Ningbo Materials Co., Ltd. adopts rare-earth magneto-refrigerator materials for optimization and efficient preparation.

Magnetic refrigeration materials, especially new room-temperature magnetic refrigeration materials, have strong magnetocrystalline coupling, volumetric phase change effects, and intrinsic properties of intermetallic compounds. Most of them exhibit fragile and difficult-to-process forming characteristics. Solving these problems is to promote their technical application. only way. Whether it is room temperature or low temperature magnetic refrigeration materials, to be made into an active or passive magnetic refrigeration working bed, it needs to undergo a large-scale and stable preparation, cutting, processing and molding, magnetic and non-magnetic testing of this process.

In recent years, while domestic and foreign scholars are developing new material systems, they are also stepping up the deployment and implementation of the magnetic refrigeration material processing strategy. It is this key link that has driven the development of magnetic refrigeration prototypes. Taking the rare earth transition compound La-Fe-Si based material as an example, people have tried to solve the problems of processing brittleness and cyclic fatigue with new processes such as eutectoid decomposition, polymer or metal bonding, introduction of porous concepts, and achieved good results; The effective method of adjusting the Curie point for low-temperature alloying and recharge of hydrogen, avoiding the problem of phase separation after half-hydrogenation material aging, and using the selective laser sintering (SML) 3D printing technology to achieve near-final processing of regular microchannels .

Although China is almost synchronized with foreign research in the development of new material systems, especially low-temperature magnetic refrigeration materials are in a leading position in the world, but in the past few years in the magnetic refrigeration material processing direction started late, the gap is obvious, and the material physics and device compatibility Not enough, to a certain extent, caused a lag in the field of domestic magnetic refrigeration.

In recent years, the Laboratory of Rare Earth Magnetic Functional Materials of the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences conducted systematic research on the organization and control of magnetic refrigeration materials, preparation molding, and new concept refrigeration. The development of large-scale rapid solidification casting and powder preparation techniques, as well as non-stoichiometric alloy composition adjustment and microstructure optimization. Developed a La-Fe-Co-Si flake with a smooth (surface near roll) surface, uniform thickness, controllable magnetic transition temperature, and several kilograms per kilogram. Its magnetic entropy change performance exceeds that produced by VAC. Sintered magnets, such as magnetic field strength and other operating temperatures, have established cooperative relations with the Baotou Rare Earth Research Institute and the French company Cooltech.

In addition, the introduction of transitional "bridge" phases and layered eutectoids in the non-positive La-based alloys has effectively shortened the formation cycle of the functional phases and the synthesis process flow, and is used to explore comprehensive balance of high magnetic entropy, high thermal conductivity, and high strength. The index of room temperature magnetic refrigeration materials, the development of low-energy preparation technology plays an important role in promoting. The relevant results applied for patents (201510096196.3, 201510078240.8) and published research results in international journals: Materials Letters (2014, vol.134, p87), Journal of Magnetism and Magnetic Materials (2014, vol.257, p73; 2015, Vol.377, p.90), Chinese Physics B (accepted), Physica B (doi:10.1016/j.physb.2015.03.012).

This study was supported by the Ningbo Innovation Team (2014B81001) and Zhejiang Outstanding Youth Fund (LR14E010001).

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