KR102589531B1 - Magneto-caloric alloy and preparing method thereof - Google Patents

Abstract

The present invention provides a magnetocaloric alloy having excellent magnetocaloric properties and a method for manufacturing the same.

Description

Magnetocaloric alloy and its manufacturing method {MAGNETO-CALORIC ALLOY AND PREPARING METHOD THEREOF}

The present invention relates to magnetocaloric alloys and their manufacturing methods. Specifically, it relates to a magnetocaloric alloy with improved cooling characteristics through composition control and a method for manufacturing the same.

Self-cooling material is a material that can be cooled without Freon gas refrigerant (CFC, chlorofluorocarbon) used in existing refrigerators and air conditioners by using the magnetocaloric effect (MCE), which heats when magnetized and cools when demagnetized.

Systems that use the magnetocaloric effect range from thermomagnetic devices that convert thermal energy into magnetic work to heat pumps in which magnetic work is used to convert thermal energy from a cold source to a hot sink (and vice versa). It can be applied. This generally applies to thermomagnetic, thermoelectric and thermomagnetic generators, magnetic refrigerators, heat exchangers, heat pumps or air conditioning systems.

Gd-based self-cooling material is a representative material that exhibits high magnetocaloric effect at room temperature. However, in the case of Gd, a rare earth element, it is difficult to apply it to actual systems in terms of price and efficiency. Accordingly, in order to replace Gd-based self-cooling materials, various materials have been studied, and La-based alloys and non-rare earth Mn-based alloys are currently attracting attention as possible replacement candidate materials.

Therefore, there is a need for a method to improve the magnetocaloric effect by controlling the composition of the magnetocaloric alloy.

1. Republic of Korea Patent Publication No. 10-2013-0051440 2. Republic of Korea Patent Publication No. 10-2012-0135233

The technical problem to be achieved by the present invention is to provide a magnetocaloric alloy with excellent magnetocaloric properties and a method for manufacturing the same.

However, the problem to be solved by the present invention is not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

One embodiment of the present invention provides a magnetocaloric alloy expressed by the chemical formula _{MnFe 0.95- x Ni}

One embodiment of the present invention includes iron (Fe)-based raw materials, manganese (Mn)-based raw materials, nickel (Ni)-based raw materials, silicon (Si)-based raw materials, and iron-phosphorus (Fe-P)-based raw materials. A raw material mixture preparation step of preparing a raw material mixture; An arc melting step of manufacturing an alloy ingot by arc melting the raw material mixture; And a heat treatment step of heat treating the alloy ingot, wherein the alloy ingot has a composition expressed by the chemical formula MnFe _0.95-x Ni _x P _0.5-y Si _0.5+y , 0.01≤x≤0.05, -0.05≤y≤ A method for manufacturing a magnetocaloric alloy of 0.1 is provided.

The magnetocaloric alloy according to an exemplary embodiment of the present invention has a high magnetic entropy change (△Sm) value and has excellent cooling efficiency, so the relative cooling efficiency can be high.

The magnetocaloric alloy according to an exemplary embodiment of the present invention has a Tc (Curie temperature) near room temperature and can be easily used in a room temperature cooling system.

The method for manufacturing a magnetocaloric alloy according to an exemplary embodiment of the present invention can produce a magnetocaloric alloy with excellent magnetocaloric properties.

The method for manufacturing a magnetocaloric alloy according to an exemplary embodiment of the present invention can easily manufacture a magnetocaloric alloy having a uniform composition.

The effects of the present invention are not limited to the effects described above, and effects not mentioned will be clearly understood by those skilled in the art from this specification.

Figure 1 is a diagram showing an example of a method for measuring magnetocaloric effect (MCE).
Figure 2 is a diagram showing XRD patterns of magnetocaloric alloys prepared in Examples 11 to 14.
Figure 3 is a diagram showing the change in magnetization properties of the magnetocaloric alloys prepared in Examples 1, 7, 15, and Comparative Example 2 of the present invention according to temperature under the condition of an externally applied magnetic field of 1T.
Figure 4 shows the Curie temperature and T ^pk of the magnetocaloric alloys prepared in Examples 2, 4, 8, 12, 16, and Comparative Example 3 of the present invention under the condition of an externally applied magnetic field of 1T. It is a drawing.
Figure 5 is a diagram showing the Curie temperature and △T _hys of the magnetocaloric alloys prepared in Examples 1 to 15 of the present invention under the condition of an externally applied magnetic field of 1T.
Figure 6 is an external view of the magnetocaloric alloy prepared in Example 2, Example 4, Example 8, Example 12, Example 16, Comparative Example 1, Comparative Example 3, and Comparative Examples 6 to 8 of the present invention. This is a diagram showing the trend of Curie temperature under 1T magnetic field conditions.
Figure 7 shows the change in magnetic entropy ( This is a drawing showing △S).

In this specification, when a part “includes” a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

Throughout this specification, when a member is said to be located “on” another member, this includes not only the case where the member is in contact with the other member, but also the case where another member exists between the two members.

Throughout the specification herein, the unit “part by weight” may refer to the ratio of weight between each component.

Throughout this specification, “A and/or B” means “A and B, or A or B.”

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention provides _a magnetocaloric alloy expressed by the chemical formula _{MnFe 0.95-x Ni}

The magnetocaloric alloy according to an exemplary embodiment of the present invention has a high magnetic entropy change (△Sm) value and has excellent cooling efficiency, so the relative cooling efficiency can be high.

The magnetocaloric alloy according to an exemplary embodiment of the present invention has a Tc (Curie temperature) near room temperature and can be easily used in a room temperature cooling system. Specifically, the magnetocaloric alloy has a Tc (Curie temperature) close to room temperature, so it can be easily used in cooling systems such as magnetic refrigerators, heat exchangers, and large-capacity air conditioning systems.

According to one embodiment of the present invention, the magnetocaloric alloy is a five-component alloy containing manganese (Mn), iron (Fe), nickel (Ni), phosphorus (P), and silicon (Si) as constituent elements, By including Fe, Ni, P, and Si in an appropriate range, the magnetocaloric effect can be improved.

According to an exemplary embodiment of the present invention, the magnetocaloric alloy has a composition expressed by the chemical formula MnFe _0.95-x Ni _x P _0.5-y Si _0.5+y . At this time, x may be 0.01 or more and 0.05 or less, 0.02 or more and 0.04 or less, 0.01 or more and 0.03 or less, or 0.03 or more and 0.05 or less. Additionally, y may be -0.05 or more and 0.1 or less, -0.05 or more and 0.05 or less, -0.05 or more and 0 or less, or -0 and 0.1 or less. The magnetocaloric alloy having the above-described composition has a high magnetic entropy change (ΔSm) value and may have a Tc (Curie temperature) relatively close to room temperature.

According to one embodiment of the present invention, the ratio of Ni content and Fe content may be 1:15 to 1:95. That is, the atomic ratio of Ni to Fe contained in the magnetocaloric alloy may be 1:15 to 1:95. Specifically, the content ratio of Ni and Fe contained in the magnetocaloric alloy (Fe/Ni) is 1:20 to 1:90, 1:25 to 1:80, 1:30 to 1:70, 1: It may be 40 to 1:60, 1:15 to 1:50, or 1:40 to 1:90. When the ratio of Ni content and Fe content contained in the magnetocaloric alloy is within the above-mentioned range, the magnetocaloric alloy has a high magnetic entropy change (△Sm) value and can have a Tc (Curie temperature) relatively close to room temperature. there is.

According to one embodiment of the present invention, the ratio of the content of P and the content of Si may be 1:0.7 to 1:1.7. That is, the atomic ratio of P to Si included in the magnetocaloric alloy may be 1:0.7 to 1:1.7. Specifically, the ratio of the content of P and the content of Si (Si/P) contained in the magnetocaloric alloy may be 1:0.8 to 1:1.5, 1:0.7 to 1:1, or 1:1 to 1:1.5. there is. When the ratio of the content of P and the content of Si contained in the magnetocaloric alloy is within the above-mentioned range, the magnetocaloric alloy has a high magnetic entropy change (△Sm) value and can have a Tc (Curie temperature) relatively close to room temperature. there is.

Curie temperature (Tc) is the temperature that appears when a phase transition occurs in a magnetocaloric material. When the temperature decreases, it changes from a paramagnetic material to a ferromagnetic material around the Curie temperature (Tc), so magnetic cooling technology can be applied. Considering the temperature range at which products or systems operate, a magnetocaloric material can be selected that has the target temperature value at which the magnetocaloric effect, which is the principle of magnetic cooling technology, appears.

According to one embodiment of the present invention, the magnetocaloric alloy may have a Tc (Curie temperature) of 270 K to 325 K. Specifically, the Tc of the magnetocaloric alloy is 275 K to 320 K, 280 K to 320 K, 285 K to 320 K, 290 K to 320 K, 295 K to 320 K, 300 K to 320 K, and 305 K to 320 K. K, 310 K to 320 K, 270 K to 300 K, or 295 K to 325 K. The magnetocaloric alloy having a Tc in the above-mentioned range is used in various cooling applications such as a heat pump cooling system, an electric vehicle cooling system, a data center cooling system, a magnetic refrigerator cooling system, a heat exchanger cooling system, and a large-capacity air conditioner cooling system. It can be easily applied to the system. At this time, the Tc (Curie temperature) of the magnetocaloric alloy may be for the condition of an externally applied magnetic field of 1T.

Figure 1 is a diagram showing an example of a method for measuring magnetocaloric effect (MCE).

The magnetocaloric effect of a given material can be evaluated as follows. First, as shown in (a) of FIG. 1, Tc (Curie temperature) can be extracted by analyzing the temperature section where the slope changes rapidly after measuring the M-T curve of the material. In addition, as shown in (b) of FIG. 1, the M-H curve in a predetermined temperature range can be measured, and the T-S curve as shown in (c) of FIG. 1 can be calculated for each M-H curve through Equation 1 below. In addition, RC (refrigeration capacity) can be derived by calculating the green area for the T-S curve shown in (c) of FIG. 1 through Equation 2 below.

[Equation 1]

Equation 1 above is “A. Smith et al. Adv. Energy Mater. 2 (2012) 1288”, where △S _m represents magnetic entropy change, T represents temperature, H represents magnetic field, and M represents magnetization.

[Equation 2]

Equation 2 above is “V. Franco et al. Prog. in Mater. Sci. 93 (2018) 112”, where RC stands for refrigeration capacity and FWMH stands for full width at half maximum.

According to one embodiment of the present invention, the magnetocaloric alloy may have a magnetic entropy change (△Sm) of 3 J/kg·K to 18 J/kg·K. Specifically, the magnetocaloric alloy has a magnetic entropy change (△Sm) of 3 J/kg·K to 10 J/kg·K, 4 J/kg·K to 10 J/kg·K under the condition of an externally applied magnetic field of 1T. , 5 J/kg·K to 10 J/kg·K, 6 J/kg·K to 10 J/kg·K, or 7 J/kg·K to 10 J/kg·K. In addition, the magnetocaloric alloy has a magnetic entropy change (△Sm) of 7 J/kg·K to 18 J/kg·K, 8 J/kg·K to 18 J/kg·K, under the condition of an externally applied magnetic field of 2T. 10 J/kg·K to 18 J/kg·K, 12 J/kg·K to 18 J/kg·K, 14 J/kg·K to 18 J/kg·K, or 16 J/kg·K to It may be 18 J/kg·K. The magnetocaloric alloy having ΔSm in the above-described range may have excellent self-cooling efficiency.

According to one embodiment of the present invention, the magnetocaloric alloy may have a Refrigeration Capacity (RC) of 90 J/kg to 170 J/kg. Specifically, the magnetocaloric alloy has an RC (refrigeration capacity) of 90 J/kg to 170 J/kg, 100 J/kg to 170 J/kg, and 110 J/kg to 170 J/kg under the condition of an externally applied magnetic field of 2T. , 120 J/kg to 170 J/kg, 130 J/kg to 170 J/kg, 140 J/kg to 170 J/kg, or 160 J/kg to 170 J/kg. The magnetocaloric alloy having an RC in the above-mentioned range may have excellent self-cooling efficiency.

In addition, the wider the temperature range (ΔT) at which the magnetocaloric effect appears, the better the cooling ability, so the cooling ability can be improved by using multiple materials with different Curie temperatures (Tc) together (layered MCMs). . In other words, when several materials with different Curie temperatures are used together, the peak area in Figure 1 (c) may appear as a graph in the form of a wide peak, and ΔT (full width at half maximum of the curve) increases accordingly. RC may increase.

One embodiment of the present invention provides a cooling system including the magnetocaloric alloy. As described above, the magnetocaloric alloy has a high magnetic entropy change (ΔSm) value and a Tc (Curie temperature) relatively close to room temperature, so it can be easily applied to a cooling system.

The cooling system may be a magnetic cooling system, for example, a heat pump cooling system, an electric vehicle cooling system, a data center cooling system, a magnetic refrigerator cooling system, a heat exchanger cooling system, a large-capacity air conditioner cooling system, etc. You can. However, the type of cooling system is not limited.

One embodiment of the present invention includes iron (Fe)-based raw materials, manganese (Mn)-based raw materials, nickel (Ni)-based raw materials, silicon (Si)-based raw materials, and iron-phosphorus (Fe-P)-based raw materials. A raw material mixture preparation step of preparing a raw material mixture; An arc melting step of manufacturing an alloy ingot by arc melting the raw material mixture; And a heat treatment step of heat treating the alloy ingot, wherein the alloy ingot has a composition expressed by the chemical formula MnFe _0.95-x Ni _x P _0.5-y Si _0.5+y , 0.01≤x≤0.05, -0.05≤y≤ A method for manufacturing a magnetocaloric alloy of 0.1 is provided.

The method for manufacturing a magnetocaloric alloy according to an exemplary embodiment of the present invention can produce a magnetocaloric alloy with excellent magnetocaloric properties. In addition, the method for manufacturing a magnetocaloric alloy according to an exemplary embodiment of the present invention can easily manufacture a magnetocaloric alloy having a uniform composition.

Conventionally, when manufacturing MnFePSi material, a magnetocaloric alloy, P has a significantly lower boiling point than other elements in addition to being hazardous, so a solid-state reaction synthesis method using Fe powder, Mn powder, Si powder, and red P powder was used. used. However, metal powders are very vulnerable to oxidation, and red phosphorus is also flammable and harmful, so all manufacturing processes must be performed in a glove box. Because of this, the conventional method had problems such as high processing costs, imbalanced composition of the produced alloy, and low productivity.

On the other hand, the method for manufacturing a magnetocaloric alloy according to an embodiment of the present invention can simplify the manufacturing process compared to the conventional solid-state reaction synthesis method through an arc-melting process, and the magnetocaloric alloy produced The composition can be effectively uniformed and high productivity can be achieved through the melting process.

According to an exemplary embodiment of the present invention, the iron (Fe)-based raw material, the manganese (Mn)-based raw material, the nickel (Ni)-based raw material, the silicon (Si)-based raw material, and the iron-phosphorus (Fe- P)-based raw materials may be in bulk form. Specifically, the iron (Fe)-based raw material, the manganese (Mn)-based raw material, the nickel (Ni)-based raw material, the silicon (Si)-based raw material, and the iron-phosphorus (Fe-P)-based raw material are chip. It can be used in (chip) form or bulk pieces. By using bulk Fe-based raw materials, Mn-based raw materials, Ni-based raw materials, Si-based raw materials, and Fe-P-based raw materials, oxidation of raw materials can be effectively prevented and at the same time, the manufacturing productivity of magnetocaloric alloy can be increased. You can.

According to one embodiment of the present invention, the raw material mixture preparation step may include a process of removing the oxide film of the manganese (Mn)-based raw material. Specifically, the oxide film of the Mn-based raw material can be removed using acid. For example, the acid may include one of nitric acid, sulfuric acid, phosphoric acid, and hydrochloric acid. Through this, it is possible to effectively suppress impurities from being included in the produced magnetocaloric alloy.

According to one embodiment of the present invention, in the raw material mixture preparation step, the Fe-based raw material, Mn-based raw material, Ni-based raw material, Si-based raw material, and Fe-P-based raw material have the chemical formula MnFe _0.95-x Ni _x P _0.5-y It can be weighed and mixed so that an ingot with a composition expressed as Si _0.5+y can be manufactured.

According to one embodiment of the present invention, the arc melting step includes: a first arc melting step of arc melting the raw material mixture under a first current condition; And a second arc melting step of arc melting the alloy ingot formed by the first arc melting under a second current condition, wherein the second arc melting step may be performed under a higher current condition than the first arc melting step. .

In the arc melting step of manufacturing an alloy ingot by arc melting the raw material mixture, the first arc melting step with a low current condition is performed first, and the second arc melting step with a higher current condition is sequentially performed, thereby producing a magnetocaloric alloy. The loss of phosphorus (P) during the manufacturing process can be effectively suppressed, and a magnetocaloric alloy having a homogeneous composition and the desired composition can be effectively manufactured.

According to one embodiment of the present invention, the arc melting step includes cooling the alloy ingot formed by the first arc melting between the first arc melting step and the second arc melting step; And it may further include preparing for the second arc melting step by reversing the vertical position of the cooled alloy ingot. Specifically, an alloy ingot may be manufactured by arc melting the raw material mixture under a first current condition, and then the alloy ingot may be cooled. The alloy ingot can be cooled at room temperature conditions. Thereafter, arc melting can be performed under the second current condition after changing the vertical position of the cooled alloy ingot. That is, the upper side of the alloy ingot formed by first arc melting is positioned downward in the second arc melting step, and the lower side of the alloy ingot formed by first arc melting may be positioned upward in the second arc melting step. . By cooling the alloy ingot and changing the vertical position of the alloy ingot between the first arc melting step and the second arc melting step, the composition of the produced magnetocaloric alloy can be more homogenized.

According to one embodiment of the present invention, the current ratio of the first current condition and the second current condition is 1:1.5 to 1:2.5, 1:1.6 to 1:2.0, 1:1.6 to 1:1.75, 1 :1.5 to 1:1.75, or 1:1.6 to 1:2.5. By adjusting the current ratio of the first current condition applied in the first arc melting step and the second current condition applied in the second arc melting step to the above-mentioned range, phosphorus (P) is produced during the manufacturing process of the magnetocaloric alloy. This loss can be effectively suppressed, and a magnetocaloric alloy having a homogeneous composition and the desired composition can be effectively manufactured.

According to an exemplary embodiment of the present invention, the first current condition may be 40 A or more and 50 A or less. Additionally, the time for performing the first arc melting step may be 0.5 minutes or more and 1 minute or less. By adjusting the current conditions and time for which the first arc melting step is performed within the above-mentioned range, loss of phosphorus (P) during the manufacturing process of the magnetocaloric alloy can be effectively suppressed.

According to an exemplary embodiment of the present invention, the second current condition may be 70 A or more and 80 A or less. Additionally, the time for performing the second arc melting step may be 1 minute or more and 2 minutes or less. By adjusting the current conditions and time for which the second arc melting step is performed within the above-described range, a magnetocaloric alloy having a homogeneous composition and a desired composition can be effectively manufactured.

Meanwhile, when the ratio of the current of the first current condition and the second current condition satisfies the above-mentioned range, depending on the device in which arc melting is performed, the current value of the first current condition and the current of the second current condition The value may be adjusted to differ from the above-mentioned range. In addition, when the current ratio of the first current condition and the second current condition satisfies the above-mentioned range, depending on the device in which the arc melting is performed, the time at which the first arc melting step is performed and the time at which the first arc melting step is performed The time at which steps are performed may be adjusted differently from the above-described range.

According to one embodiment of the present invention, the arc melting step may be performed two or more times. Specifically, the arc melting step including the first arc melting step and the second arc melting step may be performed 2 or more times, 3 or more times, 4 or more times, or 5 or more times. That is, the cycle of performing the first arc melting step and the second arc melting step may be performed 2 or more times, 3 or more times, 4 or more times, or 5 or more times. Additionally, the arc melting step may be performed 6 times or less, 5 times or less, or 4 times or less. That is, the cycle of performing the first arc melting step and the second arc melting step may be performed 6 times or less, 5 times or less, or 4 times or less. By adjusting the number of repetitions of the arc melting step within the above-mentioned range, the manufacturing process time can be appropriately adjusted and the manufactured magnetocaloric alloy can be effectively homogenized.

According to one embodiment of the present invention, the arc melting step may be performed under inert gas conditions. The inert gas may include at least one of nitrogen, argon, and helium. For example, the inert gas may be argon. By performing the arc melting step under inert gas conditions, it is possible to effectively prevent impurities from being incorporated into the produced magnetocaloric alloy.

According to one embodiment of the present invention, the heat treatment step may be performed at a temperature of 1,200 K or more and 1,600 K or less. Specifically, the temperature at which the heat treatment step is performed may be 1,300 K or more and 1,500 K or less, 1,200 K or more and 1,450 K or less, or 1,400 K or more and 1,500 K or less. More specifically, the temperature at which the heat treatment step is performed may be 1,350 K or more and 1,450 K or less, 1,375 K or more and 1,425 K or less, 1,350 K or more and 1,425 K or less, or 1,400 K and 1,450 K or less. Additionally, the heat treatment step may be performed for a period of time between 90 hours and 100 hours. Additionally, the heat treatment step may be performed in a vacuum state. By adjusting the temperature, time, and atmospheric conditions in which the heat treatment step is performed within the above-mentioned range, the produced magnetocaloric alloy can be effectively homogenized, and a magnetocaloric alloy having the desired composition can be implemented.

According to one embodiment of the present invention, the method for manufacturing the magnetocaloric alloy may further include cooling the magnetocaloric alloy manufactured by performing the heat treatment step. By cooling the heat-treated magnetocaloric alloy, defects such as pores or dislocations that may exist inside the magnetocaloric alloy can be reduced, and physical properties can be further improved. The method for cooling the magnetocaloric alloy can be any method used in the art without limitation. For example, cooling can be done using cold water of 5°C to 20°C.

According to an exemplary embodiment of the present invention, the magnetocaloric alloy manufactured through the method for manufacturing the magnetocaloric alloy may have a composition expressed by the chemical formula MnFe _0.95-x Ni _x P _0.5-y Si _0.5+y , where 0.01 It may be ≤x≤0.05, -0.05≤y≤0.1.

Hereinafter, the present invention will be described in detail with reference to examples. However, the embodiments according to the present invention may be modified into various other forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments of this specification are provided to more completely explain the present invention to those skilled in the art.

Example 1

As raw materials, Fe chips (>99.95 wt%), Mn chips (>99.9 wt%), Ni bulk pieces (>99.99 wt%), Si bulk pieces (>99.999 wt%) and Fe-P bulk pieces (>99.9 wt). %) was prepared. At this time, the Mn chip was used after removing the oxide film by treating it with nitric acid.

Thereafter, the Fe chip, Mn chip, Ni bulk piece, Si bulk piece, and Fe-P bulk piece were weighed so that an ingot having a composition expressed by the chemical formula MnFe _0.94 Ni _0.01 P _0.55 Si _0.45 could be manufactured to prepare a raw material mixture. did.

Thereafter, the raw material mixture was placed in an arc melting device (Arc Suction Melting System), and a first arc melting step was performed for 1 minute under a current condition of 50 A to form an alloy ingot. Afterwards, the alloy ingot was cooled at room temperature, its up and down positions were changed, and it was placed in the arc melting device again. Afterwards, a second arc melting step was performed for 1 minute under a current condition of 70 A. The above-described method was repeated three times, and a total of four arc melting (first arc melting step + second arc melting step) was performed.

Afterwards, the alloy ingot was sealed in a vacuum atmosphere in a quartz glass tube, heat treated at 1,423 K for 96 hours, and quenched in cold water (20 °C) to produce a magnetocaloric alloy with a composition expressed as MnFe _0.94 Ni _0.01 P _0.55 Si _0.45 . did.

Examples 2 to 16

A magnetocaloric alloy was prepared in the same manner as in Example 1, except that a raw material mixture was prepared so that a magnetocaloric alloy having the composition shown in Table 1 below was prepared.

division x y chemical formula Example 1 0.01 -0.05 MnFe _0.94 Ni _0.01 P _0.55 Si _0.45 Example 2 0 MnFe _0.94 Ni _0.01 P _0.5 Si _0.5 Example 3 0.02 -0.05 MnFe _0.93 Ni _0.02 P _0.55 Si _0.45 Example 4 0 MnFe _0.93 Ni _0.02 P _0.5 Si _0.5 Example 5 0.05 MnFe _0.93 Ni _0.02 P _0.45 Si _0.55 Example 6 0.1 MnFe _0.93 Ni _0.02 P _0.4 Si _0.6 Example 7 0.03 -0.05 MnFe _0.92 Ni _0.03 P _0.55 Si _0.45 Example 8 0 MnFe _0.92 Ni _0.03 P _0.5 Si _0.5 Example 9 0.05 MnFe _0.92 Ni _0.03 P _0.45 Si _0.55 Example 10 0.1 MnFe _0.92 Ni _0.03 P _0.4 Si _0.6 Example 11 0.04 -0.05 MnFe _0.91 Ni _0.04 P _0.55 Si _0.45 Example 12 0 MnFe _0.91 Ni _0.04 P _0.5 Si _0.5 Example 13 0.05 MnFe _0.91 Ni _0.04 P _0.45 Si _0.55 Example 14 0.1 MnFe _0.91 Ni _0.04 P _0.4 Si _0.6 Example 15 0.05 -0.05 MnFe _0.90 Ni _0.5 P _0.55 Si _0.45 Example 16 0 MnFe _0.90 Ni _0.5 P _0.5 Si _0.5

Comparative Examples 1 to 5

A magnetocaloric alloy was prepared in the same manner as in Example 1, except that a raw material mixture was prepared so that a magnetocaloric alloy having the composition shown in Table 2 below was prepared.

division x y chemical formula Comparative Example 1 0 0 MnFe _0.95 P _0.5 Si _0.5 Comparative Example 2 0.16 -0.05 MnFe _0.79 Ni _0.16 P _0.55 Si _0.45 Comparative Example 3 0 MnFe _0.79 Ni _0.16 P _0.5 Si _0.5 Comparative Example 4 0.05 MnFe _0.79 Ni _0.16 P _0.45 Si _0.55 Comparative Example 5 0.1 MnFe _0.79 Ni _0.16 P _0.4 Si _0.6

Comparative Example 6

A raw material mixture was prepared so that a magnetocaloric alloy with a composition of MnFe _0.95 P _0.5 Si _0.5 could be manufactured, and “J. Alloys & Compd. A magnetocaloric alloy was manufactured using the solid state reaction method disclosed in “730 (2018) 392”.

Comparative Example 7

A magnetocaloric alloy was prepared using a solid-state reaction method in the same manner as in Comparative Example 6, except that a raw material mixture was prepared to produce a magnetocaloric alloy with a composition of MnFe _0.87 Ni _0.08 P _0.5 Si _0.5 .

Comparative Example 8

A magnetocaloric alloy was prepared using a solid-state reaction method in the same manner as in Comparative Example 6, except that a raw material mixture was prepared to produce a magnetocaloric alloy with a composition of MnFe _0.79 Ni _0.16 P _0.5 Si _0.5 .

Experimental Example 1: XRD pattern analysis

X-ray diffraction analysis was performed on the magnetocaloric alloys prepared in Examples 11 to 14 to obtain XRD patterns.

Figure 2 is a diagram showing XRD patterns of magnetocaloric alloys prepared in Examples 11 to 14.

Referring to Figure 2, it can be seen that the crystal planes (111), (201), and (210) peaks appear as main peaks at about 40 °, 42 to 43 °, and 45 to 46 °, respectively. Through this, the magnetocaloric alloys prepared in Examples 11 to 14 were Fe ₂ P-type hexagonal (space group No. 189, ) It was confirmed that it was a Mn-Fe-P-Si alloy with a structure.

Experimental Example 2: Evaluation of magnetocaloric effect

For the magnetocaloric alloys prepared in the above examples and comparative examples, the magnetocaloric properties were evaluated through the VSM (Vibrating Sample Magnetometer) mode of the PPMS (Physical Property Measurement System) equipment. VSM records the applied magnetic field applied by a Hall probe and measures the magnetization value of the sample by recording the electromotive force obtained when vibration is applied to the sample according to Faraday's law. Through this, the Curie temperature (Tc) and magnetic entropy change (ΔS _M ) were obtained, and the RC (Refrigeration capacity) value was calculated through this. As described above, RC can be calculated by obtaining the temperature section corresponding to the full width at half maximum (FWHM) of the highest ΔS value in the ΔS-T curve and calculating the ΔS integral value in the section.

Tables 3 to 6 below show the maximum value of magnetic entropy change (│△Smax│), │ The temperature at which the △Smax│ value appeared (T ^pk ), Curie temperature (Tc), and RC value were shown.

division T ^pk @1T
(K) │△Smax│
@1T
(J/kg·K) T ^pk @2T
(K) │△Smax│
@2T
(J/kg·K) Example 1 327 7.23 325 16.90 Example 2 335 7.14 335 16.26 Example 3 318 7.81 318 17.14 Example 4 324 7.75 324 17.14 Example 5 318 4.73 318 10.84 Example 6 308 6.26 308 13.76 Example 7 310 7.62 310 17.22 Example 8 309 6.69 309 15.12 Example 9 315 6.89 315 15.45 Example 10 299 5.89 299 13.10 Example 11 282 7.61 282 17.07 Example 12 304 5.71 304 12.68 Example 13 304 7.06 304 15.32 Example 14 288 3.87 288 8.65 Example 15 280 5.87 280 13.33 Example 16 291 5.05 291 11.62

division Tc @1T
(K) RC @2T
(J/kg) Example 1 308 160.6 Example 2 320 132.1 Example 3 299 165.4 Example 4 310 137.9 Example 5 306 134.6 Example 6 297 113.0 Example 7 295 135.5 Example 8 295 125.2 Example 9 301 129.7 Example 10 288 106.9 Example 11 278 163.9 Example 12 290 152.9 Example 13 291 124.5 Example 14 277 94.5 Example 15 274 146.9 Example 16 278 127.1

division T ^pk @1T
(K) │△Smax│
@1T
(J/kg·K) T ^pk @2T
(K) │△Smax│
@2T
(J/kg·K) Comparative Example 1 341 8.02 341 17.93 Comparative Example 2 220 6.43 220 14.46 Comparative Example 3 214 5.51 214 12.17 Comparative Example 4 222 6.71 222 14.21 Comparative Example 5 226 5.95 226 13.04

division Tc @1T
(K) RC @2T
(J/kg) Comparative Example 1 326 127.9 Comparative Example 2 211 140.1 Comparative Example 3 206 152.4 Comparative Example 4 214 115.7 Comparative Example 5 213 96.5

Figure 3 is a diagram showing the change in magnetization properties of the magnetocaloric alloys prepared in Examples 1, 7, 15, and Comparative Example 2 of the present invention according to temperature under the condition of an externally applied magnetic field of 1T.

Referring to Tables 3 to 6 and FIG. 3, in a magnetocaloric alloy having a composition of MnFe _0.95-x Ni _x P _0.5-y Si _0.5+y , the Curie temperature (Tc) decreases as Ni is substituted for Fe. It was confirmed that this was the case. In particular, in the case of the magnetocaloric alloys prepared in Examples 1, 7, and 15 of the present invention, it was confirmed that the Curie temperature (Tc) was in the range of 270 K to 325 K. On the other hand, in the case of Comparative Example 2, it was confirmed that the Curie temperature (Tc) was outside the range of 270 K to 325 K.

Figure 4 shows the Curie temperature and T ^pk of the magnetocaloric alloys prepared in Examples 2, 4, 8, 12, 16, and Comparative Example 3 of the present invention under the condition of an externally applied magnetic field of 1T. It is a drawing.

Referring to Tables 3 to 6 and FIG. 4, it was confirmed that the Curie temperature (Tc) and T ^pk decreased as Ni was substituted for Fe. In particular, in the case of the magnetocaloric alloys prepared in Examples 2, 4, 8, 12, and 16 of the present invention, the Curie temperature (Tc) is in the range of 270 K to 325 K. Confirmed. On the other hand, in the case of Comparative Example 3, it was confirmed that the Curie temperature (Tc) was outside the above-mentioned range.

Figure 5 is a diagram showing the Curie temperature and △T _hys of the magnetocaloric alloys prepared in Examples 1 to 15 of the present invention under the condition of an externally applied magnetic field of 1T. Specifically, Figure 5 (a) shows the Curie temperature of the magnetocaloric alloys prepared in Examples 1 to 15 under the condition of an externally applied magnetic field of 1T. In addition, Figure 5(b) shows ΔT _hys of the magnetocaloric alloys manufactured in Examples 1 to 15 under the condition of an externally applied magnetic field of 1T. At this time, △T _hys means the difference in temperature at which the magnetocaloric effect occurs during heating and cooling of the magnetocaloric alloy, and in the temperature-magnetization curve as shown in Figure 3, each temperature at which the slope is maximum when measuring heating and cooling is obtained through differentiation. It was calculated by calculating the average value.

Referring to Tables 3 to 6 and Figure 5, it was confirmed that as the P content and Si content ratio (Si/P) increases, the Curie temperature tends to increase and then decrease, and △T _hys decreases. It was confirmed that

Figure 6 is an external view of the magnetocaloric alloy prepared in Example 2, Example 4, Example 8, Example 12, Example 16, Comparative Example 1, Comparative Example 3, and Comparative Examples 6 to 8 of the present invention. This is a diagram showing the trend of Curie temperature under 1T magnetic field conditions.

Referring to Tables 3 to 6 and Figure 6, in the composition of the formula MnFe _0.95-x Ni _x P _0.5-y Si _0.5+y , when y is 0, as x increases by 0.01, the Curie temperature is about 7.5. It was confirmed that K tends to decrease. Meanwhile, in the case of the magnetocaloric alloys of Examples 2, 4, 8, 12, and 16 manufactured using arc melting according to an embodiment of the present invention, the magnetocaloric alloys were produced using a solid-state reaction method. Compared to Comparative Examples 6 to 8 prepared, it was confirmed that the Curie temperature tended to be about 70 K lower.

Figure 7 shows the change in magnetic entropy ( This is a drawing showing △S).

Referring to Tables 3 to 6 and Figure 7, in the case of Examples 2, 4, 8, 12, and 16 of the present invention, compared to Comparative Example 3, the temperature was higher than that at a temperature close to room temperature. It was confirmed that a large magnetic entropy change (△Smax) was observed.

Referring to the above-described experimental data, by adjusting the content ratio of Ni and Fe rather than controlling the content ratio of P and Si in the magnetocaloric alloy according to an embodiment of the present invention, the Curie of the magnetocaloric alloy It was confirmed that the temperature could be controlled more effectively. In addition, it was confirmed that the magnetocaloric alloy according to an exemplary embodiment of the present invention exhibits a Curie temperature close to room temperature. Furthermore, it was confirmed that the magnetocaloric alloy according to an exemplary embodiment of the present invention has a ΔSmax value similar to Gd ₅ Si ₂ Ge ₂ , a GMCE (giant magnetocaloric effect) material. In particular, in the case of the magnetocaloric alloy prepared in Example 13, at 304 K, close to room temperature, under the condition of an externally applied magnetic field of 2T, compared to Gd ₅ Si ₂ Ge ₂ , at 304 K, close to room temperature, 15.32 J/kg, equivalent to the above material. It was confirmed that it had a △Smax value of K. Furthermore, the magnetocaloric alloy prepared in Example 3 was confirmed to have an excellent RC value of 165.4 J/kg under the condition of an externally applied magnetic field of 2T.

Accordingly, it can be seen that the magnetocaloric alloy according to an exemplary embodiment of the present invention has a Curie temperature (Tc) relatively close to room temperature and has a high magnetic entropy change (△Sm), showing excellent cooling efficiency.

Although the present invention has been described above with limited examples, the present invention is not limited thereto, and the technical idea of the present invention and the patents described below will be understood by those skilled in the art. Of course, various modifications and variations are possible within the scope of equivalence of the claims.

Claims (14)

It is expressed as the chemical formula MnFe _0.95-x Ni _x P _0.5-y Si _0.5+y ,
0.01≤x≤0.05, -0.05≤y≤0.1,
A magnetocaloric alloy having a Tc (Curie temperature) of 270 K to 325 K.
According to paragraph 1,
A magnetocaloric alloy in which the ratio of Ni content to Fe content is 1:15 to 1:95.
According to paragraph 1,
A magnetocaloric alloy wherein the ratio of the P content to the Si content is 1:0.7 to 1:1.7.
delete According to paragraph 1,
A magnetocaloric alloy having a magnetic entropy change (△Sm) of 3 J/kg·K to 18 J/kg·K.
According to paragraph 1,
A magnetocaloric alloy having an RC (Refrigeration capacity) of 90 J/kg to 170 J/kg.
A raw material mixture for preparing a raw material mixture containing iron (Fe)-based raw materials, manganese (Mn)-based raw materials, nickel (Ni)-based raw materials, silicon (Si)-based raw materials, and iron-phosphorus (Fe-P)-based raw materials. preparatory stage;
An arc melting step of manufacturing an alloy ingot by arc melting the raw material mixture; and
A heat treatment step of heat treating the alloy ingot,
The alloy ingot has a composition expressed by the chemical formula _{MnFe 0.95- x Ni} A method of manufacturing a magnetocaloric alloy.
In clause 7,
The iron (Fe)-based raw material, the manganese (Mn)-based raw material, the nickel (Ni)-based raw material, the silicon (Si)-based raw material, and the iron-phosphorus (Fe-P)-based raw material are in bulk form. Manufacturing method of phosphorus magnetocaloric alloy.
In clause 7,
The arc melting step is,
A first arc melting step of arc melting the raw material mixture under first current conditions; and
A second arc melting step of arc melting the alloy ingot formed by the first arc melting under a second current condition,
The second arc melting step is performed under higher current conditions than the first arc melting step.
According to clause 9,
A method of producing a magnetocaloric alloy, wherein the current ratio of the first current condition and the second current condition is 1:1.5 to 1:2.5.
According to clause 9,
A method of manufacturing a magnetocaloric alloy wherein the arc melting step is performed two or more times.
According to clause 9,
The arc melting step is between the first arc melting step and the second arc melting step,
Cooling the alloy ingot formed by first arc melting; and
Preparing for the second arc melting step by reversing the upper and lower positions of the cooled alloy ingot. The method of manufacturing a magnetocaloric alloy further comprising.
In clause 7,
A method of manufacturing a magnetocaloric alloy, wherein the arc melting step is performed under inert gas conditions.
In clause 7,
A method of producing a magnetocaloric alloy, wherein the heat treatment step is performed at a temperature of 1,200 K or more and 1,600 K or less.