological fluid using the composite magnetic particles prepared via Anton Paar Physica MCR 301 rheometer test its rheological properties, the results show that the composite particle-based magnetorheological fluid has good shear yield stress; At the same time, it is found that the suspension system stand for more than six months, no noticeable subsidence phenomenon, has excellent resistance to sedimentation stability. Starting from the magnetorheological fluid additives, consider a thixotropic agent, nano-sized magnetic particles on the yield stress of magnetorheological fluid initial viscosity and shear deployment preparation of multi-component additive mixed magnetorheological fluid. Which magnetorheological fluid due to the addition of SiO2 the SiO2 formation of space network structure of carbonyl iron magnetic particles played a good supporting role, and the network structure of the external magnetic field force will immediately lapse, and therefore does not affect the magnetic flux Rheological properties of magnetic fluids; adding nano Fe3O4 magnetic particles magnetorheological fluid nanoscale magnetic carbonyl iron magnetic particle chain column gain of higher shear yield stress. 4 In order to achieve higher shear yield stress of magnetorheological fluid requirements, starting from the magnetic particles with Co (Ⅱ) and Fe (Ⅲ) salt chemical co-precipitation method under alkaline conditions, the surface of the carbonyl iron particles modification, to give the carbonyl iron-CoFe2O4 composite magnetic particles (CI-CoFe2O4). Test the magnetorheological performance of the CI-CoFe2O4 composite magnetic particle-based magnetorheological fluid, found the material with high shear yield stress, in the strength of the external magnetic field 0.7T (Tesla), can be reached 90kPa.

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