JPS5946000A - Preparation of substance to operate magnetic feezing - Google Patents

Abstract

PURPOSE:To obtain the titled substance removing simply processing strain on the surface, showing improved thermal conductivity in a cryogenic range, by removing the processing strain layer on the surface by etching treatment at the final process of processing a single crystal mass of a magnetic material. CONSTITUTION:In preparing a substance to operate magnetic freezing, having a given shape, by processing a single crystal mass of a magnetic substance (e.g., single crystal mass of gadolinium gallium garnet), a processing strain layer on the surface of the material is removed by etching treatment (e.g., etching treatment with hot phosphoric acid, etc.) at the final process. The processing strain layer can be removed by a simple process. Consequently, the substance to operate magnetic freezing having good thermal conductivity at cryogenic range without complicating the production process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for producing a magnetically refrigeration working material, and includes the following steps:
The present invention relates to a manufacturing method that enables removal of a processed strain layer on the surface through a simple process.

[Background technology of the invention and its problems]

Conventionally, magnetic refrigerators that utilize the magnetocaloric effect of magnetic materials have been known. This magnetic refrigerator has a higher division capacity per unit volume than a gas refrigerator, and as a result has the advantage that the refrigerator can be made smaller.

By the way, in the case of a -air cooling kneader, there is a heat exhaustion process in which the heat generated in the magnetic material is released to the outside by adiabatic magnetization, and an endothermic process in which heat is removed from the cold object by the magnetic material cooled by adiabatic demagnetization. It is necessary to perform the two heat exchange processes alternately. Therefore, refrigeration efficiency depends on the time required for heat exchange between heat absorption and exhaust heat. For this reason, the magnetic material, ie, the magnetic refrigeration material, is desired to have not only a large magnetic moment but also a high thermal conductivity within the operating temperature range of the refrigerator.

In general, magnetic refrigeration materials are manufactured by cutting and shaping magnetic single crystal arms, but the thermal conductivity of these materials usually increases as the temperature decreases;
pl reaches a maximum at 0~40, and shows a tendency to decrease as the temperature further decreases. The thermal conductivity at a temperature lower than the above-mentioned peak value varies depending on the surface condition of the work material. 91 If processing strain remains on the surface, the thermal conductivity decreases. Therefore, when processing a magnetic single-crystal arm body to take out a magnetically frozen workpiece in a desired shape, processing distortion on the surface can be easily removed, and high-quality workpieces with good thermal conductivity can be manufactured. The reality is that the emergence of a manufacturing method is strongly desired.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to easily remove processing distortion from the surface without complicating the manufacturing process, and thereby to achieve success in the cryogenic region. An object of the present invention is to provide a method for manufacturing a magnetic refrigeration material that exhibits excellent heat conduction properties.

[Summary of the invention]

In the present invention, when obtaining a magnetic refrigeration material in a desired shape from a magnetic single-crystal arm body by one process, the strained layer on the surface of the material is removed by etching in the final process. It is characterized by

〔Effect of the invention〕

By employing the above manufacturing method, the strained layer existing on the surface of the magnetically frozen material can be easily and reliably removed. Therefore, a magnetic refrigeration material with good thermal conductivity can be produced at extremely low temperatures without complicating the production process.

[Embodiments of the invention]

The present invention will be explained in detail below.

First, a magnetic single crystal arm and a single crystal bowl of Gatrium gallium garnet (GGG) were prepared. Next, two rectangular parallelepiped blocks were cut out from the single crystal bowl, and the surfaces of these two rectangular parallelepiped blocks were finished by lapping. Next, for one block, 160°C cynic acid was bonded to the surface to form a surface layer with a thickness of 5.
A portion of 0 to 60 μm was removed, and this was designated as sample A. !
! The other block, which was only subjected to a lapping finish, was designated as reference sample B.

The thermal conductivities of Sample A and Reference Sample B at extremely low temperatures were measured, and the results shown in the figure were obtained. As can be seen from the figure, it was confirmed that sample A, whose surface layer was removed by etching treatment, had significantly improved thermal conductivity compared to reference sample B in the temperature range below 20 degrees. This is the result of the etching process eliminating the strained layer on the surface and improving the surface condition. Therefore, as in the present invention, by etching the surface of the magnetic refrigeration material in the final step, it is possible to produce a magnetic refrigeration material with excellent thermal properties.

Note that the present invention is not limited to the above embodiments. That is, in addition to GGG, Dy5At5012°Gd
5At50,7. GdPO4, Dy2Ti20. By etching the surface of magnetic single crystal arms obtained from magnetic single crystal arms with hot phosphoric acid, etc. in the final step, it is possible to produce magnetic refrigeration materials with excellent heat conduction properties at extremely low temperatures. .

[Brief explanation of drawings]

The figure is a diagram showing the thermal conductivity properties of a magnetic refrigeration material (sample A) produced by the production method according to the present invention in comparison with that of a magnetic refrigeration material (reference sample B) obtained by another production method. be.

Claims (1)

[Claims] A magnetic refrigeration work characterized in that, in obtaining a magnetic refrigeration work material of a desired shape by processing from a magnetic single crystal arm body, in the final step, a processed strain layer on the surface of the material is removed by etching treatment. A method of manufacturing a substance.