Chemical Synthesis of Next Generation High Energy Product Hybrid SmCo Permanent Magnets for High Temperature Applications

Abstract

Abstract : High performance permanent magnets, i.e. those having appreciable energy products, can be broadly classified into three categories: rare earth-3d transition metal intermetallics (Nd2Fe14B, Sm(1)Co(5) and Sm(2)Co(17)), AINiCo (alloys composed primarily of iron with additions of aluminum, nickel, cobalt, copper and sometimes titanium) and ceramic magnets (typically strontiumdoped barium hexaferrites). The magnets containing rare earth elements provide the highest energy products, (BH)max, but are expensive and prone to corrosion and, as such, pose severe cost limitations as well as supply chain challenges to commercial industries. Very few major developments in viable permanent magnet materials have occurred since the development of Nd-Fe-B in the early 1980s. Here, we report a ferromagnetic material based upon nanoscale cobalt carbide particles that provide a rare-earth free alternative to high performance permanent magnets. The cobalt carbide-based magnets described herein are processed by chemical polyol reduction of metal salts. Packaging may be in the form of isotropic or anisotropic high density compacts, bonded magnets, particle suspensions, etc. The best properties of the carbide particles of this work include room temperature coercivities greater than 3.4 kOe and room temperature saturation magnetization up to 73 emu g(-1).