CN113444942B - Ferromanganese-based magnetic composite material and design method and manufacturing method thereof - Google Patents

Ferromanganese-based magnetic composite material and design method and manufacturing method thereof Download PDF

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CN113444942B
CN113444942B CN202110718420.3A CN202110718420A CN113444942B CN 113444942 B CN113444942 B CN 113444942B CN 202110718420 A CN202110718420 A CN 202110718420A CN 113444942 B CN113444942 B CN 113444942B
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李炎
林国星
黄焦宏
张英德
戴默涵
金培育
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Baotou Rare Earth Research Institute
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
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Abstract

The invention discloses a ferromanganese-based magnetic composite material and a design method and a manufacturing method thereof. Step 1, establishing a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the application magnetic field intensity, temperature and mole ratio of a plurality of layers of ferromanganese-based magnetic materials respectively; step 2, establishing an equation to perform composite optimization on a plurality of layers of ferromanganese-based magnetic materials; and 3, calculating the molar ratio of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic material. The ferromanganese-based magnetic composite material designed by the invention can keep larger magnetocaloric effect in a wider working temperature range.

Description

Ferromanganese-based magnetic composite material and design method and manufacturing method thereof
Technical Field
The invention relates to a ferromanganese-based magnetic composite material and a design method and a manufacturing method thereof, in particular to a ferromanganese-based magnetic composite material for a room-temperature magnetic refrigerator and a design method and a manufacturing method thereof.
Background
At present, along with the development of room temperature magnetic refrigeration technology, a refrigeration working medium in a room temperature magnetic refrigerator is particularly important. In recent years, research on room temperature magnetic refrigeration materials has been greatly advanced, wherein ferromanganese (Mn-Fe) based magnetic refrigeration materials have the advantages of giant magnetocaloric effect, low price, simple preparation process and the like, and are expected to become candidate materials for large-scale commercial production.
However, due to structural phase change and magnetic phase change of the Mn-Fe-based magnetic material, the material has huge magnetocaloric effect, but is accompanied with the defect of small working temperature range, namely, the working temperature span value is small. The method brings restriction to the application of the Mn-Fe-based magnetic material in the aspect of room temperature magnetic refrigeration.
CN102881393A discloses a MnFePSi-based room temperature magnetic refrigeration material with a chemical general formula of Mn1.2Fe0.8P1- ySiyBzIn the formula, y is more than or equal to 0.4 and less than or equal to 0.55, and z is more than or equal to 0 and less than or equal to 0.05. The preparation method of the MnFePSi-based room temperature magnetic refrigeration material comprises the following steps: (1) mixing Mn, Fe, P, Si and B according to the mass percentage of each element in the general formula; (2) under the protection of high-purity argon, putting the prepared powder raw materials into a ball milling tank, and carrying out ball milling after sealing by a cover; (3) calcining the powder obtained by ball milling under the protection of argon; (4) and crushing the calcined sample, performing melt rapid quenching under the protection of argon, annealing the obtained strip, and rapidly quenching the strip into water to obtain the room-temperature magnetic refrigeration material. CN110364324A discloses a Mn-Fe-P-Si based magnetic refrigeration material, the components of which are (Mn, Fe)2-xNbx(P, Si), x is more than or equal to 0.02 and less than or equal to 0.04. The magnetic refrigeration material of the patent document can reduce thermal hysteresis. CN108642355A discloses a ferromanganese-based room temperature magnetic refrigeration material with a chemical general formula of Mn1.15Fe0.85PaSibGecBδWherein a is in the range of 0.45 to 0.65, b is in the range of 0.13 to 0.35, c is in the range of 0 to 0.2, δ is in the range of 0.0 to 0.1, and a, b, c, δ satisfy the condition that a + b + c + δ is 1. The working temperature range of the magnetic refrigeration material in the above patent document is still small. In addition, how to design ferromanganese-based magnetic refrigeration materials to guide the manufacturing process of ferromanganese-based magnetic refrigeration materials has not been reported.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a method for designing a ferromanganese-based magnetic composite material to guide a manufacturing process of a ferromanganese-based magnetic refrigeration material. By the design method, the ferromanganese-based magnetic composite material which keeps larger magnetocaloric effect in a wider temperature range can be manufactured. Another object of the present invention is a ferromanganese-based magnetic composite material that maintains a greater magnetocaloric effect over a wider temperature range. It is a further object of the present invention to provide a method of manufacturing a ferromanganese-based magnetic composite material as described above. The invention adopts the following technical scheme to achieve the purpose.
On one hand, the invention provides a design method of a ferromanganese-based magnetic composite material, wherein the ferromanganese-based magnetic composite material is formed by a plurality of layers of ferromanganese-based magnetic materials; the design method comprises the following steps:
step 1, establishing a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the application magnetic field intensity, temperature and mole ratio of a plurality of layers of ferromanganese-based magnetic materials respectively:
Figure BDA0003135945910000021
Figure BDA0003135945910000022
step 2, establishing the following equation to perform composite optimization on a plurality of layers of ferromanganese-based magnetic materials:
Figure BDA0003135945910000031
Figure BDA0003135945910000032
step 3, combining the formula (3) and the formula (4) into a matrix equation to calculate the molar ratio z of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic materialsk；
In the above formulae (1) to (4), zkThe molar ratio of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic material is set; h is the applied magnetic field strength, and the unit is T; Δ H is the applied field strength variation value; t represents temperature in K; skAnd Δ SkRespectively representing the magnetic entropy change and the isothermal magnetic entropy change of each layer of ferromanganese-based magnetic material, wherein the units are J/(kg & K); scAnd Δ ScAre respectively provided withThe unit is J/(kg.K) for the magnetic entropy and the magnetic entropy change of the ferromanganese-based magnetic composite material; k is the layer number variable of the ferromanganese-based magnetic material, and the value of k is a natural number which is more than or equal to 1 and less than or equal to n; n represents the total number of layers of the ferromanganese-based magnetic material, and n is a natural number more than or equal to 3; t ismThe conversion temperature of each layer of ferromanganese-based magnetic material is represented by K; j represents the types of ferromanganese-based magnetic materials with different Curie temperatures, and the value of j is a natural number which is more than or equal to 1 and less than or equal to n-1.
According to the design method of the present invention, it is preferable that,
magnetic entropy SkObtained according to equation (5):
Figure BDA0003135945910000033
isothermal magnetic entropy change Δ SkObtained according to equation (6):
Figure BDA0003135945910000041
wherein S is magnetic entropy, and the unit is J/(kg. K); t is temperature in K; cHThe magnetic specific heat is expressed in J/(kg. K); h is the applied magnetic field strength, and the unit is T; m is magnetization intensity and has the unit of A/M; mu.s0Is a vacuum magnetic permeability.
According to the design method of the present invention, preferably, n is 3.
According to the design method of the present invention, preferably, the ferromanganese-based magnetic composite material is formed of a first layer of a ferromanganese-based magnetic material, a second layer of a ferromanganese-based magnetic material, and a third layer of a ferromanganese-based magnetic material; the design method comprises the following steps:
step 1, establishing a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the molar ratio of the applied magnetic field intensity, temperature and three layers of ferromanganese-based magnetic materials respectively:
Figure BDA0003135945910000042
Figure BDA0003135945910000043
step 2, establishing the following equation to perform composite optimization on the three-layer ferromanganese-based magnetic material:
Figure BDA0003135945910000044
Figure BDA0003135945910000045
step 3, combining the formula (3 ') and the formula (4') into a matrix equation to calculate the molar ratio z of each layer of ferromanganese-based magnetic material to the whole ferromanganese-based magnetic materialk；
In the above formulae (1 ') to (4'), zkThe molar ratio of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic material is set; h is the applied magnetic field intensity; Δ H is the applied field strength variation value; t represents temperature in K; skAnd Δ SkRespectively representing the magnetic entropy change and the isothermal magnetic entropy change of each layer of ferromanganese-based magnetic material, wherein the units are J/(kg & K); scAnd Δ ScRespectively representing the magnetic entropy and the magnetic entropy change of the ferromanganese-based magnetic composite material, wherein the units are J/(kg.K); k is the layer number variable of the ferromanganese-based magnetic material, and the values of k are 1, 2 and 3; t ismThe conversion temperature of each layer of ferromanganese-based magnetic material is represented by K; j represents the types of ferromanganese-based magnetic materials with different Curie temperatures, and the values of j are 1 and 2.
According to the design method of the present invention, it is preferable to calculate by combining (3 ') and formula (4') as the following matrix equation:
Figure BDA0003135945910000051
in the formula:
Figure BDA0003135945910000052
Figure BDA0003135945910000053
Figure BDA0003135945910000054
Figure BDA0003135945910000055
Figure BDA0003135945910000056
Figure BDA0003135945910000057
Figure BDA0003135945910000058
the Curie temperatures of the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material and the third layer of ferromanganese-based magnetic material are respectively K; Δ H represents a magnetic field variation; delta S1、ΔS2And Δ S3Respectively the magnetic entropy changes of the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material and the third layer of ferromanganese-based magnetic material at different Curie temperatures; a ', b', c ', d', e 'and f' represent the magnetic entropy changes at different curie temperatures, respectively.
According to the designing method of the present invention, it is preferable that the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material, and the third layer of ferromanganese-based magnetic material be Mn, respectively1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5；z1＝0.22，z2＝0.33，z3＝0.45。
In another aspect, the present invention provides a ferromanganese-based magnetic composite material comprising Mn in a molar ratio of 0.22:0.33:0.451.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5Three layers of ferromanganese based magnetic material, Mn1.37Fe0.63P0.5Si0.5As an intermediate layer.
In another aspect, the present invention provides a method for manufacturing the ferromanganese-based magnetic composite material, comprising the steps of:
adding Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Respectively forming magnetic material sheets, and sequentially overlapping the magnetic material sheets to form the ferromanganese-based magnetic composite material.
The manufacturing method according to the present invention preferably includes the following specific steps:
a) respectively adding Mn in an inert atmosphere1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Mixing the required raw materials, ball-milling the mixture to obtain powder, and pressing the powder into a flaky green body;
b) respectively sintering and annealing the sheet-shaped blank to obtain a magnetic material sheet;
c) and (3) sequentially overlapping and bonding the magnetic material sheets to obtain the ferromanganese-based magnetic composite material.
According to the manufacturing method of the invention, preferably, in the step b), the sheet-shaped blank is sintered for 1.5-5 h at 1200-1500K in a vacuum state, then is annealed for the first time for 15-28 h at 1000-1350K, and then is cooled to 280-310K; and carrying out secondary annealing treatment at 1200-1500K for 15-28 h, and then quenching in water to obtain the magnetic material sheet.
By adopting the design method, the ferromanganese-based magnetic materials of each layer can be optimized so as to guide the production of the ferromanganese-based magnetic composite material. The ferromanganese-based magnetic composite material keeps larger magnetocaloric effect in a wider working temperature range. The ferromanganese-based magnetic material can have a larger working temperature span value on the basis of keeping larger magnetocaloric effect.
Drawings
FIG. 1 is a graph showing isothermal magnetic entropy change with temperature for the product of example 1 and the products of comparative examples 1 to 3, which are designed according to the present invention, under the condition of applying a magnetic field of 1.5T. Filled symbols indicate thermal lag, and open symbols indicate no thermal lag.
Detailed Description
The present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.
The vacuum in the invention refers to absolute vacuum degree; the smaller the value, the higher the degree of vacuum.
In the present invention, magnetic refrigeration means that heat is released to the outside during isothermal magnetization and heat is absorbed from the outside during demagnetization by the magnetocaloric effect of a magnetic refrigeration material, thereby achieving the purpose of refrigeration.
Design method of ferromanganese-based magnetic composite material
The design method of the ferromanganese-based magnetic composite material comprises the following steps:
step 1, establishing a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the application magnetic field intensity, temperature and mole ratio of a plurality of layers of ferromanganese-based magnetic materials respectively;
step 2, establishing an equation to perform composite optimization on a plurality of layers of ferromanganese-based magnetic materials;
step 3, calculating the molar ratio z of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic materialsk。
As described in detail below.
In the step 1, a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the application magnetic field intensity, temperature and mole ratio of a plurality of layers of ferromanganese-based magnetic materials is established:
Figure BDA0003135945910000081
Figure BDA0003135945910000082
in the above formula, zkThe molar ratio of the ferromanganese-based magnetic material to the total ferromanganese-based magnetic material in each layer is shown. z is a radical ofk0 or more and 1 or less, preferably 0 or more and 1 or less. H is the applied magnetic field intensity; the unit of H is T, and the general application range of H is 0-1.5T. T represents temperature in K; t (k) ═ 273.15+ t (° c), then, t refers to room temperature. the specific range of t may be generally 0 to 28 ℃. SkAnd Δ SkRespectively representing the magnetic entropy and the magnetic entropy change of each layer of ferromanganese-based magnetic material, wherein the unit is J/(kg. K); scAnd Δ ScRespectively representing the magnetic entropy and the magnetic entropy change of the ferromanganese-based magnetic composite material, wherein the units are J/(kg.K); k is the layer number variable of the ferromanganese-based magnetic material, and the value of k is a natural number which is more than or equal to 1 and less than or equal to n; n represents the total number of layers of the ferromanganese-based magnetic material, and n is a natural number of 3 or more.
Magnetic entropy SkAnd isothermal magnetic entropy change Δ SkRespectively, from equation (5) and equation (6).
Figure BDA0003135945910000083
Under isothermal conditions, dT is 0, and formula (6) can be obtained from formula (5).
Figure BDA0003135945910000084
Wherein S is magnetic entropy, and the unit is J/(kg. K); t is temperature in K; cHThe magnetic specific heat is expressed in J/(kg)K); h is the applied magnetic field strength, and the unit is T; m is magnetization intensity and has the unit of A/M; mu.s0Is a vacuum magnetic permeability.
According to a preferred embodiment of the invention, n-3. The ferromanganese-based magnetic composite material is formed by a first layer of ferromanganese-based magnetic material, a second layer of ferromanganese-based magnetic material and a third layer of ferromanganese-based magnetic material. Establishing a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the molar ratio of the applied magnetic field intensity, temperature and the three-layer ferromanganese-based magnetic material respectively:
Figure BDA0003135945910000091
Figure BDA0003135945910000092
in the above formula, zkThe molar ratio of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic material is set; h is the applied magnetic field intensity; Δ H is the applied field strength variation value; t represents temperature in K; skAnd Δ SkRespectively representing the magnetic entropy change and the isothermal magnetic entropy change of each layer of ferromanganese-based magnetic material, wherein the units are J/(kg & K); scAnd Δ ScRespectively representing the magnetic entropy and the magnetic entropy change of the ferromanganese-based magnetic composite material, wherein the units are J/(kg.K); k is the layer number variable of the ferromanganese-based magnetic material, and the values of k are 1, 2 and 3.
In step 2, the following equation is established to perform composite optimization on a plurality of layers of ferromanganese-based magnetic materials:
Figure BDA0003135945910000093
Figure BDA0003135945910000101
in the above, zkThe molar ratio of the ferromanganese-based magnetic material to the total ferromanganese-based magnetic material in each layer is shown. z is a radical ofk0 or more and 1 or less, preferably 0 or more and 1 or less. H is the applied magnetic field intensity; the unit of H is T, and the general application range of H is 0-1.5T. SkAnd Δ SkRespectively representing the magnetic entropy and the magnetic entropy change of each layer of ferromanganese-based magnetic material, wherein the unit is J/(kg. K); k is the layer number variable of the ferromanganese-based magnetic material, and the value of k is a natural number which is more than or equal to 1 and less than or equal to n; n represents the total number of layers of the ferromanganese-based magnetic material, and n is a natural number more than or equal to 3; t ismThe Curie temperature of each layer of ferromanganese-based magnetic material is represented by K; j represents the types of ferromanganese-based magnetic materials with different Curie temperatures, and the value of j is a natural number which is more than or equal to 1 and less than or equal to n-1.
According to a preferred embodiment of the invention, n-3. The ferromanganese-based magnetic composite material is formed by a first layer of ferromanganese-based magnetic material, a second layer of ferromanganese-based magnetic material and a third layer of ferromanganese-based magnetic material. The following equation is established to perform composite optimization on the three-layer ferromanganese-based magnetic material:
Figure BDA0003135945910000102
Figure BDA0003135945910000103
in the above formula, zkThe molar ratio of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic material is set; h is the applied magnetic field intensity; Δ H is the applied field strength variation value; skAnd Δ SkRespectively representing the magnetic entropy change and the isothermal magnetic entropy change of each layer of ferromanganese-based magnetic material, wherein the units are J/(kg & K); scAnd Δ ScRespectively representing the magnetic entropy and the magnetic entropy change of the ferromanganese-based magnetic composite material, wherein the units are J/(kg.K); k is the layer number variable of the ferromanganese-based magnetic material, and the values of k are 1, 2 and 3; t ismThe conversion temperature of each layer of ferromanganese-based magnetic material is represented by K; j represents the types of ferromanganese-based magnetic materials with different Curie temperatures, and the values of j are 1 and 2.
In step 3, the equations (3) and (4) are combined into a matrix equation to calculateThe molar ratio z of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic materialk. According to a preferred embodiment of the present invention, the ferromanganese-based magnetic composite material is formed of a first layer of a ferromanganese-based magnetic material, a second layer of a ferromanganese-based magnetic material, and a third layer of a ferromanganese-based magnetic material. Combining (3 ') and equation (4') into the following matrix equation for calculation:
Figure BDA0003135945910000111
in the formula:
Figure BDA0003135945910000112
Figure BDA0003135945910000113
Figure BDA0003135945910000114
Figure BDA0003135945910000115
Figure BDA0003135945910000116
Figure BDA0003135945910000117
Figure BDA0003135945910000118
the conversion temperatures (K) of the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material and the third layer of ferromanganese-based magnetic material are respectively set; Δ H represents a magnetic field variation; delta S1、ΔS2And Δ S3Respectively carrying out magnetic entropy change on a first layer of manganese-iron-based magnetic material, a second layer of manganese-iron-based magnetic material and a third layer of manganese-iron-based magnetic material at different conversion temperatures; a ', b', c ', d', e 'and f' represent the magnetic entropy changes at different curie temperatures, respectively.
According to a preferred embodiment of the present invention, the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material and the third layer of ferromanganese-based magnetic material are each Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5. The mol ratios of the first layer of manganese-iron-based magnetic material, the second layer of manganese-iron-based magnetic material and the third layer of manganese-iron-based magnetic material are respectively as follows: z is a radical of1＝0.22，z2＝0.33，z30.45. Namely, the molar ratio of the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material and the third layer of ferromanganese-based magnetic material is 0.22:0.33: 0.45. This can make the composite material have a larger working temperature range on the basis of keeping the large magnetocaloric effect.
Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5The Curie temperatures of (A) are 274K, 278K and 288K, respectively. The Curie temperature of the ferromanganese-based magnetic composite material designed by the invention is 280K.
< ferromanganese-based magnetic composite material >
The invention also provides a ferromanganese-based magnetic composite material which can be used as a room-temperature magnetic refrigeration material. The ferromanganese-based magnetic composite material consists of Mn with a molar ratio of 0.22:0.33:0.451.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5Three layers of ferromanganese based magnetic material, Mn1.37Fe0.63P0.5Si0.5As an intermediate layer.
The ferromanganese-based magnetic composite material can have a larger working temperature range on the basis of keeping a large magnetocaloric effect, namely, the working temperature span value is larger.
Method for manufacturing ferromanganese-based magnetic composite material
The invention also provides a manufacturing method of the ferromanganese-based composite material. The ferromanganese-based magnetic composite material is prepared from Mn with a molar ratio of 0.22:0.33:0.451.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5Three layers of ferromanganese based magnetic material, Mn1.37Fe0.63P0.5Si0.5As an intermediate layer. The manufacturing method comprises the following steps: adding Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Respectively forming magnetic material sheets, and sequentially overlapping the magnetic material sheets to form the ferromanganese-based magnetic composite material.
Specifically, the manufacturing method comprises the following steps:
a) respectively adding Mn in an inert atmosphere1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Mixing the required raw materials, ball-milling the mixture to obtain powder, and pressing the powder into a flaky green body;
b) respectively sintering and annealing the sheet-shaped blank to obtain a magnetic material sheet;
c) and (3) sequentially overlapping and bonding the magnetic material sheets to obtain the ferromanganese-based magnetic composite material.
In step a), the "inert atmosphere" refers to the protection of inert gas. The inert gas includes helium, neon, argon, krypton and xenon, preferably argon. The ball milling time is 8-15 h, preferably 9-13 h, and more preferably 9-12 h. The average particle diameter D50 of the powder was 0.5 mm. The pressing pressure when pressing into a tablet packaging blank is 1MPa, and the pressing time is 5 min. The size of each sheet of the green body was 10X 10 mm.
In step b), the sintering and annealing treatment comprises: sintering the sheet blank at 1200-1500K for 1.5-5 h in a vacuum state, then carrying out primary annealing treatment at 1000-1350K for 15-28 h, and then cooling to 293-308K; and carrying out secondary annealing treatment for 15-28 h at 1273-1500K, and then quenching in water to respectively obtain three magnetic material sheets.
In the present invention, the vacuum state means a degree of vacuum of 1X 10 or less-1Pa. The sintering temperature can be 1200-1500K, preferably 1300-1500K, and more preferably 1300-1450K; the sintering time may be 1.5 to 5 hours, preferably 2 to 4.5 hours, and more preferably 2 to 4 hours. The temperature of the first annealing treatment can be 1000-1350K, preferably 1100-1300K, and more preferably 1100-1250K; the time of the first annealing treatment can be 15-28 h, preferably 17-25 h, and more preferably 18-22 h. The cooling temperature can be 280-310K, preferably 290-305K. The temperature of the second annealing treatment can be 1200-1500K, preferably 1300-1500K, and more preferably 1300-1450K; the time of the second annealing treatment can be 15-28 h, preferably 17-25 h, and more preferably 18-22 h. Thus, the room-temperature magnetic refrigeration composite material with more excellent magnetic property can be obtained.
In the step c), the three magnetic material sheets are sequentially overlapped and bonded together to obtain the ferromanganese-based magnetic composite material with three magnetic material layers. Made of magnetic material Mn1.37Fe0.63P0.5Si0.5The layer formed is an intermediate layer.
The adhesive used for bonding is epoxy resin.
The ferromanganese-based magnetic composite material obtained by the design method provided by the invention can have a larger working temperature range on the basis of keeping a large magnetocaloric effect, namely, the working temperature span value is larger.
< test methods >
Measurement of magnetic properties: magnetic measurements were made using superconducting quantum interference devices MPMS-XL and MPMS-5S (SQUID) magnetometers.
Example 1 design of ferromanganese-based magnetic composite Material
Step 1: the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material and the third layer of ferromanganese-based magnetic material are respectively Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5Establishing a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the molar ratio of the applied magnetic field intensity, temperature and the three-layer ferromanganese-based magnetic material respectively:
Figure BDA0003135945910000141
Figure BDA0003135945910000151
step 2: the following equation is established to perform composite optimization on the three-layer ferromanganese-based magnetic material:
Figure BDA0003135945910000152
Figure BDA0003135945910000153
in step 1 and step 2, zkThe molar ratio of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic material is set; h is the applied magnetic field intensity, Delta H is the applied magnetic field intensity change value, T represents the temperature, and the unit is K; k is the layer number variable of the ferromanganese-based magnetic composite material, and the value of k is 1, 2 and 3; skAnd Δ SkAre each Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5The magnetic entropy and the isothermal magnetic entropy of (1) are changed; scAnd ΔScRespectively changing the magnetic entropy and the magnetic entropy of the ferromanganese-based magnetic composite material; sk、ΔSk、ScAnd Δ ScThe units of (A) are J/(Kg. K); j is the types of ferromanganese-based magnetic materials with different Curie temperatures and takes values of 1 and 2,
Figure BDA0003135945910000157
(i.e. the
Figure BDA0003135945910000156
) Are each Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5The curie temperature of (a) is in K.
And step 3: combining the formula (3 ') and the formula (4') into a matrix equation to calculate the molar ratio z of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic materialk。
Figure BDA0003135945910000154
In the formula:
Figure BDA0003135945910000155
Figure BDA0003135945910000161
Figure BDA0003135945910000162
Figure BDA0003135945910000163
Figure BDA0003135945910000164
Figure BDA0003135945910000165
calculated Mn of the three magnetic material layers1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5The molar ratio of (A) is as follows:
z1＝0.22，z2＝0.33，z3＝0.45。
EXAMPLE 2 fabrication of ferromanganese-based magnetic composite materials
Mixing a magnetic material Mn with a molar ratio of 0.22:0.33:0.451.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Respectively forming magnetic material sheets, and sequentially overlapping the magnetic material sheets to form the ferromanganese-based magnetic composite material. The method comprises the following specific steps:
a) respectively adding Mn under argon atmosphere1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Mixing the required raw materials, ball-milling for 10h respectively after mixing, and pressing into a sheet-shaped blank; sealed in a quartz ampoule and placed under argon atmosphere.
b) The sheet-like green bodies were sintered at 1373K for 2h, respectively, then annealed at 1123K for 20h, and then cooled to room temperature in a vacuum sintering furnace. Then carrying out secondary annealing treatment at 1373K for 20h, and finally quenching in water to obtain Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Magnetic propertyA sheet of material.
c) And (3) sequentially overlapping and bonding the magnetic material sheets to obtain the ferromanganese-based magnetic composite material. Wherein Mn is1.37Fe0.63P0.5Si0.5The magnetic material layer formed by the magnetic material sheet is an intermediate layer.
Comparative examples 1 to 3
a) Respectively adding Mn under argon atmosphere1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Mixing the required raw materials, ball-milling for 10h respectively after mixing, and pressing into a sheet-shaped blank; sealed in a quartz ampoule and placed under argon atmosphere.
b) The sheet-like green bodies were sintered at 1373K for 2h, respectively, then annealed at 1123K for 20h, and then cooled to room temperature in a vacuum sintering furnace. Then carrying out secondary annealing treatment at 1373K for 20h, and finally quenching in water to respectively obtain Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5A sheet of magnetic material.
The simulation results of example 1 are shown in fig. 1, and in fig. 1, composition refers to the ferromanganese-based magnetic composite material of example 1. 1, 2 and 3 refer to products of comparative examples 1 to 3 respectively, and the isothermal magnetic entropy change curve of the products of comparative examples 1 to 3 along with the temperature is the result measured by the experiment. Open symbols represent isothermal magnetic entropy change versus temperature curves for magnetic materials without thermal hysteresis. The solid symbols represent isothermal magnetic entropy change versus temperature curves for magnetic materials with thermal hysteresis.
As can be seen from fig. 1, the refrigeration performance of the composite material is superior to that of the single magnetic material in terms of the refrigeration performance. In terms of the working temperature range, the working temperature range of the composite material is 272-289K, namely the working temperature span value is 17K. The working temperature range of the comparative example 1 is 270-278K, namely the working temperature span value is 8K. The working temperature range of the comparative example 2 is 273-283, namely the working temperature span value is 10K. The working temperature range of comparative example 3 is 282 to 288, i.e. the working temperature span value is 6K. Therefore, the working temperature span value of the ferromanganese-based magnetic composite material designed by the invention is obviously larger than that of a single magnetic material. The performance of the ferromanganese-based magnetic composite material manufactured by the invention is consistent with that of the ferromanganese-based magnetic composite material designed by the invention, which shows that the design method of the invention has reliable theoretical guiding significance.
In conclusion, the ferromanganese-based magnetic composite material designed by the invention can keep a large magnetocaloric effect in a wide working temperature range. In addition, the influence of non-equilibrium heat return on the circulation of the refrigerator is minimized, and the aim of further improving the circulation performance of the magnetic refrigerator is fulfilled. Therefore, under the same applied magnetic field of the room-temperature magnetic refrigerator, the composite material of the invention can realize the aims of large working temperature span value and large refrigerating power by utilizing the comprehensive magnetocaloric effect. The invention can also provide technical level guidance for developing new material combination.
The present invention is not limited to the above-described embodiments, and any variations, modifications, and substitutions which may occur to those skilled in the art may be made without departing from the spirit of the invention.

Claims (10)

1. A design method of a ferromanganese-based magnetic composite material is provided, wherein the ferromanganese-based magnetic composite material is formed by a plurality of layers of ferromanganese-based magnetic materials; the design method is characterized by comprising the following steps:
step 1, establishing a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the application magnetic field intensity, temperature and mole ratio of a plurality of layers of ferromanganese-based magnetic materials respectively:
Figure FDA0003135945900000011
Figure FDA0003135945900000012
step 2, establishing the following equation to perform composite optimization on a plurality of layers of ferromanganese-based magnetic materials:
Figure FDA0003135945900000013
Figure FDA0003135945900000014
step 3, combining the formula (3) and the formula (4) into a matrix equation to calculate the molar ratio z of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic materialsk；
In the above formulae (1) to (4), zkThe molar ratio of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic material is set; h is the applied magnetic field strength, and the unit is T; Δ H is the applied field strength variation value; t represents temperature in K; skAnd Δ SkRespectively representing the magnetic entropy change and the isothermal magnetic entropy change of each layer of ferromanganese-based magnetic material, wherein the units are J/(kg & K); scAnd Δ ScRespectively representing the magnetic entropy and the magnetic entropy change of the ferromanganese-based magnetic composite material, wherein the units are J/(kg.K); k is the layer number variable of the ferromanganese-based magnetic material, and the value of k is a natural number which is more than or equal to 1 and less than or equal to n; n represents the total number of layers of the ferromanganese-based magnetic material, and n is a natural number more than or equal to 3; t ismThe Curie temperature of each layer of ferromanganese-based magnetic material is represented by K; j represents the types of ferromanganese-based magnetic materials with different Curie temperatures, and the value of j is a natural number which is more than or equal to 1 and less than or equal to n-1.
2. The design method according to claim 1, wherein:
magnetic entropy SkObtained according to equation (5):
Figure FDA0003135945900000021
isothermal magnetic entropy change Δ SkObtained according to equation (6):
Figure FDA0003135945900000022
wherein S is magnetic entropy, and the unit is J/(kg. K); t is temperature in K; cHThe magnetic specific heat is expressed in J/(kg. K); h is the applied magnetic field strength, and the unit is T; m is magnetization intensity and has the unit of A/M; mu.s0Is a vacuum magnetic permeability.
3. The design method of claim 1, wherein n-3.
4. The design method of claim 3, wherein the ferromanganese-based magnetic composite material is formed from a first layer of ferromanganese-based magnetic material, a second layer of ferromanganese-based magnetic material, and a third layer of ferromanganese-based magnetic material; the design method comprises the following steps:
step 1, establishing a relational expression of the magnetic entropy and isothermal magnetic entropy change of the ferromanganese-based magnetic composite material and the molar ratio of the applied magnetic field intensity, temperature and three layers of ferromanganese-based magnetic materials respectively:
Figure FDA0003135945900000023
Figure FDA0003135945900000031
step 2, establishing the following equation to perform composite optimization on the three-layer ferromanganese-based magnetic material:
Figure FDA0003135945900000032
Figure FDA0003135945900000033
step 3, combining the formula (3 ') and the formula (4') into a matrix equation to calculate the molar ratio z of each layer of ferromanganese-based magnetic material to the whole ferromanganese-based magnetic materialk；
In the above formulae (1 ') to (4'), zkThe molar ratio of each layer of ferromanganese-based magnetic material to the total ferromanganese-based magnetic material is set; h is the applied magnetic field intensity; Δ H is the applied field strength variation value; t represents temperature in K; skAnd Δ SkRespectively representing the magnetic entropy change and the isothermal magnetic entropy change of each layer of ferromanganese-based magnetic material, wherein the units are J/(kg & K); scAnd Δ ScRespectively representing the magnetic entropy and the magnetic entropy change of the ferromanganese-based magnetic composite material, wherein the units are J/(kg.K); k is the layer number variable of the ferromanganese-based magnetic material, and the values of k are 1, 2 and 3; t ismThe conversion temperature of each layer of ferromanganese-based magnetic material is represented by K; j represents the types of ferromanganese-based magnetic materials with different Curie temperatures, and the values of j are 1 and 2.
5. The design method according to claim 4, wherein the calculation is performed by combining (3 ') and the formula (4') into the following matrix equation:
Figure FDA0003135945900000034
in the formula:
Figure FDA0003135945900000041
Figure FDA0003135945900000042
Figure FDA0003135945900000043
Figure FDA0003135945900000044
Figure FDA0003135945900000045
Figure FDA0003135945900000046
Figure FDA0003135945900000047
the Curie temperatures of the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material and the third layer of ferromanganese-based magnetic material are respectively K; Δ H represents a magnetic field variation; delta S1、ΔS2And Δ S3Respectively the magnetic entropy changes of the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material and the third layer of ferromanganese-based magnetic material at different Curie temperatures; a ', b', c ', d', e 'and f' represent the magnetic entropy changes at different curie temperatures, respectively.
6. The design method of claim 5, wherein the first layer of ferromanganese-based magnetic material, the second layer of ferromanganese-based magnetic material, and the third layer of ferromanganese-based magnetic material are each Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5；z1＝0.22，z2＝0.33，z3＝0.45。
7. The ferromanganese-based magnetic composite material is characterized by comprising Mn with a molar ratio of 0.22:0.33:0.451.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5And Mn1.35Fe0.66P0.5Si0.5Three layers of ferromanganese based magnetic material, Mn1.37Fe0.63P0.5Si0.5As an intermediate layer.
8. The ferromanganese based magnetic composite material manufacturing method according to claim 7, characterized by comprising the steps of:
adding Mn1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Respectively forming magnetic material sheets, and sequentially overlapping the magnetic material sheets to form the ferromanganese-based magnetic composite material.
9. The manufacturing method according to claim 8, characterized by comprising the following specific steps:
a) respectively adding Mn in an inert atmosphere1.32Fe0.67P0.52Si0.49、Mn1.37Fe0.63P0.5Si0.5、Mn1.35Fe0.66P0.5Si0.5Mixing the required raw materials, ball-milling the mixture to obtain powder, and pressing the powder into a flaky green body;
b) respectively sintering and annealing the sheet-shaped blank to obtain a magnetic material sheet;
c) and (3) sequentially overlapping and bonding the magnetic material sheets to obtain the ferromanganese-based magnetic composite material.
10. The manufacturing method according to claim 9, wherein in the step b), the sheet-shaped blank is sintered at 1200 to 1500K for 1.5 to 5 hours in a vacuum state, then is annealed for the first time at 1000 to 1350K for 15 to 28 hours, and then is cooled to 280 to 310K; and carrying out secondary annealing treatment at 1200-1500K for 15-28 h, and then quenching in water to obtain the magnetic material sheet.
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