Magnetocaloric Element Production via Gas Atomization
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Solution Overview
Problem
Current methods for producing magnetocaloric materials for magnetic refrigeration face challenges such as high production costs, difficulty in creating complex shapes, and the need for sintering, which can lead to oxidation and disintegration of elements like H or N, limiting their performance and applicability.
Innovation Solution
A method involving rapid solidification by gas atomization to produce La1-x(Ce,Pr)x((Fe1-z-vMnzCov)1-ySiwXn powders, followed by heat treatment to achieve a NaZn13 structure, and subsequent dispersion in an organic matrix to form a magnetocaloric element without the need for sintering, allowing for cost-effective and industrially applicable production of materials with high magnetocaloric properties and low thermal hysteresis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional melting and solidification followed by prolonged annealing is used, then the NaZn13 structure is obtained, but the production time is excessive and productivity is low
Solution Approach 1:
The invention applies preliminary action by performing rapid solidification before the annealing step. The liquid alloy is projected onto a rotating cooled surface to obtain ribbons with suppressed phase segregation, which then require shorter annealing times (e.g., 1 hour at 900-1200°C) to achieve the desired NaZn13 structure, compared to prolonged annealing of conventionally solidified materials
Solution Approach 2:
The invention changes the thermal processing parameters by using rapid cooling rates during solidification (achieved by projecting liquid alloy onto cooled surfaces at specific rotation speeds and temperatures). This parameter change suppresses phase segregation and enables shorter subsequent annealing times while maintaining structural quality
2Stability of the object's composition
If rapid solidification by projecting liquid alloy onto rotating cooled surface is used, then phase segregation is reduced, but the material must be ground to powder adding complexity
Solution Approach 1:
The invention merges multiple operations into one by combining rapid solidification with direct powder formation. Instead of producing ribbons that require separate grinding operations, the liquid alloy is atomized during projection onto the cooled surface, directly forming fine powder particles with suppressed phase segregation, thereby eliminating the need for separate grinding steps
3Strength
If sintering is used to form magnetocaloric elements, then material consolidation is achieved, but oxidation and disintegration of elements like H or N occur
Solution Approach 1:
The invention applies inert atmosphere protection throughout the processing sequence. Powder is produced and handled in inert or reducing atmospheres, and annealing is performed in controlled atmospheres that prevent oxidation. This protective environment prevents oxidation and disintegration of sensitive elements like H or N during consolidation, eliminating the harmful effects associated with conventional sintering in atmospheric conditions
4Temperature
If Fe substitution with Co or Mn is used to adjust Tc, then Curie temperature is modified, but magnetocaloric properties are degraded
Solution Approach 1:
The invention applies local quality by using selective substitution strategies. Instead of random substitution, specific amounts of Co or Mn are introduced at controlled positions in the crystal structure during alloy formation. This localized control allows Tc adjustment while minimizing degradation of magnetocaloric properties, as the substitution is optimized for specific performance targets rather than uniform replacement
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 magnetocaloric materials with high performance, ease of shaping, and reduced thermal hysteresis, while avoiding the costs and limitations associated with traditional sintering processes, thereby enhancing energy efficiency and scalability for magnetic refrigeration applications.
Implementation Method 1
rapid solidification by gas atomization to produce La1-x(Ce,Pr)x((Fe1-z-vMnzCov)1-ySiwXn powders
Implementation Method 2
atomization of a jet of liquid alloy by means of an inert gas
Implementation Method 3
magnetic refrigeration... which consists in using a particular type of magnetic material, called magnetocaloric, which exhibits a variation in temperature when it is subjected to the action of an external magnetic field
Implementation Method 4
heat treatment to achieve a NaZn13 structure
Implementation Method 5
followed by a prolonged annealing step at 900-1200°C to remove the secondary phases and obtain the targeted NaZn 13 structure
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A method for manufacturing a magnetocaloric element comprising the following steps: - a powder of a magnetocaloric alloy is prepared, with the composition: La1-x(Ce, Pr)x(Fe1-z-vMnzCov)1-ySiy)wXn wherein: - X is one or more elements chosen from among H, C, N and B; - x = 0 to 0.5; - y = 0.05 to 0.2; - z = 0 to 0.15; - v = 0 to 0.15; - w = 12 to 16; - n = 0 to 3.5; the rest being impurities, with a maximum content of 4% by weight, preferably a maximum content of 2% by weight, of rare earth elements other than La, Ce and Pr, and a maximum content of 2% by weight for the other impurities, the preparation of the powder comprising the following steps: - a liquid alloy (4) is prepared; - it is solidified in the form of a powder of substantially spherical particles (14) of which the average diameter is between 10 and 100 mm by atomisation of a jet (8) using an inert gas; - said powder (14) is thermally treated by heating to a temperature of 900 to 1200°so that at least 70% thereof by weight has an NaZn13 structure; - optionally a hydriding and/or nitriding and/or carburising and/or carbonitriding treatment is performed to give n its final value; said powder (14) is dispersed in a matrix formed by one or more organic binders in order to form a mixture comprising 40 to 80% powder by volume; - said mixture is shaped.