The magnetic performance of the rubber magnetic strips is the highest among all magnets, so it has the title of "Magnetic King". The maximum magnetic energy product of the sintered NdFeB magnets currently produced is 30~52MGOe. Sintered NdFeB is similar to permanent ferrite and samarium cobalt magnets, and its brittleness is relatively large, which makes its machining function general.
The Curie temperature of the rubber magnetic strips sintered NdFeB is only 310C, and its operating temperature is very low, the highest only needs 230C, which seriously affects its application in some special fields. It is particularly susceptible to oxidation and corrosion, so it needs to be surface treated and coated to prevent oxidation during production. The price of sintered NdFeB for rubber magnetic strips is at a medium level, which makes it continue to replace other permanent magnets in many fields.
Rubber magnetic strips bonded NdFeB is a magnet obtained by mixing NdFeB magnetic powder with epoxy resin. Its magnetic function is stable, the maximum magnetic energy product can reach 3~13 MGOe, and the magnet function fluctuates in the range of 5%. It has a Curie temperature of 350C and an operating temperature of up to 150C. Its products have high dimensional accuracy and large degree of freedom in shape, and can produce various complex and special-shaped products. The surface of the product has epoxy resin coating and parylene coating, which has excellent corrosion resistance, smooth and beautiful appearance, and can be used for a long time in daily or harsh environments. Its price is lower than that of rubber magnetic strips sintered NdFeB, and can replace sintered NdFeB and permanent magnet ferrite in some areas.
Rubber magnetic strips have been developed rapidly in recent years. There are three categories of AlNiCo, ferrite magnets and rare earth permanent magnets. The rare earth permanent magnet has the first generation samarium cobalt 1:5, the second generation samarium cobalt 2:17 and the third neodymium iron boron.
AlNiCo is a permanent magnet material successfully developed in the 1930s, although it has the advantages of high residual magnetic induction intensity and good thermal stability. However, it has low coercivity, poor anti-demagnetization ability, and high cost due to the use of precious metal cobalt, which greatly limits its application in motors.
Rubber magnetic strips ferrite magnets are permanent magnet materials developed in the early 1950s. Its biggest feature is its low price and high coercivity. The disadvantage is that the residual magnetic induction intensity and magnetic energy product are low.
Samarium cobalt rare earth permanent magnet material was introduced in the mid-1960s. It has the same high remanence induction intensity as aluminum nickel cobalt and higher coercivity than ferrite, but the price of samarium rare earth is higher.
In the early 1980s, the rubber magnetic strips NdFeB rare earth permanent magnet material appeared. It has high residual magnetic induction intensity, high coercivity and high magnetic energy product. These characteristics are especially suitable for use in motors. However, their disadvantage is that the temperature coefficient is large, the Curie point is low, and it is easy to oxidize and rust and needs to be coated.
After several years of continuous improvement and progress, most of these shortcomings have now been overcome. At present, the highest working temperature of NdFeB permanent magnet materials can reach 180°C, and generally can reach 150°C, which is enough to meet the application requirements of most motors.
