Study On Preparation And Properties Of Reduced Iron MRF

Magnetorheological Finishing (MRF) is a new technology in recent years, an advanced optical manufacturing technology, mainly used for polishing the surface rotation, especially for small-caliber rapid polishing of optical components, it is high precision and easy to control, the other obvious advantage is that there isn’t abrasion problem in the polishing process.MRF is this:in the magnetic field, the shearstress of the liquid changed greatly, the occurrence of fluid flow through the MRF workpiece and the gap between the plate movements, the surface will make a great shear force, so that the raised surface area will be removed. Magnetorheological effect is adding a carrier liquid in the high permeability of the magnetic particles, when there is no magnetic field, the magnetorheological fluid is a Newtonian fluid, when adding an external magnetic field, a mutation happened in the rheological properties of the fluid so that the whole liquid solidify rapidly lose mobility, this transformation process is completed in milliseconds, and reversible, when the magnetic field is removed, the fluid and restore their mobility, this effect is also known as the Bingham effect, we can also describe it as Bingham model. In this paper, the raw materials are oxide iron scale, the waste of steel factory. It can realize high value-added utilization of waste steel, and there is a great space of decline than using iron carbonyl, therer is a greate research value.In this paper, the principle and preparation Magnetorheological Finishing process is as follows:First, we have the oxide scale milled, and other treatment. Then the oxide iron powder is reduded by hydrogen at650℃in4hours, than we can obtain the iron powder. The next, we have the detection of the ferrum content by various testing methods. After the reduced ferrous powder is coated, add in the carrier liquid and mixed in the ball mill. In the experiment we choose silicone oil as a carrier liquid, with a silcone coupling agent KH-550as surfactant coated particles of iron.The shear stress and apparent viscosity testing of MRF were tested by MCR301rheometer, after made into magnetorheological polishing fluid by adding polishing powder, its performance is not significantly affected, the shear stress can increase rapidly, and then to the limit. The shear stress was significantly affected by the shear rate. When there isn’t magnetic field, the viscosity of MRF has a phenomenon of thinning with the increase of the shear rate’s increase.The mechanics properties and apparent viscosity of MRF were tested by MCR-301rheometer, the test result showed that under zero magnetic field, it had good mobility, and the viscosity of MRF decreased as the rate of shear increased; The shear stress increased with the field; Compared with the magnetorheological fluid, the polishing powder had little effect to the MRF; Organic bentonite increased the viscosity, and in the same time, it increase the shear stress greatly; The Fe3O4could also increase the shear stress effectively.