WO2016204651A1

WO2016204651A1 - Magnetic material based on a crystalline form of wmnb2

Info

Publication number: WO2016204651A1
Application number: PCT/RU2016/000161
Authority: WO
Inventors: Артем Ромаевич ОГАНОВ
Original assignee: ОГАНОВ, Артур Романович
Priority date: 2015-06-17
Filing date: 2016-03-23
Publication date: 2016-12-22
Also published as: RU2015123199A

Abstract

The invention relates to magnetic materials, and more particularly to ferromagnets, and can be used in various fields of industry such as, for example, electronic engineering, metallurgy, etc. The technical result of the invention is that of preserving the magnetic moment and magnetic anisotropy and increasing the corrosion resistance and durability of a magnetic material by virtue of its chemical inertness. This technical result is achieved by using a magnetic material that is based on a crystalline form of WMnB₂, which contains (in wt%): tungsten - 25±0.1%; manganese- 25±0.1%; boron - the remainder. This magnetic material exhibits the properties of a permanent magnet without containing rare earth metals, and is inexpensive and safe for use in manufacturing.

Description

MAGNETIC MATERIAL BASED ON CRYSTAL FORM WMnB ₂ The invention relates to magnetic materials, namely to ferromagnets, and can be used in various industries, for example, in electronics, instrumentation, nuclear engineering, mechanical engineering, chemical industry, metallurgy.

Magnetic materials are currently widely used in modern technology facilities that satisfy the needs of the population in various spheres of life. However, a large proportion of the total cost of finished products in the industry falls on the cost of highly efficient permanent magnets, which are based on expensive rare-earth materials. The unique properties of rare-earth ferromagnets are explained by the fact that 4t-electrons of rare-earth metals create high magnetic anisotropy, and 3d-electrons of transition metals - a strong magnetic moment, which are necessary characteristics for industrial applications.

For example, an alloy based on the neodymium-iron-boron (Ne-Fe-B) compound, which is obtained by diffusion annealing of sintered magnets, is known, metal dysprosium (Dy) or terbium (Tb) powders are used as diffusion sources [RU2476947, 02.27.20 1 g.].

The specified alloy has a high coercive force, high anisotropy, but when it is used, expensive rare-earth elements are used, including one of the most scarce elements - dysprosium, which increases the cost of products in which this alloy is used.

Also known is a magnetic alloy containing neodymium-iron-boron (Ne-

Fe-B) together with an admixture of cerium and cobalt. This alloy uses cerium, one of the most common rare-earth metals, which reduces the cost of magnetic material by 20-40 percent while maintaining the required characteristics of a permanent magnet. In addition, this alloy retains its magnetic properties at temperatures above 150 ° C, at which traditional magnets lose these properties (for example, http://www.sciteclibrarv.ru/rus/cataloq/paqes/14862.html). However, said alloy is still expensive. In addition to the price, the main disadvantages limiting the industrial use of magnetic materials based on neodymium alloy are low corrosion resistance and high fragility. In addition to shortening the life of the product, this can lead to serious personal injury.

Studies of the last decade are aimed at synthesizing a permanent magnet (ferromagnet), which does not have rare-earth elements and at the same time has equivalent or superior characteristics. Such a replacement of magnets based on other cheaper materials will reduce the cost of many industrial products.

Known amorphous magnetically soft cobalt-based alloy containing iron, nickel, alloying components in the form of manganese and chromium and amorphizers in the form of silicon and boron [RU2123537, 12.20.1998]. This alloy allows you to achieve such values of induction and magnetic permeability, which allow its use in the production of high-frequency transformers. However, this alloy can be used narrowly, since it does not have the necessary properties of a permanent magnet (magnetic moment, magnetic anisotropy), that is, universality, which allows its use in many industries.

Known alloy containing iron, silicon, boron, one or more components from the group comprising titanium, vanadium, chromium, manganese, nickel, zirconium, niobium, molybdenum, tungsten, cobalt [RU20415 3, 08/09/1995]. This alloy also has a narrow focus and is used in the manufacture of transformers.

An analysis of these sources shows that the production of permanent magnets, which are universal and can be used in various industries, is currently possible only on the basis of alloys containing neodymium and iron. Therefore, the alloy according to patent RU2476947 can be selected as the closest solution to the claimed.

An object of the invention is to obtain a magnetic material that has the properties of a permanent magnet without the use of rare earth elements, while it has a low cost and is safe when used in production. The technical result of the invention is to preserve the magnetic moment, magnetic anisotropy, increase the corrosion resistance and strength of the magnetic material due to its chemical inertness.

The technical result is achieved using a magnetic material based on the crystalline form of WMnB ₂ , which contains wt.%:

tungsten - 25 ± 0.1%;

Manganese - 25 ± 0.1%;

boron - the rest.

The strong magnetic moment of rare-earth alloys, including the closest solution, is explained by the presence of unpaired electrons on the f shell. In the present invention, strong magnetic moment and high magnetic anisotropy are provided by replacing neodymium with tungsten having unpaired electrons on d-orbitals. Replacing iron with manganese in the composition of the magnetic material ensures the strength of the magnetic material.

The atoms of tungsten, manganese, and boron inside the material are bonded to each other by strong covalent interaction, which ensures the chemical inertness of the material and, as a result, high corrosion resistance.

In FIG. 1 shows a specific x-ray powder pattern of WMnB ₂ .

In FIG. 2 - table 1, which shows additional data of x-ray diffraction analysis, characterizing the crystalline form of WMnB ₂ .

In FIG. Figure 3 shows a graph of the energy of magnetic anisotropy WMnB ₂ .

An X-ray diffraction pattern of the crystalline form of WMnB ₂ obtained in accordance with the present invention and shown in FIG. 1 is one of the main experimental characteristics. More specifically, the crystalline form of WMnB ₂ can be characterized by characteristic

Θ

peaks (2) shown in this radiograph: 21, 7 °, 29.6 °, 30.8 °, 37.1 °, 43.3 °, 44.2 ° and 54.2 °, 30.8 ° and 43.3 ° at a wavelength of 1, 54A, corresponding to the x-ray emission of the electrons of the internal electron shells (K-alpha) of copper atoms — Cu-Κα radiation. These angles characterize the location of the peaks during powder x-ray diffraction of a given material. In this case, Θ is the scattering angle of x-ray radiation, A is an angstrom, an off-system unit of length equal to 10 ^"10 m.

Additional data of X-ray diffraction analysis characterizing the crystalline form of WMnB ₂ and are given in table 1. In this case, “d-spacing” is the distance between adjacent planes with the given Miller indices in the crystal, “lnt” is the radiation intensity (power), “F” is the scattering form factor, “h”, “k”, “I” - Miller indices characterize the location of atomic planes in a crystal, “Mult” - the number of repeating peaks (multiplicity).

The crystalline form of WMnB ₂ can also be characterized by magnetic anisotropy, as shown in FIG. Typical angles are: 0.0 °, 90.0 °, 42.0 °. These data characterize the change in the dependence of magnetic properties on the direction of magnetization with respect to the structural axes of the crystal.

The magnetic anisotropy of the crystalline form of WMnB ₂ was obtained on the basis of quantum-chemical calculations of the density functional theory.

The present invention is further illustrated by the following examples.

Example 1

To obtain the crystalline form of WMnB ₂ , manganese (powder grade MP-0, with a particle size less than 0.2 mm), tungsten (powder with a particle size less than 0.01 mm) and amorphous boron (powder grade B-99 are used as starting materials) , with a particle size of less than 0.001 mm) in a ratio of 1: 1: 2 (as a percentage of the mass: tungsten - 25%, manganese - 25%, boron - 50%). The powders of the starting components are thoroughly mixed in a porcelain mortar for 10-15 minutes until a homogeneous mixture is obtained. Cylindrical samples with a diameter of 20 mm and a height of 20-25 mm and a density of 2.6-3.1 g / cm ³ are made from the initial mixtures. Samples are placed in a constant pressure reactor in argon medium (purity 99.7%) at a pressure of 5 atm. The reactor is pre-evacuated to a residual pressure of 10 ^{~ 1} mm Hg, purged with argon, evacuated again and then filled with argon to the desired pressure. The initiation of the combustion process of the prepared mixtures is carried out by a heated electric current tungsten spiral from the upper end of the sample. After the combustion reaction is complete, the samples are allowed to cool. Obtained by this method, the maximum combustion temperature (T _g ) is 1030 ° C. Maximum combustion temperatures are measured using a tungsten-rhenium thermocouple with a diameter of 0.2 mm.

Chemical reaction diagram:

W + Mn + 2B-> WMnB ₂ (1)

Example 2

To obtain the crystalline form of WMnB ₂ , manganese (an MP-0 powder with a particle size of less than 0.2 mm), tungsten (a powder with a particle size of less than 0.01 mm) and magnesium polyboride MgBi ₂ (a powder containing approximately 85% boron, particle size less than 0.02mm). To bind magnesium (a total of about 1.5%), the required amount of tungsten oxide WO ₃ (HF grade powder with a particle size of less than 0.02 mm) is introduced into the initial mixture. The final ratio of the starting components: W: Mn: W0 _3: MgBi ₂ is 5.66: 6: 0.33: 1. The powders of the starting components are thoroughly mixed in a porcelain mortar for 10-15 minutes until a homogeneous mixture is obtained. Cylindrical samples with a diameter of 20 mm and a height of 20-25 mm and a density of 2.6-3, 1 g / cm ³ are made from the initial mixtures. Samples are placed in a constant pressure reactor under argon (purity 99.7%) at a pressure of 5 atm. The reactor is pre-evacuated to a residual pressure of 10 ^"1 mm Hg, purged with argon, evacuated again and then filled with argon to the desired pressure. The combustion of the prepared mixtures is initiated by a tungsten spiral heated by electric current from the upper end of the sample.

After the combustion reaction is complete, the samples are allowed to cool. Obtained by this method, the maximum combustion temperature (T _g ) is 1030 ° C. Maximum combustion temperatures are measured using a tungsten-rhenium thermocouple with a diameter of 0.2 mm.

Chemical reaction diagram:

Example 3

To obtain the crystalline form of WMnB ₂ , manganese (an MP-0 grade powder with a particle size of less than 0.2 mm), tungsten (a powder with a particle size of less than 0.01 mm), oxide are used as starting materials tungsten WO ₃ (powder grade B-99, with a particle size of less than 0.02 mm) necessary for the binding of magnesium (only about 1, 5%), magnesium (powder grade MPF-2, with a particle size of 0.1-0.2 mm) for complete reduction of the metal from tungsten oxide WO ₃ (that is, part of the tungsten metal is introduced as its oxide) and magnesium polyboride MgB ₁₂ (powder containing about 85% boron, particle size less than 0.02 mm).

Five different synthesis methods were implemented \ L / MnBr depending on the ratio W / WO3:

1) the ratio of the components W: W03: Mn: MgB12: Mg is

5.55: 0.45: 6: 1: 0.35;

2) the ratio of the components W: W03: Mn: MgB12: Mg is

5.52: 0.48: 6: 1: 0.44;

3) the ratio of the components W: W03: Mn: MgB12: Mg is 5.5: 0.5: 6: 1: 0.51;

4) the ratio of the components W: W03: Mn: MgB12: Mg is 5.33: 0.66: 6: 1: 1; 5) the ratio of the components W: W03: Mn: MgB12: Mg is

5.16: 0.84: 6: 1: 1, 53.

The powders of the starting components are thoroughly mixed in a porcelain mortar for 10-15 minutes until a homogeneous mixture is obtained. Cylindrical samples with a diameter of 20 mm and a height of 20-25 mm and a density of 2.6-3.1 g / cm ³ are made from the initial mixtures. Samples are placed in a constant pressure reactor in argon medium (purity 99.7%) at a pressure of 5 atm. The reactor is pre-evacuated to a residual pressure of 10 ^"1 mm Hg, purged with argon, evacuated again and then filled with argon to the desired pressure. The combustion of the prepared mixtures is initiated by a tungsten spiral heated by electric current from the upper end of the sample.

After the combustion reaction is complete, the samples are allowed to cool. Obtained by this method, the maximum combustion temperature (T _g ) is in the range from 1030 ° C to 1480 ° C (depending on the ratio W / WO ₃ ). Maximum combustion temperatures are measured using a tungsten-rhenium thermocouple with a diameter of 0.2 mm.

Chemical reaction diagram:

W + Mn + WO3 + MgB ₁₂ + Mg ^ WMnB ₂ + MgO (3) The obtained ferromagnetic compound WMnB ₂ has a magnetic moment equal to 3 O in terms of the manganese atom, where pb is the Bohr magneton, which indicates a high magnetization of the obtained material. For a material selected as the closest analogue, the magnetic moment has approximately the same value.

The present invention provides a new, previously not synthesized ferromagnetic compound \ L / MnBr, which has a strong magnetic moment and high magnetic anisotropy - the characteristics of permanent magnets. In addition, the resulting magnetic material has hardness and corrosion resistance.

Thus, this magnetic material allows you to replace permanent magnets based on rare-earth elements, reduce their cost and ensure safety in production.

The new magnetic material opens up prospects for use in devices and mechanisms in various industries. Its use will reduce the cost of equipment and make them more accessible to the public.

Claims

Claim

1. A magnetic material based on the crystalline form of WMnB ₂ , characterized in that it contains tungsten, manganese, boron in the following ratio of components, mass. %:

tungsten - 25% ± 0.1%;

Manganese - 25% ± 0, 1%

boron - everything else.

2. The magnetic material according to claim 1, characterized in that in the X-ray powder diffraction pattern at a wavelength of Cu-Κα radiation, the diffraction peaks of the peaks at 2 ^Θ are 21.7 °, 29.6 °, 30.8 °, 37.1 ° , 43.3 °, 44.2 ° and 54.2 °, 30.8 ° and 43.3 °.

3. The magnetic material according to claim 1, characterized in that the graph of magnetic anisotropy energy has characteristic angles of 0.0 °, 90.0 °, 42.0 °.

4. The magnetic material according to claim 1, characterized in that to obtain it, manganese, tungsten and amorphous boron are mixed in a ratio of 1: 1: 2.

5. The magnetic material according to claim 1, characterized in that to obtain it, manganese, tungsten, tungsten oxide, magnesium polyboride are mixed in a ratio of 5.66: 6: 0.33: 1.

6. The magnetic material according to claim 1, characterized in that to obtain it mix manganese, tungsten, tungsten oxide, magnesium magnesium polyboride in a ratio of 5.55: 0.45: 6: 1: 0.35 or 5.52: 0 , 48: 6: 1: 0.44, or 5.5: 0.5: 6: 1: 0.51 or 5.33: 0.66: 6: 1: 1 or 5.16: 0.84: 6: 1: 1, 53.