Manufacturing method for magnetic freezing module
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Solution Overview
Problem
Existing methods for producing magnetic refrigeration modules face challenges in controlling the Curie temperature and maintaining high material strength and magnetic entropy change due to dehydrogenation during heat treatment and high sintering temperatures, which reduce refrigeration performance.
Innovation Solution
A method involving a mixture of La(Fe,Si)13-based alloy powder and M powder with a melting point of 1090°C or lower, sintered in a reducing atmosphere at a temperature close to the M powder's melting point, followed by hydrogenation, to produce a sintered body with a controlled Curie temperature and high magnetic entropy change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the magnetic refrigeration material is hydrogenated before coating with Sn or Sn alloy film and then subjected to heat treatment at 100°C to 300°C, then the particles are bonded together, but the material is dehydrogenated during heat treatment making it difficult to control the Curie temperature
Solution Approach 1:
The invention performs hydrogenation after sintering rather than before coating and heat treatment. By carrying out hydrogenation as a final step at low temperature (room temperature to 200°C), the Curie temperature can be precisely controlled without subsequent high-temperature processing that would cause dehydrogenation. This preliminary action of hydrogenation at the appropriate stage resolves the contradiction between achieving material strength through bonding and maintaining Curie temperature control.
2Ease of manufacture
If spark plasma sintering is carried out at high sintering temperature of 950°C to 1200°C, then the alloy powder is shaped, but the La(Fe,Si)13 main phase is decomposed reducing magnetic refrigeration performance and material strength
Solution Approach 1:
The invention dramatically changes the sintering temperature parameter from conventional high temperatures (950-1200°C) to low temperatures (100°C to 800°C, preferably 150°C to 600°C). This parameter change prevents decomposition of the La(Fe,Si)13 main phase while still achieving effective bonding of particles through the low-temperature sintering process followed by hydrogenation, thus maintaining both ease of manufacture and high material strength with preserved magnetic refrigeration performance.
3Temperature
If low sintering temperature is used to prevent phase decomposition, then magnetic refrigeration performance is maintained, but material strength and bonding between particles are reduced
Solution Approach 1:
The invention creates a composite structure where La(Fe,Si)13-based alloy particles are sintered at low temperature and then hydrogenated to form a composite material with enhanced properties. The combination of low-temperature sintered particles and hydrogenation treatment produces a composite structure that achieves both low sintering temperature (preventing phase decomposition) and high material strength (through hydrogen-enhanced bonding), resolving the contradiction between these two parameters.
4Temperature
If hydrogenation is performed after sintering at low temperature, then Curie temperature is controlled and magnetic entropy change is enhanced, but additional process steps are required
Solution Approach 1:
The invention utilizes the phase transition phenomenon of hydrogen absorption and desorption in the La(Fe,Si)13-based alloy during hydrogenation. By controlling the hydrogenation process (exposure to hydrogen atmosphere at 100°C to 200°C), the material undergoes a phase transition that precisely controls the Curie temperature and enhances magnetic entropy change. This phase transition mechanism provides a scientifically grounded method to achieve the desired magnetic properties despite the additional process step, as the hydrogenation can be integrated into existing manufacturing workflows.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of magnetic refrigeration modules with high material strength, controlled Curie temperature, and enhanced magnetic refrigeration performance, including a high relative cooling power and large magnetic entropy change.
Implementation Method 1
utilizes a magnetic entropy change, which occurs when the magnetic order of the material is changed by a magnetic field under an isothermal condition
Implementation Method 2
an adiabatic temperature change, which occurs when the magnetic order of the material is changed by a magnetic field under an adiabatic condition
Implementation Method 3
subjecting the mixture powder A to a sintering treatment in a reducing atmosphere
Implementation Method 4
subjecting the sintered body B to a hydrogenation treatment in a hydrogen-containing atmosphere
Data Source
AI summary
There is provided a method for producing a magnetic refrigeration module. The method comprises: a step (1) of preparing a mixture powder A containing an La(Fe,Si)13-based alloy powder, an M powder, and optionally an organic binder, the La(Fe,Si)13-based alloy powder having a main phase with an NaZn13-type crystal structure, and the M powder containing a metal and/or an alloy and having a melting point of 1090° C. or lower; a step (2) of subjecting the mixture powder A to a heat treatment in a reducing atmosphere at a temperature close to the melting point of the M powder to obtain a sintered body B; and a step (3) of subjecting the sintered body B to a hydrogenation treatment in a hydrogen-containing atmosphere.