Effect of BN Spray-doping on Magnetic Properties and Resistivity of Hot-deformed Nd-Fe-B Magnets

doi:10.11901/1005.3093.2024.335

Chinese Journal of Materials Research

2025, Vol. 39

Issue (8): 612-618 DOI: 10.11901/1005.3093.2024.335

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Effect of BN Spray-doping on Magnetic Properties and Resistivity of Hot-deformed Nd-Fe-B Magnets

LU Tong¹^,², WANG Yana¹^,²^,³, ZHANG Chao¹^,², LEI Peng¹^,², ZHANG Hongrong¹^,², HUANG Guangwei¹^,²(

), ZHENG Liyun¹^,²^,⁴

^1.College of Materials Science and Engineering, Hebei University of Engineering, Handan 056038, China
^2.Hebei Engineering Research Center for Rare Earth Permanent Magnetic Materials and Application, Handan 056038, China
^3.College of Materials Science and Engineering, North University of China, Taiyuan 030051, China
^4.Division of Functional Materials, Central Iron and Steel Research Institute, Beijing 100081, China

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LU Tong, WANG Yana, ZHANG Chao, LEI Peng, ZHANG Hongrong, HUANG Guangwei, ZHENG Liyun. Effect of BN Spray-doping on Magnetic Properties and Resistivity of Hot-deformed Nd-Fe-B Magnets. Chinese Journal of Materials Research, 2025, 39(8): 612-618.

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Abstract

Nd-Fe-B permanent magnets are widely used in aerospace, new energy vehicles, wind power generation and many other fields due to their excellent performance. By increasing the resistivity of the Nd-Fe-B magnets, the temperature rise of the magnet can be effectively reduced and the working stability of the magnet can be improved. Herein, a novel technique was adopted to prepare the BN-doped hot-deformed Nd-Fe-B magnets, i.e. first, by spraying an appropriate amount of BN demolding agent onto the surface of the commercial fast-quenching Nb-Fe-B magnetic powders to obtain the BN-coated magnetic powders (namely 0, 0.2, 0.4, 0.6 and 0.8 of BN, in mass fraction respectively), subsequently, the hot-deformed bulk BN-doped Nb-Fe-B magnets were prepared with the modified powders as raw material by hot pressing process and then hot deformation process. The effect of different BN doping amount on the magnetic properties, resistivity, temperature stability and microstructure of the hot-deformed Nd-Fe-B magnets were studied. The results show that the sprayed BN presents good adhesion on the Nd-Fe-B magnetic powders; The introduction of BN by spraying can significantly improve the resistivity of the magnets, which increases from 153.5 μΩ·cm for magnets of the plain powders to 287.7 μΩ·cm for that of the powers coated with 0.8%BN, implying an increase of 87%. The grain orientation of the magnets can also be improved by the introduction of proper BN. With the increase of coated BN amount, the magnetic properties and temperature stability of the magnets decrease gradually. When the sprayed amount of 0.6% BN, the magnets has excellent comprehensive magnetoelectric performance: the maximum magnetic energy product (BH)_max is 36.67 MGOe; the remanence B_r is 12.48 kGs; the coercivity H_cj is 11.85 kOe; the resistivity is 254.8 μΩ·cm. It follows that this study provides a technical path to effectively improve the resistivity of magnets while maintaining high magnetic properties, so that the prepared magnets may be suitable for high operating temperature scenarios.

Key words: metallic materials BN doping hot deformation Nd-Fe-B magnets resistivity magnetic properties

Received: 15 August 2024

ZTFLH:

TM273

Fund: National Key Research and Development Program of China(2022YFB3505600);Central Government to Guide Local Scientific and Technological Development Project(206Z1007G);Natural Science Foundation of Hebei Province(E2021402001)

Corresponding Authors: HUANG Guangwei, Tel: 13653352095, E-mail: huangguangwei@hebeu.edu.cn

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	LU Tong
	WANG Yana
	ZHANG Chao
	LEI Peng
	ZHANG Hongrong
	HUANG Guangwei
	ZHENG Liyun

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https://www.cjmr.org/EN/10.11901/1005.3093.2024.335 OR https://www.cjmr.org/EN/Y2025/V39/I8/612

Fig.1 SEM of the surface of 0.6 % BN magnetic powder (a), Select the area of spraying magnetic powder (b~e) and the EDS diagram of Fe (c), Nd (d) and N (e)

Fig.2 Effect of BN spraying amount on the resistivity of hot-deformed magnet

Fig.3 Room temperature demagnetization curves of hot-deformed magnets with different BN spraying amount (a), the effect of different BN spraying amount on the remanence B_r, coercivity H_cj and maximum magnetic energy product (BH)_max of hot-deformed magnets (b)

Fig.4 Coercivity of hot-deformed magnets with different BN spraying amount at different temperatures

Table 1 Temperature coefficient of coercivity of hot-deformed magnets with different BN spraying amount

Fig.5 XRD patterns of hot-deformed magnets with different BN spraying amount

Fig.6 SEM patterns of hot-deformed magnets with different BN spraying amount under different multiples (a, b) 0%, (c, d) 0.2%, (e, f) 0.6%, (g, h) 0.8%

Fig.7 SEM (a) and EDS line scan (b) of hot-deformed Nd-Fe-B magnet with 0.6%BN spraying amount

Fig.8 SEM (a) and EDS element distribution (b-d) of hot-deformed Nd-Fe-B magnet with 0.6%BN spraying amount

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