A method for grain boundary diffusion treatment of sintered radiation rings and small-sized sintered radiation rings produced by the method

Abstract

This invention belongs to the field of permanent magnet material technology, and relates to a method for grain boundary diffusion treatment of sintered radiation rings and small-sized sintered radiation rings prepared by this method. Addressing the problems of small-sized radiation rings being prone to oxidation due to their large specific surface area, difficult coating due to their narrow inner pores, and easy cracking due to their low heat capacity, this invention employs a composite container of "graphite + molybdenum liner + molybdenum box" to create a low-oxygen environment during diffusion heat treatment; a combined process of "outer circle ultrasonic shot peening + inner hole through-rod roller printing" to achieve unilateral directional coating of the diffusion source; and a "multi-stage heat treatment - slow cooling - two-stage aging" process to suppress grain coarsening, reduce cracking risk, and simultaneously improve coercivity and mechanical integrity. This invention effectively solves the problems of low penetration efficiency, uneven coating, and heat treatment cracking, significantly improving coercivity and finished product yield.

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