阅读说明：本技术 一种改善热电磁制冷器件界面反应的热电磁元件及其制备方法 (Thermo-electromagnetic element for improving interface reaction of thermo-electromagnetic refrigeration device and preparation method thereof ) 是由 赵文俞 朱武 魏平 张健强 贺丹琪 朱婉婷 聂晓蕾 桑夏晗 张清杰 于 2021-08-06 设计创作，主要内容包括：本发明涉及热电器件制造领域,公开了一种改善热电磁制冷器件界面反应的热电磁元件,它包括块体热电磁材料及设计制备在其表面的合金镀层。本发明通过在热电磁材料表面设计制备合金镀层作为阻挡材料,并通过对电镀工艺进行调控,所得合金镀层可有效改善热电磁制冷器件界面反应,显著降低界面电阻和有效提高电极与热电磁材料间界面结合能力,有助于提高热电磁全固态制冷器件的热稳定性和使用寿命；且涉及的制备方法较简单、操作方便,适合推广应用。(The invention relates to the field of thermoelectric device manufacturing, and discloses a thermoelectric magnetic element for improving interface reaction of a thermoelectric magnetic refrigeration device. According to the invention, the alloy coating is designed and prepared on the surface of the thermoelectric magnetic material to serve as a barrier material, and the electroplating process is regulated and controlled, so that the obtained alloy coating can effectively improve the interface reaction of the thermoelectric magnetic refrigeration device, remarkably reduce the interface resistance, effectively improve the interface bonding capability between the electrode and the thermoelectric magnetic material, and contribute to improving the thermal stability and the service life of the thermoelectric all-solid-state refrigeration device; and the related preparation method is simple, convenient to operate and suitable for popularization and application.)

1. The thermoelectromagnetic element for improving the interface reaction of the thermoelectromagnetic refrigeration device is characterized by comprising a block thermoelectromagnetic material and an alloy coating arranged on the surface of the block thermoelectromagnetic material, wherein the alloy coating contains alloy elements comprising cobalt and auxiliary alloy elements, and the auxiliary alloy elements are one or more of nickel, iron, copper, zinc and aluminum.

2. The thermo-electromagnetic element according to claim 1, wherein the cobalt content in the alloy plating layer is 75% or more.

3. The thermo-electromagnetic element of claim 1, wherein the bulk thermo-electromagnetic material is N-type and P-type Bi₂Te₃The base alloy thermoelectric material and the magnetic material form a block composite material respectively.

4. A method for preparing a thermo-electromagnetic element for improving the interface reaction of a thermo-electromagnetic refrigerating device as recited in any one of claims 1 to 3, comprising the steps of:

1) cleaning and surface treating the thermoelectric magnetic material, wherein the surface treating sequentially comprises the steps of degreasing and pickling;

2) placing the surface-treated thermoelectric magnetic material in electroplating solution for electroplating; the electroplating solution comprises the following components in percentage by weight: 80-100 g/L of cobalt salt, 10-80 g/L of auxiliary metal salt, 20-40 g/L of boric acid, 0.05-2 g/L of sodium dodecyl sulfate, 0.05-0.2 g/L of saccharin, and the pH value of the mixture is 3-5;

3) and cleaning and drying the electroplating product to obtain the final product.

5. The method according to claim 4, wherein the cobalt salt is cobalt sulfate or cobalt chloride; the auxiliary metal salt is chloride or sulfate of one or more alloy elements of nickel, iron, copper, zinc and aluminum.

6. The method according to claim 4, wherein the content of the different alloy salts in the auxiliary metal salt includes: 10-30 g/L of nickel chloride, 10-50 g/L of ferric chloride, 10-60 g/L of copper chloride, 10-60 g/L of zinc nitrate and 10-80 g/L of aluminum nitrate.

7. The preparation method according to claim 4, wherein the degreasing step is carried out by ultrasonic treatment using a degreasing solvent, wherein the degreasing solvent comprises the following components in parts by weight: 60-80 g/L of sodium hydroxide, 20-40 g/L of sodium carbonate, 20-40 g/L of sodium phosphate and 10-40 g/L of water glass; the ultrasonic treatment temperature is 65-85 ℃, and the time is 10-30 min.

8. The method according to claim 4, wherein the acid washing step uses a mixed acid solution prepared from hydrochloric acid and hydrofluoric acid, wherein the HCl is introduced at a concentration of 20-30% by volume and the HF is introduced at a concentration of 30-40% by volume; the pickling time is 1-3 min.

9. The production method according to claim 4, wherein the plating step includes: electroplating by applying direct current with a thermoelectric magnetic material as a cathode and a platinum sheet or gold sheet electrode as an anode; wherein the temperature of the plating solution is 40-50 ℃, and the current density is 0.5-1.5A/dm²The electroplating time is 5-20 min.

10. The preparation method according to claim 4, wherein the cleaning step in the step 3) comprises sequentially performing hot water cleaning and cold water cleaning, wherein the hot water temperature is 60-80 ℃, and the hot water cleaning time and the cold water cleaning time are both 5-20 min.

Technical Field

The invention belongs to the technical field of manufacturing of all-solid-state refrigerating devices, and particularly relates to a thermo-electromagnetic element for improving interface reaction of a thermo-electromagnetic refrigerating device and a preparation method thereof.

Background

The thermal electromagnetic all-solid-state refrigerating device is electronic equipment capable of realizing thermoelectric magnetic energy conversion, has the advantages of no movable part, easiness in maintenance, small size and the like, and is widely applied to the fields of thermoelectric magnetic energy conversion refrigeration, heating, bidirectional temperature control and the like. The structure of the thermal electromagnetic all-solid-state refrigerating device is complex, and the thermal electromagnetic all-solid-state refrigerating device is formed by connecting a plurality of thermal electromagnetic refrigerating elements in series or in parallel through electrodes, wherein each thermal electromagnetic refrigerating element is in an N-shaped structure formed by connecting 1N-type and 1P-type thermal electromagnetic materials in series through electrodes.

In the device manufacturing process, in order to avoid interface thermal diffusion reaction when the thermoelectric magnetic material is soldered with the electrode, an interface reaction barrier layer is generally required to be electroplated on the surface of the thermoelectric magnetic material. At present, there are no patents and literature reports on the manufacturing aspect of the thermal electromagnetic all-solid-state refrigeration device. A similar commercial thermoelectric refrigeration device generally uses metallic nickel as a barrier layer between the thermoelectric material and the electrode to slow down the thermal diffusion reaction between the tin solder and the thermoelectric material. However, the single-metal nickel barrier layer has the problems of poor thermal stability and the like, and the metal nickel is easy to chemically react with the tellurium element which is easy to diffuse in the bismuth telluride-based thermoelectric material to form an interface layer during high-temperature soldering, so that the long-term stable service of the thermoelectric refrigerating device is not facilitated. At present, the research on the barrier layer materials is single metal, and an efficient and convenient preparation method on the surface of a sliced wafer of the thermoelectric material is not provided, so that the interface reaction barrier material capable of effectively reducing the interface resistance and improving the interface bonding capability between the electrode and the thermoelectric material and a synthesis process thereof are further explored, the thermal stability and the service life of the all-solid-state thermoelectric refrigerating device are further improved, and the method has important research and application significance.

Disclosure of Invention

The invention mainly aims to solve the problems of poor thermal stability and the like of the interface reaction barrier layer material of the existing thermoelectric magnetic device, and provides a thermoelectric magnetic element for improving the interface reaction of the thermoelectric magnetic refrigeration device, wherein the barrier material (alloy coating) for improving the interface reaction of the thermoelectric magnetic refrigeration device is designed and prepared on the surface of the thermoelectric magnetic material, so that the material can obviously reduce the interface resistance, effectively improve the interface bonding capability between an electrode and the thermoelectric magnetic material, and is favorable for improving the thermal stability and the service life of the thermoelectric magnetic all-solid-state refrigeration device; and the related preparation method is simple, convenient to operate and suitable for popularization and application.

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

a thermoelectromagnetic element for improving the interface reaction of a thermoelectromagnetic refrigeration device comprises a block thermoelectromagnetic material and an alloy coating designed and prepared on the surface of the block thermoelectromagnetic material, wherein the alloy coating contains alloy elements comprising cobalt and auxiliary alloy elements, and the auxiliary alloy elements are one or more of nickel, iron, copper, zinc and aluminum.

Preferably, the content of the cobalt element in the alloy plating layer is 75% or more.

More preferably, the content of cobalt element in the alloy plating layer is 80% or more.

In the scheme, the bulk thermoelectric magnetic material is N-type Bi or P-type Bi₂Te₃The surface of the block composite material formed by the base alloy thermoelectric material and the magnetic material is flat and smooth.

In the scheme, the thickness of the alloy coating is 1-5 mu m.

In the scheme, the magnetic material can be selected from nano Ni particles and nano Fe₃Q₄Particles, and the like.

The preparation method of the thermoelectric magnetic element for improving the interface reaction of the thermoelectric magnetic refrigeration device comprises the following steps:

1) cleaning and surface treating the thermoelectric magnetic material, wherein the surface treating sequentially comprises the steps of degreasing and pickling;

2) placing the surface-treated thermoelectric magnetic material in electroplating solution for electroplating; the electroplating solution comprises the following components in percentage by weight: 80-100 g/L of cobalt salt, 10-80 g/L of auxiliary metal salt, 20-40 g/L of boric acid, 0.05-0.2 g/L of sodium dodecyl sulfate, 0.05-2 g/L of saccharin and 3-5 of pH value;

3) and cleaning and drying the electroplating product to obtain the final product.

In the scheme, the cobalt salt can be one or more of cobalt sulfate, cobalt chloride and the like.

In the scheme, the auxiliary metal salt is chloride or sulfate of one or more alloy elements of nickel, iron, copper, zinc and aluminum.

In the above scheme, the content of different alloy salts in the auxiliary metal salt includes: 10-30 g/L of nickel chloride, 10-50 g/L of ferric chloride, 10-60 g/L of copper chloride, 10-60 g/L of zinc nitrate and 10-80 g/L of aluminum nitrate.

In the scheme, the cleaning step in the step 1) is to immerse the substrate in acetone for 10-30 min.

In the above scheme, the oil removing step adopts an oil removing solvent for ultrasonic treatment, wherein the oil removing solvent comprises the following components in percentage by weight: 60-80 g/L of sodium hydroxide, 20-40 g/L of sodium carbonate, 20-40 g/L of sodium phosphate and 10-40 g/L of water glass; the ultrasonic treatment temperature is 65-85 ℃, and the time is 10-30 min.

In the scheme, the acid washing step adopts a mixed acid solution prepared from hydrochloric acid and hydrofluoric acid, wherein the concentration of introduced HCl is 20-30% by volume, and the concentration of HF is 30-40% by volume; pickling time is 1-3 min; and washing and drying after acid washing.

In the above scheme, the electroplating step includes: electroplating by applying direct current with a thermoelectric magnetic material as a cathode and a platinum sheet or gold sheet electrode as an anode; wherein the temperature of the plating solution is 40-50 ℃, and the current density is 0.5-1.5A/dm²Controlling the electroplating time to be 5-20 min according to the thickness requirement of an electroplated layer; the electroplating solution needs to be stirred in the electroplating process, so that bubbles generated in the electroplating process are prevented from being attached to the surface of the cathode, and the quality of the coating is prevented from being influenced.

In the scheme, the cleaning step in the step 3) is to sequentially perform hot water cleaning and cold water cleaning, the hot water temperature is 60-80 ℃, and the hot water cleaning time and the cold water cleaning time are both 5-20 min.

In the scheme, the drying temperature is 70-90 ℃, and the drying time is not less than 10 min.

Compared with the prior art, the invention has the beneficial effects that:

1) according to the invention, the alloy thin film layer is designed and prepared on the surface of the thermoelectric magnetic material and is used as a barrier layer for interface reaction of the thermal electromagnetic all-solid-state refrigerating device, so that the stability of a heterogeneous interface can be effectively improved, the interface resistance is obviously reduced, the interface bonding capability between an electrode and the thermoelectric magnetic material is effectively improved, the thermal stability and the service life of the thermal electromagnetic all-solid-state refrigerating device are favorably improved, and the service performance of the device is further improved;

2) the alloy thin film layer with higher strength can simultaneously improve the yield of the thermoelectric magnetic material processing, is beneficial to reducing the manufacturing cost and further improves the economic benefit of device manufacturing enterprises;

3) the preparation method provided by the invention is simple, convenient to operate and suitable for popularization and application.

Drawings

FIG. 1 is a scanning electron microscope image of (a) the surface and (b) the cross section of the electroplated alloy barrier material obtained in example 1;

FIG. 2 is a TEM elemental surface scan of the interface between the ferromagnetic material and the Co-Ni alloy after annealing at 200 ℃ for 48h, wherein (a) is a topographical map, (b) is a Ni element distribution map, (c) is a Co metal distribution map, (d) is a Bi metal distribution map, (e) is a Te metal distribution map, and (f) is a Se metal distribution map, of the thermoelectromagnetic element obtained in example 1;

FIG. 3 is a TEM elemental surface scan of the interface of the electroplated single-metal nickel-barrier N-type thermoelectric magnetic material after annealing at 200 ℃ for 48h, wherein (a) is a topographic map, (b) is a Ni element distribution map, (c) is a Bi metal distribution map, (d) is a Te metal distribution map, and (e) is a Se metal distribution map;

fig. 4 is a graph comparing the performance of TEC1-12706 devices made from the electroplated alloy barrier layer obtained in example 1 with that of electroplated nickel devices.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the following examples, the thermo-electric magnetic materials used are each Bi₂Te₃Bulk composite material composed of base alloy thermoelectric material and nano Ni particle magnetic material or Bi₂Te₃Base alloy thermoelectric material and nano Fe₃Q₄A bulk composite material composed of a particle magnetic material; the specific preparation method is respectively referred to the Effects of Ni Magnetic Nanoparticles on thermoplastic Properties of n-Type Bi₂Te_2.7Se_0.3 Materials[J]Journal of Electronic Materials,2020 and documents Li C, Ma S, Wei P, et al, Magnetism-induced hue enhancement of room-temperature thermal and cosmetic requirements of P-type BiSbTealloys [ J].Energy&Environmental Science,2019,13(2)。

Example 1

A thermoelectricity magnetic element for improving the interface reaction of a thermoelectricity magnetic refrigeration device is prepared by the following steps:

1) preparation of a thermoelectric material from Bi₂Te₃Base alloy thermoelectric material and nano Fe₃Q₄The surface of the block composite material formed by the particle magnetic material is flat and smooth;

2) surface treatment of the thermoelectric magnetic material;

firstly, soaking the thermoelectric magnetic material in acetone for 10min, and then putting an oil removing solvent into the soaked thermoelectric magnetic material for ultrasonic cleaning for 20 min; wherein the adopted oil removing solvent comprises the following components in percentage by weight: 70g/L of sodium hydroxide, 30g/L of sodium carbonate, 30g/L of sodium phosphate and 10g/L of water glass at the temperature of 75 ℃;

soaking the deoiled thermoelectric magnetic material into an acid solution for cleaning for 1min, and then cleaning with deionized water; wherein the adopted acid solution is formed by mixing hydrochloric acid (40 vol%) and hydrofluoric acid (60 vol%) according to the volume ratio of 1: 1;

3) placing the surface-treated thermoelectric magnetic material obtained in step 2) in electroplating solution, using the thermoelectric magnetic material as cathode, platinum sheet electrode as anode, controlling the temperature of the electroplating solution at 40 deg.C, and applying DC current for electroplating (current density of 0.6A/dm)²) Root of Chinese characterControlling the electroplating time to be 10min according to the requirement of the thickness of an electroplated layer; the formula conditions of the adopted electroplating solution are as follows: 100g/L of cobalt sulfate, 20g/L of nickel chloride, 30g/L of boric acid, 0.1g/L of sodium dodecyl sulfate and 1g/L of saccharin; further adopting sulfuric acid (50 vol%) as a pH regulator to regulate the pH value of the alloy electroplating solution to 4;

4) soaking the electroplated thermoelectric magnetic material in deionized water at 60 ℃ for 5min, soaking and washing with deionized water at normal temperature, and finally placing in a forced air drying oven to dry for 15min at 80 ℃; and obtaining the final product.

FIG. 1 is a scanning electron microscope image of the surface and cross section of the product obtained in this example, which shows that the barrier layer of the cobalt-nickel alloy thin film obtained has no pinholes on the surface, the coating and the thermoelectric magnetic material are tightly bonded, and the thickness is about 1.5 μm; the proportion atomic percentage of cobalt and nickel elements in the alloy thin film coating is respectively about 94% and 6%, and further tests show that the interface bonding strength between the obtained cobalt and nickel alloy thin film and the thermoelectric magnetic material is about 9.5 MPa.

The thermoelectric magnetic material electroplated with the cobalt-nickel alloy barrier layer in the embodiment is processed into seeds used for manufacturing devices, the seeds are annealed for 48 hours at 200 ℃, and microstructural analysis shows that the Co and Ni in the cobalt-nickel alloy barrier layer are distributed very uniformly. After annealing, the thickness of the interface diffusion layer between the alloy barrier layer and the thermoelectric magnetic material is less than 100nm (the thickness of the diffusion layer of a single nickel metal barrier layer under the same condition is as high as 500nm), which shows that the cobalt-nickel alloy barrier layer obtained by electroplating can obviously improve the interface stability of the thermoelectric all-solid-state refrigerating device, and is beneficial to prolonging the service life of the device.

The thermoelectric magnetic material electroplated with the cobalt-nickel alloy barrier layer and the thermoelectric magnetic material electroplated with the single metal nickel barrier layer in the embodiment under the same electroplating condition are respectively processed into seeds for manufacturing devices, the seeds are annealed for 48 hours at 200 ℃, and then the thermal electromagnetic refrigeration devices are manufactured according to the specification TEC 1-12706. The results of the semiconductor assembly testing system tests (see fig. 4) show that the internal resistance of the thermomagnetic device based on the alloy barrier layer obtained in the embodiment is increased by only 0.2 omega after annealing compared with that before annealing, and the internal resistance of the thermomagnetic device of the same specification and based on the single-metal nickel barrier layer is increased by 0.35 omega after annealing compared with that before annealing. Therefore, the alloy barrier layer obtained by the invention can better improve the service performance of the thermal electromagnetic all-solid-state refrigerating device.

Example 2

A thermoelectricity magnetic element for improving the interface reaction of a thermoelectricity magnetic refrigeration device is prepared by the following steps:

1) preparation of a thermoelectric material from Bi₂Te₃Base alloy thermoelectric material and nano Fe₃Q₄The surface of the block composite material formed by the particle magnetic material is flat and smooth;

2) surface treatment of the thermoelectric magnetic material;

firstly, soaking the thermoelectric magnetic material in acetone for 10min, and then putting an oil removing solvent into the soaked thermoelectric magnetic material for ultrasonic cleaning for 20 min; wherein the adopted oil removing solvent comprises the following components in percentage by weight: 70g/L of sodium hydroxide, 30g/L of sodium carbonate, 30g/L of sodium phosphate, 10g/L of water glass and 75 ℃ of temperature.

Soaking the deoiled thermoelectric magnetic material into an acid solution for cleaning for 1min, and then cleaning with deionized water; wherein the adopted acid solution is formed by mixing hydrochloric acid (40 vol%) and hydrofluoric acid (60 vol%) according to the volume ratio of 1: 1;

3) placing the surface-treated thermoelectric magnetic material obtained in step 2) in electroplating solution, using the thermoelectric magnetic material as cathode, platinum sheet electrode as anode, controlling the temperature of the electroplating solution at 40 deg.C, and applying DC current for electroplating (current density of 0.8A/dm)²) Controlling the electroplating time to be 10min according to the requirement of the thickness of the electroplated layer; the formula conditions of the adopted electroplating solution are as follows: 100g/L of cobalt sulfate, 30g/L of nickel chloride, 30g/L of boric acid, 0.1g/L of sodium dodecyl sulfate and 1g/L of saccharin; further adopting sulfuric acid (50 vol%) as a pH regulator to regulate the pH value of the alloy electroplating solution to 4;

4) soaking the electroplated thermoelectric magnetic material in deionized water at 60 ℃ for 5min, soaking and washing with deionized water at normal temperature, and finally placing in a forced air drying oven to dry for 15min at 80 ℃; and obtaining the final product.

Tests prove that the surface of the cobalt-nickel alloy thin film barrier layer material obtained by electroplating in the embodiment has no pinholes (shown in a scanning electron microscope figure as figure 1), the coating and the thermoelectric magnetic material are tightly combined, and the thickness of the coating is about 1.5 mu m; the proportion atomic percentage of cobalt and nickel elements in the alloy film coating is respectively about 92% and 8%; the bond strength was about 10 MPa.

The thermo-electric magnetic element of this example was processed into seeds for device fabrication, which were annealed at 200 ℃ for 48h and then subjected to microstructural analysis (see fig. 2), and the results showed that: co and Ni in the cobalt-nickel alloy barrier layer are distributed very uniformly; and after annealing, the thickness of the interface diffusion layer between the alloy barrier layer and the thermoelectric magnetic material is less than 100nm (the thickness of the diffusion layer of the nickel metal barrier layer obtained under the same electroplating condition is as high as 500nm, see figure 3).

Processing the thermo-electromagnetic element obtained in the embodiment into seeds used for manufacturing the device, annealing the seeds at 200 ℃ for 48 hours, and then manufacturing the thermo-electromagnetic refrigeration device according to the specification TEC 1-12706; then, a semiconductor component testing system is adopted for testing, and the result shows that: the internal resistance of the thermo-magnetic device based on the alloy barrier layer obtained in the embodiment is increased by only 0.25 omega after annealing compared with that before annealing, and the internal resistance of the single-metal nickel barrier layer thermo-magnetic device with the same specification is increased by 0.35 omega after annealing compared with that before annealing. Therefore, the alloy barrier layer obtained by the invention can better improve the service performance of the thermal electromagnetic all-solid-state refrigerating device.

Example 3

A thermoelectricity magnetic element for improving the interface reaction of a thermoelectricity magnetic refrigeration device is prepared by the following steps:

1) preparation of a thermoelectric material from Bi₂Te₃A bulk composite material composed of a base alloy thermoelectric material and a nano Ni particle magnetic material;

2) surface treatment of the thermoelectric magnetic material;

firstly, soaking the thermoelectric magnetic material in acetone for 10min, and then putting an oil removing solvent into the soaked thermoelectric magnetic material for ultrasonic cleaning for 20 min; wherein the adopted oil removing solvent comprises the following components in percentage by weight: 70g/L of sodium hydroxide, 30g/L of sodium carbonate, 30g/L of sodium phosphate, 10g/L of water glass and 75 ℃ of temperature.

Soaking the deoiled thermoelectric magnetic material into an acid solution for cleaning for 1min, and then cleaning with deionized water; wherein the adopted acid solution is formed by mixing hydrochloric acid (40 vol%) and hydrofluoric acid (60 vol%) according to the volume ratio of 1: 1;

3) placing the surface-treated thermoelectric magnetic material obtained in step 2) in electroplating solution, using the thermoelectric magnetic material as cathode, platinum sheet electrode as anode, controlling the temperature of the electroplating solution at 50 deg.C, and applying direct current for electroplating (current density of 1.0A/dm)²) Controlling the electroplating time to be 13min according to the requirement of the thickness of an electroplated layer; the formula conditions of the adopted electroplating solution are as follows: 100g/L of cobalt sulfate, 30g/L of ferric chloride, 30g/L of boric acid, 0.1g/L of sodium dodecyl sulfate and 1g/L of saccharin; further adopting sulfuric acid (50 vol%) as a pH regulator to regulate the pH value of the alloy electroplating solution to 4.2;

4) soaking the electroplated thermoelectric magnetic material in deionized water at 60 ℃ for 5min, soaking and washing with deionized water at normal temperature, and finally placing in a forced air drying oven to dry for 15min at 80 ℃; and obtaining the final product.

Tests prove that the surface of the iron-cobalt alloy thin film barrier layer material obtained by electroplating in the embodiment has no pinholes, the coating and the thermoelectric magnetic material are tightly combined, the thickness of the coating is about 2 mu m, the proportion atomic percentages of cobalt and iron elements in the alloy thin film coating are respectively about 80% and 20%, and the bonding strength is about 8 MPa.

Processing the thermo-electromagnetic element obtained in the embodiment into seeds used for manufacturing the device, annealing the seeds at 200 ℃ for 48 hours, and then manufacturing the thermo-electromagnetic refrigeration device according to the specification TEC 1-12706; then, a semiconductor component testing system is adopted for testing, and the result shows that: the internal resistance of the thermo-magnetic device based on the alloy barrier layer obtained in the embodiment is increased by only 0.18 omega after annealing compared with that before annealing, and the internal resistance of the single-metal nickel barrier layer thermo-magnetic device with the same specification is increased by 0.35 omega after annealing compared with that before annealing. The result shows that the alloy film barrier layer obtained by the invention can better improve the service performance of the thermal electromagnetic all-solid-state refrigerating device.

Comparative example 1

A thermoelectric element for an electromagnetic refrigeration device is prepared by the following steps:

1) surface treatment of the thermoelectric magnetic material;

firstly, soaking the thermoelectric magnetic material in acetone for 10min, and then putting an oil removing solvent into the soaked thermoelectric magnetic material for ultrasonic cleaning for 20 min; wherein the adopted oil removing solvent comprises the following components in percentage by weight: 70g/L of sodium hydroxide, 30g/L of sodium carbonate, 30g/L of sodium phosphate and 10g/L of water glass at the temperature of 75 ℃;

soaking the deoiled thermoelectric magnetic material into an acid solution for cleaning for 1min, and then cleaning with deionized water; wherein the adopted acid solution is formed by mixing hydrochloric acid (40 vol%) and hydrofluoric acid (60 vol%) according to the volume ratio of 1: 1;

3) placing the surface-treated thermoelectric magnetic material obtained in step 2) in electroplating solution, using the thermoelectric magnetic material as cathode, platinum sheet electrode as anode, controlling the temperature of the electroplating solution at 40 deg.C, and applying DC current for electroplating (current density of 0.6A/dm)²) Controlling the electroplating time to be 10min according to the requirement of the thickness of the electroplated layer;

the electroplating solution adopted comprises the following components: cobalt sulfate (25g/L), nickel chloride (200g/L), boric acid (25g/L), sodium dodecyl sulfate (0.05-0.1 g/L) and saccharin (1 g/L); further adopting sulfuric acid (50 vol%) as a pH regulator to regulate the pH value of the alloy electroplating solution to 4;

4) soaking the electroplated thermoelectric magnetic material in deionized water at 60 ℃ for 5min, soaking and washing with deionized water at normal temperature, and finally placing in a forced air drying oven to dry for 15min at 80 ℃; and obtaining the final product.

The alloy film coating thickness of the product obtained by the comparative example is about 1.5 mu m through testing; the proportion of cobalt and nickel element is about 30% and 70% in atomic percentage, and further testing of interface reaction shows that the thickness of the diffusion layer at the interface under the same condition (annealing at 200 ℃ for 48h) is as high as 500nm, which is similar to the result of electroplating single metal nickel.

The above embodiments are merely examples for clearly illustrating the present invention and do not limit the present invention. Other variants and modifications of the invention, which are obvious to those skilled in the art and can be made on the basis of the above description, are not necessary or exhaustive for all embodiments, and are therefore within the scope of the invention.