High-cerium high-Br cerium-iron-boron magnet and preparation method thereof

Abstract

The invention relates to the field of rare earth permanent magnet materials, and discloses a high-cerium and high-Br cerium-iron-boron magnet and a preparation method thereof, the high-cerium and high-Br cerium-iron-boron magnet comprises alloy components of the following formula R1xR2yHzM1-X-Y, R1 is Nd and Pr, R2 is B, H is Ce and Fe, and M is at least one of Al, Cu, Co, Zr, Nb and Ti; wherein 22% < = x < = 26%, 0.9% < = y < = 1.1%, and 73% < = z < = 76%. According to the invention, the alloy components and process of the permanent magnet with high cerium content are regulated and controlled, on the premise of reducing the cost, the anisotropic field and saturation magnetization intensity of the main phase of the magnet are not greatly damaged on the whole, and the permanent magnet has good comprehensive magnetic performance; during processing, the oxygen content and the magnetic powder granularity are controlled during sheet casting, hydrogen decrepitation and jet milling, and through sintering and aging treatment, contact among molded compact powder particles is from point to surface, so that the surface area and the surface energy are reduced, shrinkage and densification are generated, and the comprehensive magnetic performance of the permanent magnet is improved. The method is simple and reasonable in process, convenient to operate, easy to maintain and repair, low in investment, good in effect and beneficial to reduction of production cost and increase of income of enterprises.

Description

Technical Field

[0001] The present invention relates to the field of rare earth permanent magnet materials, and specifically to a high-cerium high-Br cerium-iron-boron magnet and a preparation method thereof. Background Art

[0002] Due to its high coercivity and high remanence, neodymium-iron-boron magnet is the most cost-effective commercial magnetic material so far and is widely used in many fields such as household appliances, transportation, and medical treatment. The prices of praseodymium and neodymium are relatively high, and a large amount of lanthanum, cerium, and yttrium are produced during the development and utilization of rare earths, and their prices are often about one-fifteenth of that of praseodymium and neodymium.

[0003] At present, existing research and applications have proved the feasibility of using a high content of cerium to replace neodymium, thereby reducing costs while ensuring the remanence and intrinsic coercivity of neodymium-iron-boron magnets. It has been found through research that the alloy composition and structure with a high cerium content need to be regulated to further improve the comprehensive magnetic properties, and the high-temperature sintering process requires continuous treatment to improve the high-temperature sintering efficiency and the sintering quality of permanent magnets. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a high-cerium high-Br cerium-iron-boron magnet and a preparation method thereof, which reduce the influence of high cerium on magnetic properties and further improve the magnetic properties of high-cerium cerium-iron-boron magnets.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0006] A high-cerium high-Br cerium-iron-boron magnet, comprising an alloy component of the following formula R1 x R2 y H z M 1-X-Y : where R1 is Nd, Pr, R2 is B, H is Ce and Fe, M is at least one of Al, Cu, Co, Zr, Nb, Ti; where 22% ≤ x ≤ 26%, 0.9% ≤ y ≤ 1.1%, 73% ≤ z ≤ 76%.

[0007] Preferably, it further includes a high-temperature resistant inorganic glue.

[0008] Preferably, the high-temperature resistant inorganic glue includes at least one of aluminosilicate inorganic glue, sodium silicate inorganic glue, and alumina inorganic glue.

[0009] Preferably, the temperature range tolerated by the high-temperature resistant inorganic glue is 1200 - 1500 °C.

[0010] Preferably, the viscosity range of the high-temperature resistant inorganic glue is 300 - 600 mPa·s.

[0011] The present invention also provides a preparation method of a high-cerium high-Br cerium-iron-boron magnet, comprising the following steps:

[0012] Melt spinning: Weigh the alloy components of formula R1 x R2 y H z M 1-X-Y for smelting, where R1 is Nd, Pr, R2 is B, H is Ce and Fe, and M is at least one of Al, Cu, Co, Zr, Nb, Ti; where 22% ≤ x ≤ 26%, 0.9% ≤ y ≤ 1.1%, 73% ≤ z ≤ 76%. The obtained molten liquid is spun to obtain a spun strip;

[0013] Hydrogen decrepitation and grinding: The spun strip is hydrogen decrepitated and then ground by a jet mill to obtain magnetic powder;

[0014] Mixing and pressing: Add a high-temperature resistant inorganic adhesive to the magnetic powder, mix evenly to obtain a mixed powder, and place the mixed powder under nitrogen protection for molding by die pressing to obtain a green compact;

[0015] Sintering and tempering: The green compact is sintered, and then after one-time tempering and two-time tempering heat treatments, a high-Ce high-Br neodymium-iron-boron magnet is obtained.

[0016] Preferably, the sintering temperature is 1065 °C - 1075 °C.

[0017] Preferably, the first tempering temperature is 775 °C - 785 °C.

[0018] Preferably, the second tempering temperature is 635 °C - 645 °C.

[0019] The present invention provides a high-Ce high-Br neodymium-iron-boron magnet and a preparation method thereof. It has the following beneficial effects:

[0020] The present invention regulates the alloy composition and process of the permanent magnet with a high Ce content. On the premise of reducing costs, the anisotropy field and saturation magnetization intensity of the main phase of the magnet are not greatly damaged as a whole, and it has good comprehensive magnetic properties; during processing, the oxygen content and magnetic powder particle size are controlled during casting, hydrogen embrittlement, and jet milling. Sintering and aging treatments make the contact between the powder particles of the formed green compact change from point to surface, reduce the surface area and surface energy, and cause shrinkage and densification, improving the comprehensive magnetic properties of the permanent magnet.

[0021] The process of the present invention is simple and reasonable, easy to operate, easy to maintain and repair, with less investment and good effects, which is beneficial for enterprises to reduce production costs and increase profits. Specific embodiments

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the solution of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0023] A preparation method of a high-cerium and high-Br neodymium-iron-boron magnet includes the following steps:

[0024] Melting and strip casting: Weigh the alloy components of formula R1 x R2 y H z M 1-X-Y for melting, where R1 is Nd, Pr, R2 is B, H is Ce and Fe, and M is at least one of Al, Cu, Co, Zr, Nb, Ti; where 22% ≤ x ≤ 26%, 0.9% ≤ y ≤ 1.1%, 73% ≤ z ≤ 76%, and the obtained molten liquid is strip cast to obtain strip cast sheets;

[0025] Hydrogen decrepitation and grinding: Subject the strip cast sheets to hydrogen decrepitation and then grind them by jet milling to obtain magnetic powder;

[0026] Mixing and pressing: Add a high-temperature resistant inorganic adhesive to the magnetic powder, mix evenly to obtain a mixed powder, and place the mixed powder under nitrogen protection for molding by die pressing to obtain a green compact;

[0027] Sintering and tempering: Sinter the green compact, and then perform primary tempering and secondary tempering heat treatments to obtain a high-cerium and high-Br neodymium-iron-boron magnet.

[0028] The sintering temperature is 1065°C - 1075°C.

[0029] The primary tempering temperature is 775°C - 785°C.

[0030] The secondary tempering temperature is 635°C - 645°C.

[0031] According to the preparation method of the present application, the aging process for preparing the neodymium-iron-boron magnet is specifically as follows.

[0032] Example 1:

[0033] A preparation method of a high-cerium and high-Br neodymium-iron-boron magnet includes the following steps:

[0034] Melting and strip casting: Weigh 6% cerium, 24% praseodymium-neodymium, 0.98% boron, 68.22% iron, 0.1% aluminum, 0.15% copper, 0.2% cobalt, 0.15% zirconium, 0.1% niobium, and 0.1% titanium according to the formula ratio for melting, and perform strip casting on the obtained molten liquid to obtain strip cast sheets;

[0035] Hydrogen decrepitation grinding: subject the strip-cast sheet to hydrogen decrepitation, and then perform jet milling to obtain magnetic powder;

[0036] Mixing and pressing: add high-temperature resistant inorganic glue to the magnetic powder, mix evenly to obtain a mixed powder, and subject the mixed powder to molding by die pressing under nitrogen protection to obtain a green compact;

[0037] Sintering and tempering: sinter the green compact, and then perform primary tempering and secondary tempering heat treatments to obtain a high-cerium high-Br cerium-iron-boron magnet.

[0038] The sintering temperature is 1072 °C.

[0039] The primary tempering temperature is 780 °C.

[0040] The secondary tempering temperature is 640 °C.

[0041] Example 2:

[0042] A method for preparing a high-cerium high-Br cerium-iron-boron magnet, comprising the following steps:

[0043] Melting and strip-casting: weigh 7% cerium, 23.2% praseodymium-neodymium, 1.1% boron, 67.9% iron, 0.1% aluminum, 0.15% copper, 0.2% cobalt, 0.15% zirconium, 0.1% niobium, and 0.1% titanium according to the formula ratio for melting, and subject the obtained molten liquid to strip-casting to obtain a strip-cast sheet;

[0044] Hydrogen decrepitation grinding: subject the strip-cast sheet to hydrogen decrepitation, and then perform jet milling to obtain magnetic powder;

[0045] Mixing and pressing: add high-temperature resistant inorganic glue to the magnetic powder, mix evenly to obtain a mixed powder, and subject the mixed powder to molding by die pressing under nitrogen protection to obtain a green compact;

[0046] Sintering and tempering: sinter the green compact, and then perform primary tempering and secondary tempering heat treatments to obtain a high-cerium high-Br cerium-iron-boron magnet.

[0047] The sintering temperature is 1070 °C.

[0048] The primary tempering temperature is 783 °C.

[0049] The secondary tempering temperature is 642 °C.

[0050] Example 3:

[0051] A method for preparing a high-cerium high-Br cerium-iron-boron magnet, comprising the following steps:

[0052] Melt Spinning: Weigh 8% cerium, 22% praseodymium-neodymium, 1.2% boron, 68% iron, 0.1% aluminum, 0.15% copper, 0.2% cobalt, 0.1% zirconium, 0.1% niobium, and 0.15% titanium according to the formula ratio for smelting. The obtained molten liquid is subjected to melt spinning to obtain spun strips.

[0053] Hydrogen Decrepitation and Grinding: The spun strips are subjected to hydrogen decrepitation and then ground by a jet mill to obtain magnetic powder.

[0054] Mixing and Pressing: High-temperature inorganic glue is added to the magnetic powder and mixed evenly to obtain a mixed powder. The mixed powder is placed under nitrogen protection for molding by die pressing to obtain a green compact.

[0055] Sintering and Tempering: The green compact is sintered and then subjected to primary tempering and secondary tempering heat treatments to obtain a high-cerium high-Br cerium-iron-boron magnet.

[0056] The sintering temperature is 1075 °C.

[0057] The primary tempering temperature is 785 °C.

[0058] The secondary tempering temperature is 644 °C.

[0059] Table 1

[0060] Project Example 1 Example 2 Example 3 Br / kGs 14.2 14.1 14.15 Hcj / kOe 12.5 12.4 12.3 HK / HCJ 97％ 96％ 96.5％

[0061] Performance Detection Test: The high-cerium high-Br cerium-iron-boron magnets of Examples 1-3 are subjected to the following performance detections. The detection results are shown in Table 1 above:

[0062] Remanence, Intrinsic Coercivity, Ratio of Knee Point Coercivity to Intrinsic Coercivity: According to GB / T 3217-2013 "Magnetic Test Methods for Permanent (Hard Magnetic) Materials", the remanence (Br), intrinsic coercivity (Hcj), and ratio of knee point coercivity to intrinsic coercivity (HK / HCJ) of the high-cerium cerium-iron-boron magnet are tested.

[0063] Br (Remanence): It refers to the magnetic induction intensity exhibited by the magnet when the external magnetic field is removed after the magnet is magnetized to technical saturation under closed-circuit conditions. It reflects the "magnetic content" of the magnet after magnetization. Under the same size, the higher the remanence, the stronger the magnetic force of the magnet.

[0064] Hcj (Intrinsic Coercivity): It is the reverse magnetic field intensity required to reduce the magnetization intensity of the magnet to zero. It is an important index to measure the demagnetization resistance of permanent magnetic materials. The higher the intrinsic coercivity, the stronger the demagnetization resistance of the magnet.

[0065] HK / HCJ (Ratio of Knee Point Coercivity to Intrinsic Coercivity):

[0066] HK (Knee Point Coercivity): On the demagnetization curve, the point where the magnetic polarization intensity J drops to 0.9Br or 0.8Br is called the knee point, and the corresponding magnetic field intensity is HK. When the external magnetic field is greater than HK, irreversible losses will occur in the magnet performance.

[0067] HK / HCJ (Squareness Q): The squareness Q of the demagnetization curve is represented by the ratio of HK to Hcj (HK / Hcj). The closer the squareness Q is to 1, the closer the demagnetization curve is to a square, and the better the anti-interference ability and stability of the magnet.

[0068] Referring to Table 1, by comparing Examples 1-3, it can be seen that the three examples all have excellent performance in Br, Hcj, and HK / HCJ.

[0069] It shows that the component ratio and process method of the present invention can effectively improve the reduction of the magnetic properties of the high-cerium cerium-iron-boron magnet caused by high cerium, thereby effectively improving the magnetic properties of the high-cerium cerium-iron-boron magnet.

[0070] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-cerium and high-Br cerium-iron-boron magnet, characterized in that, Comprising the following formula R1 x R2 y H z M 1-X-Y alloy components: wherein R1 is Nd, Pr, R2 is B, H is Ce and Fe, M is at least one of Al, Cu, Co, Zr, Nb, Ti; wherein 22% ≤ x ≤ 26%, 0.9% ≤ y ≤ 1.1%, 73% ≤ z ≤ 76%.

2. The high-cerium and high-Br cerium-iron-boron magnet according to claim 1, characterized in that : It also includes a high-temperature resistant inorganic glue.

3. The high-cerium cerium-iron-boron magnet according to claim 2, wherein : The high-temperature resistant inorganic glue includes at least one of aluminosilicate inorganic glue, sodium silicate inorganic glue, and alumina inorganic glue.

4. The high-cerium cerium-iron-boron magnet according to claim 2, characterized in that : The temperature range that the high-temperature resistant inorganic glue can withstand is 1200 - 1500 °C.

5. The high-cerium cerium-iron-boron magnet according to claim 2, wherein : The viscosity range of the high-temperature resistant inorganic glue is 300 - 600 mPa·s.

6. The preparation method of a high-cerium and high-Br cerium-iron-boron magnet according to any one of claims 1-5, characterized in that , including the following steps: Melt spinning: Weigh the alloy components of formula R1 x R2 y H z M 1-X-Y for melting according to the formula amount, where R1 is Nd, Pr, R2 is B, H is Ce and Fe, and M is at least one of Al, Cu, Co, Zr, Nb, Ti; where 22% ≤ x ≤ 26%, 0.9% ≤ y ≤ 1.1%, 73% ≤ z ≤ 76%, and the obtained molten liquid is spun to obtain a spun strip; Hydrogen breaking and grinding: Subject the strip casting to hydrogen breaking, and then perform jet milling to obtain magnetic powder. Mixing and pressing: Add the high-temperature resistant inorganic glue to the magnetic powder, mix evenly to obtain a mixed powder, and place the mixed powder under nitrogen protection for molding by die pressing to obtain a green compact. Sintering and tempering: Sinter the green compact, and then perform primary tempering and secondary tempering heat treatments to obtain a high-cerium and high-Br cerium-iron-boron magnet.

7. The preparation method of the high-cerium cerium-iron-boron magnet according to claim 6, wherein : The sintering temperature is 1065 °C - 1075 °C.

8. The preparation method of the high-cerium cerium-iron-boron magnet according to claim 6, wherein : The primary tempering temperature is 775 °C - 785 °C.

9. The preparation method of the high-cerium cerium-iron-boron magnet according to claim 6, wherein : The secondary tempering temperature is 635 °C - 645 °C.