Samarium-Cobalt Magnet : Improve Efficiency Under Extremly High Temperature
Samarium Cobalt (SmCo) magnets,a type of rare-earth magnet,is a strong permanent magnet made of two basic elements:samarium and cobalt.
SmCo magnets are generally ranked similarly in strength to NdFeB magnets,but have higher temperature ratings and higher coercivity
Samarium-Cobalt Magnet Features
Extremely Resistant To Demagnetization
The remanence of SmCo magnets lies between 0.86-1.16 Tesla,which is comparable to NdFeB magnets.But SmCo magnets have much better temperature stability.
SmCo magnets have high coercivity(Hcj) to resist demagnetisation and can be used up to +350 degrees C(662F).Above 180 degrees C(356F) SmCo magnets start to provide higher performance than NdFeB magnets.
SmCo magents could also be used in extremely cold conditions (e.g. to a few Kelvin above absolute zero).
SmCo magents have a strong resistance to corrosion and oxidation,due to its low containing of iron,making them an excellent choice for difficult environments.
Generally SmCo magnets do not require surface treatment.Only in very damp,acid,alkali or other worse environment,do SmCo magnets require coating.(It usually refers to Sm2Co17 magnets,Sm1Co5 does not rust as it contains no iron).
Expensive Price
In SmCo magents,the rare earth elements samrium and cobalt account for about 70 percent.While NdFeB magnets contains more iron,so the price of SmCo magnets will be relatively higher.
Brittle and Prone to Cracking and Chipping
Among all magnets,SmCo magents are the most brittle one.The processablity of SmCo magnets is lower than NdFeB magnets and are much prone to fracture in the machining process.Therefore,extreme care must be taken to avoid cracking and chipping.
Comparison of Physical Properties of Samarium-Cobalt Magnet and Neodymium Magnets
Samarium-coblt magnets is well-knowm to operate in higher temperatures than neodymium magnets.SmCo magnets have a flatter curve of temperature coefficient.
The Br temperature coefficient of SmCo magnets is -0.03-0.5%/degree C,much smaller than that of NdFeB magnet.The Br coefficient of NdFeB magnets is -0.11%/degree C.This means SmCo magnets lose much slower in Br than NdFeB magnets when temperature increases.
The Hcj temperature coefficient of SmCo magnets is even more impressive,which is around 0.2-0.3%/degree C.But that of NdFeB magnets is 0.45-0.60%/degree C.
Samarium-cobalt magnets can be used in more corrosive environmrents than neodymium magnets.Generally samarium-cobalt magnets need not coating.But neodymium are very easy to corrupt and must need coating.
Samarium-coblat magnets are comprised of about 65% cobalt,which is a major component of stainless steel and good at corrosion resistance.Neodymium magnets are about 65% iron,which are very easy to corrupt.
Somtimes Samarium-cobalt magnets also get coating for improved cleanliness and resistance to chipping,since they are brittle.
Neodymium magnets have a stronger magnetic field than samarium-cobalt magnets.
Samarium-cobalt magents and neodymium magnets both make very strong magnets. But neodymium magnets are the strongest at room temperature or under 180 degree C.Above temperature 180 degree C,samarium-cobalt magnets begin to outperform neodymium magnets.
Neodymium magnets are cheaper than Samarium cobalt magnets.
Two Series Of SmCo Magnets
SmCo?magnets are available in two series,defined?by?the?ratio?of?Samarium?to Cobalt.The two alloy compositions SmCo5 and Sm2Co17,also known as 1/5 alloy or 2/17 alloy.
SmCo5 Magnets
SmCo5 magnets ?are?composed?of?one?atom?of?Samarium?with?five?atoms?of? Cobalt.By weight this magnet alloy will typically contain 37% samarium and 63% cobalt.The energy products of SmCo5?magnets range from 16 MGOe to 25 MGOe,that is approx. 128–200 kJ/m3.?Their maximum recommended operating temperature is 250 degrees C.This series of magnet is easier to calibrate to a specific magnetic field than the Sm2Co17 magnets.
Sm2Co17 Magnets
Sm2Co17 magnets are composed of 2 atoms of samarium with 13-17 atoms of transition metals (TM).he TM content is rich in cobalt, but contains other elements such as iron and copper.?By weight the alloy are made up of approximately 25% samarium,50% cobalt,18% iron,5% copper,2% hafnium or zirconium.Hafniun and zirconium are added to achieve better heat treatment response.The maximum energy products of these alloys range from 20 to 32 MGOe,that is approx. 160-260 kJ/m3.?
Sm2Co17 is more stronger and more commonly used.But the iron content in Sm2Co17 means a risk of some surface corrosion when in water.However,plating,for example Ni coating could fix it.
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Production of SmCo Magnet
Process Flow
流程图
Maximum&Minimum Machining Size
SmCo magnets is brittleness and lack of ductilitys,so it's not suitable for being used as structural parts when being designed.The physical properties of SmCo5 are better than Sm2Co17 because SmCo5 are easy to machine while SmCo17 is more brittle.
尺寸图
Handling
The magnetised SmCo magnets must be picked up carefully during the process of assembling to avoid attracting mutually,resulting in magnet breaking.
Transportation
SmCo magnets would make some slight cillision in the process of production or transportation,so there may be some chips.However,it wouldn't damage its magnetic properties and functions.
SmCo Magnet Applications
SmCo magnets are the ideal selection for applications where a little power can be sacrificed in exchange for corrosion resistance or high operating temperature.They are mostly used in high-end electric motors in areospace,automotive and military industries.
SmCo Magnets vs. NdFeB Magnets In Application
NdFeB magnets are great for powerful motors and generators ,or where miniaturization is a major driving force.Here are some of the place NdFeB magents are likely to be found:
SmCo magnets are typically used for elevated temperature applications with heavy loads,in the most demanding environments:
Three Points You Should Consider When Choosing SmCo Magnets
When you are deciding whether or not to use SmCo magnets instead of NdFeB magnets,you should consider the following factors:
XGS33H Grade-Breaking Performance Under Extreme Conditions
Ningbo Costar provides high performance SmCo magnets in the market.Its XGS33H grade Sm2Co17 magnet is one of the most powerful magnets under extreme conditions with Br ranging 1.14-1.17 Tesla.
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CONTACT
Ningbo Co-star Materials Hi-Tech Co.,Ltd
No.756,Qihang South Road,Ningbo,China.
Tel:+086?0574?5680?1355?
E-Mail:[email protected]