Design of high temperature permanent magnets

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.364615· OSTI ID:496608

Kim, A S ^[1]

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1. Crucible Research Center, A Division of Crucible Materials Corporation, 6003 Campbells Run Road, Pittsburgh, Pennsylvania 15205-1022 (United States)

There has been a demand for permanent magnet materials which can be used at up to 450{endash}500{degree}C. Normal Sm{sub 2}TM{sub 17} magnets have a coercivity H{sub ci} of {approximately}10 kOe at room temperature. At 150{degree}C, the coercivity is decreased by about 50{percent}. The maximum operating temperature (MOT) of these magnets is 150{endash}200{degree}C. By increasing the H{sub ci} to 30 kOe, the MOT is increased to about 300{degree}C. Further increases in MOT are anticipated with further increases in coercivity. However, the degree of increase in a MOT will be small as long as the same temperature coefficient of coercivity ({beta}) is maintained, resulting in MOT that is far below the required operating temperature. Therefore we studied the effect of {beta} when they have the same H{sub ci} at room temperature. This study indicates that the MOT is more effectively increased by reducing the {beta} than increasing the H{sub ci}. For example, a 1:7 magnet having a {beta} of {minus}0.13{percent}/{degree}C and a H{sub ci} of 18.6 kOe starts an irreversible loss at 550{degree}C, while a 2:17 magnet having a {beta} of {minus}0.29{percent}/{degree}C and a H{sub ci} of 28.5 kOe starts an irreversible loss at 350{degree}C. Therefore, high temperature permanent magnets (MOT{gt}500{degree}C) are possible when the {beta} is lower than {minus}0.15{percent}/{degree}C with moderately high coercivity ({approximately}20 kOe). {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 496608
• Report Number(s): CONF-961141--
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 8 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHEMICAL COMPOSITION
COERCIVE FORCE
DESIGN
FERROMAGNETIC MATERIALS
MICROSTRUCTURE
PERMANENT MAGNETS
SAMARIUM ALLOYS
STOICHIOMETRY
TEMPERATURE COEFFICIENT
TEMPERATURE RANGE 0400-1000 K