CN102443749A - Method for improving performance of fast-setting Ni-Mn-based magnetic refrigeration alloy ribbon material - Google Patents

Abstract

The present invention relates to a method for improving the performance of fast-solidifying Ni-Mn-based magnetic refrigeration ribbon materials, and belongs to the field of magnetic refrigeration materials. The method of the present invention determines the ordering transition temperature of the material by thermal analysis technology, and performs a heat treatment of a composite pulse magnetic field on the material at a certain temperature of 30 to 50 K above the ordering transition temperature, with the highest heating temperature being 1173 K, the pulse width being 26 ms, the action frequency being 0.3 to 1 Hz, and the magnetic induction intensity B being 0.5 T to 1.5 T. Compared with conventional heat treatment, the method of the present invention is simple to operate, has a lower heat treatment temperature, and can effectively improve the magnetocaloric properties of fast-solidifying Ni-Mn-based magnetic refrigeration ribbon materials.

Description

A Method for Improving the Properties of Rapidly Solidified Ni-Mn-based Magnetic Refrigeration Alloy Strip Material

technical field

The invention relates to a method for improving the performance of a fast-setting Ni-Mn-based magnetic refrigeration alloy strip material, belonging to the technical field of magnetic refrigeration materials.

Background technique

In today's world, refrigeration technology plays a very important role, especially in food storage, air conditioning, medical and other industries. Modern refrigeration technology is basically based on the refrigeration cycle process of gas compression/expansion, which not only has low efficiency and high energy consumption, but also destroys the ozone layer of the atmosphere or leads to the greenhouse effect. Therefore, finding a new, efficient, energy-saving and environmentally friendly refrigeration technology has become an urgent problem in today's society.

Magnetic refrigeration technology is a green technology that uses magnetic materials as working fluids to refrigerate with the help of the magnetocaloric effect of the material itself. The refrigeration efficiency is as high as 5 to 10 times that of traditional gas refrigeration, which can significantly save energy; Much larger than gas, the refrigerator is small in size, does not require large-scale gas compression movement, and runs smoothly and reliably; more importantly, this technology does not contain freon, ammonia and other refrigerants, and will not pollute the environment. Therefore, this technology has been widely used in the low temperature field, but it is still in the experimental exploration stage in the room temperature field. At present, how to improve the magnetocaloric effect of room temperature magnetic refrigeration materials is the key to the breakthrough of this technology and its commercial application. There are two main ways to obtain a large magnetic entropy change: (1) a high magnetic field is applied from the outside; (2) the magnetic refrigeration material itself has a strong magnetocaloric effect. The former can be solved by using superconducting magnets, but superconducting magnets make the structure of the magnetic refrigeration system particularly complicated and expensive, and it is difficult to popularize in practical industrial applications. Therefore, a more feasible way is to develop magneto-refrigerating materials with strong magnetocaloric effect in order to obtain higher magnetic entropy change under the magnetic field provided by conventional permanent magnets to meet the cooling needs.

For the fast-setting thin strip material, compared with the as-cast material prepared by the conventional electric arc furnace, the composition is relatively uniform, so there is no need for high temperature and long-term homogenization quenching treatment. How to formulate a reasonable heat treatment process is crucial to improving its magnetocaloric properties.

Contents of the invention

The purpose of the present invention is to provide a method to improve the magneto-caloric performance of the fast-solidifying Ni-Mn-based magnetic refrigeration alloy strip material, so that it has a large magnetic entropy change, so as to improve the refrigeration capacity of the material.

The present invention is a method for improving the properties of fast-solidifying Ni-Mn-based magnetic refrigeration alloy thin strip material, which is characterized in that it has the following processes and steps: (a) determining the heat treatment temperature of the alloy thin strip through thermal analysis; through thermal analysis technology Measuring the ordered transition temperature of alloy thin strips, so as to determine the heat treatment temperature at a temperature 30-50K above the ordering temperature; (b), heat treatment of Ni-Mn based alloy thin strips with a composite pulsed magnetic field; heat treatment in the protection It is carried out under the atmosphere; the maximum heating temperature is 1173K; the parameters of the pulsed magnetic field power supply used are: output voltage U=1500~2200V, pulse width 26ms, action frequency 0.3~1Hz, magnetic induction intensity B of the pulsed magnetic field is 0.5T~1.5T .

The present invention is a heat treatment device for a compound pulse magnetic field used in the above method, which is characterized in that the device includes: a high-voltage pulse power supply, a magnetic field coil, heating equipment, a temperature control system, an atmosphere protection system, a water cooling device for the magnetic field coil, a quartz tube, a control Thermocouples, protective gas tubes, wires and thin alloy strips; the thin alloy strips are placed at the bottom of the quartz tube and compacted with high-temperature cotton, and the quartz tube is placed in the overlapping part of the magnetic field coil and the constant temperature section of the heating equipment; atmosphere protection The system communicates with the quartz tube through the protective gas tube, and the temperature control system controls the temperature in the quartz tube through the temperature control thermocouple inserted into the bottom of the quartz tube; the high-voltage pulse power supply is connected with the magnetic field coil by a wire.

The advantage of the inventive method:

The method of the invention is simple to operate, and a pulsed magnetic field is introduced at the same time as the conventional thermal field treatment to form a compound treatment. Compared with the conventional heat treatment process, the heat treatment temperature is lower and can effectively improve the magnetocaloric properties of the material and improve the refrigeration capacity of the material.

Description of drawings

Fig. 1 is a schematic diagram of a heat treatment device under pulsed magnetic field conditions of the present invention.

The codes of the numbers in the figure are as follows:

1-pulse power supply, 2-magnetic field coil, 3-heating equipment, 4-temperature control system, 5-atmosphere protection system, 6-magnetic field coil water cooling device, 7-quartz tube, 8-temperature control thermocouple, 9-protective gas Trachea, 10-wire, 11-alloy thin strip. the

Detailed ways

Now the inventive method is further described as follows by specific examples:

Example 1 Ni ₄₈ Mn ₃₉ In ₁₃ alloy thin strips were prepared by single-roll strip stripping technology, and part of the thin strip alloys were subjected to combined treatment with pulsed magnetic field under conventional thermal field. The specific process is as follows: firstly, the ordering transition temperature is determined to be about 920K by thermal analysis technology. During the test, the heat treatment of the composite pulsed magnetic field is carried out under the protection of Ar atmosphere, and the alloy thin strip 11 is placed on the bottom of the quartz tube 7. Cotton compacts the alloy thin strip 11; the quartz tube 7 is connected to the atmosphere protection system 5, and before the quartz tube 7 is put into the heating device 3 for heat treatment, the protective gas is passed into the quartz tube 7 through the air inlet part of the air tube 9, and the gas is ventilated. After a few minutes, put the quartz tube 7 into the uniform temperature zone of the heating device 3, and keep the temperature in the heat-treated quartz tube 7 constant at 950K through the temperature control thermocouple 8 and the temperature control system 4, then turn on the pulse power supply, set The output voltage is set to 1800V, the action frequency is 0.5Hz, the pulse width is 26ms, and the pulse magnetic field is 1.0T. After 20 minutes of treatment, water quenching is performed immediately to obtain heat-treated alloy thin strips. As a comparative example, another part of thin strip alloy was subjected to conventional thermal field treatment, and the sample was sealed in a quartz tube under the protection of Ar atmosphere for 960K annealing treatment for 20 minutes, and then water quenched immediately. The results show that the magnetic entropy changes of the materials after two different treatments are 41.4Jkg ^-1 K ^-1 and 30.1Jkg ^-1 K ^-1 respectively under the magnetic field strength of 2T. The magnetic entropy change performance is improved by about 37%.

Example 2 Ni ₅₅ Mn _19.6 Ga _25.4 alloy thin strips were prepared by the single-roll strip stripping technique, and part of the thin strips were subjected to combined treatment with pulsed magnetic fields under conventional thermal fields. The specific process is as follows: firstly, the ordering transition temperature is determined to be about 915K by thermal analysis technology. During the test, heat treatment of a composite pulsed magnetic field is carried out under the protection of an Ar atmosphere, and the alloy thin strip 11 is placed on the bottom of the quartz tube 7. Cotton compacts the alloy thin strip 11; the quartz tube 7 is connected to the atmosphere protection system 5, and before the quartz tube 7 is put into the heating device 3 for heat treatment, the protective gas is passed into the quartz tube 7 through the air inlet part of the air tube 9, and the gas is ventilated. After a few minutes, put the quartz tube 7 into the uniform temperature zone of the heating device 3, and keep the temperature in the heat-treated quartz tube 7 constant at 960K through the temperature control thermocouple 8 and the temperature control system 4, then turn on the pulse power supply, set The output voltage is set to 1800V, the action frequency is 0.5Hz, the pulse width is 26ms, and the pulse magnetic field is 1.0T. After 20 minutes of treatment, water quenching is performed immediately to obtain heat-treated alloy thin strips. As a comparative example, another part of thin strip alloy was subjected to conventional thermal field treatment, and the sample was sealed in a quartz tube under the protection of Ar atmosphere for 960K annealing treatment for 20 minutes, and then water quenched immediately. The results show that the magnetic entropy changes of materials treated by two different methods are 38.2Jkg ^-1 K ^-1 and 27.5Jkg ^-1 K ^-1 respectively under the magnetic field strength of 2T. The magnetic entropy change performance is improved by about 38%.

Example 3 The Ni ₅₀ Mn ₃₇ Sn ₁₃ alloy prepared by single-roll strip stripping technology, and part of the thin strip materials were subjected to combined treatment with pulsed magnetic field under conventional thermal field. The specific process is as follows: firstly, the ordering transition temperature is determined to be about 925K by thermal analysis technology. During the test, the heat treatment of the composite pulsed magnetic field is carried out under the protection of Ar atmosphere, and the alloy thin strip 11 is placed on the bottom of the quartz tube 7. Cotton compacts the alloy thin strip 11, and the quartz tube 7 is connected to the atmosphere protection system 5, and before the quartz tube 7 is put into the heating device 3 for heat treatment, the protective gas is passed into the quartz tube 7 through the air inlet part of the gas pipe 9, and the gas is ventilated. After a few minutes, put the quartz tube 7 into the uniform temperature zone of the heating device 3, and keep the temperature in the heat-treated quartz tube 7 constant at 955K through the temperature control thermocouple 8 and the temperature control system 4, then turn on the pulse power supply, set The output voltage is set to 1800V, the action frequency is 0.5Hz, the pulse width is 26ms, and the pulse magnetic field is 1.0T. After 20 minutes of treatment, water quenching is performed immediately to obtain heat-treated alloy thin strips. As a comparative example, another part of thin strip alloy was subjected to conventional thermal field treatment, and the sample was sealed in a quartz tube under the protection of Ar atmosphere for 960K annealing treatment for 20 minutes, and then water quenched immediately. The results show that the magnetic entropy changes of materials treated by two different methods are 45.4Jkg ^-1 K ^-1 and 35.1Jkg ^-1 K ^-1 respectively under the magnetic field strength of 2T. The magnetic entropy change performance is improved by about 29%.

Fig. 1 is the thermal treatment device of composite pulse magnetic field of the present invention, and this device comprises: High-voltage pulse power supply 1, magnetic field coil 2, heating equipment 3, temperature control system 4, atmosphere protection system 5, magnetic field coil water cooling device 6, quartz tube 7, Temperature control thermocouple 8, protective gas tube 9, wire 10 and alloy thin strip 11; when loading samples, place the alloy thin strip 11 at the bottom of the quartz tube 7, use high temperature cotton to compact the alloy thin strip 11, NiCr-NiSi One end of the temperature control thermocouple 8 is inserted into the bottom of the quartz tube, and the other end is connected to the temperature control system 4; one end of the air inlet part of the protective gas pipe 9 is inserted into the bottom of the quartz tube, and the other end is connected to the atmosphere protection system 5, and one end of the gas outlet part of the protective gas pipe 9 It is connected to the bottom of the quartz tube, and the other end is connected to the atmosphere; during the process, the quartz tube 7 with the sample is placed in the resistance wire heating device 3 with an inner diameter of Ф25mm, and the heating device 3 is placed in the magnetic field coil 2 with an inner diameter of Ф80mm , The magnetic field coil 2 is connected with the high-voltage pulse power supply 1 through the wire 10 to form a closed loop.

The preparation method of alloy thin strip among the present invention:

The alloy thin strip involved in the present invention is prepared by a single-roll strip stripping technique. The preparation process is as follows: the purity of the raw materials used in the alloy is higher than 99.9 wt.%, and the cast alloy is prepared in a vacuum electric arc furnace under the protection of high-purity argon. Put the obtained cast alloy into a quartz tube with a rectangular nozzle at the lower end (the width of the nozzle is about 0.5mm), heat again to melt and spray it onto a copper roller rotating at a line speed of 10m/s to obtain alloy thin strips. the

Claims (2)

1. A method for improving the performance of a fast-solidifying Ni-Mn-based magnetic refrigeration alloy strip material, characterized in that it has the following processes and steps: (a), determining the heat treatment temperature of the alloy strip by thermal analysis; Measuring the ordered transition temperature of alloy thin strips, so as to determine the heat treatment temperature at a temperature 30-50K above the ordering temperature; (b), heat treatment of Ni-Mn based alloy thin strips with a composite pulsed magnetic field; heat treatment in the protection It is carried out under the atmosphere; the maximum heating temperature is 1173K; the parameters of the pulsed magnetic field power supply used are: output voltage U=1500~2200V, pulse width 26ms, action frequency 0.3~1Hz, magnetic induction intensity B of the pulsed magnetic field is 0.5T~1.5 T. 2. A thermal treatment device of a compound pulse magnetic field for improving the performance of fast solidified Ni-Mn-based magnetic refrigeration alloy thin strip material, characterized in that the device includes: high-voltage pulse power supply (1), magnetic field coil (2), heating equipment (3), temperature control system (4), atmosphere protection system (5), magnetic field coil water cooling device (6), quartz tube (7), temperature control thermocouple (8), protective gas tube (9), wire (10 ) and alloy thin strip (11); the alloy thin strip (11) is placed on the bottom of the quartz tube (7) and compacted with high-temperature cotton; the quartz tube (7) is placed on the homogeneous section of the magnetic field coil (2) and the heating device (3 ) in the overlapping portion of the constant temperature section; the atmosphere protection system (5) communicates with the quartz tube (7) through the protective gas pipe (9); the temperature control system (4) passes through the temperature control thermocouple (8) inserted into the bottom of the quartz tube (7) ) to control the temperature in the quartz tube (7); the high-voltage pulse power supply (1) is connected with the magnetic field coil (2) by a wire (10).

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