Antioxidation Study of Sm(Co, Cu, Fe, Zr)z-Sintered Permanent Magnets by Metal Injection Molding

Antioxidation effects on Sm(Co, Cu, Fe, Zr)z-sintered magnets treated by different methods were studied through TGA and DTA. Microstructure of Sm(Co, Cu, Fe, Zr)z-sintered magnets was analyzed through SEM and EDS. The results indicate that the antioxidation effect of the alloy powder treated in silane solution is better than that of the other methods. The alloy powders treated in stearic acid (SA) solution and polymethyl methacrylate (PMMA) solution can prevent powders from oxidation for a short period of time. Silane solution is not suitable for metal injection molding (MIM) because it severely damages the magnetic properties and microstructure of Sm(Co, Cu, Fe, Zr)z-sintered magnets. SA solution can not only prevent powders from oxidizing in MIM, but also does not damage magnetic properties and microstructure of Sm(Co, Cu, Fe, Zr)z magnets. The oxygen content of Sm(Co, Cu, Fe, Zr)z-sintered magnets by MIM is 3300 μg·g−1.