How to Understand the Rare Earth Permanent Magnets’ Grades? Part 3 – Sintered Samarium Cobalt Magnets

Samarium cobalt (SmCo) magnets include 1:5 type (SmCo5) and 2:17 type (Sm2Co17) magnets. For both of sintered SmCo5 and Sm2Co17 magnets, their grades basically include three parts, i.e. “letter 1” + “number” + “letter 2”. Similar to sintered NdFeB magnets, the three parts in sintered SmCo magnets’ grades also present material type, (BH)max value (in CGS unit) and Hcj level, respectively. The difference is that the left part “letter 1” are “XG” and “XGS” for sintered SmCo5 and Sm2Co17 magnets, respectively. Besides, the Hcj levels of sintered SmCo5 magnets include “default” (Hcj ≥ 15 kOe) and “H” (Hcj ≥ 23 kOe) and those of sintered Sm2Co17 magnets include “L” (Hcj ≥ 8 kOe), “M” (Hcj ≥ 12 kOe), “default” (Hcj ≥ 18 kOe), “H” (Hcj ≥ 25 kOe) and “LT” (Hcj ≥ 18 kOe). Although the grades with the right part “default” and “LT” have same Hcj level, they actually contains different meanings in the aspect of temperature coefficient of remanence α(Br). The grades with “LT” mean that the corresponding magnets have low/near zero |α(Br)| compared to the others without “LT”.

samarium cobalt, SmCo magnets, XGS32H Demagnetization Curve, rare earth permanent magnets

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