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Method for preparing magnetic refrigeration alloy using spark plasma sintering technology (SPS)

A magnetic refrigeration and magnetic alloy technology, applied in the field of magnetic refrigeration materials, to achieve the effects of fast sintering speed, easy storage, and controllable grain growth

Inactive Publication Date: 2021-02-26
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, like all other MM'X compounds, it still faces a big obstacle in its application, which is its brittleness.

Method used

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  • Method for preparing magnetic refrigeration alloy using spark plasma sintering technology (SPS)
  • Method for preparing magnetic refrigeration alloy using spark plasma sintering technology (SPS)
  • Method for preparing magnetic refrigeration alloy using spark plasma sintering technology (SPS)

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033]Example 1: The preparation chemical formula of this example is Mn0.8Fe0.2NiSi0.85Ga0.15Magnetic alloy block, where Mn0.8Fe0.2NiSi0.85Ga0.15The alloy refers to replacing 20% ​​(molar ratio) of Mn with Fe and replacing 15% (molar ratio) of Si with Ga in the MnNiSi alloy. In other embodiments, the same explanation is also given. The preparation method is carried out according to the following specific steps:

[0034]Step 1, according to the molar ratio of Mn: Fe: Ni: Si: Ga = 0.8: 0.2: 1: 0.85: 0.15, weigh Mn, Fe, Ni, Si, Ga and other raw materials with a purity of 99.9%;

[0035]Step 2: Put the weighed raw materials into a water-cooled copper crucible, vacuum with a mechanical pump, and purge with argon gas. Repeat this 4 times. The suspension smelting method melts the polycrystalline sample ingot, and each sample is turned over 3 times. Co-melt 4 times to ensure uniform composition and prepare alloy ingots;

[0036]Step 3: Wrap the obtained ingots or fine particles with tantalum flakes,...

Embodiment 2

[0040]Example 2: The preparation chemical formula of this example is Mn0.8Fe0.2NiSi0.84Ga0.16The preparation method of the magnetic alloy block is similar to the method in Example 1, except that the step four screening uses three particle size ranges, namely P1 (74~150μm), P2 (50~74μm), P3(37~ 50μm) sample; Step 5 is sintered at 900°C and 50Mpa.

[0041]Mn prepared in this example0.8Fe0.2NiSi0.84Ga0.16The alloy has the same crystal structure and similar change laws as in Example 1.image 3 Mn0.8Fe0.2NiSi0.84Ga0.16The magnetic entropy change and temperature dependence curve of the alloy, as the particle size decreases, the magnetic entropy change decreases, and the maximum magnetic entropy change is as high as 11.14J / kg·K.

Embodiment 3

[0042]Example 3: The preparation chemical formula of this example is Mn0.8Fe0.2NiSi0.83Ga0.17The preparation method of the magnetic alloy block is similar to that of Example 1, except that in step four, samples with a particle size range of P3 (37-50μm) will be screened; step five will be sintered at 800°C and 80Mpa.

[0043]Mn prepared in this example0.8Fe0.2NiSi0.83Ga0.17The alloy has a different crystal structure from Example 1 and Example 2.Figure 4Mn0.8Fe0.2NiSi0.83Ga0.17The backscattered electron image of the alloy. It can be seen from the image that there are a large number of micro-cracks inside a single particle. This indicates that the destruction of the particles during the hot pressing process further reduces the size of the particles and introduces particle defects, thereby reducing the alloy The phase transition temperature.

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Abstract

The invention discloses a method for preparing a magnetic refrigeration alloy by using a spark plasma sintering technology (SPS), and belongs to the field of magnetic refrigeration materials. The general chemical formula of the magnetic refrigeration alloy is Mn0.8 Fe0.2 NiSi(1-x)Ga x, Fe is doped with Mn, Ga is doped with Si, and x is larger than or equal to 0.15 and smaller than or equal to 0.17. Materials are proportioned in a molar ratio, are put into a suspension smelting furnace, subjected to vacuum-pumping, and smelted under the protection of argon gas to obtain an alloy ingot; the alloy ingot is annealed under the protection of pure inert gas, and then is directly quenched in ice water; the magnetic alloy ingot is ground into powder and subjected to size grading; and Mn0. 8Fe0. 2NiSi(1-x)Gax magnetic alloy powder is put into a mold, and sintered into a block by using a spark plasma sintering (SPS) method. The alloy can generate structural phase change in a wide temperature range, and can be used as a magnetic refrigerant along with a great magnetocaloric effect.

Description

Technical field[0001]This patent has invented a new type of manganese nickel silicon (MnNiSi) magnetic refrigeration alloy and its preparation process, belonging to the field of magnetic refrigeration materials in magnetic functional materials.Background technique[0002]The magnetic refrigeration technology based on the magnetocaloric effect (MCE) is a technology that replaces the traditional refrigeration technology and has the advantages of high efficiency, high reliability, low noise, and environmental friendliness. This technology relies on a working medium with a large magnetocaloric effect. In the adiabatic process, when the magnetic field is reduced, it can effectively absorb heat; in the isothermal process, when the magnetic field increases, it can effectively release heat. Therefore, solving the problems faced by various MCE materials is crucial to the development of magnetic refrigeration applications.[0003]MM'X (M and M'are transition metals, X is Si, Ge, Sn and other main...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C1/04B22F9/04B22F3/105C22C30/00C21D1/26C21D1/18
CPCB22F3/105B22F9/04B22F2009/041C21D1/18C21D1/26C22C1/04C22C30/00
Inventor 张红国吴正石晋豪岳明张东涛刘卫强路清梅
Owner BEIJING UNIV OF TECH
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