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December 12, 2023
Materials and selection factors for magnetostrictive displacement sensors
1. The saturation magnetostriction coefficient of the material λ S as large as possible;
The magnetic crystal anisotropy of the material should be sufficiently high. Without sufficient anisotropic performance, it is impossible to have significant magnetostriction. However, the anisotropic energy cannot be too large, otherwise, the magnetic field required for magnetic moment rotation will be too large, making it impossible to achieve significant magnetostriction at lower magnetic fields;
3. Materials( λ- H) The maximum slope of the curve d=(d) λ⁄ DH) max should be larger. In this way, the material has a higher efficiency in converting electromagnetic energy into mechanical energy;
4. Require materials to have the maximum possible electromechanical coupling coefficient (or magneto elastic coupling coefficient);
5. It has a certain compressive strength (for positive magnetostrictive materials) and tensile strength (for negative magnetostrictive materials), as well as a certain toughness, to avoid the failure and damage of magnetostriction caused by external stress when the material undergoes magnetostriction;
6. Good temperature characteristics. The guide wire is a key material for magnetostrictive displacement sensors, and the temperature variation of various parameters is the main factor determining the temperature characteristics of the sensor, especially the temperature coefficient of the propagation speed of torsional waves must be as small as possible; In order to obtain practical and high-performance magnetostrictive materials, people have been conducting research on this, resulting in a series of magnetostrictive materials
There are three main types of its development process:;
(1) Traditional magnetostrictive metals and alloys, ferrite, and amorphous materials
① Traditional magnetostrictive metals and alloys include annealed pure nickel, nickel cobalt alloys, iron nickel alloys, iron aluminum alloys, etc.
② Ferrite magnetostrictive materials include Ni Co ferrite and Ni Co Cu ferrite, and the composition of these materials can be adjusted appropriately according to different performance requirements. Usually, they are formulated with different proportions of nickel oxide (NiO), iron oxide (Fe ₂ O æ), copper oxide (CuO), and zinc oxide (ZnO).
③ Amorphous materials mainly include three categories: iron-based, iron-nickel based, and cobalt based. There is no long-range ordered metal or alloy with internal atomic arrangement.
(2) Non rare earth magnetostrictive materials. The most prominent material of this type is the Ni Mn Ga series ferromagnetic shape memory alloy (FSMA), which can induce several percent of huge strain under the action of a magnetic field.
(3) Giant Magnetostrictive Materials (GMM) are ferroalloys of heavy rare earth metals Tb terbium and Dy dysprosium, with a magnetostrictive coefficient of up to (1-2) × 10-3 (0.1-0.2%), which is two orders of magnitude higher in performance than traditional products, is therefore called a giant magnetostrictive material. Such as TbFe Å (Terfenol) and Tbo. Å Dyo.7Fe ₂ (Terfenol D).
① Rare earth metals, especially heavy rare earth metals, exhibit significant magnetostriction at low temperatures, reaching the order of 10-3-10-2 at 0K and 77K. Due to the low Curie temperature of rare earth metals, they cannot be directly applied at room temperature.
② Rare earth transition metal compounds were proposed by Callen in 1969 based on the characteristics of transition metal electron clouds, which have a higher Curie temperature point. The magnetostriction coefficient of rare earth metal oxides such as Tb3Fe5O12 at 4.2K is 2460 × At 78K, the magnetostriction coefficient is 560 × 10-6.
③ Actinide metal compounds also exhibit significant magnetostriction at low temperatures, some even surpassing rare earth compounds, such as US at 4.2K λ 111 up to 7000 × 10-6. But the Curie temperature of these compounds is only around 100K, making it difficult to apply in engineering practice.
④ Giant magnetostrictive powder composite (GMPC) is developed to overcome the shortcomings of Terfenol-D rods, such as high brittleness, processing difficulties, and material heating under high-frequency magnetic fields. It is based on giant magnetostrictive alloys and can greatly overcome the above drawbacks. GMPC will become a new development direction for Terfenol-D magnetostrictive materials.
The magnetic crystal anisotropy of the material should be sufficiently high. Without sufficient anisotropic performance, it is impossible to have significant magnetostriction. However, the anisotropic energy cannot be too large, otherwise, the magnetic field required for magnetic moment rotation will be too large, making it impossible to achieve significant magnetostriction at lower magnetic fields;
3. Materials( λ- H) The maximum slope of the curve d=(d) λ⁄ DH) max should be larger. In this way, the material has a higher efficiency in converting electromagnetic energy into mechanical energy;
4. Require materials to have the maximum possible electromechanical coupling coefficient (or magneto elastic coupling coefficient);
5. It has a certain compressive strength (for positive magnetostrictive materials) and tensile strength (for negative magnetostrictive materials), as well as a certain toughness, to avoid the failure and damage of magnetostriction caused by external stress when the material undergoes magnetostriction;
6. Good temperature characteristics. The guide wire is a key material for magnetostrictive displacement sensors, and the temperature variation of various parameters is the main factor determining the temperature characteristics of the sensor, especially the temperature coefficient of the propagation speed of torsional waves must be as small as possible; In order to obtain practical and high-performance magnetostrictive materials, people have been conducting research on this, resulting in a series of magnetostrictive materials
There are three main types of its development process:;
(1) Traditional magnetostrictive metals and alloys, ferrite, and amorphous materials
① Traditional magnetostrictive metals and alloys include annealed pure nickel, nickel cobalt alloys, iron nickel alloys, iron aluminum alloys, etc.
② Ferrite magnetostrictive materials include Ni Co ferrite and Ni Co Cu ferrite, and the composition of these materials can be adjusted appropriately according to different performance requirements. Usually, they are formulated with different proportions of nickel oxide (NiO), iron oxide (Fe ₂ O æ), copper oxide (CuO), and zinc oxide (ZnO).
③ Amorphous materials mainly include three categories: iron-based, iron-nickel based, and cobalt based. There is no long-range ordered metal or alloy with internal atomic arrangement.
(2) Non rare earth magnetostrictive materials. The most prominent material of this type is the Ni Mn Ga series ferromagnetic shape memory alloy (FSMA), which can induce several percent of huge strain under the action of a magnetic field.
(3) Giant Magnetostrictive Materials (GMM) are ferroalloys of heavy rare earth metals Tb terbium and Dy dysprosium, with a magnetostrictive coefficient of up to (1-2) × 10-3 (0.1-0.2%), which is two orders of magnitude higher in performance than traditional products, is therefore called a giant magnetostrictive material. Such as TbFe Å (Terfenol) and Tbo. Å Dyo.7Fe ₂ (Terfenol D).
① Rare earth metals, especially heavy rare earth metals, exhibit significant magnetostriction at low temperatures, reaching the order of 10-3-10-2 at 0K and 77K. Due to the low Curie temperature of rare earth metals, they cannot be directly applied at room temperature.
② Rare earth transition metal compounds were proposed by Callen in 1969 based on the characteristics of transition metal electron clouds, which have a higher Curie temperature point. The magnetostriction coefficient of rare earth metal oxides such as Tb3Fe5O12 at 4.2K is 2460 × At 78K, the magnetostriction coefficient is 560 × 10-6.
③ Actinide metal compounds also exhibit significant magnetostriction at low temperatures, some even surpassing rare earth compounds, such as US at 4.2K λ 111 up to 7000 × 10-6. But the Curie temperature of these compounds is only around 100K, making it difficult to apply in engineering practice.
④ Giant magnetostrictive powder composite (GMPC) is developed to overcome the shortcomings of Terfenol-D rods, such as high brittleness, processing difficulties, and material heating under high-frequency magnetic fields. It is based on giant magnetostrictive alloys and can greatly overcome the above drawbacks. GMPC will become a new development direction for Terfenol-D magnetostrictive materials.
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Privacy statement: Your privacy is very important to Us. Our company promises not to disclose your personal information to any external company with out your explicit permission.