1. Different ingredients
In NdFeB permanent magnets, the rare earth metal neodymium accounts for about 29%~32.5%, the metal element iron accounts for 64%~69%, the non-metal element boron accounts for 1.1%~1.2%, and a small amount of dysprosium, terbium, niobium, copper, etc. are added. element. For samarium cobalt magnets, taking the 2:17 type as an example, the rare earth metal samarium accounts for 23%~28%, metal cobalt accounts for 48%~52%, metal element iron accounts for 14%~17%, and a small amount of copper, zirconium and other elements.
2. Different performance and price
It can be found from the previous performance table that the overall magnetic performance of SmCo permanent magnets is lower than that of NdFeB permanent magnets. In addition, compared with NdFeB magnets and SmCo magnets with the same performance size, SmCo magnets are slightly more expensive. It can be seen from the ratio of the two metal elements that the content of iron in NdFeB magnets is the highest, while the content of samarium and cobalt in samarium cobalt magnets accounts for about 70%, which is not unreasonable~
3. Different high temperature resistance, oxidation resistance and corrosion resistance
The working temperature of NdFeB permanent magnets is between 80°C and 200°C, while the working temperature of SmCo permanent magnets can reach 250°C~350°C. The iron content in NdFeB magnets is relatively high, so it is easy to be oxidized and corroded. The process of surface treatment is essential. The service life of the magnet depends largely on the effect of the coating; while the iron content in SmCo magnets is less, Basically, it is a metal element that is not easy to be oxidized and corroded. Generally, it does not need surface treatment, unless the working environment is relatively harsh or electroplating is used to beautify the appearance.
4. Different effects of high and low temperature
Samarium cobalt magnets are suitable for working in a higher working temperature environment, and the maximum working temperature of samarium cobalt magnets can reach 350 degrees Celsius. When the temperature exceeds 150 degrees, its magnetic performance can exceed that of NdFeB high-temperature magnets. For every 1-degree Celsius increase in the temperature of samarium cobalt, the temperature coefficient of cobalt cobalt is about -0.04%, and if the maximum operating temperature is not exceeded, this loss will be fully compensated. Due to their thermal stability, samarium cobalt magnets are also ideal permanent magnets for aerospace, automotive, sensors, speakers, motors and military applications. Samarium cobalt magnets not only excel at high temperatures, but also maintain their magnetic properties even below absolute zero (-237 degrees Celsius), making them popular for cryogenic applications. Samarium cobalt magnets can withstand high temperature and low temperature. Temperature resistance is a characteristic of samarium cobalt magnets, but its high price makes it less widely used than neodymium iron boron.
5. Example comparison of demagnetization curve
NdFeB N45 demagnetization curve
Sintered samarium cobalt XGS32 demagnetization curve
