Coercivity and corrosion resistance enhancement of multi-main-phase Nd-Ce-Fe-B sintered magnets by the grain boundary diffusion process using Pr81.5Ga19.5 and Pr81.5Ga14.5Cu5 alloys

2020 ◽  
Vol 503 ◽  
pp. 166639 ◽  
Author(s):  
Jiahui Wang ◽  
Gang Wang ◽  
Dechang Zeng
Keyword(s):  
Corrosion Resistance ◽  
Grain Boundary ◽  
Diffusion Process ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Main Phase ◽  
Sintered Magnets

Study on microstructure and properties of Zn-Sn coating on sintered Nd-Fe-B magnets by grain boundary diffusion process

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zhihua Hu
Keyword(s):  
Corrosion Resistance ◽  
Grain Boundary ◽  
Diffusion Process ◽  
Boundary Diffusion ◽  
Grain Boundary Diffusion ◽  
Diffusion Method ◽  
Content Type ◽  
Microstructure And Properties ◽  
Binding Force ◽  
Diffusion Temperature

Purpose The microstructure and properties of Zn-Sn coating on sintered Nd-Fe-B magnets were investigated by the grain boundary diffusion process, to improve the corrosion resistance of magnet surface and explore the feasibility of realizing the lower-temperature grain boundary diffusion. Design/methodology/approach The Zn-Sn coating was deposited on sintered Nd-Fe-B magnets by magnetron sputtering, and then the Zn-Sn coated magnets were put into the vacuum tube furnace for grain boundary diffusion process. The morphology and structure of Zn-Sn coating as well as its mechanical properties and corrosion resistance were investigated. Findings Results showed that the particle size of vacuum diffusion-treated Zn-Sn coating increased and the particle agglomeration was weakened with increasing diffusion temperature, and the non-vacuum diffusion-treated Zn-Sn coating was oxidized to generate SnO2 and ZnO compounds. The binding force of coating first increased and then decreased with increasing diffusion temperature, and the maximum binding force was obtained at 540 °C. The binding force and corrosion resistance of non-vacuum diffusion-treated Zn-Sn coating were higher than the vacuum diffusion-treated Zn-Sn coating at the same diffusion temperature. Originality/value The Zn-Sn coating after diffusion treatment can provide complete protection, and the coating elements diffusion can be carried out at the same temperature as the secondary aging of sintered Nd-Fe-B magnets. Simultaneously, further diffusion process optimization needs to be completed because the diffusion depth is very low and only about 10 µm, which does not meet the requirements of traditional grain boundary diffusion method.

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