WO2013060267A1 - 小滞后损耗的一级相变La(Fe,Si)13基磁热效应材料及其制备方法和用途 - Google Patents

小滞后损耗的一级相变La(Fe,Si)13基磁热效应材料及其制备方法和用途 Download PDF

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WO2013060267A1
WO2013060267A1 PCT/CN2012/083420 CN2012083420W WO2013060267A1 WO 2013060267 A1 WO2013060267 A1 WO 2013060267A1 CN 2012083420 W CN2012083420 W CN 2012083420W WO 2013060267 A1 WO2013060267 A1 WO 2013060267A1
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magnetocaloric
range
particle size
μηι
magnetocaloric effect
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English (en)
French (fr)
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胡凤霞
陈岭
王晶
包立夫
武荣荣
沈保根
孙继荣
宫华扬
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中国科学院物理研究所
湖北全阳磁性材料制造有限公司
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Priority to US14/353,618 priority Critical patent/US9657971B2/en
Publication of WO2013060267A1 publication Critical patent/WO2013060267A1/zh

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B21/00Machines, plants or systems, using electric or magnetic effects
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01FMAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/012Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials adapted for magnetic entropy change by magnetocaloric effect, e.g. used as magnetic refrigerating material
    • H01F1/015Metals or alloys
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09KMATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K5/00Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
    • C09K5/08Materials not undergoing a change of physical state when used
    • C09K5/14Solid materials, e.g. powdery or granular
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C28/00Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/005Ferrous alloys, e.g. steel alloys containing rare earths, i.e. Sc, Y, Lanthanides
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/10Ferrous alloys, e.g. steel alloys containing cobalt
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/30Ferrous alloys, e.g. steel alloys containing chromium with cobalt
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00Aspects linked to processes or compositions used in powder metallurgy
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00Making metallic powder or suspensions thereof
    • B22F9/02Making metallic powder or suspensions thereof using physical processes
    • B22F9/04Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C2202/00Physical properties
    • C22C2202/02Magnetic
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25BREFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2321/00Details of machines, plants or systems, using electric or magnetic effects
    • F25B2321/002Details of machines, plants or systems, using electric or magnetic effects by using magneto-caloric effects
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/29Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2982Particulate matter [e.g., sphere, flake, etc.]

Definitions

  • the invention relates to a first phase change La(Fe,Si) 13 -based magnetocaloric effect material with small hysteresis loss, a preparation method thereof and a magnetic refrigeration machine comprising the same and application of the material in manufacturing a refrigeration material.
  • the energy consumption of the refrigeration industry accounts for more than 15% of the total energy consumption of the society.
  • the gas compression refrigeration technology currently in common use has the disadvantages of high energy consumption and environmental pollution. Exploring non-polluting, green and environmentally friendly refrigeration materials and research and development New low-energy, high-efficiency refrigeration technologies are urgently needed in today's world.
  • Magnetic refrigeration technology is characterized by environmental protection, high efficiency, energy saving, stability and reliability. It has attracted worldwide attention in recent years.
  • Several types of room-temperature and high-temperature giant magnetocaloric materials discovered in the United States, China, the Netherlands, and Japan have greatly promoted people's expectations for green magnetic refrigeration technology, such as:
  • the common feature of these new giant magnetocaloric materials is that the magnetic entropy change is higher than that of the traditional room temperature magnetic refrigeration material Gd, the phase transition property is one grade, and most of them exhibit strong magnetocrystalline coupling characteristics, and the magnetic phase transition is accompanied by significant crystal structure phase transition. happened.
  • These new materials also exhibit different material characteristics. For example, Gd-Si-Ge is expensive, and the raw materials need to be further purified during the preparation process. The raw materials of Mn-Fe-P-As and MnAs are poisonous, and the NiMn-based Heusler alloy has hysteresis. Large loss characteristics and so on.
  • La(Fe,Si) 13 -based compounds are currently widely accepted internationally and are most likely to achieve high temperature and even room temperature magnetic refrigeration applications.
  • the alloy has the characteristics of low raw material price, phase transition temperature, phase change property, hysteresis loss and composition adjustment, and the magnetic entropy near room temperature is higher than Gd-fold.
  • the laboratory will have a number of countries 1 ⁇ (? 6, 81) 13 base material for magnetic refrigeration prototype testing to prove its cooling capacity is superior to Gd.
  • the phase transition properties of the La(Fe,Si) 13 -based compound may vary depending on the adjustment of the components.
  • the phase transition property of a compound with a low Si content is generally one stage. As the Co content increases, the Curie temperature rises, the first-order phase transition property weakens, and gradually transitions to the second stage (the second-order phase change has no hysteresis loss), and the hysteresis loss gradually Decrease, however, the magnitude of the magnetocaloric effect also decreases due to changes in composition and exchange.
  • La(Fe,Si) 13 -based compounds having a first-order phase transition characteristic exhibit a large magnetocaloric effect, but are often accompanied by significant hysteresis loss.
  • the hysteresis loss appears as heat leakage in the refrigeration cycle of the magnetic refrigeration machine, and the significant hysteresis loss accompanying the first-order phase change process will greatly reduce the cooling efficiency of the material. Therefore, materials scientists and engineers dream of reducing the hysteresis loss while ensuring the large magnetocaloric effect of La(Fe,Si) 13 -based compounds. Summary of the invention
  • La(Fe,Si) 13 -based magnetocaloric effect material and preparation method thereof and magnetic refrigeration machine comprising the same and application of the material in manufacturing refrigeration materials.
  • Hysteresis loss is the intrinsic property of the first-order phase change system. Effectively reducing the hysteresis loss can significantly improve the cooling efficiency.
  • the lag mainly comes from two factors, one is the intrinsic factor of the phase transition process: such as nucleation factor, grain boundary, internal stress, phase boundary friction, etc.; second is the extrinsic factor: such as variable field velocity, and surrounding environment The heat exchange and so on.
  • the inventors of the present invention crushed a first-order phase-change La(Fe,Si) 13 -based magnetocaloric material having a large hysteresis loss into an irregular powder having a particle diameter of 15 to 200 ⁇ m ( ⁇ ) without changing the composition. It has been unexpectedly found that the hysteresis loss greatly decreases with the decrease of the particle size.
  • FeFe 13 _ x M x corresponding to &211 type 13 structure or "1 : 13 structure” as used herein refers to a structure in which the space group is Fm ⁇ . Fe atoms occupy two in a ratio of 1:12. One crystal position Sb e 1 ) and 96i (Fe n ). La and Fe 1 atoms constitute a CsCl structure. The subunit is surrounded by 24 Fe 11 atoms, and the Fe 1 atom is surrounded by 12 Fe 11 atoms constituting an icosahedron. Each Fe 11 atom is surrounded by 9 nearest neighbor Fe 11 atoms, 1 Fe 1 atom and 1 La atom. .
  • the present invention provides a first-order phase-change La(Fe,Si) 13 -based magnetocaloric effect material having a small hysteresis loss, the material having a NaZn 13 type structure and being a particle having a particle size ranging from 15 to 200 mm, the particle The particle size is not less than 15 ⁇ .
  • the magnetocaloric effect material when the particle diameter of the particles is reduced to 15 ⁇ or less, particularly ⁇ ⁇ or less, the magnetocaloric effect material loses stability, the magnetic transformation behavior is weakened, and the magnetic entropy change amplitude is drastically decreased. , no longer suitable for the practical application of magnetic refrigeration technology. Therefore, the removal of particles with a particle size of less than 10 ⁇ during the actual application of the material can maximize the magnetocaloric effect of the material.
  • the chemical formula of the magnetocaloric material can be:
  • R is selected from one or more of ⁇ (Ce ) , ⁇ ( Pr ) and ⁇ ( Nd ) elements,
  • A is selected from one or more of the elements of carbon (C), hydrogen (H) and boron (B),
  • the range of X is: 0 ⁇ x ⁇ 0.5
  • the range of a is: 0 ⁇ a ⁇ 3.0.
  • the magnetocaloric material has the chemical formula:
  • R is selected from one or more of ⁇ (Ce ) , ⁇ ( Pr ) and ⁇ ( Nd ) elements,
  • A is selected from one or more of the elements of carbon (C), hydrogen (H) and boron (B),
  • the range of X is: 0 ⁇ x ⁇ 0.5
  • the range of y is: 1.0 ⁇ y ⁇ 1.6
  • the range of p is: 0 ⁇ p ⁇ 0.05
  • the range of a is: 0 ⁇ a ⁇ 1.8.
  • A is a gap atom having a small atomic radius (for example, carbon, hydrogen, and boron), and the addition of these interstitial atoms occupies a gap of 24d in the NaZn 13 structure.
  • the effect on the structure plays the same role.
  • the range of ⁇ is: 0.1 ⁇ ⁇ ⁇ 2.0.
  • the material has a first-order phase change characteristic, and the bulk material exhibits a significant magnetic hysteresis loss. When the particle size ranges from 15 to 50 ⁇ m, the maximum intrinsic hysteresis loss is less than 60 J/kg.
  • the magnetocaloric material has a chemical formula of: La 1-x R x (Fe 1-p Co p ) 13-y Si y A a , wherein R is selected from Ce, Pr And one or more of Nd elements, A is selected from one or two of H, C and B elements, the range of X is: 0.2 ⁇ x ⁇ 0.5, and the range of y is: 0.8 ⁇ y ⁇ 1.6, The range of p is: 0 ⁇ p ⁇ 0.03, and the range of a is: 0.1 ⁇ a ⁇ 2.0.
  • the chemical formula of the magnetocaloric material may be:.
  • the magnetocaloric material has a particle diameter of not less than 15 ⁇ m, and may be particles having a particle size ranging from 15 to 200 ⁇ , more preferably from 15 to 50 ⁇ .
  • the effective magnetic entropy change value of the magnetocaloric material under the variation of 0 ⁇ 5 ⁇ magnetic field may be 5.0 ⁇ 50.0J/kgK, and the phase change temperature zone may be located at 10 ⁇ 400K.
  • the invention also provides a preparation method of the above magnetocaloric effect material, the method comprising the following steps: 1) preparing a raw material other than hydrogen according to a chemical formula;
  • step 2) The raw materials prepared in step 1) are placed in an electric arc furnace, vacuumed, cleaned with argon gas, and smelted under argon gas to obtain an alloy ingot;
  • Step 2) melting ingots good vacuum annealing and then quenching in water or in liquid nitrogen, thereby preparing iUFe ⁇ qCOpMV ⁇ magnetocaloric material 13 having a structure ySiyAa La ⁇ NaZn; and 4) Step 3) obtained in The magnetocaloric effect material is crushed, ground and sieved to obtain particles having a particle size ranging from 15 to 200 ⁇ m;
  • the method further comprises: 5) annealing the particles obtained in the step 4) in hydrogen, or crushing the magnetocaloric material obtained in the step 3) Anneal in hydrogen and then proceed to step 4).
  • particles having a particle diameter of less than 15 ⁇ are removed by screening, and in particular, particles having a particle diameter of less than 10 ⁇ are removed by screening.
  • the raw materials La, R may be commercial elemental rare earth elements, or may be industrial pure LaCe alloy or industrial pure LaCePrNd mixed rare earth.
  • the purity of the industrial pure LaCe alloy is usually 95-98 at.% (atomic ratio), the atomic ratio of La and Ce in the alloy is 1:1.6-1:2.3, and the purity of industrial pure LaCePrNd mixed rare earth is about 99 wt.%.
  • the elemental La may be used to supplement the portion of the LaCe alloy relative to the La which is insufficient in the material to be prepared; similarly, the industrial pure LaCePrNd mixed rare earth may also be operated as such.
  • the carbon may be provided by a FeC alloy. Since the FeC alloy also contains Fe element, it is necessary to appropriately reduce the added elemental Fe, so that the ratio of the added elements still satisfies the atomic ratio of the chemical formula of the magnetic material.
  • the step 2) may include: placing the raw materials prepared in the step 1) into an electric arc furnace, and vacuuming to a degree of vacuum of less than lxl O_ 2 Pa, with a purity greater than 99%.
  • the high-purity argon gas is used to clean the furnace chamber 1 ⁇ 2 times, then the argon gas is filled into the furnace chamber to 0.5 ⁇ 1.5 atmospheres, and the arc is arc-started to obtain alloy ingots.
  • Each alloy ingot is repeatedly smelted at 1500 ⁇ 2500 °C. 1 ⁇ 6 times, for example 2 ⁇ 6 times.
  • the step 3) may include: annealing the alloy ingot obtained in the step 2) at 1000 ⁇ 1400 ° C, and the vacuum degree is less than lxl (T 3 Pa for 1 hour to For 60 days, then quench in liquid nitrogen or water.
  • the step 4) may include: crushing and/or dividing the magnetocaloric material obtained in the step 3) into coarse particles having a particle diameter of less than 1 mm, and then protecting the gas. Or coarsely grind the coarse particles with agate mortar to a particle size of ⁇ 200 ⁇ , and then sieve the metal powder with a standard sieve to collect particles with a particle size ranging from 15 to 200 ⁇ , preferably collecting the particle size range from 15 to 50. ⁇ particles.
  • the amount of hydrogen in the alloy is controlled by adjusting the hydrogen pressure, the annealing temperature and the time.
  • the pressure of hydrogen is from 10 _ 3 Pa to 80 atm
  • the annealing temperature is from 0 to 400 ° C
  • the annealing time is from 1 min to 24 hours.
  • the present invention also provides a magnetic refrigerator comprising the magnetocaloric material provided by the present invention or a magnetocaloric material obtained by the preparation method provided by the present invention.
  • the invention also provides the use of the magnetocaloric material or the magnetocaloric material produced by the method of the invention in the manufacture of a refrigerating material.
  • the advantages of the present invention are: For La(Fe,Si) 13 -based magnetocaloric effect materials, an effective method for reducing hysteresis loss is to adjust the components, but the result is often a hysteresis reduction while magnetocaloric effect. The magnitude has also dropped significantly.
  • the invention can greatly reduce the bulk material by dividing the bulk material into an irregular powder having a particle size range of 15 ⁇ 200 ⁇ in a protective atmosphere or liquid while keeping the composition unchanged. Low hysteresis loss (reduced by 64%), the magnitude of the magnetocaloric effect remains essentially unchanged. Therefore, the present invention is of great significance for the practical industrialization of La(Fe,Si) 13 -based magnetocaloric materials in magnetic refrigeration applications. BRIEF DESCRIPTION OF THE DRAWINGS
  • Example 1 is a room temperature X-ray diffraction (XRD) pattern of a La ⁇ Cec Feu.sSiMQ sample prepared in Example 1.
  • Figure 3 shows the La ⁇ Cec Feu.sSiMQ block prepared in Example 1 and three samples in the particle size range (90 ⁇ 120 ⁇ , 50 ⁇ 90 ⁇ , 15 ⁇ 50 ⁇ ) a) The ascending field measured at different temperatures , the magnetization (MH) curve of the down-field process; b) the dependence of the hysteresis loss on temperature;
  • Figure 4 is the AS of the La ⁇ Cec Feu.sSiMQ block prepared in Example 1 and the samples of three particle size ranges (90 ⁇ 120 ⁇ , 50 ⁇ 90 ⁇ , 15 ⁇ 50 ⁇ ) in different magnetic fields. Dependence diagram on temperature;
  • Figure 5 is a particle size range of ⁇ 10 111 (average particle size of about 8 ⁇ ) prepared in Example 1.
  • La) Cec Feu.sSiMQ powder samples a) magnetization (M-H) curve; b) dependence of AS on temperature in the field process under different magnetic fields;
  • Figure 6 shows that the particle size obtained in Example 1 is smaller than ⁇ (average particle size of about 4 ⁇ )
  • La ⁇ Cei Feu.sSiMQ powder samples a) temperature-increasing thermomagnetic (M-T) curve; b) magnetization (M-H) curve; c) dependence of AS on temperature in the field up process under different magnetic fields;
  • Example 7 is a room temperature X-ray diffraction (XRD) pattern of a La Ce i ⁇ NdKFe ⁇ Coo SiM sample prepared in Example 2;
  • Example 8 is a thermal magnetic field of a Lao ⁇ Ce i ⁇ NdKFe ⁇ Coo ⁇ n.sSiM bulk material prepared in Example 2 and two sample sizes (150-200 ⁇ , 15-50 ⁇ ) in a magnetic field of 0.02 ⁇ . (MT) curve;
  • Fig. 9 is a graph showing the dependence of the hysteresis loss on the temperature of the Lao ⁇ Ce i ⁇ NdKFe ⁇ Coo ⁇ n.sSiM bulk material prepared in Example 2 and the samples of two particle size ranges (150 ⁇ 200 ⁇ , 15 ⁇ 50 ⁇ ) ;
  • Figure 10 shows the La ⁇ Ce i ⁇ NdKFe ⁇ Coo.c ⁇ n.sSiM bulk material prepared in Example 2 and two sample sizes (150 ⁇ 200 ⁇ , 15 ⁇ 50 ⁇ ) in the range of 5 ⁇ magnetic field. A dependence of temperature on the process;
  • Figure 11 is a particle size of 40-70 ⁇ and an average particle size of about 3 ⁇ obtained in Example 3.
  • La sPro.sFeu.sSi two kinds of powder samples in the 0.02T magnetic field heating magnetic (MT) curve
  • Figure 12 is the particle size 30-60 ⁇ produced in Example 4 and the average particle size of about 8 ⁇ La 07 (Ce , Pr, Nd sFen.eSiL.Co.oiH!.; temperature-increasing thermomagnetic (MT) curves of two powder samples at 0.02 T magnetic field;
  • Figure 13 shows the particle size of 30-60 ⁇ and the average particle size of about 5 ⁇ obtained in Example 5.
  • Fig. 14 is a graph showing the temperature-increasing thermomagnetic (M-T) curve of a powder sample of La wCeo ⁇ Fe ⁇ Coo Mn o ⁇ Siu having a particle diameter of 40-70 ⁇ m and an average particle diameter of about 7 ⁇ in a magnetic field of 0.02 T.
  • M-T temperature-increasing thermomagnetic
  • the raw materials used in the examples of the present invention are: Commercial LaCe alloy purchased from Inner Mongolia Baotou Steel Rare Earth International Trading Co., Ltd., purity: 97.03 at.%, La, Ce atomic ratio is 1:1.88; La-Ce- Pr-Nd mixed rare earth, purchased from Inner Mongolia Baotou Steel Rare Earth International Trading Co., Ltd., with a purity of 99.6wt.%, La, Ce, Pr, Nd element ratio: 28.3wt.% La, 50.5wt.% Ce, 5.2 wt .°/c ⁇ Pr, 15.7wt.°/c ⁇ Nd.
  • FeB alloy 99.9 wt.%, Fe, B weight ratio: 77.6 wt%: 22.4 wt% was purchased from Beijing Zhongke Sanhuan High Technology Co., Ltd. (The above raw materials are all in the form of blocks).
  • the electric arc furnace used is produced by Beijing Shike Optoelectronic Technology Co., Ltd., model: WK-II non-consumable vacuum arc furnace; Cu target X-ray diffractometer is produced by Rigaku, model RINT2400; superconducting quantum interference vibration sample Magnetometer (MPMS (SQUID) VSM), manufactured by Quantum Design (USA), model MPMS (SQUID) VSM.
  • Example 1 First order phase transition L a with small hysteresis loss. 7 3 ⁇ 116 ⁇ 4 ⁇ .
  • the raw materials are LaCe alloy, Fe, Si, La and FeC, wherein the elemental La is used to supplement the La-deficient part of the LaCe alloy, and the FeC alloy is used to provide C, due to the FeC alloy.
  • step 1) mixing the raw materials in step 1) into the electric arc furnace, pumping Vacuum to 2xlO_ 3 Pa, clean the cavity twice with high purity argon with a purity of 99.996%, then fill the cavity with 99.996% purity pure argon to an atmospheric pressure, arc arcing (the raw material after arc arcing) Melting together to form an alloy), obtaining an alloy ingot, each alloy spindle is repeatedly smelted 4 times, the melting temperature is 2000 ° C, after the melting is finished, cooling in a copper crucible to obtain an as-cast alloy ingot;
  • step 2) The as-cast alloy ingots prepared in step 2) are separately wrapped with molybdenum foil and sealed in a high vacuum.
  • step 4) The material obtained in step 3) is crushed into a coarse particle with a particle size of less than 1 mm in a metal mortar, and then the coarse particles are further ground to an irregularity of particle size ⁇ 200 ⁇ under an acetone protection with an agate mortar.
  • the powder is then sieved with a standard mesh of different mesh sizes to prepare powders having different particle size ranges. To prevent oxidation, the sieving process is carried out in an acetone liquid.
  • the specific screening methods are as follows:
  • a powder sample having a particle size of 90 to 120 ⁇ m was separated by a standard sieve of 170 mesh and 120 mesh; a powder sample having a particle diameter of 50 to 90 ⁇ m was separated by a standard sieve of 270 mesh and 170 mesh; 800 mesh and 270 mesh were used.
  • a standard sieve sieve separates a powder sample having a particle size ranging from 15 to 50 ⁇ m; a sample having a particle size smaller than ⁇ powder is separated by a 1600-mesh standard sieve.
  • the Curie temperature moves to a high temperature to 203K (the a-Fe may be precipitated due to the accumulation of stress introduced during the grinding process, and the relative Si content increases. ), the Curie temperatures of the other three particle size ranges are consistent with the bulk material and are located at 200K.
  • Figure 3 (a) and (b) respectively The MH curve of the bulk and three particle size ranges in the ascending and descending fields and the dependence of the hysteresis loss on temperature are shown.
  • the appearance of significant inflection points on the M-H curve indicates magnetic field induced changes from paramagnetic to ferromagnetic.
  • the existence of magnetic transition behavior Comparing the curves of each group, it can be seen that the hysteresis loss decreases greatly with the decrease of the granularity, and the maximum magnetic hysteresis decreases from 98.4 J/kg at the block to 15 ⁇ 50 ⁇ at the particle size range. 35.4J/kg, the drop ratio reaches 64%.
  • the MH curve of the high temperature zone (the paramagnetic zone of 1:13 phase) is a straight line, which indirectly proves that the block and the three particle size range samples are clean 1:13 phase, basic There is no appearance of the ⁇ -Fe phase.
  • La ⁇ Cec Fe ⁇ SiMCc samples maintain a large effective magnetic entropy change, with an average of 26 J/kgK 0
  • FIG. 5 shows a ⁇ - ⁇ curve and a magnetic entropy change temperature curve when the particle size range is lowered to ⁇ 10 ⁇ (the average particle size is about 8 ⁇ ). It can be seen from Fig. 5 that the particle size is reduced to ⁇ 10 ⁇ , although the maximum magnetic hysteresis is further reduced to 27 J/kg, but the precipitation of the ⁇ -Fe phase reduces the magnitude of the magnetocaloric effect to 21 J/kgK.
  • FIG. 5(a) is still curved in the paramagnetic high temperature region of the 1:13 phase, and the contribution from the ⁇ -Fe hetero phase indicates the precipitation of the a-Fe phase.
  • (a), (b) and (c) of Fig. 6 respectively show the temperature rise M-T curve of the material when the average particle diameter is further reduced to 4 ⁇ m, and the magnetization curves of different temperatures ( ⁇ - ⁇ curve) and magnetic entropy change temperature curve. It can be seen from Fig. 6(a) that there is a magnetic transition near the Curie temperature of 200K, but the magnetization of the high temperature region is very large and does not decrease to zero until 390K.
  • the MT curve rises around 350K, indicating that the 1:13 phase may decompose. , the material loses stability.
  • the isothermal magnetization curve shows that the magnetic lag of the material disappears substantially when the average particle size is reduced to about 4 ⁇ (Fig. 6b), but the magnetic entropy change value drops significantly (Fig. 6c), and the peak value is only 8.0 J/kgK. And 1/3 of the entropy change of the powder sample in the range of 15 ⁇ 120 ⁇ .
  • Example 2 First order phase transition L a with small hysteresis loss. 7 (C e , P r , NdW .. 98 .
  • La-Ce-Pr-Nd is mixed with rare earth, Fe, Si, La and Co, wherein elemental La is used to supplement the La-deficient portion of the La-Ce-Pr-Nd mixed rare earth;
  • step 3 The as-cast alloy ingots prepared in step 2) are respectively wrapped with molybdenum foil, sealed in a high vacuum (lxlO_ 4 Pa) quartz tube, annealed at 1080 ° C for 30 days, breaking the quartz tube liquid nitrogen quenching, A sample of Lao ⁇ Ce i ⁇ NdKFe ⁇ Coo.o n.sSiM having a NaZn 13 structure was obtained.
  • step 4) The material obtained in step 3) is crushed into a coarse particle having a particle diameter of less than 1 mm in a metal mortar, and then the coarse particles are further ground into an irregular powder having a particle diameter of ⁇ 200 ⁇ under an acetone protection with an agate mortar. Then, the metal powder is sieved with a standard sieve of a different mesh number to prepare powders having different particle diameter ranges. To prevent oxidation, the sieving process is carried out in an acetone liquid.
  • the specific screening methods are as follows:
  • Powder samples with a particle size of 150 ⁇ 200 ⁇ were separated by a standard sieve of 110 mesh and 80 mesh; powder samples with a particle size of 15 ⁇ 50 ⁇ were separated by a standard sieve of 800 mesh and 270 mesh; sample detection and result analysis:
  • the room temperature X-ray diffraction (XRD) pattern of the sample is shown in Fig. 7. It can be seen that the main phase of the sample is NaZn 13 type structure, and a small amount of unknown heterophase appears, marked by *, which may be related to the low purity of the raw material. The presence of impurities in low purity raw materials does not affect the formation of the main phase NaZn 13 structure.
  • ⁇ SiM block single particle, weight: 4.6mg
  • samples of different particle size range 150 ⁇ 200 ⁇ (weight: 2.47 mg), 15 ⁇ 50 ⁇ (weight: 1.95mg) up and down at different temperatures
  • the magnetization curve (MH curve) of the process has the same ascending and descending velocity, which is 500 Oersted/second.
  • Figure 9 shows the dependence of the hysteresis loss on the temperature of the block and the two particle size ranges. The comparison of the curves shows that the hysteresis loss decreases greatly with the decrease of the particle size.
  • the maximum magnetic hysteresis decreases from 98.6 J/kg at the block to 47.5 J/kg at the particle size range of 15 ⁇ 50 ⁇ , and the decrease ratio reaches 52.
  • the MH curve of the high temperature zone (1: 13 phase paramagnetic zone) is a straight line, which indirectly proves that the block and the two particle size range samples are all clean 1:13 phase, and there is basically no a-Fe phase.
  • Example 3 First-order phase change with small hysteresis loss L a ⁇ P r ⁇ F ei ⁇ Si 1A
  • the magnetocaloric effect material was prepared by using a single material of La, Pr, Fe, Si as a raw material, and was prepared by a process similar to that of Example 1.
  • a Lao.sPro.sFeu.sSi ⁇ alloy having a NaZn 13 structure followed by crushing, grinding, and sieving a particle sample having a particle size ranging from 40 to 70 ⁇ m and a powder smaller than ⁇ .
  • the powder having a particle diameter smaller than ⁇ was further ground to prepare an ultrafine powder sample having an average particle diameter of about 3 ⁇ .
  • Figure 11 shows the ⁇ - ⁇ curve of two samples of 40 ⁇ 70 ⁇ particles and ultrafine powder with an average particle size of about 3 ⁇ .
  • the Curie temperature of the 40 ⁇ 70 ⁇ powder sample is the same as that of the block, located at 181K;
  • the sample with a diameter of about 3 ⁇ has a Curie temperature of 185 K, which is 4 ⁇ higher than the bulk material, and the magnetization in the high temperature region is large and does not decrease to zero until 390 , which is similar to the case in Example 1, indicating that the material loses stability.
  • the ⁇ - ⁇ curve measurement results show that the maximum hysteresis loss of Lao.sPro.sFeu.sSi block is about 91 J/kg, and the maximum hysteresis loss of 40-70 ⁇ powder is 45 J/kg, which is about 51%, and the magnetic entropy change Basically remains the same.
  • Example 4 First-order phase transition La ⁇ (Ce,Pr, Nd Fe 11 fi Si 14 CnmH 17 magnetocaloric effect material with small hysteresis loss
  • La-Ce-Pr-Nd, elemental La, Fe, Si and FeC alloys (for providing C element) were used as raw materials, and Lao ⁇ having a NaZn 13 structure was prepared by a method similar to that of Example 1.
  • Ce ⁇ i ⁇ Nd Fen.sSiMCacH alloy sample The sample is crushed and annealed in hydrogen to obtain La ⁇ C ⁇ P ⁇ Nd sFen.sSiMCacnH, which is then crushed, ground and sieved to obtain a particle size of 30-60 ⁇ and less than 10 ⁇ (average particle size of about 8 ⁇ ).
  • La 7 (Ce, Pr, Nd Fen.sSiMCo.mH powder La 7 (Ce, Pr, Nd Fen.sSiMCo.mH powder.
  • Figure 12 shows a granule sample of 30 ⁇ 60 ⁇ and a powder sample with an average particle size of about 8 ⁇ , and a Curie of 30 ⁇ 60 ⁇ particles.
  • the temperature is at 318K, which is the same as the bulk material; the average particle size of about 8 ⁇ powder sample has a Curie temperature of 321K, which is 3 ⁇ higher than the bulk material, and still has a high magnetization in the high temperature region far from the Curie temperature, and Example 1
  • the situation in the case is similar, indicating that the material loses stability.
  • the ⁇ - ⁇ curve measurement results show that La.. 7 (Ce, Pr,
  • the maximum hysteresis loss of Nd Fen.sSiMCo.mH block is about 40 J/kg, and the maximum hysteresis loss of 30-60 ⁇ particles is 18 J/kg, which is about 55%, and the magnetic entropy change rate remains basically unchanged.
  • the hysteresis loss of the powder sample with an average particle size of about 8 ⁇ is reduced to near zero, and the magnetic entropy change is greatly reduced.
  • the powder having a particle diameter of less than 10 ⁇ m was further ground to prepare an ultrafine powder sample having an average particle diameter of about 5 ⁇ m.
  • Figure 13 shows the ⁇ - ⁇ curve of the two particle size materials.
  • the Curie temperature of the 30 ⁇ 60 ⁇ powder sample is the same as that of the block, located at 226 ⁇ ; the sample with an average particle size of about 5 ⁇ has a Curie temperature of 229 ⁇ , which is better than the block. It is 3 inches higher and still has a higher magnetization in a high temperature region far from the Curie temperature, similar to the case in Example 1, indicating that the material has lost stability.
  • the ⁇ - ⁇ curve measurement results show that
  • Lao. Ce i ⁇ Nd Feu.sSi Co.cn Bo.osHo.s block maximum hysteresis loss is about 160J/kg, 30-60 ⁇ powder sample maximum hysteresis loss is 67 J/kg, a decrease of about 58%, magnetic entropy change
  • the amplitude remains basically unchanged.
  • the hysteresis loss of the sample with an average particle size of about 5 ⁇ is basically reduced to zero, and the magnetic entropy is greatly reduced.
  • Example 6 First-order phase transition with small hysteresis loss La ⁇ Ce ⁇ iFe ⁇ Co ⁇ Mn ⁇ o ⁇ ) ii QSII 1 Magnetocaloric effect material
  • the industrial pure LaCe alloy (used to provide Ce element), elemental La, Fe, Si, Co, Mn was used as a raw material, and a particle size of 40 to 70 ⁇ and an average particle diameter of about 7 ⁇ were prepared in the same manner as in Example 1.
  • Lao.95Ceo.o5 (Feo.94Coo.o 3 Mn 0 .o 3 ) ii.9 Si L1 powder sample.
  • Figure 14 shows the MT curves for the two particle sizes.
  • the Curie temperature of the 40 ⁇ 70 ⁇ particle samples is ⁇ 153K, which is the same as the block.
  • the sample with an average particle size of about 7 ⁇ has a Curie temperature of 156K, which is 3 ⁇ higher than the bulk material, and still has a higher magnetization in the high temperature region far from the Curie temperature, similar to the case in Example 1, indicating that the material has been lost. stability.
  • the ⁇ - ⁇ curve measurement results show that
  • the industrially pure mixed rare earth La-Ce-Pr-Nd (used to provide Ce element), elemental La, Fe, Si, Co as raw materials, and prepared in a similar manner to that of Example 1 to have a particle size of 30-60 ⁇ La 0 . 7 (Ce, Pr, Nd ⁇ Feo ⁇ Co od ⁇ SiM particle sample.
  • the magnetic results show that the grain sample has a Curie temperature of 223K and a magnetic entropy change of about 24J/kgK, which is basically consistent with the block.
  • the maximum hysteresis is about 24J/kg, and the maximum hysteresis of the particle sample with particle size of 30 ⁇ 60 ⁇ is reduced to about 10J/kg, which is about 58%.
  • La(Fe, Si) is reduced in the range of 15-120 ⁇ .
  • the particle size of the 13 -base magnetocaloric effect material the material still maintains a large magnetic entropy change value, and can effectively reduce the hysteresis loss in the first-order phase transition process, which is of great significance for the work efficiency of the enhanced magnetic refrigeration cycle in practical applications.
  • the particle size of the material below ⁇ the sample loses stability, the magnetic transformation behavior is weakened, and the magnetic entropy change amplitude is greatly reduced, which is no longer suitable for practical application of magnetic refrigeration technology. Therefore, the particle size is removed during the actual application of the material. Particles smaller than 10 ⁇ Maintaining a large maximum magnetocaloric material.

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Abstract

本发明提供了一种小滞后损耗的一级相变La(Fe,Si)13基磁热效应材料及其制备方法和用途,所述材料具有NaZn13型结构,为粒径15~200μm的颗粒,粒径不小于15μm,化学通式为:La1-xRx(Fe1-p-qCopMnq)13-ySiyAα,所述材料的制备方法包括:通过熔炼、退火制备出La1-xRx(Fe1-p-qCopMnq)13-ySiyAα材料,之后制成粒径范围15~200μm的粉末。在组分不变的情况下在15~200μm范围内调节晶粒度可获得具有小的滞后损耗强磁热效应的La(Fe,Si)13基磁热效应材料,对于这类材料实际的磁制冷应用具有重要意义。当粒径10μm以下时,所述磁热效应材料失去稳定性,磁熵变幅度大幅下降,不再适合磁制冷技术的实际应用。因此材料实际应用过程中筛除掉粒径小于10μm的颗粒可最大限度保持材料的大磁热效应。

Description

小滞后损耗的一级相变 La(Fe,Si)^磁热效应材料及其制备方法和用途 技术领域
本发明涉及一种小滞后损耗的一级相变 La(Fe,Si)13基磁热效应材料及其 制备方法和包括该材料的磁制冷机器以及该材料在制造制冷材料中的应用。 背景技术
制冷业耗能占社会总耗能的 15%以上。 目前普遍使用的气体压缩制冷技 术具有能耗高、 污染环境等缺点。 探求无污染、 绿色环保的制冷材料和研发 新型低能耗、 高效率的制冷技术是当今世界需要迫切解决的问题。
磁制冷技术具有绿色环保、 高效节能、 稳定可靠的特点, 近些年来已经 引起世界范围的广泛关注。 美国、 中国、 荷兰、 日本相继发现的几类室温乃 至高温区巨磁热材料大大推动了人们对绿色环保磁制冷技术的期待, 例如:
Gd-Si-Ge、 LaCaMn03、 Ni-Mn-Ga、 La(Fe,Si)13基化合物、 Mn-Fe-P-As、 MnAs 等化合物。这些新型巨磁热效应材料的共同特点是磁熵变均高于传统室温磁 制冷材料 Gd, 相变性质为一级, 并且多数呈现强烈的磁晶耦合特点, 磁相 变伴随显著的晶体结构相变的发生。 这些新型材料还表现出不同的材料特 点, 例如, Gd-Si-Ge 价格昂贵, 制备过程中需要对原材料进一步提纯, Mn-Fe-P-As、 MnAs等化合物原材料有毒, NiMn基 Heusler合金具有滞后损 耗大的特点等等。
近十多年来发现的几类新材料中, 目前被国际上广泛接受、 最有可能实 现高温乃至室温区磁制冷应用的是 La(Fe,Si)13基化合物。 该合金具有原材料 价格低廉, 相变温度、 相变性质、 滞后损耗可随组分调节等特点, 室温附近 磁熵变高于 Gd—倍。 多个国家的实验室纷纷将 1^(?6,81)13基磁制冷材料用 于样机试验, 证明其制冷能力优于 Gd。
La(Fe,Si)13基化合物的相变性质可随组分的调节而改变。 例如低 Si含量 的化合物相变性质一般为一级, 随 Co含量的增加居里温度上升, 一级相变 性质减弱, 并逐渐过渡到二级(二级相变没有滞后损耗), 滞后损耗逐渐减 小, 然而由于组分、 交换作用的改变磁热效应幅度也随之下降。 Mn的加入 通过影响交换作用使居里温度下降,一级相变性质减弱,滞后损耗逐渐减小, 磁热效应幅度也随之下降。 相反人们发现, 小的稀土磁性原子(例如 Ce、 Pr、 Nd )替代 La可增强一级相变性质, 滞后损耗增大, 磁热效应幅度增大。 人们期待将具有巨磁热效应的一级相变 La(Fe,Si)13基化合物用于实际的磁制 冷应用, 并获得理想的制冷效果。
然而, 具有一级相变特征的 La(Fe,Si)13基化合物虽然表现出巨大磁热效 应, 但是往往伴随着显著的滞后损耗。 滞后损耗在磁制冷机器的制冷循环中 表现为漏热, 一级相变过程中所伴随的显著的滞后损耗将大大降低材料的制 冷效率。 因此, 材料学家和工程学家梦寐以求在保证 La(Fe,Si)13基化合物巨 大磁热效应的同时有效降低滞后损耗。 发明内容
因此, 本发明的目的在于提供一种具有小的滞后损耗的一级相变
La(Fe,Si)13基磁热效应材料及其制备方法和包含该材料的磁制冷机器以及该 材料在制造制冷材料中的应用。
滞后损耗是一级相变体系的本征特性, 有效降低滞后损耗可显著提高制 冷效率。 滞后主要来源于两方面因素, 一是相变过程的本征因素: 如成核因 素、 晶界、 内应力、 相界摩擦力等等; 二是非本征因素: 如变场速度、 与周 围环境的热交换等等。
本发明的发明人将具有巨大滞后损耗的一级相变 La(Fe,Si)13基磁热效应 材料在组分不变的情况下破碎成粒径为 15~200微米(μηι ) 的不规则粉末, 意外地发现滞后损耗随颗粒度的减小大幅下降。在粒径不小于 15 μηι的情况 下, 材料的结构、 原子占位、 原子间距均不受影响, 因此稀土 (R)-Fe、 Fe-Fe 间的铁磁交换作用不受影响, 铁磁-顺磁相变温度(居里温度)、 饱和磁化强 度保持不变, 材料仍然表现出巨大磁热效应。 当粒径小于 ΙΟ μηι时, 由于粉 末研磨过程中引入的应力作用的积累材料将析出 α-Fe或者分解,虽然滞后损 耗进一步降低,但是磁热效应幅度也随之降低。研究结果表明,在 15~200 μηι 范围内调节晶粒度可获得具有小的滞后损耗强磁热效应的 La(Fe,Si)13基磁热 效应材料。 通过将材料破碎有效减少了晶界、 增大了比表面积, 发现滞后损 耗随粒径的减小大幅下降。 对于这类材料实际的磁制冷应用具有重要意义。
为有助于理解本发明, 下面定义了一些术语。 本文定义的术语具有本发 明相关领域的普通技术人员通常理解的含义。
除非另外说明, 本文所用的术语 LaFe13_xMx对应的 &21113型结构" 或 者 "1 :13结构" 是指空间群为 Fm^的一种结构。 Fe原子以 1:12比例分别占 据两个晶位 Sb e1)和 96i(Fen)位。 La和 Fe1原子组成 CsCl结构。 其中 La原 子被 24个 Fe11原子包围, Fe1原子被组成二十面体的 12个 Fe11原子包围, 每 一个 Fe11原子周围有 9个最近邻的 Fe11原子、 1个 Fe1原子以及一个 La原子。 对于 LaFe13^Mx ( M = A1、 Si )化合物, 中子衍射实验表明: 8b位完全由 Fe 原子占据, M原子和剩下的 F e原子随机占据在 96 i位上。
本发明的目的是通过如下的技术方案实现的。
本发明提供了一种具有小滞后损耗的一级相变 La(Fe,Si)13基磁热效应材 料, 所述材料具有 NaZn13型结构, 并且为粒径范围 15~200 mm的颗粒, 该 颗粒的粒径不小于 15 μηι。
根据本发明提供的磁热效应材料, 其中, 当颗粒的粒径降低到 15 μηι以 下, 特别是 ΙΟ μηι以下时, 所述磁热效应材料失去稳定性, 变磁转变行为削 弱, 磁熵变幅度大幅下降, 不再适合磁制冷技术的实际应用。 因此材料实际 应用过程中筛除掉粒径小于 10 μηι 的颗粒可最大限度保持材料的大磁热效 应。
所述磁热效应材料的化学通式可以为:
Lai -xRx(Fe i -p-qCopMnq)! 3-y SiyAa , 其中,
R选自铈 (Ce ) 、 镨 (Pr ) 和钕 ( Nd ) 元素中的一种或多种,
A选自碳 (C ) 、 氢 (H ) 和硼 (B ) 元素中的一种或多种,
X的范围是: 0<x≤0.5 ,
y的范围是: 0.8<y≤1.6,
p的范围是: 0≤p≤0.2,
q的范围是: 0<q<0.2,
a的范围是: 0≤a≤3.0。
在本发明的一些实施方案中, 所述磁热效应材料的化学通式为:
Lai -xRx(Fe i -p-qCopMnq)! 3-y SiyAa , 其中,
R选自铈 (Ce ) 、 镨 (Pr ) 和钕 ( Nd ) 元素中的一种或多种,
A选自碳 (C ) 、 氢 (H ) 和硼 (B ) 元素中的一种或多种,
X的范围是: 0<x≤0.5 ,
y的范围是: 1.0≤y≤1.6,
p的范围是: 0≤p≤0.05,
q的范围是: 0≤q≤0.03 ,
a的范围是: 0≤a≤1.8。
在本发明磁热效应材料的化学通式中, A为原子半径小的间隙原子(例 如碳、氢和硼),这些间隙原子的加入在 NaZn13结构中均占据 24d间隙位, 对结构的影响起到相同作用。 优选地, α的范围是: 0.1≤α≤2.0。 所述材料具有一级相变特征, 块体材料表现出明显的磁滞后损耗, 当 粒径范围为 15~50μηι时, 其最大本征滞后损耗小于 60 J/kg。
在本发明的一些实施方案中, 所述磁热效应材料的化学通式为: La1-xRx(Fe1-pCop)13-ySiyAa, 其中, R选自 Ce、 Pr和 Nd元素中的一种 或多种, A选自 H、 C和 B元素中的一种或两种, X的范围是: 0.2≤x≤0.5, y的范围是: 0.8<y≤1.6, p的范围是: 0≤p≤0.03, a的范围是: 0.1≤a≤2.0。
例如, 在本发明的更具体的实施方案中, 所述磁热效应材料的化学式 可以为: LaojCeojFen.sSiMQ ; La07(Ce, Pr, Nd)0.3(Feo.98Coo.o2) 11.eSii .4; LaosProsFensSiis; Lao CCe^^Nd sFen.eSiL.Co.oiH^; La07(Ce,Pr,
d)o.3Fei i .6Sii .4Co.oiBo.o2¾.6 Lao.95Geo.o5(Feo.94Goo.o3Mno.o3)ii.9Si1.1; Lao.7(Ce,Pr, Nd)0.3(Fe0.96Co0.04)1L6SiL4
根据本发明提供的磁热效应材料, 优选情况下, 所述磁热效应材料粒 径不小于 15μηι, 可以为粒径范围 15~200 μηι的颗粒, 更优选为 15~50 μηι 的颗粒。
根据本发明提供的磁热效应材料, 优选情况下, 所述磁热效应材料在 0~5Τ磁场变化下的有效磁熵变值可以为 5.0~50.0J/kgK, 相变温区可以位 于 10~400K。
本发明还提供了上述磁热效应材料的制备方法,该方法包括如下步骤: 1 ) 按化学式配制除氢以外的原料;
2) 将步骤 1 ) 中配制好的原料放入电弧炉中, 抽真空, 用氩气清洗, 并在氩气保护下熔炼, 获得合金锭;
3)将步骤 2)熔炼好的合金锭真空退火, 然后在液氮或水中淬火, 从 而制备出具有 NaZn13结构的 La^iUFe^qCOpMV ^ySiyAa磁热效应材料; 4 )对步骤 3)制得的磁热效应材料进行破碎、 研磨和筛分, 得到粒径 范围 15~200μηι的颗粒;
其中, 当化学通式中的 Α包括氢元素时, 所述方法还包括: 5) 将步 骤 4) 制得的颗粒在氢气中退火, 或者将步骤 3) 制得的磁热效应材料破 碎后先在氢气中退火, 然后再进行步骤 4) 。
根据本发明的制备方法, 在所述步骤 4) 中, 筛除掉粒径小于 15 μηι 的颗粒, 特别地筛除掉粒径小于 10 μηι的颗粒。
根据本发明提供的制备方法, 其中, 原材料 La、 R可以是商业化单质 稀土元素, 也可以是工业纯 LaCe合金或工业纯 LaCePrNd混合稀土。 商业 化的工业纯 LaCe合金的纯度通常为 95-98 at.% (原子比) , 合金中 La、 Ce 原子比为 1:1.6-1:2.3 , 工业纯 LaCePrNd混合稀土通常纯度为 99 wt.%左右。 可以用单质 La来补充 LaCe合金相对于待制备的材料中 La不足的部分; 类似地, 工业纯 LaCePrNd混合稀土也可以按此操作。
当 A包括碳元素时, 优选地, 碳可以由 FeC合金提供。 由于 FeC合金 中也含有 Fe元素, 需要适当减少添加的单质 Fe, 使得添加的各种元素的 配比仍旧满足磁性材料化学式的原子配比。
化学式中的其他原材料均为商业化单质元素。
根据本发明提供的制备方法, 具体地, 所述步骤 2 ) 可以包括: 将步 骤 1 ) 中配制好的原料放入电弧炉中, 抽真空至真空度小于 l x l O_2Pa, 用 纯度大于 99%的高纯氩气清洗炉腔 1~2次, 之后炉腔内充入该氩气至 0.5~1.5个大气压, 电弧起弧, 获得合金锭, 每个合金锭在 1500~2500°C下 反复熔炼 1~6次, 例如 2~6次。
根据本发明提供的制备方法, 具体地, 所述步骤 3 ) 可以包括: 将步 骤 2 )熔炼好的合金锭在 1000~1400°C、 真空度小于 l x l(T3 Pa的条件下退 火 1小时至 60天, 然后在液氮或水中淬火。
根据本发明提供的制备方法, 具体地, 所述步骤 4 ) 可以包括: 将步 骤 3 ) 制得的磁热效应材料敲碎和 /或分割制成粒径小于 1 mm的粗颗粒, 之后在保护气或保护液中用玛瑙研钵将粗颗粒进一步研磨至粒径≤ 200 μηι, 之后用标准筛对金属粉末进行筛分, 收集粒径范围 15~200 μηι的颗粒, 优 选收集粒径范围 15~50 μηι的颗粒。
根据本发明提供的制备方法, 其中, 在所述步骤 5 ) 中, 通过调节氢 气压力、 退火温度和时间来控制合金中氢的量。 一般情况下, 氢气的压力 为 10_3Pa至 80个大气压, 退火的温度为 0-400°C , 退火的时间为 lmin至 24小时。
本发明还提供了一种磁制冷机, 所述制冷机包括本发明提供的磁热效 应材料或者按照本发明提供的制备方法制得的磁热效应材料。
本发明还提供了所述磁热效应材料或者按照本发明方法制得的磁热 效应材料在制造制冷材料中的应用。
与现有技术相比,本发明的优势在于: 对于 La(Fe,Si)13基磁热效应材料, 通常用于降低滞后损耗的有效办法是调节组分,但结果往往是滞后下降的同 时磁热效应幅度也大幅下降。本发明在保持组分不变的情况下通过在保护气 氛或者液体中将块体材料分割成粒径范围 15~200μηι的不规则粉末可大幅降 低滞后损耗(降低幅度可达到 64%) , 磁热效应幅度基本保持不变。 因此, 本发明对于 La(Fe,Si)13基磁热效应材料在磁制冷应用中的实际产业化具有重 要的意义。 附图的简要说明
以下, 结合附图来详细说明本发明的实施方案, 其中:
图 1 为实施例 1制得的 La^Cec Feu.sSiMQ 样品的室温 X射线衍射 (XRD) 图谱;
图 2 为实施例 1制得的 La^Cec Feu.sSiMQ 块材以及 3个粒径范围 的样品( 90~120 μηι、 50~90 μηι、 15~50 μηι )在 0.02Τ磁场下的热磁( Μ-Τ ) 曲线;
图 3 为实施例 1制得的 La^Cec Feu.sSiMQ 块材以及 3个粒径范围 的样品 (90~120 μηι、 50~90 μηι、 15~50 μηι ) a)不同温度下测量的升场、 降场过程的磁化 (M-H) 曲线; b)滞后损耗对温度的依赖关系图;
图 4 为实施例 1制得的 La^Cec Feu.sSiMQ 块材以及 3个粒径范围 的样品 (90~120 μηι、 50~90 μηι、 15~50 μηι )在不同磁场下升场过程的 AS 对温度的依赖关系图;
图 5 为实施例 1制得的粒径范围<10 111 (平均粒径约 8μηι) 的
La^Cec Feu.sSiMQ 粉末样品的 a) 磁化 ( M-H ) 曲线; b)不同磁场下升 场过程的 AS对温度的依赖关系图;
图 6为实施例 1制得的粒径小于 ΙΟμηι (平均粒径约 4μηι ) 的
La^Cei Feu.sSiMQ 粉末样品的 a) 升温热磁( M-T )曲线; b) 磁化(M-H) 曲线; c) 不同磁场下升场过程的 AS对温度的依赖关系图;
图 7 为实施例 2制得的 La Ce i^NdKFe ^Coo SiM样品的室 温 X射线衍射 (XRD) 图谱;
图 8 为实施例 2制得的 Lao^Ce i^NdKFe ^Coo^n.sSiM块材以及 2个粒径范围的样品( 150-200 μηι、15~50 μηι )在 0.02Τ磁场下的热磁( M-T ) 曲线;
图 9 为实施例 2制得的 Lao^Ce i^NdKFe ^Coo^n.sSiM块材以及 2个粒径范围的样品 ( 150~200 μηι、 15~50 μηι )滞后损耗对温度的依赖关 系图;
图 10 为实施例 2制得的 La ^Ce i^NdKFe ^Coo.c^n.sSiM块材以及 2个粒径范围的样品 (150~200 μηι、 15~50 μηι ) 在 5Τ磁场下升场过程的 A 对温度的依赖关系图;
图 11 为实施例 3制得的粒径 40-70μηι以及平均粒径约 3 μηι的 La sPro.sFeu.sSi 两种粉末样品在 0.02T磁场下的升温热磁 ( M-T ) 曲线; 图 12 为实施例 4制得的粒径 30-60μηι以及平均粒径约 8 μηι 的 La07(Ce, Pr, Nd sFen.eSiL.Co.oiH!.;两种粉末样品在 0.02T磁场下的升温热 磁 (M-T) 曲线;
图 13 为实施例 5制得的粒径 30-60μηι以及平均粒径约 5 μηι的
Lao^Ce i^Nd Fen.sSiMC cnB osH s两种粉末样品在 0.02T磁场下的升温 热磁 (M-T) 曲线;
图 14 为实施例 6 制得的粒径 40-70μηι 以及平均粒径约 7 μηι 的 La wCeo^Fe^Coo Mn o^ Siu两种粉末样品在 0.02T磁场下的升温热 磁 (M-T) 曲线。 实施发明的最佳方式
以下参照具体的实施例来说明本发明, 本领域技术人员能够理解, 这些 实施例仅用于说明本发明的目的, 其不以任何方式限制本发明的范围。
关于实施例中使用的原料和设备的说明如下:
(1)本发明实施例中所用原料为: 商业化的 LaCe合金购自内蒙古包 钢稀土国际贸易有限公司, 纯度为: 97.03 at.%, La、 Ce原子比为 1:1.88; La-Ce-Pr-Nd混合稀土,购自内蒙古包钢稀土国际贸易有限公司, 纯度为 99.6wt.%, La、 Ce、 Pr、 Nd元素比例: 28.3wt.%的 La、 50.5wt.%的 Ce、 5.2 wt.°/c^Pr、 15.7wt.°/c^Nd。 其它原材料及其纯度分别是: 单质 La (纯度 99.52 wt% ),单质 Ce( 99.90wt.% ),单质 Pr( 98.97wt.% ),单质 Nd( 99.9wt.% ), 购自湖南升华稀土金属材料有限责任公司; Fe ( 99.9 wt% ) 购自北京有色 金属研究院; FeC (99.9wt%, Fe:C重量比: 95.76:4.24) , 由单质 C和纯 度为 99.9 wt%的 Fe熔炼而成; Si ( 99.91 wt% ) , 购自北京有色金属研究 院; Co ( 99.97wt%) , 购自北京有色金属研究院。 Mn (99.8wt.%) , 购 自北京双环化学试剂厂。 FeB合金(99.9wt.%, Fe、 B重量比为 77.6wt%: 22.4wt%),购自北京中科三环高技术股份有限公司。(以上原料都为块状)。
(2)所用电弧炉为北京物科光电技术有限公司生产, 型号: WK-II型 非自耗真空电弧炉; Cu靶 X射线衍射仪为 Rigaku公司生产, 型号为 RINT2400; 超导量子干涉振动样品磁强计( MPMS ( SQUID ) VSM ) , 为 Quantum Design ( USA )公司生产, 型号为 MPMS ( SQUID ) VSM。 实施例 1: 具有小滞后损耗的一级相变 La7 3^116§ 4^。7磁热效应材料 1 ) 按 LaojCec Fe^SiMQ^化学式配料, 原料为 LaCe合金、 Fe、 Si、 La和 FeC, 其中, 单质 La用来补充 LaCe合金中 La不足的部分, FeC合 金用来提供 C, 由于 FeC合金中也含有 Fe元素, 需要适当减少添加的单 质 Fe, 使得添加的各种元素的配比仍旧满足磁性材料化学式的原子配比; 2)将步骤 1) 中的原料混合, 放入电弧炉中, 抽真空至 2xlO_3Pa, 用 纯度为 99.996%的高纯氩气清洗炉腔 2次,之后炉腔内充入纯度为 99.996% 高纯氩气至一个大气压, 电弧起弧(电弧起弧后原材料就熔在一起成为合 金了) , 获得合金锭, 每个合金锭子反复熔炼 4次, 熔炼温度为 2000°C, 熔炼结束后, 在铜坩锅中冷却获得铸态合金锭;
3)将步骤 2)中制备好的铸态合金锭分别用钼箔包好, 密封在高真空
( lxlO_4Pa)石英管中, 在 1080°C下退火 30天, 打破石英管液氮淬火, 获 得具有 NaZn13 结构的 Lao Cec Feu.sSiMQ 样品。
4) 将步骤 3) 制得的材料在金属研钵中敲碎分割成粒径小于 1mm的 粗颗粒, 之后在丙酮保护下用玛瑙研钵将粗颗粒进一步研磨成粒径≤ 200 μηι 的不规则粉末, 之后用不同目数的标准筛对金属粉末进行筛分, 从而制备 出具有不同粒径范围的粉末。 为防止氧化, 筛分过程在丙酮液体中进行。 具 体的筛分方式如下:
用 170目和 120目的标准筛筛分出粒径在 90~120μηι范围的粉末样品; 用 270目和 170目的标准筛筛分出粒径在 50~90μηι范围的粉末样品; 用 800目和 270目的标准筛筛分出粒径在 15~50μηι范围的粉末样品; 用 1600目的标准筛筛分出粒径小于 ΙΟμηι粉末样品。 样品检测及结果分析:
一、利用 Cu靶 X射线衍射仪测定 La^Cec Feu.sSiMQ^样品的室温 X 射线衍射(XRD) 图谱, 结果如图 1所示, 可以看出样品为干净的 NaZn13 型单相结构, 几乎没有杂相出现。
二、 在超导量子干涉振动样品磁强计【MPMS (SQUID) VSM】上测 定 La^Cec Fe^SiMQ^块材 (单个颗粒, 重量: 2.7mg ) 以及不同粒径范 围的样品 (90~120 μηι (重量: 2.31 mg) 、 50~90μηι (重量: 1.86 mg) 、 15~50μηι (重量: 1.28 mg ) 、 <10 μηι (重量: 0.86 mg ) 在 0.02Τ磁场下 的热磁(M-T) 曲线, 如图 2所示。 结果显示: 除了粒径<10 111的样品的 居里温度向高温移动到 203K之外 (由于研磨过程中引入应力作用的积累材 料可能析出了 a-Fe, 相对 Si含量增加) , 其它 3个粒径范围的样品的居里 温度均与块体材料一致, 位于 200K。
三、 在 MPMS ( SQUID ) VSM上测定 La。.7Ce。.3Fe1L6SiL4C 2块材(单 个颗粒,重量: 2.7mg)以及不同粒径范围样品(90~120μηι(重量: 2.31 mg)、 50~90μηι (重量: 1.86 mg) 、 15~50μηι (重量: 1.28 mg ) 、 <10 μηι (重 量: 0.86 mg) 在不同温度下升场、 降场过程的磁化曲线 (M-H曲线) , 升场、 降场速度相同, 为 500奥斯特 /秒。 图 3的 (a)和 (b)组分别示出块材 和 3个粒径范围样品在升、 降场过程的 M-H曲线以及滞后损耗对温度的 依赖关系。 M - H曲线上显著拐点的出现表明磁场诱导的从顺磁至铁磁态变 磁转变行为的存在。 将各组曲线进行对比可以看出: 滞后损耗随颗粒度的 减小大幅下降,最大磁滞后从块材时的 98.4 J/kg下降到粒径范围 15~50 μηι 时的 35.4J/kg, 下降比例达到 64%。 高温区 ( 1:13相的顺磁区域) 的 M-H 曲线为直线, 间接证明块材以及 3个粒径范围样品均为干净的 1:13相,基 本没有 α-Fe相的出现。
四、 根据麦克斯韦关系: A^r,H) = wr,H)-^r,0)= iH( ^) H ,
JO 可从等 温磁化曲线计算磁熵变 AS。 图 4示出块材以及 3个粒径范围的
La^Cec Feu.sSiMQ 样品在不同磁场下升场过程的 AS对温度的依赖关 系。 图 4中可以看出, AS峰形随着磁场的增加向高温区不对称展开, 尖 峰后跟一个平台, 这是 1^(?6,8013基一级相变体系的典型特征, 来源于居 里温度以上磁场诱导的变磁转变行为。 Δ S峰形进一步验证了体系的一级 相变特征和变磁转变行为的存在。 已有研究表明, AS尖峰的出现是由于 一级相变过程的两相共存而产生, 是不存在热效应的假象, AS平台反应 了磁热效应的本质。 可以看出, 块材以及 3个粒径范围的
La^Cec Fe^SiMCc 样品均保持大的有效磁熵变幅度, 平均值为 26 J/kgK0
作为与上述结果的对比, 图 5的 (a)和 (b)分别示出了粒径范围降低到 <10μηι (平均粒度约为 8μηι) 时的 Μ-Η曲线和磁熵变温度曲线。 从图 5 可以看出: 减小颗粒度至 <10μηι, 虽然最大磁滞后进一步减小到 27 J/kg, 但是 α-Fe相的析出使磁热效应幅度下降至 21 J/kgK。 图 5(a)的 Μ-Η曲线 在 1:13相的顺磁高温区域依然弯曲,来自于 α-Fe杂相的贡献,表明了 a-Fe 相的析出。 进一步研磨获得更小粒径样品, 图 6的 (a)、 (b)和 (c)分别示出 了平均粒径进一步降低到 4 μ m时材料的升温 M- T曲线、 不同温度磁化曲 线(Μ-Η曲线)和磁熵变温度曲线。 从图 6(a)中可以看出居里温度 200K 附近存在磁性转变, 但高温区的磁化强度非常大且直到 390K也未降低到 零, M-T曲线在 350K附近隆起表明 1:13相可能出现分解, 材料丧失稳定 性。 等温磁化曲线表明平均粒度降低到约为 4 μηι时, 材料的磁滞后基本 消失(图 6b), 但磁熵变值大幅下降(图 6c), 峰值仅 8.0J/kgK, 不足块材 及 15~120μηι范围内粉末样品熵变值的 1/3。 实施例 2:具有小滞后损耗的一级相变 La7(Ce,Pr,NdW 。.98
磁热效应材料
1 ) 按 Lao. Ce i^NdKFeo^Co c^u.sSiM化学式配料, 原料为
La-Ce-Pr-Nd混合稀土、 Fe、 Si、: La和 Co,其中,单质 La用来补充 La-Ce-Pr-Nd 混合稀土中 La不足的部分;
2)将步骤 1 ) 中的原料混合, 放入电弧炉中, 抽真空至 2xlO_3Pa, 用 纯度为 99.996%的高纯氩气清洗炉腔 2次,之后炉腔内充入纯度为 99.996% 高纯氩气至一个大气压, 电弧起弧(电弧起弧后原材料就熔在一起成为合 金了) , 获得合金锭, 每个合金锭子反复熔炼 4次, 熔炼温度为 2000°C, 熔炼结束后, 在铜坩锅中冷却获得铸态合金锭;
3)将步骤 2)中制备好的铸态合金锭分别用钼箔包好, 密封在高真空 ( lxlO_4Pa)石英管中, 在 1080°C下退火 30天, 打破石英管液氮淬火, 获 得具有 NaZn13 结构的 Lao^Ce i^NdKFe ^Coo.o n.sSiM样品。
4) 将步骤 3) 制得的材料在金属研钵中敲碎分割成粒径小于 1mm的 粗颗粒,之后在丙酮保护下用玛瑙研钵将粗颗粒进一步研磨成粒径 ≤200μηι 的不规则粉末, 之后用不同目数的标准筛对金属粉末进行筛分, 从而制备 出具有不同粒径范围的粉末。 为防止氧化, 筛分过程在丙酮液体中进行。 具 体的筛分方式如下:
用 110目和 80目的标准筛筛分出粒径在 150~200μηι范围的粉末样品; 用 800目和 270目的标准筛筛分出粒径在 15~50μηι范围的粉末样品; 样品检测及结果分析:
一、利用 Cu靶 X射线衍射仪测定
Figure imgf000012_0001
样品的室温 X射线衍射(XRD) 图谱, 结果如图 7所示, 可以看出样品主 相为 NaZn13型结构, 少量未知杂相出现, 由 *号标出, 可能与原材料低纯 度有关。 低纯度原材料中杂质的存在并没有影响主相 NaZn13型结构的生 成。
二、 在超导量子干涉振动样品磁强计【MPMS (SQUID) VSM】上测 定 La Ce ^NdKFeo^Co c^u.sSiM块材 (单个颗粒, 重量: 4.6mg ) 以 及不同粒径范围的样品( 150~200μηι (重量: 2.47mg ) 、 15~50μηι (重量: 1.95mg)在 0.02Τ磁场下的热磁 (Μ-Τ) 曲线, 如图 8所示。 结果显示: 2 个粒径范围的样品的居里温度均与块体材料一致, 位于 200K。 三、 在 MPMS ( SQUID ) VSM上测定
Figure imgf000013_0001
^SiM块材 (单个颗粒, 重量: 4.6mg ) 以及 不同粒径范围样品 ( 150~200 μηι (重量: 2.47 mg ) 、 15~50 μηι (重量: 1.95mg ) 在不同温度下升场、 降场过程的磁化曲线 (M-H曲线) , 升场、 降场速度相同, 为 500奥斯特 /秒。 图 9给出块材和 2个粒径范围样品的滞 后损耗对温度的依赖关系。 将各组曲线进行对比可以看出: 滞后损耗随颗 粒度的减小大幅下降, 最大磁滞后从块材时的 98.6 J/kg下降到粒径范围 15~50 μηι时的 47.5 J/kg, 下降比例达到 52%。 高温区 ( 1 : 13相的顺磁区 域) 的 M-H曲线为直线, 间接证明块材以及 2个粒径范围样品均为干净 的 1 : 13相, 基本没有 a-Fe相的出现。
四、 根据麦克斯韦关系: A^r,H) = ^r,H)-^r,o) = i
JOH( H , 可从等 温磁化曲线计算磁熵变 AS。 图 10示出块材以及 2个粒径范围的
1^0.7( 6,?1^(1)。.3(?6。.980)。.。2)11.(^1.4样品在5丁磁场下升场过程的八8对温度 的依赖关系。 图 10中可以看出, AS峰形随着磁场的增加向高温区不对称 展开, 尖峰后跟一个平台, 这是 1^(?^8013基一级相变体系的典型特征, 来源于居里温度以上磁场诱导的变磁转变行为。 AS峰形验证了体系的一 级相变特征和变磁转变行为的存在。 已有研究表明, AS尖峰的出现是由 于一级相变过程的两相共存而产生, 是不存在热效应的假象, AS平台反 应了磁热效应的本质。 可以看出, 块材以及 2个粒径范围的
Lao.7(Ce,Pr,Nd)o.3(Fe0.98Coo.o2) i i .6Sii .4样品均保持大的有效磁熵变幅度,平均 值为 27.5 J/kgK, 但是滞后损耗大幅下降。 实施例 3: 具有小滞后损耗的一级相变 La^Pr^Fei^Si1A磁热效应材料 以单质 La、 Pr、 Fe、 Si为原材料, 釆用与实施例 1类似的工艺制备出 具有 NaZn13结构的 Lao.sPro.sFeu.sSi^合金, 之后破碎、 研磨、 筛分出粒径 范围为 40~70 μηι颗粒样品和小于 ΙΟμηι的粉末。 将粒径小于 ΙΟμηι的粉末 进一步研磨, 制备出超细粉末样品, 平均粒径约 3 μηι。 图 11给出了 40~70 μηι颗粒和平均粒径约 3 μηι的超细粉末两种样品的 Μ-Τ曲线, 40~70 μηι 粉末样品的居里温度与块材相同, 位于 181K; 平均粒径约 3 μηι的样品居里 温度位于 185K, 比块材高出 4Κ,并且高温区的磁化强度较大且直到 390Κ 也未降低到零, 和实施例 1中情况类似, 表明材料失去稳定性。 Μ-Η曲线 测量结果表明, Lao.sPro.sFeu.sSi 块材最大滞后损耗约 91 J/kg, 40-70 μηι粉 末的最大滞后损耗为 45 J/kg, 降幅约 51%, 磁熵变幅度基本保持不变。 平均 粒径约 3 μηι的样品的滞后损耗基本降到零, 但是磁熵变幅度大幅下降。 实施例 4: 具有小滞后损耗的一级相变 La^(Ce,Pr,Nd Fe11 fiSi14CnmH17 磁热效应材料
以工业纯混合稀土 La-Ce-Pr-Nd、 单质 La、 Fe、 Si以及 FeC合金(用于 提供 C元素)为原料, 釆用与实施例 1类似的方法制备出具有 NaZn13结构 的 Lao^Ce^i^Nd Fen.sSiMCacH合金样品。将样品破碎在氢气中退火处理 获得 La ^C^P^Nd sFen.sSiMCacnH , 之后经过再破碎、 研磨、 筛分后 得到粒径为 30~60 μηι和小于 10 μηι (平均粒径约 8μηι ) 的 La 7(Ce, Pr, Nd Fen.sSiMCo.mH 粉末。 图 12给出了 30~60 μηι的颗粒样品和平均粒径 约 8μηι的粉末样品 Μ-Τ曲线, 30~60 μηι颗粒样品的居里温度位于 318K, 与块材相同; 平均粒径约 8μηι粉末样品居里温度为 321K, 比块材高出 3Κ, 且在远离居里温度的高温区仍具有较高的磁化强度, 与实施例 1中的情形类 似, 表明材料失去稳定性。 Μ-Η曲线测量结果表明, La。.7(Ce,Pr,
Nd Fen.sSiMCo.mH 块材最大滞后损耗约 40 J/kg, 30-60 μηι颗粒的最大滞 后损耗为 18 J/kg, 降幅约 55%,磁熵变幅度基本保持不变。平均粒径约 8 μηι 的粉末样品滞后损耗降到接近于零, 磁熵变幅度大幅下降。 实施例 5·· 具有小滞后损耗的一级相变
Figure imgf000014_0001
以工业纯混合稀土 La-Ce-Pr-Nd、 单质 La、 Fe、 Si、 以及 FeC (用于提供 C元素)、 FeB合金 (用于提供 B元素)为原材料, 釆用与实施例 1类似的方 法制备出具有 NaZn13结构的 Lao^Ce i^Nd Feu.sSiMC cnBo.os合金样品。 将样品破碎在氢气中退火处理获得 Lao. Ce i^Nd Fen.sSiMCo.cnBo H^, 之后经过再破碎、 研磨、 筛分后得到粒径为 30~60μηι和小于 ΙΟμηι的 Lao. Ce i^Nd Feu.sSiMCo.cnBo.osHo.s粉末。 将粒径小于 10 μηι的粉末进一 步研磨制备出超细粉末样品, 平均粒径约 5μηι。 图 13给出了这两种粒径材 料的 Μ-Τ曲线, 30~60μηι粉末样品的居里温度与块材相同, 位于 226Κ; 平 均粒径约 5μηι的样品居里温度位于 229Κ, 比块材高出 3Κ, 且在远离居里 温度的高温区仍具有较高的磁化强度, 与实施例 1中的情况类似, 表明材料 已失去稳定性。 Μ-Η曲线测量结果表明,
Lao. Ce i^Nd Feu.sSi Co.cnBo.osHo.s块材最大滞后损耗约 160J/kg, 30-60 μηι粉末样品最大滞后损耗降为 67 J/kg, 降幅约 58%, 磁熵变幅度基本保持 不变。 平均粒径约 5 μηι的样品的滞后损耗基本降到零, 磁熵变幅度大幅下 实施例 6: 具有小滞后损耗的一级相变 La^Ce^iFe^Co^Mn^ o^) i i QSII 1 磁热效应材料
以工业纯 LaCe合金 (用于提供 Ce元素)、 单质 La、 Fe、 Si、 Co、 Mn为 原材料, 釆用与实施例 1类似的方法制备出粒径为 40~70 μηι和平均粒径 约 7μηι的 Lao.95Ceo.o5(Feo.94Coo.o3Mn0.o3)ii.9 SiL1粉末样品。 图 14给出了这两 种粒径材料的 M-T曲线, 40~70 μηι颗粒样品的居里温度位于〜 153K, 与块 材相同。 平均粒径约 7μηι的样品居里温度位于 156K, 比块材高出 3Κ, 且 在远离居里温度的高温区仍具有较高的磁化强度,与实施例 1中的情况类似, 表明材料已失去稳定性。 Μ-Η曲线测量结果表明,
Lao.95Ceo.o5(Feo.94Coo.o3Mno.o3)ii.9Sii.i块材最大滞后损耗约 32J/kg, 40-70 μηι 粉末样品最大滞后损耗为 16 J/kg, 降幅约 50%, 磁熵变幅度基本保持不变。 平均粒径约 7 μηι的样品的滞后损耗基本降到零, 磁熵变幅度大幅下降。 实施例 7: 具有小滞后损耗的一级相变 Lan 7(Ce. Pr.
Ndy^Fe^Co^y^Si^磁热效应材料
以工业纯混合稀土 La-Ce-Pr-Nd (用于提供 Ce元素)、 单质 La、 Fe、 Si、 Co为原材料, 釆用与实施例 1类似的方法制备出粒径为 30~60 μηι的 La0.7(Ce, Pr, Nd^Feo^Co od^SiM颗粒样品。 磁性结果测量表明颗粒样 品居里温度位于 223K, 磁熵变值约 24J/kgK, 均与块材基本一致。 块材最 大滞后约 24J/kg, 粒径为 30~60 μηι的颗粒样品最大滞后降至约 10J/kg, 降 幅约 58%。 综合以上实施例, 在 15-120μηι粒径范围内降低 La(Fe,Si)13基磁热 效应材料的颗粒尺寸, 材料仍保持大的磁熵变值, 并且能够有效减小一级 相变过程中的滞后损耗, 这对实际应用中增强磁制冷循环的工作效率具有 重要意义。 进一步将材料颗粒尺寸降低到 ΙΟμηι以下, 样品失去稳定性, 变磁转变行为削弱, 磁熵变幅度大幅下降, 不再适合磁制冷技术的实际应 用。 因此材料实际应用过程中筛除掉粒径小于 10 μηι的颗粒可最大限度 保持材料的大磁热效应。

Claims

杈 利 要 求
1. 一种小滞后损耗的一级相变 La(Fe,Si)13基磁热效应材料,所述磁热效 应材料具有 NaZn13型结构, 所述磁热效应材料为粒径范围 15μηι ~200 μηι 的颗粒并且该颗粒的粒径不小于 15 μηι,所述磁热效应材料优选为粒径范围 15μηι -50 μηι的颗粒。
2. 根据权利要求 1所述的磁热效应材料, 其中, 当颗粒的粒径降低到 15 μηι以下, 特别是 ΙΟ μηι以下时, 所述磁热效应材料失去稳定性, 变磁 转变行为削弱, 磁熵变幅度大幅下降, 不再适合磁制冷技术的实际应用, 因此材料实际应用过程中筛除掉粒径小于 10 μηι的颗粒可最大限度保持材 料的大磁热效应。
3. 根据权利要求 1或 2所述的磁热效应材料, 其中, 所述磁热效应材 料的化学通式为:
Lai -xRx(Fe i -p-qCopMnq)! 3-y SiyAa , 其中,
R选自铈 (Ce ) 、 镨 (Pr ) 和钕 ( Nd ) 元素中的一种或多种,
A选自碳 (C ) 、 氢 (H ) 和硼 (B ) 元素中的一种或多种,
X的范围是: 0<x≤0.5 ,
y的范围是: 0.8<y≤1.6,
p的范围是: 0≤p≤0.2,
q的范围是: 0≤q≤0.2,
a的范围是: 0≤a≤3.0。
4. 根据权利要求 1或 2所述的磁热效应材料, 其中, 所述磁热效应材 料的化学通式为:
Lai -xRx(Fe i -p-qCopMnq)! 3-y SiyAa , 其中,
R选自 Ce、 Pr和 Nd元素中的一种或多种,
A选自 C、 H和 B元素中的一种或多种,
X的范围是: 0<x≤0.5 ,
y的范围是: 1.0≤y≤1.6,
p的范围是: 0≤p≤0.05 ,
q的范围是: 0≤q≤0.03 ,
a的范围是: 0≤a≤1.8。
5. 权利要求 1至 4中任一项所述的磁热效应材料的制备方法, 该方法 包括如下步骤:
1 ) 按化学式配制除氢以外的原料;
2 ) 将步骤 1 ) 中配制好的原料放入电弧炉中, 抽真空, 用氩气清洗, 并在氩气保护下熔炼, 获得合金锭;
3 )将步骤 2 )熔炼好的合金锭真空退火, 然后在液氮或水中淬火, 从 而制备出具有 NaZn13结构的 La^iUFe^qCOpMV ^ySiyAa磁热效应材料;
4 )对步骤 3 )制得的磁热效应材料进行破碎、 研磨和筛分, 得到粒径 范围 15~200 μηι的颗粒;
其中, 当化学通式中的 Α包括氢元素时, 所述方法还包括: 步骤 5 ) 将步骤 4 ) 制得的颗粒在氢气中退火, 或者将步骤 3 ) 制得的磁热效应材 料破碎后先在氢气中退火, 然后再进行步骤 4 ) 。
6. 根据权利要求 5所述的制备方法, 其中, 在所述步骤 4 ) 中, 筛除 掉粒径小于 15 μηι的颗粒, 特别地筛除掉粒径小于 10 μηι的颗粒。
7. 根据权利要求 5或 6所述的制备方法, 其中, 原材料 La、 R为商 业化单质稀土元素和 /或工业纯 LaCe合金和 /或工业纯 LaCePrNd混合稀土; 优选地, 当 A包括碳元素时, 碳由 FeC合金提供。
8. 一种磁制冷机,所述制冷机包括权利要求 1至 4中任一项所述的磁 热效应材料或者按照权利要求 5至 7中任一项所述方法制得的磁热效应材 料。
9. 权利要求 1至 4中任一项所述的磁热效应材料或者按照权利要求 5 至 7中任一项所述方法制得的磁热效应材料在制造制冷材料中的应用。
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