KR101553091B1 - Method for producing metal-based materials for magnetic cooling or heat pumps - Google Patents

Abstract

A method of manufacturing a metal-based material for a self-cooling or heat pump comprises the steps of: a) reacting chemical elements and / or alloys with a stoichiometry corresponding to solid and / or liquid metal-based materials; b) if appropriate, converting the reaction product obtained in step a) to a solid phase; c) sintering and / or heat treating the solid phase obtained from step a) or b); d) quenching the sintered and / or heat treated solid phase obtained from step c) at a cooling rate of at least 100 K / s.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing a metal-

The present invention relates to a method of manufacturing a metal-based material for magnetic cooling or a heat pump, and to the use of such materials and materials thereof. Such materials made in accordance with the present invention are used in self-cooling, heat pumps, or air conditioning systems.

Such a type of material is generally known, for example, in International Patent Application Publication No. WO 2004/068512. The self-cooling technique is based on the magnetocaloric effect (MCE) and can be an alternative to the known steam circulation cooling method. In a material exhibiting a magnetocaloric effect, alignment by an external magnetic field of randomly aligned magnetic moments results in heat generation in the material. This heat can be removed from the MCE material to the ambient environment by heat transfer. Thereafter, when the magnetic field is turned off or removed, the magnetic moment returns to the random arrangement again, which causes the material to cool below ambient temperature. These effects can be developed for cooling (see Nature 415, Jan. 15, 2002, pages 150-152). Generally, a heat transfer medium such as water is used to remove heat from the magnetocaloric material.

A typical such material is prepared by solid phase reaction of the starting element or starting alloy of the material in a ball mill, followed by compression molding, sintering in an inert gas atmosphere and heat treatment and then slowly cooling to room temperature have. This process is described, for example, in J. Appl. Phys. 99, 2006, 08Q107.

It is also possible to treat by melt spinning. This can distribute the elements more homogeneously and improve the magnetic calorie effect (see Rare Metals, 25th October 2006, pages 544-549). In the process disclosed herein, the starting element is first inductively melted in an argon gas atmosphere and then sprayed onto a copper roller rotating through the nozzle in a molten state. Thereafter, it is sintered at 1000 캜 and is slowly cooled to room temperature.

Materials obtained by known processes often exhibit high thermal hysteresis. In a Fe ₂ P type compound substituted with germanium or silicon, a large value of heat history is observed over a wide range of 10K or more. Therefore, the materials are not well suited for magnetocaloric cooling.

It is an object of the present invention to provide a method of manufacturing a metal-based material for self-cooling with reduced thermal history. At the same time, a large magnetic calorie effect (MCE) must be achieved.

According to the present invention,

a) reacting chemical elements and / or alloys with a stoichiometry corresponding to a solid and / or liquid metal-based material;

b) if appropriate, converting the reaction product obtained in step a) to a solid phase;

c) sintering and / or heat treating the solid material obtained from step a) or b);

d) quenching the sintered and / or heat treated solid matter obtained from step c) at a cooling rate of at least 100 K / s

And a method of manufacturing a metal-based material for a self-cooling or heat pump.

According to the present invention, it has been confirmed that the thermal history can be remarkably reduced when the metal-based material is quenched at a large cooling rate instead of gradually cooling to the ambient temperature after sintering and / or heat treatment. The cooling rate is at least 100 K / s. The cooling rate is preferably 100 to 10000 K / s, and more preferably 200 to 1300 K / s. Particularly preferably, the cooling rate is 300 to 1000 K / s.

This quenching can be achieved by any suitable cooling process, for example by quenching the solid matter in water or an aqueous liquid such as cold water or an ice / water mixture. For example, solid matter can be soaked in ice / cold water. In addition, the solid material may be quenched by a sub-cooled gas such as liquid nitrogen. Other quench processes are known to those skilled in the art. Beneficial is controlled rapid cooling.

Without wishing to be bound by theory, the reduced thermal history can be attributed to the smaller particle size for the quenched composition.

In the conventionally known process, after sintering and heat treatment, respectively, the cryogen is formed, resulting in a large particle size and thus a thermal history.

The remainder of the manufacturing process of the metal-based material is not critical if the solid material sintered and / or heat treated in the last step is quenched at the cooling rate of the present invention. The process can be applied to produce any suitable metal-based material for self-cooling. Conventional materials for self-cooling are multi-metal mixtures, often containing at least three metallic elements and, if applicable, further non-metallic elements. Here, the term "metal-based material" means that the material consists of a substantial proportion of metallic or metallic elements. Typically, the proportion in the total material is at least 50% by weight, preferably at least 75% by weight, particularly preferably at least 80% by weight. Hereinafter, a suitable metal-based material will be described in detail.

In step a) of the process according to the invention, the elements and / or alloys which will later be present in the metal-based material react in a stoichiometrical manner corresponding to solid or liquid metal-based materials.

The reaction in step a) is preferably carried out by heating the elements and / or alloys together in a closed vessel or extruder, or by a solid phase reaction in a ball mill. Particularly preferably in a ball mill. This reaction is basically known (see literature cited in the introduction). Usually, the powders of the individual elements present in the metal-based material or the powders of the alloys of two or more elements are mixed in powder form at an appropriate weight ratio. If desired, the mixture may be further pulverized to obtain a microcrystalline powder mixture. Preferably, the powder mixture is heated in a ball mill to further reduce size and to achieve good mixing and to achieve a solid phase reaction in the powder mixture.

Alternatively, the individual elements are mixed as powders in the selected stoichiometry and then melted.

Co-heating in a closed vessel allows fixing of volatile elements and control of stoichiometry. In particular, when phosphorus is used, phosphorus will easily vaporize in the oven system.

After such a reaction, the sintering and / or heat treatment of the solid material is followed, and one or more intermediate steps may be provided for this purpose. For example, the solid material obtained in step a) may be compression molded before sintering and / or heat treatment. This increases the density of the material so that high density magnetic calorific material can be present in future applications. This is particularly advantageous in that it is possible to achieve a reduction in the volume at which a magnetic field is present which can be associated with significant cost savings. Compression molding is essentially known and can be carried out with or without the use of a compression molding apparatus. Any suitable mold may be used for compression molding. By this compression molding, a molded body having a desired three-dimensional structure can be obtained in advance. After compression molding, sintering and / or heat treatment of step c) may be performed followed by quenching of step d).

Alternatively, the solid material obtained from the ball mill can be sent to the melt spinning process. The molten spinning process is known in the art and is disclosed, for example, in Rare Metals, Oct. 25, 2006 (see pages 544-549) and in International Patent Application Publication No. WO 2004/068512.

In this process, the composition obtained in step a) is melted and sprayed onto a rotating low-temperature metal roller. Such spraying may be accomplished by an elevated pressure on the upstream side of the spray nozzle or a reduced pressure on the downstream side of the spray nozzle. Typically, a rotating copper drum or roller can be used, and the drum or roller can be further cooled, if appropriate. The copper drum is preferably rotated at a surface speed of 10 to 40 m / s, particularly at a surface speed of 20 to 30 m / s. The liquid composition is preferably applied on the copper drum at a speed of from 10 ² to 10 ⁷ K / s, more preferably at a speed of at least 10 ⁴ K / s, particularly preferably from 0.5 × 10 ⁶ to 2 × 10 ⁶ K / s. < / RTI >

Melting spinning can be carried out under reduced pressure or in an inert gas atmosphere as in the reaction in step a).

Melting spinning achieves high throughput rates because it can shorten subsequent sintering and heat treatment. Thus, especially on an industrial scale, the production of metallic materials is considerably more practical in terms of economy. Spray drying can also lead to high throughput rates. It is particularly preferred to perform melt spinning.

Alternatively, in step b) spray cooling may be performed to spray the melt of the composition obtained from step a) into the spray tower. The spray tower can be further cooled, for example. At the spray tower, a cooling rate of 10 ³ to 10 ⁵ K / s, especially about 10 ⁴ K / s, is often achieved.

The sintering and / or heat treatment of the solid material is effected in step c), preferably by first sintering at a temperature in the range of 800 to 1400 占 폚 and then at a temperature in the range of 500 to 750 占 폚. Such temperature values are particularly applicable to the shaped body, but lower sintering and heat treatment temperatures may be used for the powder. In that case, for example, the sintering can be carried out at a temperature in the range of 500 to 800 ° C. In the case of the molded body / solid phase, the sintering is preferably carried out at a temperature in the range of 1000 to 1300 占 폚, particularly preferably at a temperature of 1100 to 1300 占 폚. Thereafter, the heat treatment may be performed at, for example, 600 to 700 占 폚.

The sintering is preferably performed for 1 to 50 hours, more preferably 2 to 20 hours, particularly preferably 5 to 15 hours. The heat treatment is preferably performed for 10 to 100 hours, more preferably 10 to 60 hours, particularly preferably 30 to 50 hours. The exact time can be adjusted according to the material requirements of the material.

In the case of using a melt spinning process, sintering can often be omitted, and the heat treatment can be considerably shortened, for example, from 5 minutes to 5 hours, preferably from 10 minutes to 1 hour. This has significant temporal advantages when compared to 10 hours for normal sintering and 50 hours for heat treatment.

The sintering and / or heat treatment results in partial melting of the grain boundaries, making the material more dense.

Thus, melting and rapid cooling in step b) can significantly reduce the duration of step c). This also enables the continuous production of metal-based materials.

According to the present invention, a method according to the following procedure is particularly preferable.

a) solid-phase reaction of a chemical element and / or an alloy in a ball mill with a stoichiometry corresponding to the metal-based material,

b) melt spinning the material obtained in step a)

c) subjecting the solid material obtained from step b) to a heat treatment at a temperature in the range of 430 to 1200 ° C, preferably 800 to 1000 ° C for 10 seconds or 1 minute to 5 hours, preferably 30 minutes to 2 hours,

d) The shaped body heat-treated in step c) is quenched at a cooling rate of 200 to 1300 K / s.

The method according to the invention can be used for any suitable metal-based material.

The metal-based material is more preferably selected from the following compounds.

(1) a compound of general formula (I)

(A _y B _1-y ) _{2 + 隆} C _w D _x E _z (I)

Here, A: Mn or Co,

B: Fe, Cr or Ni,

C, D and E: at least two of C, D and E are different and are selected from P, B, Se, Ge, Ga, Si, Sn, N, As and Sb with non- , At least one of C, D and E is Ge or Si,

?: a number in the range of -0.1 to 0.1,

w, x, y, z: w + x + z = 1 in the range of 0 to 1;

(2) The La-based and Fe-based compounds represented by the following general formulas (II), (III), and /

La (Fe _x Al _{1 -x} ) ₁₃ H _y or La (Fe _x Si _{1 -x} ) ₁₃ H _y (II)

Where x is a number in the range of 0.7 to 0.95,

y is a number ranging from 0 to 3, preferably from 0 to 2;

La (Fe _x Al _y Co _z ) ₁₃ or La (Fe _x Si _y Co _z ) ₁₃ (III)

Where x is a number in the range of 0.7 to 0.95,

y is a number in the range of 0.05 to 1-x,

z is a number in the range of 0.005 to 0.5;

LaMn _x Fe _{2 - x} Ge (IV)

Where x is a number in the range of 1.7 to 1.95,

(3) a Heusler alloy of the MnTP type, wherein T is a transition metal, and P is a p-doped metal having an electron number e / a in the range of 7 to 8.5 per atom.

Particularly suitable materials for the present invention are described, for example, in International Patent Application Publication No. WO 2004/068512, Rare Metals (see No. 254, pages 544-549, 2006), J. Appl. Phys., Vol. 99, 08Q107 (2006), Nature (Jan. 10, 2002, 415, pp. 150-152), and Physica B (327 (2003), 431-437).

In the above general formula (I), C, D and E are preferably the same or different and are selected from at least one of P, Ge, Si, Sn and Ga.

The metal-based material of general formula (I) preferably comprises Mn, Fe, P and, if applicable, Sb, further comprising Ge or Si, or As, or Ge and Si, or Ge and As or Si and As or Ge, at least one quaternary compound further comprising Si and As.

Preferably, at least 90 wt.%, More preferably at least 95 wt.% Of component A is Mn. Preferably, at least 90 wt.%, More preferably at least 95 wt.% Of component B is Fe. Preferably at least 90% by weight, more preferably at least 95% by weight, of component C is P. Preferably, at least 90 wt.%, More preferably at least 95 wt.% Of component D is Ge. Preferably, at least 90 wt.%, More preferably at least 95 wt.% Of component E is Si.

The material preferably has the general formula MnFe (P _w Ge _x Si _z).

In this case, x is preferably a number in the range of 0.3 to 0.7, w is 1-x or less, and z is 1-x-w.

The material preferably has a hexagonal Fe ₂ P structure. An example of a suitable construction is a MnFeP _{0.45 to 0.7} Ge _{0 .55 to 0,30} and MnFeP _{0 .5 to 0.70} (Si / Ge) _{0.5 to 0.30.}

Suitable compounds further include Mn _{1 + x} Fe _1-x P _{1 -y} Ge _y where x ranges from -0.3 to 0.5 and y ranges from 0.1 to 0.6. Similarly, the general formula Mn _{1 + x} Fe _1-x P _1-y Ge _yz Sb _z (where x is in the range of -0.3 to 0.5, y is in the range of 0.1 to 0.6, and z is a number less than 0.2, Suitable. Further, the general formula _{Mn 1 + x Fe 1-x} P 1-y Ge yz Si z ( where, x is 0.3 to 0.5 range, y is from 0.1 to 0.66 range, and z is a number less than 0.6 less than y) is also suitable Do.

General formula (Ⅱ), (Ⅲ), and / or (Ⅳ) Preferred La-based, and Fe-based compound as the _{La (Fe 0.90 Si 0.10) 13} , of the _{La (Fe 0 .89 Si 0 .11} ) 13, La ( _{Fe 0 .880 Si 0 .120) 13} , La (Fe 0 .877 Si 0 .123) 13, LaFe 11.8 Si 1.2, La (Fe 0.88 Si 0.12) 13 H 0.5, La (Fe 0.88 Si 0.12) 13 H 1.0 , LaFe _11.7 Si _1.3 H _1.1 , LaFe _11.57 Si _1.43 H _1.3 , La (Fe _0.88 Si _0.12 ) H _1.5 , LaFe _11.2 Co _0.7 Si _1.1 , LaFe _11.5 Al _1.5 C _0.1 , LaFe _11.5 Al _1.5 C _0.2 , LaFe _11.5 Al _1.5 C _0.4 , LaFe _11.5 Al _1.5 Co _0.5 , La (Fe _0.94 Co _0.06 ) _11.83 Al _1.17 , and La (Fe _0.92 Co _0.08 ) _11.83 Al _1.17 .

Examples of suitable manganese-containing compounds include MnFeGe, MnFe _0.9 Co _0.1 Ge, MnFe _0.8 Co _0.2 Ge, MnFe _0.7 Co _0.3 Ge, MnFe _0.6 Co _0.4 Ge, MnFe _0.5 Co _0.5 Ge, MnFe _0.4 Co _0.6 Ge, MnFe _0.3 Co _0.7 Ge , MnFe _0.2 Co _0.8 Ge, MnFe _0.15 Co _0.85 Ge, MnFe _0.1 Co _0.9 Ge, MnCoGe, Mn ₅ Ge _2.5 Si _0.5 , Mn ₅ Ge ₂ Si, Mn ₅ Ge _1.5 Si _1.5 , Mn ₅ GeSi ₂ , Mn ₅ Ge _{3 , Mn 5 Ge 2.9 Sb 0.1,} Mn 5 Ge 2.8 Sb 0.2, Mn 5 Ge 2.7 Sb 0.3, LaMn 1.9 Fe 0.1 Ge, .8 LaMn 1 .85 Fe 0 .15 Ge, LaMn 1 Fe 0 .2 Ge, (Fe _{0 .9 Mn 0 .1) 3 C} , (Fe 0 .8 Mn 0 .2) 3 C, (Fe 0.7 Mn 0.3) 3 C, Mn 3 GaC, MnAs, (Mn, Fe) As, Mn 1 + δ As _{0 .8} Sb _{0 .2} , MnAs _{0 .75} Sb _{0 .25} , Mn _1.1 As _0.75 Sb _0.25 , Mn _{1 .5} As _{0 .75} Sb _{0 .25} .

Suitable Hoesler alloys in the present invention include: For example, Fe ₂ MnSi _0.5 Ge _0.5 , Ni _52.9 Mn _22.4 Ga _24.7 , Ni _50.9 Mn _24.7 Ga _24.4 , Ni _55.2 Mn _18.6 Ga _26.2 , Ni _51.6 Mn _24.7 Ga _23.8 , Ni _52.7 Mn _23.9 Ga _23.4 , CoMnSb, CoNb _0.2 Mn _{0.8 Sb, CoNb 0.4 Mn 0.6 Sb} , CoNb 0.6 Mn 0.4 Sb, Ni 50 Mn 35 Sn 15, Ni 50 Mn 37 Sn 13, MnFeP 0.45 As 0.55, MnFeP 0 .47 As 0 .53, Mn 1 .1 Fe 0. ₉ P _{0 .47} As _{0 .53} , MnFeP _{0 .89-χ} Si _χ Ge _{0 .11} (where χ = 0.22, χ = 0.26, χ = 0.30, χ = 0.33).

The present invention also relates to a metal-based material for self-cooling which can be obtained by the above-described method.

In addition, the present invention relates to a composition as defined above for a composition other than an As-containing material having an average crystal size in the range of 10 to 400 nm, more preferably in the range of 20 to 200 nm, particularly preferably in the range of 30 to 80 nm And to a self-cooling metal-based material. The average crystal size can be measured by X-ray diffraction. When the crystal size is too small, the maximum magnetic calorie effect decreases. Conversely, when the crystal size is too large, the history of the system increases.

The metal-based material of the present invention is preferably used for self-cooling as described above. The refrigerator includes a magnet, preferably a permanent magnet, as well as a metal-based material as described above. Cooling of computer chips and solar generators is also possible. Other applications include heat pumps and air conditioning systems.

The metal-based material produced by the method according to the present invention can be in any desired solid phase shape. These materials can also be in the form of flakes, ribbons, wires, powders, or shaped bodies. A molded body such as a monolith or a honeycomb can be produced by, for example, a hot extrusion process. For example, it may have a cell density of 400 to 1600 CPI or higher. According to the present invention, a thin sheet obtainable by a rolling process is also preferable. Advantageous non-porous shaped bodies include those formed of thin shapes such as tubes, plates, meshes, grids or rods. According to the present invention, metal injection molding (MIM) molding is also possible.

Hereinafter, the present invention will be described in detail by way of examples thereof.

Example

Example 1

A vacuum quartz ampoule containing a compression molded sample of MnFePGe was maintained at 1100 [deg.] C for 10 hours to sinter the powder. After the sintering, it was heat treated at a temperature of 650 ° C for 60 hours to homogenize it. Instead of slowly cooling from the oven to room temperature, the sample was quenched directly in water to room temperature. Quenching in water caused some oxidation at the sample surface. The crushed husks were removed by etching with dilute acid. In the XRD (X-ray diffraction) pattern, all the samples were found to be crystallized into Fe ₂ P type structure.

The following composition was obtained.

_{Mn 1 .1 Fe 0 .9 P 0} .81 Ge 0 .19, Mn 1 .1 Fe 0 .9 P 0 .78 Ge 0 .22, Mn 1 .1 Fe 0 .9 P 0 .75 Ge 0 .25 _, And Mn _1.2 Fe _0.8 P _0.81 Ge _0.19 . The observed values for thermal history were 7K, 5K, 2K and 3K, respectively, for the samples in the order mentioned. When compared with the slow cooling sample having a thermal history larger than 10K, the thermal history was remarkably reduced.

The thermal history was measured at a magnetic field of 5 Tesla.

FIG. 1 shows the isothermal magnetization of Mn _1.1 Fe _0.9 P _0.78 Ge _0.22 while increasing the magnetic field near the magnetic transformation temperature. Field-induced transition behavior was observed that produced large MCEs in magnetic fields of up to 5 Tesla.

The magnetostriction temperature can be controlled by varying the Mn / Fe ratio and Ge concentration as well as the value for the thermal history.

The change in magnetic entropy calculated from the DC current magnetization using the Maxwell relation is 14 J / kgK, 20 J / kgK, and 12.7 J / kgK for the three frontal samples, respectively, in the case of the maximum magnetic field change from 0 to 2 Tesla, kgK.

The magnetostriction temperature and thermal history decrease with increasing Mn / Fe ratio. Thus, MnFePGe compounds exhibit relatively large MCEs at low magnetic fields. The thermal history of these materials is very low.

Example 2

Melt Spinning of MnFeP (GeSb)

First, International Patent Application Publication No. WO 2004/068512 and J. Appl. Polycrystalline MnFeP (GeSb) alloys were prepared by the solid state reaction method using a high energy input in a ball mill as disclosed in Phys. (99, 08Q107 (2006)). The material specimen was then introduced into a quartz tube with a nozzle. These chambers were evacuated to a vacuum of 10 ^-2 mbar and then filled with high purity argon gas. After melting the sample at high frequencies, the spinning copper drum was sprayed through the nozzle by a pressure differential to the chamber receiving it. The surface speed of the drum was copper can be adjusted, the cooling rate of about 10 ⁵ K / s were achieved. The molten spinning ribbon was then heat treated at 900 占 폚 for 1 hour.

X-ray diffraction analysis revealed that all the samples were crystallized into a hexagonal Fe ₂ P structure pattern. Unlike the sample not prepared by the melt spinning method, a small contamination phase of MnO was not observed.

The values obtained for the Curie temperature, the thermal hysteresis, and the entropy were measured for different circumferential speeds in melt spinning. The results are shown in Tables 1 and 2 below. In each case a low hysteresis temperature was measured.

Claims (10)

A method of manufacturing a metallic material for a self-cooling or heat pump,
a) reacting either or both of the chemical elements and the alloys with a stoichiometry corresponding to the metal-based material in a state of either or both of a solid phase and a liquid phase;
b) if appropriate, converting the reaction product obtained in step a) to a solid phase;
c) carrying out either or both of sintering and heat treatment of the solid material obtained from step a) or b);
d) quenching the solid material obtained from step c), in which either or both of sintering and heat treatment have been carried out, at a cooling rate in the range of 200 to 1300 K / s
Lt; / RTI >
The metal-
(1) a compound of general formula (I)
(A _y B _1-y ) _{2 + 隆} C _w D _x E _z (I)
Here, A: Mn or Co,
B: Fe, Cr or Ni,
C, D and E: at least two of C, D and E are different and are selected from P, B, Se, Ge, Ga, Si, Sn, N, As and Sb with non- , At least one of C, D and E is Ge or Si,
?: a number in the range of -0.1 to 0.1,
w, x, y, z: w + x + z = 1 in the range of 0 to 1; And
(2) a Hoesler alloy of the MnTP type, where T is a transition metal and P is a p-doped metal having an electron number e / a in the range of 7 to 8.5 per atom,
≪ / RTI > The process according to claim 1, wherein the reaction in step a) is carried out by heating the element and / or the alloys together in a closed vessel or extruder, or by a solid phase reaction in a ball mill Based on the total amount of the metal material. The method according to claim 1, wherein the conversion to solid phase in step b) is carried out by melt spinning or spray cooling. The method according to claim 1, wherein in step c), sintering is first carried out at a temperature in the range of 800 to 1400 占 폚, followed by a heat treatment at a temperature in the range of 500 to 750 占 폚. The method of claim 1, wherein the metal-based material comprises Mn, Fe, P, and if appropriate Sb, and further comprises Ge or Si, or As, or Ge and As, or Si and As, or Ge , At least one quaternary compound of general formula (I) further comprising Si and As. The method according to claim 1,
comprising the steps of: a) solid-reacting either or both of the chemical elements and the alloys in a ball mill in a stoichiometry corresponding to the metal-based material;
b) melt spinning the material obtained in step a);
c) heat treating the solid phase obtained from step b) at a temperature in the range of 430 to 1200 ° C, preferably 800 to 1000 ° C for 10 seconds or 1 minute to 5 hours, preferably 30 minutes to 2 hours; And
d) quenching the shaped body heat-treated in step c) at a cooling rate of 200 to 1300 K / s
Based on the weight of the metal material. A metal-based material for a self-cooling or heat pump having an average crystal size in the range of 10 to 400 nm, which can be obtained by the method of manufacturing a metal-based material according to claim 1, delete delete delete