Bonded magnets made with atomized permanent magnetic powders

Abstract

The invention relates to magnets, particularly bonded magnets, of the Re-Fe-B type made from atomized magnetic powders and to methods of producing the powders and the magnet. The magnetic powders comprise, by weight, about 15 % to 25 % of RE; about 0.8 % to 2.0 % of B; about 1 % to 10 % of T; and balanced with Fe, Co, or mixtures thereof; wherein RE is one or more rare earth elements selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Er, Gd, Tb, Dy, Ho, Tm, Yb and Lu, and T is one or more elements selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W. To produce bonded magnets, the atomized powders are heat treated, combined with a binder, pressed or molded, and cured to produce the bonded magnets. As compared to bonded magnets made from melt-spun powders or from other conventional atomized powders, bonded magnets of the present invention exhibit one or more of the following properties: less loss of intrinsic coercivity under repeated injection molding cycles; less internal magnetic shearing loss; improved flowability of the magnetic powders; improved Br and part integrity; less environmental degradation after exposure to high temperature and less flux loss; complex shapes and high part integrity; lower viscosity of the magnetic powder-binder mixtures; and high magnetic strength even for small-dimension magnets.

Description

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AI Technical Summary

Benefits of technology

This patented inventor describes an improvement on traditional permanent magnets that use iron oxide (Fe2O3). These improvements include reduced losses caused during repetitive casting processes due to large external forces applied thereto, increased stability when exposed to heat over time, less susceptibility towards chemical reactions compared to other materials used for making them, lower levels of electrical resistance at room temperatures, better flowability than liquid binder mixtures, and greater structural rigidness without compromising their effectiveness.

Problems solved by technology

This technical problem addressed in this patents relates to improving the efficiency of making strong magnets while maintaining desired levels of intrinsic intensity without losing magneque stability when exposed to external environments like airborne dustors or moisture sources over time. Existing techniques involve injectable binders, including metal alloys containing iron cations, dendritisferriphilites, amorphous rare earth materials, etc., which may lead to reduced quality of magnet cores and decreased durability under harsh conditions.