The knowledge of magnetic materials
What is magnetic material?
Table of Contents
- What is magnetic material?
- Classification of magnetic materials
- Application of magnetic material transformer
- Characteristics of magnetic materials
- Part 1. Magnetism and Magnetism
- Part 2. Production and performance of sintered NdFeB
- Part 3. Application of Sintered NdFeB
- Part 4. Global Vision
- Part 5. Magnetic materials
- Part 6. Excellent paper recommendation
- Glossary of magnets
- Magnetic property of sintered neodymium magnets
- Magnetic property of bonded neodymium magnets
- Magnetic property of AlNiCo magnets
- Magnetic property of samarium cobalt magnets
- Magnetic property of ceramic magnets
- Magnetic property of flexible rubber magnets
- Plating & Coatings
A material that can react in some way to a magnetic field is called a magnetic material. According to the magnetic strength of matter in external magnetic field, it can be divided into diamagnetic matter, paramagnetic matter, ferromagnetic matter, antiferromagnetic matter and ferromagnetic matter. Most of the materials are diamagnetic or paramagnetic, and their reaction to external magnetic field is weak. Ferromagnetic materials and ferromagnetic materials are strong magnetic materials. Generally speaking, magnetic materials refer to strong magnetic materials. For magnetic materials, magnetization curve and hysteresis loop are characteristic curves reflecting their basic magnetic properties. Ferromagnetic materials are generally Fe, Co, Ni elements and their alloys, rare earth elements and their alloys, and some Mn compounds. According to the difficulty of magnetization, magnetic materials are generally divided into soft magnetic materials and hard magnetic materials.
Experiments show that any matter can be magnetized more or less in the external magnetic field, but the degree of magnetization is different. According to the characteristics of matter in the external magnetic field, matter can be divided into five categories: paramagnetic matter, diamagnetic matter, ferromagnetic matter, ferromagnetic matter and diamagnetic matter.
According to the molecular current hypothesis, matter should show similar characteristics in the magnetic field, but it tells us that the characteristics of matter in the external magnetic field are very different. This reflects the limitation of molecular current hypothesis. In fact, there are differences in the microstructure of various materials, which is the reason for the differences in magnetic properties.
We call paramagnetic material and diamagnetic material weak magnetic material and ferromagnetic material strong magnetic material.
Generally speaking, magnetic materials refer to strong magnetic materials. According to the difficulty of demagnetization after magnetization, magnetic materials can be divided into soft magnetic materials and hard magnetic materials. After magnetization, the material that is easy to remove magnetism is called soft magnetic material, and the material that is not easy to remove magnetism is called hard magnetic material. Generally speaking, the remanence of soft magnetic materials is smaller than that of hard magnetic materials.
Classification of magnetic materials
Magnetic materials have strong magnetic materials with magnetic order. In a broad sense, they also include weak magnetic and antiferromagnetic materials which can apply their magnetism and magnetic effect. Magnetism is a basic property of matter. Materials can be divided into diamagnetic, paramagnetic, ferromagnetic, antiferromagnetic and ferromagnetic materials according to their internal structure and properties in external magnetic field. Ferromagnetic and ferromagnetic materials are strong magnetic materials, diamagnetic and paramagnetic materials are weak magnetic materials. Magnetic materials can be divided into metal and non-metal according to their properties. The former mainly includes electrical steel, nickel based alloy and rare earth alloy, while the latter mainly includes ferrite materials. According to the use, it can be divided into soft magnetic materials, permanent magnetic materials and functional magnetic materials. Functional magnetic materials mainly include magnetostrictive materials, magnetic recording materials, magnetoresistance materials, magnetic bubble materials, magneto-optical materials, gyromagnetic materials and magnetic thin film materials. The basic magnetic properties of magnetic materials include magnetization curve, hysteresis loop and magnetic loss.
Permanent magnet material
After magnetization in an external magnetic field, even under the action of a considerable reverse magnetic field, part or most of the original magnetization direction can still be maintained. The requirements for this kind of materials are high residual magnetic induction (BR) and high coercivity (BHC).
The magnetic energy product (BH) (that is, the magnetic energy provided to space) is large. Compared with soft magnetic material, it is also called hard magnetic material. There are three kinds of materials: permanent magnetic alloy, ferrite.
- ① Alloys: including casting, sintering and machinable alloys. The main types of casting alloys are: AlNi (CO), FeCr (CO), FeCrMo, FeAlC, FeCo (V) (W); sintered alloys are: re CO (re stands for rare earth elements), re Fe, AlNi (CO), FeCrCo, etc.; Machinable alloys are: FeCrCo, PtcO, mnalc, cunifie and almnag, etc. the latter two kinds of low BHC are also called semi permanent magnetic materials.
- ② Ferrite: mainly composed of Mo · 6fe2o3, M represents Ba, Sr, Pb or SRCA, LACA and other composite components.
- ③ Intermetallic compounds: mainly represented by MnBi.
Permanent magnet materials have many uses.
- ① Applications based on the principle of electromagnetic force mainly include: speaker, microphone, meter, button, motor, relay, sensor, switch, etc.
- ② The applications based on the principle of magnetoelectric action mainly include: microwave electron tubes such as magnetron and traveling wave tubes, picture tubes, titanium pumps, microwave ferrite devices, magnetoresistive devices, Hall devices, etc.
- ③ Applications based on the principle of magnetic force mainly include: magnetic bearing, concentrator, magnetic separator, magnetic sucker, magnetic seal, magnetic blackboard, toy, sign, code lock, copier, temperature controller, etc. Other applications include: magnetic therapy, magnetized water, magnetic anesthesia, etc.
According to the needs of use, permanent magnet materials can have different structures and shapes. Some materials are also isotropic and anisotropic.
Soft magnetic materials
Its main function is magnetic conduction, electromagnetic energy conversion and transmission. Therefore, high permeability and magnetic induction are required for this kind of material, and the area of hysteresis loop or magnetic loss is small. On the contrary, the smaller the BR and BHC, the better, but the larger the saturation magnetic induction BS.
A kind of soft magnetic material: iron powder core
Soft magnetic materials can be divided into four categories.
- ① Alloy thin strip or sheet: FeNi (MO), FeSi, FeAl, etc.
- ② Amorphous alloy ribbons: Fe based, Co based, FeNi based or fenico based with appropriate Si, B, P and other doping elements, also known as magnetic glass.
- ③ Magnetic medium (iron powder core): FeNi (MO), FeSiAl, carbonyl iron, ferrite and other powders, which are coated and bonded by electrical insulating medium, are pressed and formed as required.
- ④ Ferrite: including spinel type Mo · Fe2O3 (m for NiZn, MnZn, MgZn, Li1 / 2fe1 / 2Zn, CaZn, etc.), magnetite type ba3me2fe24o41 (me for CO, Ni, Mg, Zn, Cu and their composite components).
Soft magnetic materials are widely used in magnetic antenna, inductor, transformer, magnetic head, earphone, relay, vibrator, TV deflection yoke, cable, delay line, sensor, microwave absorbing material, electromagnet, accelerator high-frequency accelerating cavity, magnetic probe, magnetic substrate, magnetic shielding, high-frequency quenching and energy gathering, electromagnetic chuck, magnetic sensitive element (such as magnetocaloric material) Switch, etc.
Magnetic moment and magnetic recording materials
It is mainly used for information recording, contactless switch, logic operation and information amplification. The characteristic of this material is that the hysteresis loop is rectangular.
It has unique microwave magnetism, such as tensor properties of permeability, Faraday rotation, resonance absorption, field shift, phase shift, birefringence and spin wave effects. The devices designed on this basis are mainly used for the transmission and conversion of microwave energy, such as isolators, circulators, filters (fixed or electrically regulated), attenuators, phase shifters, modulators, switches, limiters, delay lines, etc., as well as the developing magnetic surface wave and magnetostatic wave devices (see microwave ferrite devices). The commonly used materials have formed a series, including Ni, Mg, Li, ylg and bicav ferrites, and can be made into single crystal, polycrystalline, amorphous or thin film according to the needs of devices.
This kind of material is characterized by mechanical deformation under the action of external magnetic field, so it is also called magnetostrictive material. Its function is to convert Magnetoacoustic or magnetic energy. It is commonly used in the vibration head of ultrasonic generator, mechanical filter of communication machine and delay line of electric pulse signal. Combined with microwave technology, micro acoustic (or rotary acoustic) devices can be made. Because of the high mechanical strength of alloy material, anti vibration and no crack, the vibration head is mostly made of Ni and Nico alloys, and the vibration head is mainly made of Ni and Nico ferrites under small signal. The new type of amorphous alloy with stronger piezomagnetism is suitable for making delay line. The production and application of piezomagnetic materials are far less than the former four materials.
Application of magnetic material transformer
Magnetic materials are widely used in production, life and national defense science and technology. For example, manufacturing various motors and transformers in power technology, various magnetic components and microwave tubes in electronic technology, filters and sensitizers in communication technology, magnetic mines and electromagnetic guns in national defense technology, various household appliances, etc. In addition, magnetic materials have been widely used in geological exploration, ocean exploration, information, energy, biology and space technology. Magnetic materials are widely used. It is mainly used to make components or devices with various magnetic properties and special effects; it is used to store, transmit and convert electromagnetic energy and information, or to generate a certain intensity and distribution of magnetic field in a specific space; sometimes it is directly used in the natural form of materials (such as magnetic liquid). Magnetic materials play an important role in the field of electronic technology and other fields of science and technology.
Characteristics of magnetic materials
Ferromagnetic materials have the following characteristics:
- ① Even if there is no external magnetic field, there is still permanent magnetic moment in each small region (domain) of the material. But when there is no external magnetic field, the magnetic moment direction of each domain is arbitrarily distributed, and the vector sum is zero, so the material as a whole is not magnetic.
- ② Easy to magnetize. This is due to the fact that the magnetic field can be transferred to the direction of the external magnetic field. According to the formula B = μ RB0 (B0 is the magnetic induction intensity in vacuum), the relative permeability μ r of magnetic materials is very large. In fact, the μ r of magnetic materials is 10 ~ 10, but that of non-magnetic materials is about 1.
- ③ There is a phenomenon of magnetic saturation, that is, B increases with the increase of H, but when BS increases to a certain value, it does not increase with H. BS is the saturation magnetic induction of the magnetic material. The reason for saturation is that when h reaches a certain value, the magnetic moments of all domains turn to the direction of magnetic field. For this reason, B and H do not have a linear relationship, so the permeability is not a constant, but is related to the strength of the magnetic field.
- ④ There is hysteresis. That is to say, the change of magnetic induction lags behind the change of magnetic field.
Part 1. Magnetism and Magnetism
- 1.1 Superficial magnetic field, residual magnetism and magnetic flux
- 1.2 Hysteresis loop
- 1.3 Electromagnetic unit conversion (conversion between SI system and CGS system)
- 1.4 15 basic concepts related to magnetic materials
- 1.5 15 advanced concepts related to magnetic materials
- 1.6 The working principle of the Hall element
- 1.7 Principles and methods of demagnetization
- 1.8 Halbach Array
- 1.9 Magnetism and magnetic moment
- 1.10 Magnetic moment and magnetic flux, magnetic moment and remanence (Pc value, operating point)
- 1.11 Squareness Q of demagnetization curve and knee point Hk
- 1.12 Remanence temperature coefficient, coercivity temperature coefficient, reversible temperature coefficient
- 1.13 Magnetic field intensity H and magnetic induction intensity B, magnetization intensity M and magnetic polarization intensity J
- 1.14 Magnetic domain
- 1.15 Eddy current loss
Part 2. Production and performance of sintered NdFeB
- 2.1 The production process of sintered NdFeB
- 2.2 The meaning of performance grades
- 2.3 Curie temperature and working temperature
- 2.4 Orientation and magnetization direction
- 2.5 Surface treatment and plating
- 2.5.1 Electroplating
- 2.5.2 Electrophoresis
- 2.5.3 Phosphating
- 2.5.4 Parylene
- 2.5.5 Passivation
- 2.6 Dimensional and geometric tolerances
- 2.7 Mechanical properties (fracture, compression resistance, bending resistance)
- 2.8 Principle and technology of relative detection of magnetic properties
- 2.9 Service life of sintered NdFeB
- 2.10 Waste and regenerated sintered NdFeB
- 2.11 Reasons and methods affecting magnet performance
- 2.12 The role of elements such as dysprosium, terbium, gadolinium and holmium
- 2.13 What is dysprosium permeation and terbium permeation technology
- 2.14 Dysprosium permeation and terbium permeation by magnetron sputtering
- 2.15 Relationship and calculation of table magnetism and magnet performance
- 2.16 The suction of sintered NdFeB
- 2.17 Weight loss test of sintered NdFeB (HAST&PCT)
Part 3. Application of Sintered NdFeB
- 3.1 Speakers and Speakers Magnet
- 3.2 Permanent magnet motor and permanent magnet
- 3.3 Coreless motor and permanent magnet
- 3.4 Magnetic separator and permanent magnet
- 3.5 Magnetic coupling and permanent magnet
- 3.6 Wind turbines and high-performance permanent magnets
Part 4. Global Vision
- 4.1 Comparison of global grades of sintered NdFeB
- 4.2 Global Certification Mark for Magnetic Materials
- 4.3 How to transport magnetic materials by air
Part 5. Magnetic materials
- 5.1 Magnetism and magnetic materials
- 5.2 Bonded NdFeB
- 5.3 Hot-pressed NdFeB
- 5.4 Samarium Cobalt Permanent Magnet
Part 6. Excellent paper recommendation
- Factors affecting corrosion weight loss of sintered NdFeB magnets and improvement of corrosion resistance
- Perspective and Prospects for Rare Earth Permanent Magnets
- The effect of magnetron sputtering dysprosium on the properties and microstructure of sintered NdFeB
- Development trend analysis of NdFeB permanent magnet material patent technology
- Research progress of sintered NdFeB permanent magnets with high coercivity
- Comparative study on product standards of NdFeB permanent magnet materials at home and abroad
- Application and prospect of additive manufacturing technology in the preparation of permanent magnetic materials
- Research status and challenges of corrosion and protection of sintered NdFeB permanent magnet materials
- The development of rare earth permanent magnet materials and its application in permanent magnet motors
- Research on local demagnetization behavior of sintered NdFeB rare earth permanent magnet materials
- Research progress of NdFeB waste recycling methods
- Rare earth functional materials 2035 development strategy research (excerpts from rare earth permanent magnet materials)
- Chemical synthesis and performance optimization of rare earth permanent magnet materials and their coupling magnets
- Exploration on the mechanism of re-enhancing coercivity of dual main phase (Nd, Dy)-Fe-B magnets
- Development status and prospects of rare earth NdFeB materials in 2021
Glossary of magnets
- Air Gap – The “external” distance from one pole of the magnet to the other though a non-magnetic material (usually air).
- Anisotropic – An anisotropic material has different properties in different directions. For example, wood which has a grain is stronger in some one direction than another. Like wood, neodymium magnets are also anisotropic. Even before it is magnetized, a neodymium magnet has a “preferred” magnetization direction. Neodymium magnets are made with a preferred magnetization direction which can not be changed. These materials are either manufactured in the influence of strong magnetic fields or pressed a specific way, and can only be magnetized through the preferred axis.Sintered Neodymium (Iron Boron) and Samarium Cobalt magnets are anisotropic.
- B/H Curve – The result of plotting the value of the magnetic field (H) that is applied against the resultant flux density (B) achieved. This curve describes the qualities of any magnetic material.
- BHmax (Maximum Energy Product) – The Maximum Energy Product at the point on the B/H Curve that has the most strength, expressed in MGOe (MegaGaussOersteds). When describing the grade of a neodymium magnet, this number is commonly referred to as the “N” number, as in Grade N52 magnets.
- Brmax (Residual Induction) – Also called “Residual Flux Density”. The magnetic induction remaining in a saturated magnetic material after the magnetizing field has been removed. This is the point at which the hysteresis loop crosses the B axis at zero magnetizing force, and represents the maximum flux output from the given magnet material. By definition, this point occurs at zero air gap, and therefore cannot be seen in practical use of magnet materials.
- C.G.S. – Abbreviation for the “Centimeter, Grams, Second” system of measurement.
- Coercive Force (Hc) – The demagnetizing force, measured in Oersteds, necessary to reduce observed induction, B, to zero after the magnet has previously been brought to saturation.
- Curie Temperature (Tc) – The temperature at which a magnet loses all of its magnetic properties.
- Demagnetization Curve – The second quadrant of the hysteresis loop, generally describing the behavior of magnetic characteristics in actual use. Also known as the B-H Curve. Find these curves for some of our most popular magnet grades on our BH Curves page.
- Demagnetization Force – A magnetizing force, typically in the direction opposite to the force used to magnetize it in the first place. Shock, vibration and temperature can also be demagnetizing forces.
- Dimensions – The physical size of a magnet including any plating or coating.
- Dimensional Tolerance – An allowance, given as a permissible range, in the nominal dimensions of a finished magnet. The purpose of a tolerance is to specify the allowed leeway for variations in manufacturing.
- (Magnetic) Dipole Moment (m) – a quantity that describes the torque a given magnet will experience in an external magnetic field. Some folks (like physicists) use a magnetic dipole model to simulate or mathematically model a magnet or group of magnets. Mathematically, it’s easier than considering the complexities of weird magnet shapes. It’s not theoretically perfect. Using it won’t always match measured field strengths near a neodymium magnet. It works great for a sphere, but isn’t correct near other shapes like discs or blocks. It’s a great approximation when you’re measuring far away from a magnet, but not so good close up, especially near the edges of a magnet. Calculate the dipole moment using the formula m = dipole moment in A m2 = Br x V / μo, where: Br is Br max, the Residual Flux Density, expressed in Tesla. V is the volume of the magnet, expressed in cubic meters. μo is the permeability of a vacuum, or 4 π x 10-7 N/A2.
- Electromagnet – A magnet consisting of a solenoid with an iron core, which has a magnetic field only during the time of current flow through the solenoid.
- Ferromagnetic Material – A material that either is a source of magnetic flux or a conductor of magnetic flux. Most ferromagnetic materials have some component of iron, nickel, or cobalt.
- Gauss – Unit of magnetic induction, B. Lines of magnetic flux per square centimeter in the C.G.S. system of measurement. Equivalent to lines per square inch in the English system, and webers per square meter or tesla in the S.I. system. 10,000 gauss equals 1 tesla.
- Gauss meter – An instrument used to measure the instantaneous value of magnetic induction, B, usually measured in Gauss (C.G.S.). Also called a DC magnetometer.
- Gilbert – The unit of magnetomotive force, F, in the C.G.S. system.
- Hysteresis Loop – A plot of magnetizing force versus resultant magnetization (also called a B/H curve) of the material as it is successively magnetized to saturation, demagnetized, magnetized in the opposite direction and finally remagnetized. With continued recycles, this plot will be a closed loop which completely describes the characteristics of the magnetic material. The size and shape of this “loop” is important for both hard and soft materials. With soft materials, which are generally used in alternating circuits, the area inside this “loop” should be as thin as possible (it is a measure of energy loss). But with hard materials the “fatter” the loop, the stronger the magnet will be. The first quadrant of the loop (that is +X and +Y) is called the magnetization curve. It is of interest because it shows how much magnetizing force must be applied to saturate a magnet. The second quadrant (-X and +Y) is called the Demagnetization Curve.
- Induction, (B) – The magnetic flux per unit area of a section normal to the direction of flux. Measured in Gauss, in the C.G.S. system of units.
- Intrinsic Coercive Force (Hci) – Indicates a materials’ resistance to demagnetization. It is equal to the demagnetizing force which reduces the intrinsic induction, Bi, in the material to zero after magnetizing to saturation; measured in oersteds.
- Irreversible Losses – Partial demagnetization of the magnet, caused by exposure to high or low temperatures, external fields, shock, vibration, or other factors. These losses are only recoverable by remagnetization. Magnets can be stabilized against irreversible losses by partial demagnetization induced by temperature cycles or by external magnetic fields.
- Isotropic Material – A material that can be magnetized along any axis or direction (a magnetically unoriented material). The opposite of Anisotropic Magnet.
- Keeper – A soft iron piece temporarily added between the poles of a magnetic circuit to protect it from demagnetizing influences. Also called a shunt. Keepers are generally not needed for Neodymium and other modern magnets.
- Kilogauss – One Kilogauss = 1,000 Gauss = Maxwells per square centimeter.
- Magnet – A magnet is an object made of certain materials which create a magnetic field. Every magnet has at least one north pole and one south pole. By convention, we say that the magnetic field lines leave the North end of a magnet and enter the South end of a magnet. This is an example of a magnetic dipole (“di” means two, thus two poles). If you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole. If you take one of those pieces and break it into two, each of the smaller pieces will have a North pole and a South pole. No matter how small the pieces of the magnet become, each piece will have a North pole and a South pole. It has not been shown to be possible to end up with a single North pole or a single South pole which is a monopole (“mono” means one or single, thus one pole).
- Magnetic Circuit – Consists of all elements, including air gaps and non-magnetic materials that the magnetic flux from a magnet travels on, starting from the north pole of the magnet to the south pole.
- Magnetic Field (B) – （from: kjmagnetics.com） When specified on our site, the surface field or magnetic field refers to the strength in Gauss. For axially magnetized discs and cylinders, it is specified on the surface of the magnet, along the center axis of magnetization. For blocks, it is specified on the surface of the magnet, also along the center axis of magnetization. For rings, you may see two values. By,center specifies the vertical component of the magnetic field in the air at the center of the ring. By,ring specifies the vertical component of the magnetic field on the surface of the magnet, mid-way between the inner and outer diameters.
- Magnetic Field Strength (H) – Magnetizing or demagnetizing force, is the measure of the vector magnetic quantity that determines the ability of an electric current, or a magnetic body, to induce a magnetic field at a given point; measured in Oersteds.
- Magnetic Flux – Is a contrived but measurable concept that has evolved in an attempt to describe the “flow” of a magnetic field. When the magnetic induction, B, is uniformly distributed and is normal to the area, A, the flux, Φ = BA.
- Magnetic Flux Density – Lines of flux per unit area, usually measured in Gauss (C.G.S.). One line of flux per square centimeter is one Maxwell.
- Magnetic Induction (B) – The magnetic field induced by a field strength, H, at a given point. It is the vector sum, at each point within the substance, of the magnetic field strength and the resultant intrinsic induction. Magnetic induction is the flux per unit area normal to the direction of the magnetic path.
- Magnetic Line of Force – An imaginary line in a magnetic field, which, at every point, has the direction of the magnetic flux at that point.
- Magnetic Pole – An area where the lines of flux are concentrated.
- Magnetomotive Force (F or mmf) – The magnetic potential difference between any two points. Analogous to voltage in electrical circuits. That which tends to produce a magnetic field. Commonly produced by a current flowing through a coil of wire. Measured in Gilberts (C.G.S.) or Ampere Turns (S.I.).
- Material Grade – Neodymium (NdFeB) magnets are graded by the magnetic material from which they are manufactured. Generally speaking, the higher the grade of material, the stronger the magnet. We find that the Pull Force of a magnet relates directly to the “N” number. Neodymium magnets currently range in grade from N35 to N52. The theoretical limit for Neodymium magnets is grade N64, though it isn’t currently feasible to manufacture magnets this strong. The grade of most of our stock magnets is N42 because we feel that N42 provides the optimal balance between strength and cost. We also stock a wide range of sizes in grade N52 for customers who need the strongest permanent magnets available.
- Maximum Energy Product (BHmax) – The magnetic field strength at the point of maximum energy product of a magnetic material. The field strength of fully saturated magnetic material measured in Mega Gauss Oersteds, MGOe.
- Maximum Operating Temperature (Tmax) – Also known as maximum service temperature, is the temperature at which the magnet may be exposed to continuously with no significant long-range instability or structural changes.
- Maxwell – Unit of magnetic flux in the C.G.S. electromagnetic system. One maxwell is one line of magnetic flux.
- Magnetization Curve – The first quadrant portion of the hysteresis loop (B/H) Curve for a magnetic material.
- Magnetizing Force (H) – The magnetomotive force per unit of magnet length, measured in Oersteds (C.G.S.) or ampere-turns per meter (S.I). Maxwell – The C.G.S. unit for total magnetic flux, measured in flux lines per square centimeter.
- MGOe – Mega (million) Gauss Oersteds. Unit of measure typically used in stating the maximum energy product for a given material. See Maximum Energy Product.
- North Pole – The north pole of a magnet is the one attracted to the magnetic north pole of the earth. This north-seeking pole is identified by the letter N. By accepted convention, the lines of flux travel from the north pole to the south pole.
- Oersted (Oe) – The C.G.S. unit for magnetizing force. The English system equivalent is Ampere Turns per Inch (1 Oersted equals 79.58 A/m). The S.I. unit is Ampere Turns per Meter.
- Orientation – Used to describe the direction of magnetization of a material. Orientation Direction – The direction in which an anisotropic magnet should be magnetized in order to achieve optimum magnetic properties.
- Paramagnetic Materials – Materials that are not attracted to magnetic fields (wood, plastic, aluminum, etc.). A material having a permeability slightly greater than 1.
- Permanent Magnet – A magnet that retains its magnetism after it is removed from a magnetic field. A permanent magnet is “always on”. Neodymium magnets are permanent magnets.
- Permeance (P) – A measure of relative ease with which flux passes through a given material or space. It is calculated by dividing magnetic flux by magnetomotive force. Permeance is the reciprocal of reluctance.
- Permeance Coefficient (Pc) – Also called the load-line, B/H or “operating slope” of a magnet, this is the line on the Demagnetization Curve where a given magnet operates. The value depends on both the shape of the magnet, and it’s surrounding environment (some would say, how it’s used in a circuit). In practical terms, it’s a number that define how hard it is for the field lines to go from the north pole to the south pole of a magnet. A tall cylindrical magnet will have a high Pc, while a short, thin disc will have a low Pc.
- Permeability (μ) – The ratio of the magnetic induction of a material to the magnetizing force producing it (B/H). It is a measure of how much a material becomes magnetized in the presence of a magnetic field.
- The magnetic permeability of a vacuum (µo) is 4π×10-7 N/A2.
- Pole – An area where the lines of magnetic flux are concentrated.
- Plating/Coating – Most neodymium magnets are plated or coated in order to protect the magnet material from corrosion. Neodymium magnets are mostly composed of neodymium, iron, and boron. The iron in the magnet will rust if it is not sealed from the environment by some sort of plating or coating. Most of the neodymium magnets that we stock are triple plated in nickel-copper-nickel, but some are plated in gold, silver, or black nickel, while others are coated in epoxy, plastic or rubber.
- Polarity – The characteristic of a particular pole at a particular location of a permanent magnet. Differentiates the North from the South Pole.
- Pull Force – The force required to pull a magnet free from a flat steel plate using force perpendicular to the surface. The limit of the holding power of a magnet. The pull force listed is actual data acquired by testing using our state-of-the-art force test stand.
- Rare Earth – Commonly used to describe high energy magnet material such as NdFeB (Neodymium-Iron-Boron) and SmCo (Samarium-Cobalt).
- Relative Permeability – The ratio of permeability of a material to that of a vacuum. In the C.G.S. system, the permeability is equal to 1 in a vacuum by definition. The permeability of air is also for all practical purposes equal to 1 in the C.G.S. system.
- Reluctance (R)- A measure of the relative resistance of a material to the passage of flux. It is calculated by dividing magnetomotive force by magnetic flux. Reluctance is the reciprocal of permeance.
- Remanence, (Bd) – The magnetic induction that remains in a magnetic circuit after the removal of an applied magnetizing force.
- Return Path – Conduction elements in a magnetic circuit which provide a low reluctance path for the magnetic flux.
- Reversible Temperature Coefficient – A measure of the reversible changes in flux caused by temperature variations.
- Saturation – The state where an increase in magnetizing force produces no further increase in magnetic induction in a magnetic material.
- Shunt – A soft iron piece temporarily added between the pole of a magnetic circuit to protect it from demagnetizing influences. Also called a keeper. Not needed for Neodymium and other modern magnets.
- S.I. – Abbreviation for “Système International”. Refers to the International Standard System of units. It is also known as the MKS system.
- South Pole – The south pole of a magnet is the one attracted to the south pole of the earth. This south-seeking pole is identified by the letter S. By accepted convention, the lines of flux travel from the north pole to the south pole.
- Stabilization – The process of exposing a magnet or a magnetic assembly to elevated temperatures or external magnetic fields to demagnetize it to a predetermined level. Once done the magnet will suffer no future degradation when exposed to that level of demagnetizing influence.
- Surface Field (Surface Gauss) – The magnetic field strength at the surface of the magnet as measured by a Gauss meter.
- Temperature Coefficient – A factor that is used to calculate the decrease in magnetic flux corresponding to an increase in operating temperature. The loss in magnetic flux is recovered when the operating temperature is decreased.
- Tesla – The S.I. unit for magnetic induction (flux density). One Tesla equals 10,000 Gauss.
- Weber – The S.I. unit for total magnetic flux. The practical unit of magnetic flux. It is the amount of magnetic flux which, when linked at a uniform rate with a single-turn electric circuit during an interval of 1 second, will induce in this circuit an electromotive force of 1 volt.
- Weight – The weight of a single magnet.
Magnetic property of sintered neodymium magnets
|Grade||Remanence||Coercive Force||Intrinsic Coercive force||Max Energy Product||Max Working Temp.|
|N35||11.4-11.8||1.18-1.28||≥ 10.8||≥ 836||≥ 12||≥ 955||33-36||263-287||80||176|
|N38||11.8-12.3||1.18-1.28||≥ 10.8||≥ 860||≥ 12||≥ 955||36-39||287-310||80||176|
|N40||12.7-12.9||1.27-1.29||≥ 11.0||≥ 876||≥ 12||≥ 955||38-41||303-326||80||176|
|N42||12.9-13.3||1.29-1.33||≥ 10.5||≥ 836||≥ 12||≥ 955||40-43||318-342||80||176|
|N45||13.3-13.8||1.33-1.38||≥ 9.5||≥ 756||≥ 12||≥ 955||43-46||342-366||80||176|
|N48||13.8-14.2||1.38-1.42||≥ 10.5||≥ 835||≥ 12||≥ 955||46-49||366-390||80||176|
|N50||13.8-14.5||1.38-1.45||≥ 10.5||≥ 835||≥ 11||≥ 955||47-51||374-406||80||176|
|N52||14.3-14.8||1.43-1.48||≥ 10.8||≥ 860||≥ 11||≥ 876||50-53||398-422||80||176|
|33M||11.4-11.8||1.14-1.18||≥ 10.3||≥ 820||≥ 14||≥ 1114||31-33||247-263||100||212|
|35M||11.8-12.3||1.18-1.23||≥ 10.8||≥ 860||≥ 14||≥ 1114||33-36||263-287||100||212|
|38M||12.3-12.7||1.23-1.27||≥ 11.0||≥ 876||≥ 14||≥ 1114||38-41||303-326||100||212|
|40M||12.7-12.9||1.27-1.29||≥ 11.4||≥ 907||≥ 14||≥ 1114||38-41||303-326||100||212|
|42M||12.8-13.2||1.28-1.32||≥ 11.6||≥ 923||≥ 14||≥1114||40-43||318-342||100||212|
|45M||13.2-13.8||1.32-1.38||≥ 11.8||≥ 939||≥ 14||≥ 1114||43-46||342-366||100||212|
|48M||13.6-14.0||1.36-1.40||≥ 11.8||≥ 939||≥ 14||≥ 1114||46-49||366-390||100||212|
|50M||14.0-14.5||1.40-1.45||≥ 13.0||≥ 1033||≥ 14||≥ 1114||48-51||382-406||100||212|
|30H||10.8-11.4||1.08-1.14||≥ 10.2||≥ 812||≥ 17||≥ 1353||28-31||223-247||120||248|
|33H||11.4-11.8||1.14-1.18||≥ 10.6||≥ 844||≥ 17||≥ 1353||31-33||247-263||120||248|
|35H||11.8-12.3||1.18-1.28||≥ 11.0||≥ 876||≥ 17||≥ 1353||33-36||263-287||120||248|
|38H||12.3-12.7||1.23-1.27||≥ 11.2||≥ 890||≥ 17||≥ 1353||36-39||287-310||120||248|
|40H||12.7-12.9||1.27-1.29||≥ 11.5||≥ 915||≥ 17||≥ 1353||38-41||303-326||120||248|
|42H||12.8-13.2||1.28-1.32||≥ 12.0||≥ 955||≥ 17||≥ 1353||40-43||318-342||120||248|
|45H||13.2-13.5||1.32-1.38||≥ 12.0||≥ 955||≥ 17||≥ 1353||42-46||335-366||120||248|
|46H||13.3-13.8||1.33-1.38||≥ 12.2||≥ 972||≥ 16||≥ 1274||44-47||350-374||120||248|
|48H||13.6-14.3||1.36-1.43||≥ 12.5||≥ 995||≥ 16||≥ 1274||46-49||366-390||120||248|
|30SH||10.8-11.4||1.081.14||≥ 10.0||≥ 796||≥ 20||≥ 1672||28-31||223-247||150||302|
|33SH||11.4-11.8||1.14-1.18||≥ 10.5||≥ 836||≥ 20||≥ 1672||31-34||247-276||150||302|
|35SH||11.8-12.3||1.18-1.23||≥ 11.0||≥ 876||≥ 20||≥ 1672||33-36||263-287||150||302|
|38SH||12.3-12.7||1.23-1.27||≥ 11.4||≥ 907||≥ 20||≥ 1972||36-39||287-310||150||302|
|40SH||12.5-12.8||1.25-1.28||≥ 11.8||≥ 939||≥ 20||≥ 1972||38-41||302-326||150||302|
|42SH||12.8-13.2||1.28-1.32||≥ 11.8||≥ 939||≥ 20||≥ 1672||40-43||320-343||150||302|
|45SH||13.2-13.8||1.32-1.38||≥ 12.6||≥ 1003||≥ 20||≥ 1592||43-46||342-366||150||302|
|30UH||10.8-11.4||1.08-1.14||≥ 10.2||≥ 812||≥ 25||≥ 1990||28-31||223-247||180||356|
|33UH||11.3-11.7||1.13-1.17||≥ 10.7||≥ 852||≥ 25||≥ 1990||31-33||247-263||180||356|
|35UH||11.7-12.1||1.17-1.21||≥ 10.7||≥ 852||≥ 25||≥ 1990||33-36||263-287||180||356|
|38UH||12.1-12.5||1.21-1.25||≥ 11.4||≥ 907||≥ 25||≥ 1990||36-39||287-310||180||356|
|40UH||12.5-12.8||1.25-1.28||≥ 11.4||≥ 907||≥ 25||≥ 1990||38-41||302-326||180||356|
|28EH||10.5-10.8||1.05-1.08||≥ 9.5||≥ 756||≥ 30||≥ 2388||26-29||207-231||200||392|
|30EH||10.8-11.4||1.08-1.14||≥ 9.5||≥ 756||≥ 30||≥ 2388||28-31||223-241||200||292|
|33EH||11.3-11.7||1.13-1.17||≥ 10.2||≥ 812||≥ 30||≥ 2388||31-33||247-263||200||392|
|35EH||11.7-12.1||1.17-1.21||≥ 10.2||≥ 812||≥ 30||≥ 2388||33-36||263-287||200||392|
|38EH||12.1-12.5||1.21-1.25||≥ 11.4||≥ 907||≥ 30||≥ 2388||36-39||287-310||200||392|
|30AH||10.8-11.3||1.08-1.13||≥ 10.2||≥ 812||≥ 35||≥ 2785||28-32||223-255||220||428|
|33AH||11.2-11.7||1.12-1.17||≥ 10.2||≥ 812||≥ 35||≥ 2785||31-34||247-271||220||428|
Magnetic property of bonded neodymium magnets
|Grade||Br (Gauss)||Hc (Oe)||Hci (Oe)||(BH)max (MGO)||Max Working Temp. ( °C / °F)|
|BN-8||6,000 – 6,500||4,500 – 5,500||8,000 – 12,000||7 – 9||140 / 275|
|BN-10||6,500 – 7,000||4,500 – 5,800||8,000 – 12,000||9 -10||110 / 220|
|BN-12||7,000 – 7,600||5,300 – 6,000||8,000 – 11,000||10 – 12||130 / 260|
|BN-8H||5,500 – 6,200||5,000 – 6,000||12,000 – 16,000||6 – 9||125 / 250|
Magnetic property of AlNiCo magnets
AlNiCo magnets are very stable and have good corrosion resistance and a typical hardness of 50 Rockwell C. AlNiCo represents the most versatile magnet material available. The range of properties can be accurately designed for specific applications by changes to element analysis and heat treatment.
|Grade Name||Br (KG)||HcB (KOe)||BHmax(MGOe)||Tmax|
450℃ / 842°F
450℃ / 842°F
450℃ / 842°F
|LNG13||7.0||≥0.6||1.6||450℃ / 842°F|
525℃ / 977°F
525℃ / 977°F
|LNG40||12.5||≥0.6||5.0||525℃ / 977°F|
|LNG44||12.5||≥0.65||5.5||525℃ / 977°F|
|LNG52||13.0||≥0.7||6.5||525℃ / 977°F|
|LNGT28||10.0||0.72||3.5||550℃ / 1022°F|
|LNGT36J||7.0||1.75||4.5||550℃ / 1022°F|
|LNGT32||8.0||1.25||4.0||550℃ / 1022°F|
|LNGT40||8.0||1.38||5.0||550℃ / 1022°F|
|LNGT60||9.0||1.38||7.5||550℃ / 1022°F|
|LNGT72||1.05||1.4||9.0||550℃ / 1022°F|
Magnetic property of samarium cobalt magnets
SmCo magnets are made of a strong permanent magnet alloy of samarium and cobalt. Compared to NdFeB magnets, SmCo magnets are weaker, but are more suiteable for working in higher temperatures. SmCo magnets are very anti-corrosive and generally do not require electroplated surface treatment.
1. SmCo5 materials:
2. Sm2Co17 materials:
3. SmCo5 materials with Low Temperature Coefficient:
4. Sm2Co17 materials with Low Temperature Coefficient:
Magnetic property of ceramic magnets
Ceramic, also known as Ferrite magnets are made of a composite of iron oxide and barium/strontium carbonate by ceramic processing technology. Ferrites are, like most other ceramics, hard and brittle. In terms of the magnetic properties, ferrites are often classified as “soft” and “hard” which refers to their low or high coercivity of their magnetism, respectively.
|Grade Name||Br (KG)||HcB (KOe)||Hci (KOe)||BHmax(MGOe)||Tmax|
|C1||2.3||1.86||3.5||1.05||250℃ / 482°F|
250℃ / 482°F
||250℃ / 482°F|
250℃ / 482°F
|C8B||4.2||2.913||2.96||4.12||250℃ / 482°F|
250℃ / 482°F
|C10||4.0||3.617||3.51||3.82||250℃ / 482°F|
|C11||4.3||2.512||2.56||4.32||250℃ / 482°F|
Magnetic property of flexible rubber magnets
Flexible rubber magnets are made by mixing Ferrite or Neodymium magnet powders and synthetic or natural rubber binders. They are made by rolling (calendaring) or extrusion methods. Flexible magnets are applied because of their advantages of versatility, low cost, and ease of use. These magnets are usually manufactured in strip or sheet form that is widely used in micro-motors, gaskets, novelties, signs, and displays.
|Grade Name||Br (KG)||HcB (KOe)||Hci (KOe)||BHmax(MGOe)||Tmax|
|FRM-5||1.55-1.75||1.25-1.45||1.55-1.75||0.60-0.70||80℃ / 176°F|
80℃ / 176°F
||80℃ / 176°F|
80℃ / 176°F
|FRM-12||2.45-2.5||2.0-2.2||2.70-2.90||1.45-1.55||80℃ / 176°F|
Plating & Coatings
Plating neodymium magnets is an important process to protect the magnet against corrosion. The substrate NdFeB (Neodymium, Iron, Boron) will oxidize quickly without a protective layer. Below is a list of platings and their effectiveness in certian environments.
Note: All coatings / platings must be done at the factory before the magnet is saturated(charged). The magnetic field will disrupt the electroplating process, while the heat required for other types of platings would demagnetize the magnet.All of the Neodymium Iron Boron we stock are protected. The majority are Ni-Cu-Ni plated which consists of 3 layers (Nickel, Copper, and Nickel).
Superior > Excellent > Good > Bad
The most common plating. Ni-Cu-Ni is a durable 3 layer (nickel, copper, nickel coating). Great for indoor use. They may be used outdoors if protected from rain and humidity. Good abrasion resistance.
Zinc Plating (Zn)
Zinc is a standalone (one layer) plating. Zinc is self- sacrificing, meaning when it starts to oxidize the outside turns white creating a durable layer of protection.
A very thin / cosmetic layer of gold. Usually produced with an underlying layer of nickel to create a brighter finish.
Black Epoxy (Ni-Cu-BE)
Black Epoxy plating is consists of 3 layers Nickel, Copper, and Epoxy exposed as the top layer. Great for outdoor applications. However, black epoxy is not as abrasion resistant as other platings. In harsh conditions the epoxy layer may be scrached off to expose the copper layer underneath.
Raw Epoxy (BE)
Raw Epoxy is designed specifically for gluing applications where the magnet requires a good adhesion to epoxy glue. This coating consists of one layer of epoxy covering the magnet.
ABS Plastic is highly corrosion resistant. This coating requires an injection mold to be created in order to encase the magnet. The plastic shell needs to be thicker than other coatings so the plastic can flow during the injection process. Multiple colors available.
Teflon is very resilient and can withstand harsh environments. It is highly corrosion resistant. An injection mold is required to create the shell around the magnet. There will be a noticeable mold seam around the magnet where the injection mold separates.
Everlube 6155 is a aluminized barrier coating specially formulated to maximize adhesion and corrosion protection when applied to rare earth magnets. The coating is very durable and provides excellent chemical and corrosion resistance.
Xylan coatings are fluorocarbon coatings that contain dry lubricants. Slippery and highly corrosion resistant. Multiple colors available.
Source: China Permanent Magnet Manufacturer – www.ymagnet.com