Samarium Cobalt Magnets
What is Samarium Cobalt Magnets
Samarium cobalt magnets are a type of rare-earth magnet. Also known as SmCo magnets, they are made of an alloy of samarium and cobalt. Samarium cobalt magnets often contain traces of other elements, such as copper and iron, but they consist mostly of the elements of their namesake: samarium and cobalt. Samarium is a rare-earth metal, which is why these magnets are known as “samarium cobalt magnets.”
Benefits of Samarium Cobalt Magnets
Temperature Stability
The defining characteristic of Samarium Cobalt magnets is their exceptional temperature stability. These magnets can operate at higher temperatures compared to other types of magnets, without significant loss of magnetic strength. This property makes them required for applications in industries with elevated temperature environments, such as aerospace, defense, and medical.
Corrosion Resistance
Samarium Cobalt magnets are known for their resistance to corrosion, which enhances their durability and longevity. This corrosion resistance means samarium cobalt magnets do not need to be plated to protect them, unlike neodymium iron boron. This property reduces the cost and potential failure of plating magnets.
High Magnetic Strength
Samarium Cobalt magnets exhibit extremely high magnetic strength, surpassing many other types of permanent magnets. This characteristic makes them ideal for applications where a strong and stable magnetic field is crucial, such as in sensors, magnetic couplings, and certain types of motors.
Low Temperature Coefficient
SmCo magnets have a low-temperature coefficient of magnetic remanence and coercivity. This means that their magnetic properties are less sensitive to temperature changes compared to other magnet materials. The stability across a range of temperatures is beneficial for applications requiring consistent magnetic performance in variable environmental conditions.
Long Operational Life
The robustness and stability of Samarium Cobalt magnets contribute to their long operational life. Their resistance to demagnetization, corrosion, and temperature variations ensures that they can maintain their magnetic properties over an extended period. This makes them a cost-effective choice for applications where reliability and longevity are critical factors.
1. Smco magnet has excellent high temperature resistance. 2. Smco magnet has excellent corrosion resistance, without coating protection on the surface. 3. High working temperature of Smco magnet. 4. SmCo is suitable for machinery with high magnetic requirements and for machinery with strict working environment requirements.
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Application
The company focuses on the research, development, and production of precast concrete magnets, fishing magnets, magnet hooks, and magnetic separators. Our products are widely used in precast concrete, food, medicine, chemicals, minerals, industrial filtration, recycling, and other industries.
Samarium Cobalt Magnet Temperature Coefficients
SmCo is well-known for operating at higher temperatures than NdFeB, but another important factor in favor of SmCo is the flatter curve of its temperature coefficient.
The (Br) temperature coefficient of SmCo magnets is only -0.03-05%/degree C. It’ s much smaller than the -0.11%/degree C value for NdFeB. (Br) stands for ‘‘Remanence’’ and you can learn more about Magnetic Remanence on our website here.
This means SmCo loses less field strength per degree of temperature increase than does NdFeB. This makes it easier for the engineer to make adjustments for temperature effects since these effects are smaller over a larger temperature range.
If you think the Temperature Coefficient of Remanence (Br) of SmCo was impressive, you will find the Temperature Coefficient of Coercivity of SmCo is even more impressive. Coercivity is the measure of a magnet’ s resistance to demagnetization.
The Temperature Coefficient of SmCo is around 0.20-0.30 %/degree C. But the Temperature Coefficient of NdFeB is 0.45-0.60 %/degree C.
The two things that cause a magnet to demagnetize are high temperatures and high opposing magnetic fields. By this measure, SmCo magnets greatly excel over NdFeB magnets –especially at elevated temperatures.
How Are Samarium Cobalt Magnets Made
Heated
Firstly, the raw materials required to produce a samarium cobalt magnet are heated in an induction furnace filled with argon gas and melted to form the alloy material.
Milling
Next, the liquid alloy is then poured into moulds and cooled with water to form ingots. Once the ingots have cooled they are then broken down, ground and milled to produce tiny particles.
Mixing
As an alternative to sintering, the alloy powder is mixed with a binding chemical such as an epoxy resin, die pressed and heated in the presence of an externally applied magnetic field to orientate the particles.
As a result, most bonded samarium cobalt magnets are anisotropic but typically have a lower maximum energy value than sintered samarium cobalt magnets.
Pressed & Coated
Typically, bonded samarium cobalt magnets don’ t require any additional machining as they are pressed into their desired form.
The final step is for the magnets to be coated if a coating is required and then magnetised using an externally applied magnetic field.
Sintered
As an alternative to bonding the alloy particles using a binding chemical, the powder is pressed into a die and sintered at a temperature up to 1250˚C, fusing the powder into a solid.
The sintered material is then given a solution treatment at similar temperatures before being tempered between 700˚C and 900˚C, and then cooled in the presence of an externally applied magnetic field.
Machining
The next process in manufacturing a sintered samarium cobalt magnet is machining and grinding.
Unlike the bonded form, a level of grinding and finishing is required and must be done using water-cooled diamond-coated grinding machinery as the material is very hard and brittle and the dust produced highly flammable.
Coated & Magnetised
The final process sees the formed magnet is then coated and magnetised.
Samarium cobalt magnets are classified into two based on the ratio of samarium to cobalt used during production.
SmCo5
In this type of samarium cobalt magnet, the ratio of samarium to cobalt is 1:5. This means five cobalt atoms are used for every atom of samarium used. This type of samarium cobalt magnet was discovered before the other type. However, it is no longer used frequently because the second type of samarium cobalt magnet has overtaken it. Its maximum energy product is 15 to 24 MGOe. This type of samarium cobalt magnet is highly resistant to corrosion.
Sm2Co7
In this type of samarium cobalt magnet, the ratio of samarium to cobalt is 2:7. This implies that two samarium atoms are added per seven atoms of cobalt. Although this type of samarium cobalt magnet was discovered after SmCo5, it has gained wider popularity for being stronger. Its maximum energy product is 20 to 32 MGOe. The downside of using this type of samarium cobalt magnet is that it is susceptible to corrosion when it comes in contact with water because it contains traces of iron.
Size Range of SmCo Magnets
|
Shape |
Grade |
Range |
|
Disc |
26M |
Diameter: 2mm-10mm, Thickness: 1/16''-3/8'' |
|
Block |
26M |
Legth: 3/8''-2'' ,Width: 3/8''-1/2'', Thickness:1/16''-1/2'' |
|
Ring |
26M |
Diameter: 10mm- 25mm Thickness: 5mm-20mm |
|
Rod |
26M |
Diameter: 5mm- 6mm Thickness: 6mm-10mm |
|
Pot |
26M |
Diameter: 25 mm, Thickness: 10mm |
Samarium cobalt magnets are applied in various industries around the world. Some of their properties make them well-suited for specific industries.
Sensors
Samarium cobalt magnets are used in sensors. These sensors are concerned with converting a magnetic field into electrical signals. The sensors are usually used in aerospace and automobiles.
Generators
Samarium cobalt magnets are used in generators. The samarium cobalt magnet provides the magnetic field for the generator. These generators are reliable and can be used in wind turbines.
Refrigerators
Samarium cobalt magnets are fast becoming popular in the refrigeration industry. Massachusetts Institute of Technology is currently researching how magnets can be used as refrigerants.
Nuclear Magnetic Resonance Spectrometer
Samarium cobalt magnets are also used in NMR spectrometers. In NMR spectrometers, magnets are used to investigate the spin of protons and neutrons. NMR spectrometers are used to study both the physical and chemical properties of organic compounds.
Medicine
Samarium cobalt magnets are used in medical equipment that require high temperatures for sterilization. This is because samarium cobalt magnets are stable under high temperatures. They are also used for medical implants.
How to Choose between Samarium Cobalt Magnets and Neodymium Magnets
When choosing between Samarium Cobalt (SmCo) magnetsand Neodymium (NdFeB) magnets, consider the following factors with specific figures and data:
Neodymium Magnets: Known for their extremely high magnetic strength, with a maximum energy product (BHmax) ranging from 35 to 52 MGOe (Mega Gauss Oersteds).
SmCo Magnets: Have a lower magnetic strength compared to Neodymium, with a BHmax typically between 22 to 30 MGOe.
Neodymium Magnets: Generally have a maximum operating temperature of 80°C to 150°C. High-temperature grades can reach up to approximately 200°C.
SmCo Magnets: Exhibit excellent thermal stability, with operating temperatures up to 300°C or higher. Some grades can function at temperatures as high as 350°C.
Neodymium Magnets: Susceptible to oxidation and corrosion. They typically require protective coatings such as nickel, zinc, or epoxy to prevent degradation.
SmCo Magnets: Naturally more resistant to oxidation and corrosion, making them suitable for harsh environments without needing additional coatings.
Neodymium Magnets: Brittle and can crack or shatter under mechanical stress or impact. They have a tensile strength of about 80 MPa.
SmCo Magnets: Also brittle but tend to be slightly more robust than Neodymium. They have a tensile strength of around 150 MPa.
Neodymium Magnets: Susceptible to demagnetization at high temperatures or if exposed to reverse magnetic fields, with a coercivity (Hcj) of 10 to 30 kOe.
SmCo Magnets: Superior resistance to demagnetization, with a coercivity (Hcj) of 15 to 30 kOe, maintaining their magnetic properties under challenging conditions.
Neodymium Magnets: Ideal for applications requiring high magnetic strength in compact sizes, such as electric motors, hard drives, and consumer electronics.
SmCo Magnets: Preferred in applications requiring high thermal stability, corrosion resistance, and reliable performance in harsh environments, such as aerospace, military, and high-temperature industrial uses.
Why Should Samarium Cobalt Magnets Be Electroplated
Samarium in the sintered samarium cobalt permanent magnet is quite stable in dry air, cobalt does not react with water at room temperature, it is also very stable in humid air, cobalt has strong corrosion resistance, and the new phase formed by the two is also quite stable, in the dry, wet and high temperature environment has a strong oxygen resistance, chemical and corrosion resistance, so at room temperature sintered samarium cobalt permanent magnet does not need surface protection, However, under high temperature conditions (temperature 2400'C), samarium cobalt magnets are prone to samarium desamarization, resulting in magnetic attenuation of the magnet, which requires necessary surface protection.
Our Factory
Xiamen Qianci Magnet Technology Co., Ltd. was founded in 2000, has a history of more than 20 years, ourcompany is located in Xiamen, Fujian province, is a specialized production and sales of magnet materials, magnet components suppliers. Since the completion of the factory in 2000, our company has continuously innovated products, from the initial iron and boron magnets to now have eight series of products, the company has realized the evolution of products from single to mixed forms, and constantly strengthen its own advantages. More than 100 million new magnet magnets have been transported to the world. For motor, generator and speaker, etc. Our company has always adhered to the "quality first, customer first, quality service, abide by the contract" purpose, with high quality products, good reputation, quality service, products sold in the world Europe, whole heartedly with domestic and foreign merchants win-win cooperation, common development, create brilliant!
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We always feel that all success of our company is directly related to the quality of the products we offer. They meet the highest quality requirements as stipulated in ISO9001, ISO14000:14001 SGS guidelines and our stringent quality control system.
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