Search
Home > Issues > SearchHigh Coercive RE-Fe-B Powders Recycled via HD and HDDR Process from Waste Magnets
Journal of Magnetics, Volume 27, Number 2, 30 Jun 2022, Pages 117-122
Tae-Sung Noh (Korea Institute of Materials Science), Hee-Ryoung Cha (Korea Institute of Materials Science), Yang-Do Kim * 
(Pusan National University), Jung-Goo Lee * (Korea Institute of Materials Science)
(Pusan National University), Jung-Goo Lee * (Korea Institute of Materials Science)
Abstract
In order to fabricate high-coercivity hard magnetic RE-Fe-B powders from the waste bulk magnets, the hydrogen
decrepitation (HD) and hydrogenation-disproportionation-desorption-recombination (HDDR) processes
were employed to the waste RE-Fe-B magnets. The optimum HD and HDDR conditions for the waste RE-Fe-B
magnets were established through the systematic investigation on the effect of HD and HDDR treatment temperature
on the magnetic and microstructural properties of final recycled powders. We found that the waste
magnets were crushed into the flakes with a uniform size distribution when the HD treatment was carried at
200 ℃. By applying the HDDR process to the HD treated flakes at 920 ℃, high coercivity of 11.2 kOe could be
achieved in the recycled RE-Fe-B HDDR powders. Based on the results from the microstructural characterization,
the underlying reasons for the magnetic and microstructural changes of the recycled powders as a function
of the HD and HDDR treatment temperature is discussed in detail.
decrepitation (HD) and hydrogenation-disproportionation-desorption-recombination (HDDR) processes
were employed to the waste RE-Fe-B magnets. The optimum HD and HDDR conditions for the waste RE-Fe-B
magnets were established through the systematic investigation on the effect of HD and HDDR treatment temperature
on the magnetic and microstructural properties of final recycled powders. We found that the waste
magnets were crushed into the flakes with a uniform size distribution when the HD treatment was carried at
200 ℃. By applying the HDDR process to the HD treated flakes at 920 ℃, high coercivity of 11.2 kOe could be
achieved in the recycled RE-Fe-B HDDR powders. Based on the results from the microstructural characterization,
the underlying reasons for the magnetic and microstructural changes of the recycled powders as a function
of the HD and HDDR treatment temperature is discussed in detail.
Keywords: Nd-Fe-B magnets; recycling; hydrogen decrepitation (HD); hydrogenation-disproportionation-desorptionrecombination(HDDR)
DOI: https://doi.org/10.4283/JMAG.2022.27.2.117
Full Text : PDF
