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La-Fe based magnetic refrigeration composite material and preparation method thereof

A technology of magnetic refrigeration materials and composite materials, which is applied in the fields of magnetic materials, heat exchange materials, chemical instruments and methods, etc., can solve the problems of material pulverization, high energy consumption, poor impact resistance, etc. Effect

Active Publication Date: 2017-02-08
SOUTH CHINA UNIV OF TECH
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  • Abstract
  • Description
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AI Technical Summary

Problems solved by technology

Due to NaZn 13 Type La-Fe-based compound is a kind of metal interstitial compound, which is brittle and poor in impact resistance. It is difficult to process these materials into the shape required by the magnetic refrigeration prototype by traditional processing technology, which limits its application in magnetic refrigeration to a large extent. machine application
On the other hand, the more serious problem lies in the large magnetocaloric effect induced by the large negative expansion of the lattice near the magnetic phase transition temperature (ie, the Curie temperature of the alloy) NaZn 13 Type La-Fe-based magnetic refrigeration materials, reciprocating cycles near the magnetic phase transition temperature during work will cause regular changes in the volume of the material unit cell "expansion-contraction-expansion-contraction...", which will inevitably lead to pulverization of the material in the long run. The existence of this problem will also seriously restrict its application on magnetic refrigerators.
At present, the processing and forming methods and techniques of magnetic refrigeration materials mainly include composite method, powder metallurgy, and vacuum diffusion welding; by selecting a metal whose melting point is lower than that of the refrigerant and whose thermal conductivity is higher than that of the refrigerant, it will be formed after heating and melting. The limitation of the method is that it is difficult to ensure that the two materials do not form intermetallic compounds when they are melted
The vacuum diffusion welding process is to pressurize under the protection of vacuum or inert gas to make the base metal in close contact. However, this method is not suitable for brittle samples; these forming methods of magnetic refrigeration materials based on high temperature melting or hot pressing, The processing temperature is high, the energy consumption is large, and it is difficult to treat NaZn 13 It is more difficult to prepare porous magnetic refrigeration materials by fine-tuning the morphology of La-Fe-based magnetic refrigeration materials.

Method used

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Effect test

Embodiment 1

[0032]A kind of La-Fe base magnetic refrigeration composite material, its preparation method is as follows:

[0033] Step 1: Calculate based on the total mass of 1.4g, where 10% of the metal tin is 0.14g, and the rest is La with good phase formation 0.8 Ce 0.2 (Fe 0.95 co 0.05 ) 11.8 Si 1.2 The compounds are all composed of 180-250 μm coarse main phase particles, that is, the weight ratio of the fine main phase powder less than 45 μm is 0%.

[0034] Step 2: Mix the weighed materials until they are uniform. When they are uniform, the aggregation of fine powder cannot be seen with the naked eye. Then put the mixed materials into a Φ8 mold and perform pre-compacting.

[0035] Step 3: Heat the mold to 151°C at a heating rate of 10-15°C / min, pressurize to 980MPa after the temperature is stable, stop heating after holding the heat for 2 minutes, and release the pressure when the temperature cools below 100°C. The mold temperature can be demoulded when it is close to room tempe...

Embodiment 2

[0043] A kind of La-Fe base magnetic refrigeration composite material, its preparation method is as follows:

[0044] Step 1: Calculate based on the total mass of 1.4g, where 10% of the metal tin is 0.14g, and the rest is La with good phase formation 0.8 Ce 0.2 (Fe 0.95 co 0.05 ) 11.8 Si 1.2 The compound is composed of coarse main phase particles of 180-250 μm and fine main phase powder less than 45 μm, wherein the weight ratio of the fine main phase powder less than 45 μm is 5%.

[0045] Step 2: Mix the weighed materials until they are uniform. When they are uniform, the aggregation of fine powder cannot be seen with the naked eye. Then put the mixed materials into a Φ8 mold and perform pre-compacting.

[0046] Step 3: Heat the mold to 148°C at a heating rate of 10-15°C / min, pressurize to 950MPa after the temperature is stable, stop heating after holding the heat for 2 minutes, and release the pressure when the temperature cools below 100°C. The mold temperature can be ...

Embodiment 3

[0054] A kind of La-Fe base magnetic refrigeration composite material, its preparation method is as follows:

[0055] Step 1: Calculate based on the total mass of 1.4g, where 10% of the metal tin is 0.14g, and the rest is La with good phase formation 0.8 Ce 0.2 (Fe 0.95 co 0.05 ) 11.8 Si 1.2 The compound is composed of coarse main phase particles of 180-250 μm and fine main phase powder of less than 45 μm, wherein the weight ratio of the fine main phase powder of less than 45 μm is 10%.

[0056] Step 2: Mix the weighed materials until they are uniform. When they are uniform, the aggregation of fine powder cannot be seen with the naked eye. Then put the mixed materials into a Φ8 mold and perform pre-compacting.

[0057] Step 3: Heat the mold to 145°C at a heating rate of 10-15°C / min, pressurize to 930MPa after the temperature is stable, stop heating after holding the heat for 2 minutes, and release the pressure when the temperature cools below 100°C. The mold temperature ...

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Abstract

The invention discloses a La-Fe based magnetic refrigeration composite material and a preparation method thereof. The method includes the steps of: subjecting a La-Fe based magnetic refrigeration material with good phase formation to mechanical grinding and screening out 180-250micrometer thick main phase particles and fine main phase powder less than 45micrometer; mixing two La-Fe based magnetic refrigeration materials with different particle sizes according to different weight ratios, then adding metal tin powder accounting for 9%-1% of the total weight, and mixing the substances evenly; and carrying out hot embossing processing forming, thus obtaining the La-Fe based magnetic refrigeration composite material. The main phase involved in the invention is composed of multiple components, the particle size difference of the components is greater than 4 times to reduce porosity, therefore high density, high strength and high magnetocaloric performance La-Fe based magnetic refrigeration composite material can be obtained, and a good solution is provided for the problems of large hardness, great brittleness, difficult processing forming and the like in La-Fe based magnetic refrigeration materials.

Description

technical field [0001] The invention relates to a metal-based magnetic refrigeration composite material, in particular to a La-Fe-based magnetic refrigeration composite material with high density, high compressive strength and high magnetocaloric performance and a preparation method thereof. Background technique [0002] With the rapid development of society, refrigeration technology has become one of the indispensable driving factors, involving many important fields of national economy and people's livelihood, such as cryogenic engineering, petrochemical industry, high energy physics, electric power industry, precision instruments, superconducting technology, aerospace, According to statistics, the energy consumption of the refrigeration industry accounts for more than 15% of the total energy consumption of the whole society. [0003] At present, the main refrigeration technologies mainly include liquid vaporization refrigeration, adsorption refrigeration, gas compression r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K5/14C22C33/02H01F1/00
CPCH01F1/012C09K5/14C22C33/02
Inventor 钟喜春封小亮刘仲武焦东玲邱万奇
Owner SOUTH CHINA UNIV OF TECH
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