SAMARIUM COBALT
There are two families of Sm-Co magnets — SmCo5 and Sm2Co17. SmCo5
was developed in the 1960s and further development produced Sm2Co17
in the 1970s.
SmCo5 has a hexagonal crystal structure that consists of five atoms
of cobalt for each samarium atom. SmCo5 magnets are also known as
Sm-Co 1:5, samarium-cobalt 1:5 magnets, SmCo series 1:5 magnets, or
sometimes as 1:5 magnets.
Sm2Co17 has a rhombohedral crystal structure, which is obtained by
replacing Sm atoms in the SmCo5 hexagonal structure with a pair of
Co atoms. Other elements are added to improve properties such as
intrinsic coercivity or reversible temperature coefficient.
Elements such as iron, copper, hafnium, gadolinium, terbium, erbium
and zirconium are commonly used. Sm2Co17 is also known as
samarium-cobalt 2:17, SmCo Series 2:17, Sm(Co,Fe,Cu,Zr)z or
sometimes as 2:17 magnets.
1:5 has a maximum energy product, (BH)max, around 20 MGOe. The
reversible temperature coefficient of residual induction of SmCo5
is about -0.04%/°C. 2:17 has a maximum energy product (BH)max as
high as 35 MGOe. The reversible temperature coefficient of residual
induction is about -0.035%/oC.
Both SmCo5 and Sm2Co17 have very high intrinsic coercivity, Hci, a
measurement of resistance to demagnetization. They also have very
good corrosion resistance, thermal stability and resistance to
radiation. Although brittle, they do not require a surface coating
and can be used at temperatures up to 300℃.
Dimensions anf Toleranfces
