We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What are Samarium Cobalt Magnets?

By M.J. Casey
Updated May 17, 2024
Our promise to you
AboutMechanics is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At AboutMechanics, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Samarium cobalt magnets are a type of rare-earth magnet. The alloy content varies from about 25% to 36% samarium by weight. These permanent, strong magnets are especially useful for high-temperature applications.

The term rare earth refers not to the scarcity of the minerals in the Earth’s crust, but to the relatively low concentration of the atoms of interest in rare-earth mineral deposits. Because they are less concentrated, extraction of these compounds tends to be more costly. Certain rare-earth minerals exhibit permanent magnetism, like iron and iron compounds. Magnets manufactured from rare-earth minerals are superior to iron based magnets in that their magnetic force is stronger. Smaller parts can be made with the same magnetic field from rare-earth minerals.

Magnetism is due to a slight net charge distribution that is not zero. At the atomic and subatomic levels, the lowest, most stable energy state of electrons and other charged particles is in orbitals or other movements that are not geometrically symmetrical. This off-center characteristic is sufficient to be attracted by the Earth’s magnetic pole. In the case of lodestone, a naturally occurring magnetic mineral, magnetism was introduced when the rock cooled from the molten lava state, giving the atoms time to align themselves with the Earth’s magnetic field before being frozen into solid rock.

Magnetic materials have an upper temperature limit, the Curie temperature, above which the material is no long constrained at the atomic or molecular level. Samarium cobalt magnets are second in strength only to neodymium magnets, but may be used in higher temperature operations. The Curie temperatures of samarium cobalt magnets are between 1,100°F to 1,300°F (600°C to 710°C), with a favorable working range between 500°F to 1,000°F (250°C to 550°C).

The strength of magnets is typically measured in energy products with units of megagauss-oersteds, or MGOe. The theoretical limit is 34MGOe. Samarium cobalt magnets range from 16 to 32 MGOe. Although they have a very high magnetic force, they are extremely brittle and prone to breaking and chipping. Even handling is difficult, so machine finishing with diamond cutting tools is a highly skilled operation.

Alloys used in samarium cobalt magnets are of two types. The first is known as Series 1:5, with a ratio of one samarium atom to five cobalt atoms. Their magnetic strength ranges from 16 to 25 MGOe. Series 2:17 designates a spectrum of compounds with ratios of about two samarium to 17 cobalt atoms. Some cobalt atoms may be replaced with other transition metal atoms such as iron and copper. Magnetic strength of these alloys ranges from 20 to 32 MGOe.

Magnets of samarium cobalt are manufactured by a variety of sintering and pressing steps. Sintering fuses small particles of the samarium cobalt materials together. The pressing operations can entail die pressing, with pressure applied from one direction or from isotatic pressing in rubber molds, where pressure is applied in all directions. Trade-offs among tolerances, Curie temperature, and magnetic strength are made in manufacturing processes.

AboutMechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

AboutMechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

AboutMechanics, in your inbox

Our latest articles, guides, and more, delivered daily.