阅读说明：本技术 一种具有低热滞的锰铁基磁制冷材料及其制备方法和应用 (Ferromanganese-based magnetic refrigeration material with low thermal hysteresis and preparation method and application thereof ) 是由 王高峰 谭欣 赵增茹 李永峰 马强 于 2019-12-16 设计创作，主要内容包括：本发明属于制冷技术领域,公开了一种具有低热滞的锰铁基磁制冷材料及其制备方法和应用,所述具有低热滞的锰铁基磁制冷材料由硬磁粉和含有锰、铁的混合粉末烧结制作而成；所述硬磁粉由钕铁硼、钐钴、钐铁氮硬磁体中的一种或几种构成；所述混合粉末的摩尔配比满足化学通式Mn<Sub>x</Sub>Fe<Sub>y-x</Sub>P<Sub>a</Sub>Si<Sub>b</Sub>,其中,x的范围为：0.9≤x≤1.3；y的范围为：1.9≤y≤2；a的范围为：0.15≤a≤0.75；a、b满足条件a+b＝1。本发明通过向含有锰、铁的混合材料中加入硬磁粉,制备得到了具有低热滞、高致密度的块体材料,硬磁粉的加入有效改变了磁制冷材料的相变温度和热滞,制备出具有低热滞、大磁热效应、高致密度的块状材料,有利于应用于室温磁制冷技术领域。(The invention belongs to the technical field of refrigeration, and discloses a ferromanganese-based magnetic refrigeration material with low thermal hysteresis, a preparation method and application thereof, wherein the ferromanganese-based magnetic refrigeration material with low thermal hysteresis is prepared by sintering hard magnetic powder and mixed powder containing manganese and iron; the hard magnetic powder is composed of one or more of neodymium iron boron, samarium cobalt and samarium iron nitrogen hard magnets; the molar ratio of the mixed powder meets the chemical general formula Mn x Fe y‑x P a Si b Wherein, the range of x is: x is more than or equal to 0.9 and less than or equal to 1.3; the range of y is: y is more than or equal to 1.9 and less than or equal to 2; the range of a is: a is more than or equal to 0.15 and less than or equal to 0.75; a. b satisfies the condition a + b is 1. The invention prepares the block material with low thermal hysteresis and high density by adding hard magnetic powder into the mixed material containing manganese and iron, and the addition of the hard magnetic powder effectively changesThe phase transition temperature and the thermal hysteresis of the magnetic refrigeration material are adopted to prepare the bulk material with low thermal hysteresis, large magnetocaloric effect and high density, which is beneficial to the technical field of room temperature magnetic refrigeration.)

1. The ferromanganese-based magnetic refrigeration material with low thermal hysteresis is characterized in that the ferromanganese-based magnetic refrigeration material with low thermal hysteresis is prepared by sintering hard magnetic powder and mixed powder containing manganese and iron; the molar ratio of the mixed powder meets the chemical general formula Mn_xFe_y-xP_aSi_bWherein, the range of x is: x is more than or equal to 0.9 and less than or equal to 1.3; the range of y is: y is more than or equal to 1.9 and less than or equal to 2; the range of a is: a is more than or equal to 0.15 and less than or equal to 0.75; a. b satisfies the condition a + b is 1.

2. The ferromanganese-based magnetic refrigeration material with low thermal hysteresis according to claim 1, wherein the mass ratio of the mixed powder to the hard magnetic powder is 2-99.9: 1.

3. The ferromanganese-based magnetic refrigeration material with low thermal hysteresis according to claim 2, wherein the mass ratio of the mixed powder to the hard magnetic powder is 9: 1.

4. The ferromanganese-based magnetic refrigeration material with low thermal hysteresis according to claim 1, wherein the hard magnetic powder is composed of one or more of neodymium-iron-boron, samarium-cobalt and samarium-iron-nitrogen hard magnets.

5. The ferromanganese-based magnetic refrigeration material with low thermal hysteresis as claimed in claim 1, wherein x is 1.2, y is 0.75, a is 0.5, and b is 0.5.

6. The preparation method of ferromanganese-based magnetic refrigeration material with low thermal hysteresis according to any one of claims 1 to 5, characterized by comprising the steps of:

ball-milling hard magnetic powder and mixed powder containing manganese and iron in a protective gas atmosphere, then loading the mixed powder into a mold, sintering by adopting a discharge plasma sintering technology, and cooling along with the furnace to obtain the magnetic powder; the sintering temperature is 700-900 ℃, and the sintering pressure is 10-50 MPa.

7. The preparation method of the ferromanganese-based magnetic refrigeration material with low thermal hysteresis as claimed in claim 6, wherein the raw material powder is ball-milled by a high energy ball milling method, the mass ratio of ball milling steel balls to raw materials is 5-10:1, and the ball milling time is 5-10 h.

8. The preparation method of ferromanganese-based magnetic refrigeration material with low thermal hysteresis as claimed in claim 6, wherein the temperature rise rate during sintering is 10-40 ℃/min, and the retention time is 5-30 min.

9. Use of the ferromanganese-based magnetic refrigeration material with low thermal hysteresis according to any one of claims 1 to 5 in the refrigeration field.

Technical Field

The invention belongs to the technical field of refrigeration, and particularly relates to a ferromanganese-based magnetic refrigeration material with low thermal hysteresis, and a preparation method and application thereof.

Background

Refrigeration is an indispensable part of current social activities, and at present, people mainly adopt a gas expansion/compression refrigeration mode to achieve the purpose of refrigeration. However, such a refrigeration technique has many disadvantages, such as low refrigeration efficiency, high energy consumption, environmental pollution, and the like.

Magnetic refrigeration is a new technology which achieves the aim of refrigeration by utilizing the temperature change (namely the magnetocaloric effect) of a magnetic material caused by the disordered-ordered magnetic phase change of the magnetic material under the action of an external magnetic field. When the magnetic working medium is magnetized in a heat insulation way, the temperature is increased, and heat is released to the outside; when the magnetic working medium is demagnetized by heat insulation, the temperature is reduced, and heat is absorbed from the outside, thereby achieving the purpose of refrigeration. Compared with the traditional gas expansion/compression type refrigeration technology, the magnetic refrigeration technology has the following advantages: (1) refrigerants such as Freon, ammonia and the like are not used, so that the environment is not polluted; (2) a compressor is not used, so that the energy consumption is low and the noise is low; (3) the solid magnetic refrigeration working medium is used, so that the efficiency is high, and the durability is long. Therefore, magnetic refrigeration technology has attracted attention in recent years.

The key point for realizing the magnetic refrigeration technology is to find a magnetic refrigeration material with large magnetocaloric effect and low thermal hysteresis under the condition of low magnetic field. In recent years, materials with giant magnetocaloric effect, such as Gd, have been studied and developed₅(Si,Ge)₄、MnAs、La(Fe,Si)₁₃、(Mn,Fe)₂(P, As) and the like. The giant magnetocaloric effect of the materials is caused by the first-order magnetic-structure coupling phase change of the materials, and is accompanied by a narrower phase change temperature region and larger phase change thermal hysteresis. Corresponding to the above, the second-order phase change material, such as metal Gd and its alloys, has a wider phase change temperature region and no thermal hysteresis, although it has a lower magnetocaloric effect. Therefore, the first-order phase change magnetic material with smaller thermal hysteresis can be developedObtain larger magnetocaloric effect and wider phase-change temperature area, which is very beneficial to improving the magnetic refrigeration efficiency.

Fe₂The P-type ferromanganese, phosphorus, silicon, germanium, boron compound has giant magnetocaloric effect near room temperature, the phase transition temperature of the P-type ferromanganese, phosphorus, silicon, germanium and boron compound can be adjusted in a larger temperature range, and the prepared raw materials are cheap, so that the P-type ferromanganese, phosphorus, silicon, germanium and boron compound is a room-temperature magnetic refrigeration material with application. However, the first-order phase transition of the ferromanganese, phosphorus, silicon, germanium and boron compound is accompanied by larger thermal hysteresis, which greatly reduces the effective refrigerating capacity and limits the application of the compound in practical application.

In research, a certain amount of hard magnetic powder is added into the manganese-iron-phosphorus-silicon-germanium-boron compound, so that the thermal hysteresis of the compound can be effectively reduced, and the obtained material can be applied to a room-temperature magnetic refrigeration technology.

Disclosure of Invention

One aspect of the invention is to provide a ferromanganese-based magnetic refrigeration material with low thermal hysteresis, large magnetocaloric effect and high compactness.

In order to achieve the purpose, the invention adopts the following technical scheme:

a ferromanganese-based magnetic refrigeration material with low thermal hysteresis is prepared by sintering hard magnetic powder and mixed powder containing manganese and iron; the molar ratio of the mixed powder meets the chemical general formula Mn_xFe_y-xP_aSi_bWherein, the range of x is: x is more than or equal to 0.9 and less than or equal to 1.3; the range of y is: y is more than or equal to 1.9 and less than or equal to 2; the range of a is: a is more than or equal to 0.15 and less than or equal to 0.75; a. b satisfies the condition a + b is 1.

In some embodiments of the invention, the mass ratio of the mixed powder to the hard magnetic powder is 2-99.9: 1.

In a further embodiment, the mass ratio of the mixed powder to the hard magnetic powder is 7:3 to 99: 1.

In some embodiments of the invention, the mass ratio of the mixed powder to the hard magnetic powder is 9: 1.

In some embodiments of the present invention, the hard magnetic powder is made of one or more of neodymium iron boron, samarium cobalt, samarium iron nitrogen hard magnets.

In some embodiments of the invention, x is 1.2, y is 0.75, a is 0.5, and b is 0.5.

Another aspect of the present invention provides a preparation method of the ferromanganese-based magnetic refrigeration material with low thermal hysteresis, including the steps of:

ball-milling hard magnetic powder and mixed powder containing manganese and iron in a protective gas atmosphere, then loading the mixed powder into a mold, sintering by adopting a discharge plasma sintering technology, and cooling along with the furnace to obtain the magnetic powder; the sintering temperature is 700-900 ℃, and the sintering pressure is 10-50 MPa.

In some embodiments of the invention, the ball milling is carried out by a high-energy ball milling method, the mass ratio of ball milling steel balls to raw materials is 5-10:1, and the ball milling time is 5-10 h.

In some embodiments of the invention, the temperature rise rate during sintering is 10-40 ℃/min, and the retention time is 5-30 min.

The invention also provides application of the ferromanganese-based magnetic refrigeration material with low thermal hysteresis in the refrigeration field.

The invention has the beneficial effects that:

the ferromanganese-based magnetic refrigeration material with low thermal hysteresis is prepared by sintering hard magnetic powder and mixed powder containing manganese and iron, the preparation method combining high-energy ball mill ball milling and spark plasma sintering is adopted, the obtained ferromanganese-based magnetic refrigeration material is a block material with high density, the phase change temperature and the thermal hysteresis of the magnetic refrigeration material can be changed by adding the hard magnetic powder, the block material with low thermal hysteresis, large magnetocaloric effect and high density is prepared, and the application in the technical field of room temperature magnetic refrigeration is facilitated.

Drawings

In order to more clearly illustrate the detailed description of the invention or the technical solutions in the prior art, the drawings that are needed in the detailed description of the invention or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale.

FIG. 1 is an X-ray diffraction pattern of ferromanganese-based magnetic refrigeration materials with low thermal hysteresis prepared in examples 1-3 of the present invention;

fig. 2 is a thermomagnetic curve of ferromanganese-based magnetic refrigeration materials with low thermal hysteresis prepared in examples 1-3 of the present invention.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and therefore are only examples, and the protection scope of the present invention is not limited thereby.

It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the invention pertains.

The experimental procedures in the following examples are conventional unless otherwise specified. The test materials used in the following examples were purchased from a conventional biochemical reagent store unless otherwise specified. In the quantitative tests in the following examples, three replicates were set, and the data are the mean or the mean ± standard deviation of the three replicates.

The invention provides a ferromanganese-based magnetic refrigeration material with low thermal hysteresis, which is prepared by sintering hard magnetic powder and mixed powder containing manganese and iron.

As a specific implementation mode, the hard magnetic powder is composed of one or more of neodymium iron boron, samarium cobalt and samarium iron nitrogen hard magnets.

As a specific embodiment, the molar ratio of the mixed powder satisfies the chemical formula Mn_xFe_y-xP_aSi_bWherein, the range of x is: 0.9<x<1.3; the range of y is: 1.9<y<2; the range of a is: 0.15<a<0.75, a and b satisfy the condition that a + b is 1.

As a specific embodiment, the mass ratio of the hard magnetic powder to the mixed powder is 1:2 to 99.9.