Recycling of SmCo5 magnets by HD process

TL;DR

This study introduces a novel hydrogen decrepitation process for recycling SmCo5 magnets, demonstrating effective powder production and improved microstructure, with comparable or enhanced magnetic properties compared to original magnets.

Contribution

First application of hydrogen decrepitation for direct recycling of SmCo5 magnets, showing improved microstructure and magnetic performance.

Findings

Recycled magnets have higher remanence and energy product.

Microstructure is refined after recycling.

Hydrogen decrepitation effectively produces usable powder.

Abstract

Hydrogen decrepitation process has been applied for the first time for the direct recycling of SmCo5 magnets. Industrially produced sintered SmCo5 magnets were decrepitated by hydrogen gas at a pressure of 1 bar to 9.5 bar at room temperature in a planetary rotating jar. After decrepitation, the starting sintered magnets were reduced to a powder with a particle size of less than 200 microns. The produced powder was used for the preparation of recycled SmCo5 magnets. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction studies and magnetic measurements were used to follow the decrepitation and the sintering processes. The measured remanence and maximum energy product of the recycled magnet are 0.94 T and 171.1 kJ/m3, respectively, in comparison with 0.91 T and 156.8 kJ/m3, respectively for the original magnet before recycling. It was also observed that, there is refinement in the microstructure after recycling in comparison to the original magnet.