[Introduction]Aiming at the size effect of hybrid and inlaid magnetic abrasives and the problem of hard impact caused by the inconsistent height of abrasive particles out of the edge during polishing.[Method]Irregular aluminum powder and spherical carbonyl iron powder were uniformly mixed,and some intermetallic compounds which were generated at the contact interface through heating and diffusion were distributed uniformly on the surface of the spherical carbonyl iron powder,so as to form the iron-aluminum core-shell spherical magnetic abrasives.[Result]The parameters for preparing the core-shell iron-based magnetic abrasives were optimized by single-factor experiment:reaction time 4 hours,reaction temperature 770 ℃,and Al content 12％by mass.The results of X-ray diffraction(XRD),scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS),and magnetization measurement showed that the prepared magnetic abrasive material consists of a carbonyl iron powder core with metal compounds such as FeAl,Fe3Al,and Fe0.4Al0.6 as the shell.The grain size of the abrasives conforms to normal distribution.The abrasive phases were uniformly distributed and their height out of the edge was consistent.The root mean square roughness of calcium fluoride crystal surface after being polished with the iron/aluminum core-shell magnetic abrasives can be reduced from 1.102 μm initially to 33 nm finally.[Conclusion]The core-shell magnetic abrasives can be used for magnetic polishing of some soft and brittle materials.
magnetic abrasivecore-shell structurecarbonyl iron powderaluminumin-situ alloyingcalcium fluoride crystalpolishing
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