Improving Coating Technologies for Synthesis of Interface-Exchange-Coupled Permanent Magnets

The critical technical issue in synthesizing bulk anisotropic interface-exchange-coupled magnets with magnetic performance superior to conventional magnets is to create a composite magnet microstructure in which a highly dispersed nanometer-sized magnetically soft phase, such as -Fe-or Fe-Co, is uniformly distributed in a nanograin magnetically hard phase, such as Nd-Fe-B or Sm-Co. Previously, sputtering, pulse laser deposition, electroless coating, and electrolyte coating were used to coat Nd-Fe-B or Sm-Co particles with thin -Fe-or Fe-Co layers followed by rapid inductive hot compaction and hot deformation. Bulk interface-exchange-coupled magnets synthesize using these technologies can have (BH)max = 45 – 55 MGOe. In order to accomplish better magnetic performance with (BH)max ≥ 60 MGOe, technical problems associated with the above-mentioned powder coating technologies, such as low deposition rate, high processing cost, and high oxygen pickup, must be solved. In this proposed SBIR Phase I research project, innovative powder coating technologies will be studied and developed and their feasibility in crating the desired microstructure and in synthesizing high performance interface-exchange-coupled nanograin magnets will be demonstrated. The advantage of these technologies include high deposition rate, low processing cost, and low oxygen pickup.