Antioxidant composition, rare earth permanent magnet, sintered magnet material, and production method

Abstract

The application discloses an antioxidant composition, a rare earth permanent magnet, a sintered magnet material and a preparation method. The antioxidant composition comprises the following components: poly-alpha olefin 30mas% to 60mas%; butyl oleate 10mas% to 30mas%; fatty acid methyl ester 1mas% to 20mas%; and solvent oil 10mas% to 40mas%. The antioxidant composition can improve the dispersibility of the powder and the grinding efficiency, has excellent wettability, can well wrap the magnetic powder, prevents the contact between oxygen, nitrogen and the magnetic powder, plays an antioxidation role, reduces the nitrogen content, and ensures the high remanence and coercive force of the sintered magnet and the rare earth permanent magnet under the premise of high carbon content.

Description

TECHNICAL FIELD

[0001] The present application relates to an antioxidant composition, a rare earth permanent magnet, a sintered magnet material and a preparation method. BACKGROUND

[0002] Sintered neodymium-iron-boron magnet is the strongest permanent magnet in the present age, which has excellent characteristics such as high magnetic energy product and high cost performance, and has been applied in the fields of aviation, aerospace, microwave communication technology, electronics, electroacoustics, electromechanics and the like. However, with the continuous expansion of the application range of the permanent magnet, the demand for the permanent magnet is also increasing, and higher demand for the magnetic performance of the permanent magnet is put forward.

[0003] In the process of preparing the neodymium-iron-boron magnet material in the prior art, a certain amount of lubricant or antioxidant will be mixed in during the airflow grinding process or the forming process, that is, a certain amount of carbon element will be introduced. A high carbon content will lead to a decrease in coercivity, so the carbon content is generally controlled to be below 1050 ppm by the person skilled in the art.

[0004] Therefore, an appropriate antioxidant is urgently needed, which can not only reduce the oxidation risk in the preparation process of the neodymium-iron-boron magnet material, but also still maintain high magnetic performance under the premise of a high introduced carbon content and without the need for additional control of the carbon content. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the defects that the traditional antioxidant in the prior art introduces carbon into the rare earth magnet, leading to a high carbon content and a decrease in coercivity, and to provide an antioxidant composition, a rare earth permanent magnet, a sintered magnet material and a preparation method. The antioxidant composition of the present application can not only reduce the oxidation risk in the preparation process of the rare earth magnet material, but also still maintain high magnetic performance under the premise of a high introduced carbon content and without the need for additional control of the carbon content.

[0006] The present application solves the above technical problems by the following scheme:

[0007] The present application provides an antioxidant composition, which comprises the following components in mass percentage:

[0008] Poly-alpha olefin 30 mas% to 60 mas%;

[0009] Butyl oleate 10 mas% to 30 mas%;

[0010] Fatty acid methyl ester 1 mas% to 20 mas%;

[0011] Solvent oil 10 mas% to 40 mas%;

[0012] mas% refers to the mass percentage of each component in the antioxidant composition.

[0013] In the antioxidant composition, the four components are poly-alpha-olefin with good stability and infiltration, powder covered to isolate other gases from direct contact with the powder; fatty acid methyl ester, a surface active agent for solution modification, which makes other solutions have better affinity with the powder and makes the powder have better dispersibility; butyl oleate, which lubricates the powder, is conducive to the flow and rotation of the powder; solvent oil as a solvent for the above three organic matters, which has the characteristics of easy evaporation and easy removal.

[0014] In the present application, the content of poly-alpha-olefin is preferably 30 mas% to 45 mas%, for example 40 mas%, and mas% refers to the mass percentage of each component in the antioxidant composition.

[0015] In the present application, the content of butyl oleate is preferably 10 mas% to 20 mas%, and mas% refers to the mass percentage of each component in the antioxidant composition.

[0016] In the present application, the content of fatty acid methyl ester is preferably 1 mas% to 15 mas%, for example 5 mas% or 10 mas%, and mas% refers to the mass percentage of each component in the antioxidant composition.

[0017] In the present application, the solvent oil can be 90# solvent oil or 120# solvent oil.

[0018] In the present application, the content of solvent oil is preferably 10 mas% to 30 mas%, for example 20 mas% or 25 mas%, and mas% refers to the mass percentage of each component in the antioxidant composition.

[0019] In a preferred embodiment of the present application, the antioxidant composition consists of the following components in mass percentage: poly-alpha-olefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 30 mas%. In a preferred embodiment of the present application, the antioxidant composition preferably consists of the following components in mass percentage: poly-alpha-olefin 60 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 10 mas%.

[0020] In a preferred embodiment of the present application, the antioxidant composition preferably consists of the following components in mass percentage: poly-alpha-olefin 40 mas%, butyl oleate 10 mas%, fatty acid methyl ester 10 mas%, and solvent oil 40 mas%.

[0021] In a preferred embodiment of the present application, the antioxidant composition preferably consists of the following components in mass percentage: poly-alpha-olefin 40 mas%; butyl oleate 20 mas%; fatty acid methyl ester 15 mas%; solvent oil 25 mas%.

[0022] In a preferred embodiment of the present application, the antioxidant composition preferably consists of the following components in mass percentage: poly-alpha-olefin 30 mas%; butyl oleate 30 mas%; fatty acid methyl ester 20 mas%; solvent oil 20 mas%.

[0023] In a preferred embodiment of the present application, the antioxidant composition preferably consists of the following components in mass percentage: poly-alpha-olefin 45 mas%; butyl oleate 20 mas%; fatty acid methyl ester 5 mas%; solvent oil 30 mas%.

[0024] The present application also provides a method for preparing the antioxidant composition, which comprises the following steps: mixing the components in the antioxidant composition.

[0025] The present application also provides the use of the antioxidant composition in preparing permanent magnets as an antioxidant.

[0026] The present application provides a material for sintered magnets, which comprises the antioxidant composition.

[0027] In the present application, the content of the antioxidant composition is preferably 0.15 mas% to 0.45 mas%, for example 0.2 mas% or 0.4 mas%, and mas% is the mass percentage of each component in the material for sintered magnets.

[0028] In the present application, the material for sintered magnets generally further comprises rare earth element R. The content of R is preferably 29 mas% to 33 mas%, more preferably 29.5 mas% to 32 mas%, for example 31 mas%, and mas% is the mass percentage of each component in the material for sintered magnets.

[0029] Preferably, R comprises PrNd and / or Nd. Preferably, R further comprises heavy rare earth element RH. RH preferably comprises one or more of Tb, Dy, Ho and Gd. Preferably, the content of RH is 0 to 2.5 mas% and not 0, for example 1.5 mas%, and mas% is the mass percentage of each component in the material for sintered magnets.

[0030] In the present application, preferably, the sintered magnet material further includes B (boron). The content of B is preferably 0.86 mas% to 1 mas%, for example, 0.99 mas%, 0.88 mas%, or 0.95 mas%, mas% being the mass percentage of each component in the sintered magnet material.

[0031] In the present application, preferably, the sintered magnet material further includes Ga (gallium). The content of Ga is preferably 0 to 0.7 mas% and not 0, for example, 0.05 mas%, 0.5 mas%, or 0.25 mas%, mas% being the mass percentage of each component in the sintered magnet material.

[0032] In the present application, preferably, the sintered magnet material further includes Cu (copper). The content of Cu is preferably 0 to 0.5 mas% and not 0, for example, 0.36 mas%, 0.4 mas%, or 0.16 mas%, mas% being the mass percentage of each component in the sintered magnet material.

[0033] In the present application, preferably, the sintered magnet material further includes M, the M including at least one of Ti, Zr, and Nb. The content of M is preferably 0 to 0.4 mas% and not 0, for example, 0.2 mas%, 0.28 mas%, or 0.3 mas%, mas% being the mass percentage of each component in the sintered magnet material.

[0034] wherein, when the M includes Nb, the content of Nb is preferably 0 to 0.1 mas% and not 0, mas% being the mass percentage of each component in the sintered magnet material.

[0035] wherein, when the M includes Ti, the content of Ti is preferably 0 to 0.2 mas% and not 0, for example, 0.18 mas%, mas% being the mass percentage of each component in the sintered magnet material.

[0036] wherein, when the M includes Zr, the content of Zr is preferably 0 to 0.3 mas% and not 0, mas% being the mass percentage of each component in the sintered magnet material.

[0037] In the present application, preferably, the sintered magnet material further includes Co (cobalt). The content of Co is preferably 0 to 2 mas%, more preferably 0 to 1.5 mas%, for example, 0.5 mas% or 1 mas%, mas% being the mass percentage of each component in the sintered magnet material.

[0038] In the present application, preferably, the sintered magnet material further comprises Al (aluminum). The content of Al is preferably 0-0.5 mas%, for example, 0.3 mas%, mas% being the mass percentage of each component in the sintered magnet material.

[0039] In the present application, the sintered magnet material generally further comprises Fe (iron). The content of Fe is preferably 64 mas%-70 mas%.

[0040] In a preferred embodiment of the present application, the sintered magnet material consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, the balance being iron; wherein the antioxidant composition consists of the following components: poly-alpha olefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 30 mas%, mas% being the mass percentage of each component in the antioxidant composition.

[0041] In a preferred embodiment of the present application, the sintered magnet material consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, the balance being iron; wherein the antioxidant composition consists of the following components: poly-alpha olefin 60 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 10 mas%, mas% being the mass percentage of each component in the antioxidant composition.

[0042] In a preferred embodiment of the present application, the sintered magnet material consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, the balance being iron; wherein the antioxidant composition consists of the following components: poly-alpha olefin 40 mas%, butyl oleate 10 mas%, fatty acid methyl ester 10 mas%, and solvent oil 40 mas%, mas% being the mass percentage of each component in the antioxidant composition.

[0043] In a preferred embodiment of the present application, the sintered magnet material is composed of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition is composed of the following components: poly-alpha olefin 40 mas%; butyl oleate 20 mas%; fatty acid methyl ester 15 mas%; solvent oil 25 mas%, and mas% means the mass percentage of each component in the antioxidant composition.

[0044] In a preferred embodiment of the present application, the sintered magnet material is composed of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition is composed of the following components: poly-alpha olefin 30 mas%; butyl oleate 30 mas%; fatty acid methyl ester 20 mas%; solvent oil 20 mas%, and mas% means the mass percentage of each component in the antioxidant composition.

[0045] In a preferred embodiment of the present application, the sintered magnet material is composed of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition is composed of the following components: poly-alpha olefin 45 mas%; butyl oleate 20 mas%; fatty acid methyl ester 5 mas%; solvent oil 30 mas%, and mas% means the mass percentage of each component in the antioxidant composition.

[0046] In a preferred embodiment of the present application, the sintered magnet material is composed of the following components in mass percentage: PrNd 31 mas%, Co 0.5 mas%, Cu 0.4 mas%, Ga 0.5 mas%, Ti 0.2 mas%, B 0.88 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition is composed of the following components: poly-alpha olefin 40 mas%; butyl oleate 20 mas%; fatty acid methyl ester 10 mas%; solvent oil 30 mas%, and mas% means the mass percentage of each component in the antioxidant composition.

[0047] In a preferred embodiment of the present application, the sintered magnet material comprises, in mass percent, PrNd 29.5 mas%, Dy 2.5 mas%, Co 1.5 mas%, Cu 0.16 mas%, Ga 0.25 mas%, Al 0.3 mas%, Zr 0.3 mas%, B 0.95 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises poly-alpha olefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 30 mas%, mas% referring to the mass percent of each component in the antioxidant composition.

[0048] In a preferred embodiment of the present application, the sintered magnet material comprises, in mass percent, PrNd 31 mas%, Co 0.5 mas%, Cu 0.4 mas%, Ga 0.5 mas%, Ti 0.2 mas%, B 0.88 mas%, and an antioxidant composition 0.4 mas%, with the balance being iron; wherein the antioxidant composition comprises poly-alpha olefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 30 mas%, mas% referring to the mass percent of each component in the antioxidant composition.

[0049] The present application also provides a sintered magnet comprising, in mass percent:

[0050] R: 29 mas% to 33 mas%, the R being a rare earth element;

[0051] B: 0.86 mas% to 1 mas%;

[0052] Ga: 0 to 0.7 mas%, and not 0;

[0053] Cu: 0 to 0.5 mas%, and not 0;

[0054] M: 0 to 0.4 mas%, and not 0; the M comprising at least one of Ti, Zr, and Nb;

[0055] Al: 0 to 0.5 mas%, and not 0;

[0056] Fe: 64 mas% to 70 mas%;

[0057] C: 0.1 to 0.2 mas%;

[0058] Co: 0 to 2 mas%; mas% being the mass percent of each component in the sintered magnet.

[0059] In the present application, preferably, the R includes PrNd and / or Nd. Among them, preferably, the R further includes a heavy rare earth element RH. Preferably, the RH includes one or more of Tb, Dy, Ho and Gd. Preferably, the content of the RH is 0-2.5 mas%, and is not 0, for example, 1.5 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0060] In the present application, preferably, the content of the R is 29.5 mas%-32 mas%, for example, 31 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0061] In the present application, preferably, the content of the B is preferably 0.86 mas%-0.99 mas%, for example, 0.88 mas% or 0.95 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0062] In the present application, preferably, the content of the Ga is preferably 0-0.5 mas%, and is not 0, for example, 0.05 mas% or 0.25 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0063] In the present application, preferably, the content of the Cu is preferably 0-0.4 mas%, and is not 0, for example, 0.36 mas% or 0.16 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0064] In the present application, the content of the M is preferably 0-0.3 mas%, and is not 0, for example, 0.2 mas% or 0.28 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0065] Among them, when the M includes Nb, the content of the Nb is preferably 0-0.1 mas%, and is not 0, mas% being the mass percentage of each component in the sintered magnet.

[0066] Among them, when the M includes Ti, the content of the Ti is preferably 0-0.2 mas%, and is not 0, for example, 0.18 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0067] Among them, when the M includes Zr, the content of the Zr is preferably 0-0.3 mas%, and is not 0, mas% being the mass percentage of each component in the sintered magnet.

[0068] In the present application, preferably, the content of the Co is 0-1.5 mas%, for example, 0.5 mas% or 1 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0069] In the present application, the content of Al is preferably 0-0.3 mas%, and not 0, mas% being the mass percentage of each component in the sintered magnet.

[0070] In the present application, the content of C is preferably 0.1126 mas%, 0.1378 mas%, 0.109 mas%, 0.117 mas%, 0.1209 mas%, 0.1140 mas%, 0.1165 mas%, 0.1178 mas% or 0.1255 mas%, mas% being the mass percentage of each component in the sintered magnet.

[0071] In the present application, the sintered magnet generally further comprises Fe (iron). The content of Fe is preferably 64-70 mas%.

[0072] In a preferred embodiment of the present application, the sintered magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas% and C 0.1126 mas%, the balance being iron.

[0073] In a preferred embodiment of the present application, the sintered magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas% and C 0.1378 mas%, the balance being iron.

[0074] In a preferred embodiment of the present application, the sintered magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas% and C 0.109 mas%, the balance being iron.

[0075] In a preferred embodiment of the present application, the sintered magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas% and C 0.117 mas%, the balance being iron.

[0076] In a preferred embodiment of the present application, the sintered magnet consists of, in mass percent, Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and C 0.1209 mas%, with the balance being iron.

[0077] In a preferred embodiment of the present application, the sintered magnet consists of, in mass percent, Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and C 0.114 mas%, with the balance being iron.

[0078] In a preferred embodiment of the present application, the sintered magnet consists of, in mass percent, PrNd 31 mas%, Co 0.5 mas%, Cu 0.4 mas%, Ga 0.5 mas%, Ti 0.2 mas%, B 0.88 mas%, and C 0.1255 mas%, with the balance being iron.

[0079] In a preferred embodiment of the present application, the sintered magnet consists of, in mass percent, PrNd 31 mas%, Co 0.5 mas%, Cu 0.4 mas%, Ga 0.5 mas%, Ti 0.2 mas%, B 0.88 mas%, and C 0.1255 mas%, with the balance being iron.

[0080] In a preferred embodiment of the present application, the sintered magnet consists of, in mass percent, PrNd 31 mas%, Co 0.5 mas%, Cu 0.4 mas%, Ga 0.5 mas%, Ti 0.2 mas%, B 0.88 mas%, and C 0.1255 mas%, with the balance being iron.

[0081] The present application also provides a rare earth permanent magnet, which comprises, in mass percent:

[0082] R: 29 mas% to 33 mas%; the R is a rare earth element and includes a heavy rare earth element RH;

[0083] B: 0.86 mas% to 1 mas%;

[0084] Ga: 0 to 0.7 mas% and not 0;

[0085] Cu: 0 to 0.5 mas% and not 0;

[0086] M: 0-0.4 mas%, and not 0; the M comprises at least one of Ti, Zr and Nb;

[0087] Al: 0-0.5 mas%, and not 0;

[0088] Fe: 64-70 mas%;

[0089] C: 0.1-0.2 mas%;

[0090] Co: 0-2 mas%; mas% is the mass percentage of each component in the rare earth permanent magnet.

[0091] In the present application, preferably, the R comprises PrNd and / or Nd.

[0092] In the present application, preferably, the content of the R is 29.5-32 mas%, for example 31 mas% or 30 mas%, mas% is the mass percentage of each component in the rare earth permanent magnet.

[0093] In the present application, the RH preferably comprises one or more of Tb, Dy, Ho and Gd, more preferably Dy and / or Tb.

[0094] In the present application, preferably, the content of the RH is 0-2.5 mas%, and not 0, for example 1.5 mas% or 0.5 mas%, mas% is the mass percentage of each component in the rare earth permanent magnet.

[0095] In the present application, preferably, the content of the B is 0.86-0.99 mas%, for example 0.88 mas% or 0.95 mas%, mas% is the mass percentage of each component in the rare earth permanent magnet.

[0096] In the present application, preferably, the content of the Ga is 0-0.5 mas%, and not 0, for example 0.05 mas% or 0.25 mas%, mas% is the mass percentage of each component in the rare earth permanent magnet.

[0097] In the present application, preferably, the content of the Cu is 0-0.4 mas%, and not 0, for example 0.36 mas% or 0.16 mas%, mas% is the mass percentage of each component in the rare earth permanent magnet.

[0098] In the present application, the content of the M is preferably 0-0.3 mas%, and not 0, for example 0.2 mas% or 0.28 mas%, mas% is the mass percentage of each component in the rare earth permanent magnet.

[0099] When the M comprises Nb, the content of the Nb is preferably 0-0.1 mas% and not 0, mas% being the mass percentage of each component in the rare earth permanent magnet.

[0100] When the M comprises Ti, the content of the Ti is preferably 0-0.2 mas% and not 0, for example 0.18 mas%, mas% being the mass percentage of each component in the rare earth permanent magnet.

[0101] When the M comprises Zr, the content of the Zr is preferably 0-0.3 mas% and not 0, mas% being the mass percentage of each component in the rare earth permanent magnet.

[0102] In the present application, the content of the Co is preferably 0-1.5 mas%, for example 0.5 mas% or 1 mas%, mas% being the mass percentage of each component in the rare earth permanent magnet.

[0103] In the present application, the content of the Al is preferably 0-0.3 mas% and not 0, mas% being the mass percentage of each component in the rare earth permanent magnet.

[0104] In the present application, the content of the C is preferably 0.115 mas%, 0.1392 mas%, 0.111 mas%, 0.1195 mas%, 0.1225 mas%, 0.1165 mas%, 0.1165 mas%, 0.1178 mas% or 0.1255 mas%, mas% being the mass percentage of each component in the rare earth permanent magnet.

[0105] In the present application, the rare earth permanent magnet generally further comprises Fe (iron). The content of the Fe is preferably 64-70 mas%.

[0106] In a preferred embodiment of the present application, the rare earth permanent magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, Tb 0.5 mas% and C 0.115 mas%, the balance being iron.

[0107] In a preferred embodiment of the present application, the rare earth permanent magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, Tb 0.5 mas% and C 0.1392 mas%, the balance being iron.

[0108] In a preferred embodiment of the present application, the rare earth permanent magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, Tb 0.5 mas%, and C 0.111 mas%, with the balance being iron.

[0109] In a preferred embodiment of the present application, the rare earth permanent magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, Tb 0.5 mas%, and C 0.1195 mas%, with the balance being iron.

[0110] In a preferred embodiment of the present application, the rare earth permanent magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, Tb 0.5 mas%, and C 0.1225 mas%, with the balance being iron.

[0111] In a preferred embodiment of the present application, the rare earth permanent magnet consists of the following components in mass percentage: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, Tb 0.5 mas%, and C 0.1165 mas%, with the balance being iron.

[0112] In a preferred embodiment of the present application, the rare earth permanent magnet consists of the following components in mass percentage: PrNd 31 mas%, Co 0.5 mas%, Cu 0.4 mas%, Ga 0.5 mas%, Ti 0.2 mas%, B 0.88 mas%, and C 0.1165 mas%, with the balance being iron.

[0113] In a preferred embodiment of the present application, the rare earth permanent magnet consists of the following components in mass percentage: PrNd 29.5 mas%, Dy 2.5 mas%, Co 1.5 mas%, Cu 0.16 mas%, Ga 0.25 mas%, Al 0.3 mas%, Zr 0.3 mas%, B 0.95 mas%, and C 0.1178 mas%, with the balance being iron.

[0114] In a preferred embodiment of the present application, the rare earth permanent magnet is composed of PrNd31mas%, Co0.5mas%, Cu0.4mas%, Ga0.5mas%, Ti0.2mas%, B0.88mas%, and C0.1255mas%, with the balance being iron.

[0115] The present application also provides a preparation method of the sintered magnet, which comprises the following steps:

[0116] The components of the sintered magnet material except the antioxidant composition are smelted and coarsely crushed to obtain a coarse powder; the coarse powder and a mixture of the antioxidant composition in an amount of 40% to 60% are finely crushed to obtain a fine powder; and the fine powder and the remaining antioxidant composition are molded and sintered to obtain the sintered magnet.

[0117] In the present application, the operation and conditions of smelting can be conventional smelting processes in the art, and generally are ingot casting processes or rapid solidification sheet processes.

[0118] In the present application, the temperature of smelting can be 1300-1700°C, for example, 1500°C.

[0119] In the present application, the equipment of smelting generally is a high-frequency vacuum smelting furnace and / or a medium-frequency vacuum smelting furnace. The medium-frequency vacuum smelting furnace can be a medium-frequency vacuum induction rapid solidification strip casting furnace.

[0120] As known by those skilled in the art, rare earth elements are generally lost in the smelting and sintering processes, and therefore, to ensure the quality of the final product, 0-0.3wt% of rare earth elements (generally Nd elements) are additionally added in the smelting process based on the formula of the raw material composition, and the percentage is the content of the additionally added rare earth elements in the mass percentage of the sintered magnet material; in addition, the content of the additionally added rare earth elements is not included in the category of the raw material composition.

[0121] In the present application, the coarse crushing generally is hydrogen crushing.

[0122] The hydrogen crushing generally includes hydrogen absorption, hydrogen desorption, and cooling treatment. The temperature of hydrogen absorption generally is 20-200°C, preferably 20-40°C (i.e. room temperature). The pressure of hydrogen absorption generally is 50-600kPa, for example, 90kPa. The temperature of hydrogen desorption generally is 400-650°C, for example, 550°C.

[0123] In the present application, the fine grinding is generally jet milling. The jet mill can use nitrogen and / or argon as the gas flow. The pressure of the jet mill is generally 0.1-2 MPa, preferably 0.5-0.7 MPa, for example 0.65 MPa. The efficiency of the jet mill can vary depending on the equipment, for example, it can be 30-400 kg / h, preferably 200 kg / h.

[0124] In the present application, the forming operation and conditions can be conventional forming processes in the art, for example, magnetic field forming. The magnetic field strength of the magnetic field forming is generally above 1.5 T.

[0125] In the present application, the sintering operation and conditions can be conventional sintering processes in the art, for example, vacuum sintering process and / or inert atmosphere sintering process. Both the vacuum sintering process and the inert atmosphere sintering process are conventional operations in the art. When the inert atmosphere sintering process is used, the initial stage of the sintering can be carried out under a vacuum of less than 0.5 Pa. The inert atmosphere can be conventional atmospheres containing inert gases in the art, not limited to helium and argon, and can also be nitrogen.

[0126] In the present application, the sintering temperature can be 1000-1200°C, preferably 1030-1090°C.

[0127] In the present application, the sintering time can be 0.5-10 h, preferably 2-8 h.

[0128] The present application also provides a sintered magnet prepared by the preparation method of the sintered magnet.

[0129] The present application also provides a preparation method of a rare earth permanent magnet, which comprises the following steps: preparing the sintered magnet above by one of the following two methods:

[0130] Method one: sequentially performing primary aging treatment and secondary aging treatment;

[0131] Method two: sequentially performing grain boundary diffusion treatment and secondary aging treatment.

[0132] In the present application, the heavy rare earth elements in the grain boundary diffusion treatment preferably include Tb and / or Dy.

[0133] In the present application, the grain boundary diffusion treatment can be performed according to conventional processes in the art, for example, by evaporating, coating or sputtering a substance containing Tb or a substance containing Dy on the surface of the sintered magnet, and then performing diffusion heat treatment.

[0134] The substance containing Tb or Dy can be Tb or Dy metal, a compound or an alloy containing Tb or Dy.

[0135] The temperature of the grain boundary diffusion treatment can be 800-900℃, for example 850℃.

[0136] The time of the grain boundary diffusion treatment can be 12-48h, for example 24h.

[0137] In the present application, the temperature of the first aging treatment is preferably 880-920℃, for example 900℃.

[0138] The time of the first aging is preferably 2-4h, for example 2h.

[0139] In the present application, the temperature of the second aging treatment is preferably 460-520℃, for example 490℃.

[0140] The time of the second aging is preferably 2-4h, for example 2h.

[0141] The present application also provides a rare earth permanent magnet prepared by the above preparation method.

[0142] The present application also provides a sintered magnet and / or a rare earth permanent magnet for use as a rotor of a permanent magnet motor.

[0143] On the basis of common general knowledge in the art, the above preferred conditions can be combined in any manner, to obtain various preferred examples of the present application.

[0144] The reagents and raw materials used in the present application are commercially available.

[0145] The positive progress effect of the present application is that the antioxidant composition can improve the dispersibility of the powder and the flour milling efficiency, and the functional groups carried by the organic matter in the antioxidant composition have good binding property with NdFeB and excellent wettability, can well wrap the magnetic powder, prevent the contact of oxygen and nitrogen with the magnetic powder, play an antioxidation role, and reduce the nitrogen content; meanwhile, under the premise of high carbon content, the sintered magnet and the rare earth permanent magnet of the present application still maintain high remanence and coercive force. BRIEF DESCRIPTION OF DRAWINGS

[0146] Figure 1 EPMA diagram of the rare earth permanent magnet in Example 1. DETAILED DESCRIPTION

[0147] The present application will be further described by way of examples, but the present application is not limited to the examples. In the following examples, the experimental methods not specified are selected according to the conventional methods and conditions, or according to the instructions of the commercial products.

[0148] Examples 1-6 and Comparative Example 1

[0149] (1) Melting Process: The raw materials except for the antioxidant composition (the formulation of the antioxidant composition is shown in Table 2) were prepared according to the formulations in Tables 1 and 2, vacuum melted at 1500°C in a high frequency vacuum melting furnace, and then cast in an intermediate frequency vacuum induction rapid solidification casting furnace under argon atmosphere to rapidly cool the alloy, thereby obtaining an alloy sheet.

[0150] (2) Coarse pulverization process: The alloy sheet was placed in a hydrogen decrepitation furnace, the hydrogen decrepitation furnace was vacuumed at room temperature, and then pure hydrogen gas having a purity of 99.9% was introduced into the hydrogen decrepitation furnace to maintain a hydrogen pressure of 90 kPa. After sufficient hydrogen absorption, the hydrogen was removed while the temperature was increased, and then the hydrogen was removed again while the temperature was decreased, thereby obtaining a hydrogen decrepitated powder. The hydrogen absorption temperature was room temperature, and the hydrogen removal temperature was 550°C.

[0151] (3) Fine pulverization process: The hydrogen decrepitated powder was mixed with the antioxidant composition in an amount of 50%, and then the mixture was subjected to air jet milling under a nitrogen atmosphere at a pulverization chamber pressure of 0.65 MPa (the efficiency of the air jet milling can vary depending on the equipment, and for example, can be 200 kg / h), thereby obtaining a fine powder.

[0152] (4) Forming process: The fine powder was mixed with the remaining antioxidant composition, and then formed by pressing in a magnetic field having a strength of 1.5 T or more, thereby obtaining a formed body.

[0153] (5) Sintering process: The formed body was moved to a sintering furnace to be sintered at 1030-1090°C for 8 h under a vacuum of less than 0.5 Pa, thereby obtaining a sintered magnet.

[0154] (6) Grain boundary diffusion and aging process: The sintered magnet was cleaned, and then a Tb alloy containing 0.5 mas% Tb was coated on the surface of the sintered magnet. The coated sintered magnet was diffused at 850°C for 24 h, and then cooled to room temperature. The sintered magnet was vacuum heat-treated at 490°C for 2 h, thereby obtaining a rare earth permanent magnet.

[0155] Table 1: Materials for sintered magnet (mas%)

[0156]

[0157] Note: " / " in the above table means that the element is not contained

[0158] Table 2

[0159]

[0160]

[0161] Examples 7-9 and Comparative Examples 2-3

[0162] The only difference between the preparation method of Examples 1-6 and Comparative Example 1 is that step (6) is as follows:

[0163] (6) Aging treatment process: the sintered magnet is vacuum heat treated at 900°C for 2h, and then vacuum heat treated at 490°C for 2h, to obtain the rare earth permanent magnet.

[0164] Effect example

[0165] The sintered magnets and rare earth permanent magnets of Examples 1-9 and Comparative Examples 1-3 are respectively taken to measure their magnetic properties and compositions.

[0166] (1) The compositions of the sintered magnets and rare earth permanent magnets of Examples 1-9 and Comparative Examples 1-3 are measured by high-frequency inductively coupled plasma emission spectrometer (ICP-OES, Icap6300); the composition detection results are shown in Tables 3 and 4 below.

[0167] Table 3 Sintered magnet (mas%)

[0168] No. Nd PrNd Dy Co Cu Ga Al Nb Ti Zr B Fe C / ppm Example 1 29.5 / / / 0.36 0.05 / 0.10 0.18 / 0.99 Bal. 1126 Example 2 29.5 / / / 0.36 0.05 / 0.10 0.18 / 0.99 Bal. 1378 Example 3 29.5 / / / 0.36 0.05 / 0.10 0.18 / 0.99 Bal. 1090 Example 4 29.5 / / / 0.36 0.05 / 0.10 0.18 / 0.99 Bal. 1170 Example 5 29.5 / / / 0.36 0.05 / 0.10 0.18 / 0.99 Bal. 1209 Example 6 29.5 / / / 0.36 0.05 / 0.10 0.18 / 0.99 Bal. 1140 Example 7 / 31 / 0.5 0.4 0.5 / / 0.2 / 0.88 Bal. 1165 Example 8 / 29.5 2.5 1.5 0.16 0.25 0.3 / / 0.3 0.95 Bal. 1178 Example 9 / 31 / 0.5 0.4 0.5 / / 0.2 / 0.88 Bal. 1255 Comparative Example 1 29.5 / / / 0.36 0.05 / 0.10 0.18 / 0.99 Bal. 873 Comparative Example 2 / 31 / 0.5 0.4 0.5 / / 0.2 / 0.88 Bal. 845 Comparative Example 3 / 29.5 2.5 1.5 0.16 0.25 0.3 / / 0.3 0.95 Bal. 880

[0169] Note: " / " in the above table means that the element is not contained

[0170] Table 4 Rare earth permanent magnet (mas%)

[0171]

[0172]

[0173] Note: " / " in the above table means that the element is not contained

[0174] (2) Magnetic property evaluation: the sintered magnets and rare earth permanent magnets of Examples 1-9 and Comparative Examples 1-3 are measured for magnetic properties by PFM-14 magnetic property measuring instrument of British Hirst Company; the magnetic property measurement results are shown in Table 5 below.

[0175] As shown in Table 5, the oxygen content in the examples is comparable to that in the comparative examples, indicating that the antioxidant effect of the antioxidant composition of this application is comparable to that of existing antioxidants. Meanwhile, the nitrogen content in the examples has decreased significantly from about 400 ppm to more than 100 ppm. This is because the nitrogen in the magnet is mainly introduced by air jet milling, and the working gas of the air jet mill is nitrogen (if argon were used during air jet milling, this might not occur). The air jet carries the coarse powder to collide with each other at a high instantaneous temperature, which causes the magnetic powder to combine with nitrogen. The antioxidant composition of this invention has good affinity with the magnetic powder and good high-temperature stability due to the presence of long-chain hydrocarbons. Therefore, it has a protective effect on the powder surface when the powder collides, reducing direct contact with nitrogen, thus significantly reducing the nitrogen content. Furthermore, although the carbon content in the examples is high, the sintered magnets and rare earth permanent magnets of this application still maintain high remanence and coercivity.

[0176] Table 5 Evaluation of Magnetic Properties

[0177]

[0178]

[0179] Note: In the table above, " / " indicates that the element is not present.

[0180] (3) Microstructure determination: The rare earth permanent magnet of Example 1 (e.g., ...) was tested using an EPMA-1720 micrometer. Figure 1 As shown), by Figure 1 It is known that C is mainly distributed at the three grain boundaries, and some of its positions overlap with O to form rare earth oxides. However, some of its positions do not overlap with O, and C overlaps with the rare earth distribution positions to form rare earth carbides. These changes in microstructure explain, from a mechanistic perspective, how the sintered magnets or rare earth permanent magnets of this application can still maintain high remanence and coercivity even with high carbon content.

Claims

1. An antioxidant composition, characterized in that, It comprises the following components by mass percentage: Polyalphaolefins 30mas%~60mas%; Butyl oleate 10 mas% ~ 30 mas%; Fatty acid methyl esters: 1 mas% to 20 mas%; Solvent oil 10mas%~40mas%; mas% refers to the percentage by mass of each component in the antioxidant composition.

2. The antioxidant composition according to claim 1, characterized in that, The content of the polyalphaolefin is 30 mas% to 45 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; And / or, the content of butyl oleate is 10mas% to 20mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; And / or, the content of the fatty acid methyl ester is 1 mas% to 15 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; And / or, the solvent oil is 90# solvent oil or 120# solvent oil; And / or, the content of the solvent oil is 10mas% to 30mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, the antioxidant composition, by weight percentage, comprises the following components: 40 mas% polyalphaolefin; 20 mas% butyl oleate; 10 mas% fatty acid methyl ester; and 30 mas% solvent oil. Alternatively, the antioxidant composition, by weight percentage, comprises the following components: 60 mas% polyalphaolefin; 20 mas% butyl oleate; 10 mas% fatty acid methyl ester; and 10 mas% solvent oil. Alternatively, the antioxidant composition, by weight percentage, comprises the following components: 40 mas% polyalphaolefin; 10 mas% butyl oleate; 10 mas% fatty acid methyl ester; and 40 mas% solvent oil. Alternatively, the antioxidant composition, by weight percentage, comprises the following components: 40 mas% polyalphaolefin; 20 mas% butyl oleate; 15 mas% fatty acid methyl ester; and 25 mas% solvent oil. Alternatively, the antioxidant composition, by weight percentage, comprises the following components: 30 mas% polyalphaolefin; 30 mas% butyl oleate; 20 mas% fatty acid methyl ester; and 20 mas% solvent oil; Alternatively, the antioxidant composition, by weight percentage, comprises the following components: 45 mas% polyalphaolefin; 20 mas% butyl oleate; 5 mas% fatty acid methyl ester; and 30 mas% solvent oil.

3. The antioxidant composition according to claim 2, characterized in that, The content of the polyalphaolefin is 40 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; And / or, the content of the fatty acid methyl ester is 5 mas% or 10 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; And / or, the content of the solvent oil is 20 mas% or 25 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition.

4. Use of the antioxidant composition as described in any one of claims 1-3 in the preparation of permanent magnets as an antioxidant.

5. A material for sintered magnets, characterized in that, It includes the antioxidant composition as described in any one of claims 1-3.

6. The material for sintered magnets as described in claim 5, characterized in that, The content of the antioxidant composition is 0.15 mas%-0.45 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the material for the sintered magnet further includes the rare earth element R; And / or, the material for the sintered magnet further includes B; And / or, the material for the sintered magnet further includes Ga; And / or, the material for the sintered magnet further includes Cu; And / or, the material for the sintered magnet further includes M, wherein M comprises at least one of Ti, Zr and Nb; And / or, the material for the sintered magnet further includes Co; And / or, the material for the sintered magnet further includes Al; And / or, the material for the sintered magnet also includes Fe.

7. The material for sintered magnets as described in claim 6, characterized in that, The content of the antioxidant composition is 0.2 mas% or 0.4 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the content of R is 29mas% to 33mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the R includes PrNd and / or Nd; And / or, the content of B is 0.86 mas% to 1 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Ga content is 0 to 0.7 mas%, and not 0, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Cu content is 0 to 0.5 mas%, and not 0, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the content of M is 0 to 0.4 mas%, and not 0, where mas% is the mass percentage of each component in the sintered magnet material; And / or, when M includes Nb, the content of Nb is 0 to 0.1 mas% and is not 0, where mas% is the mass percentage of each component in the sintered magnet material; And / or, when M includes Ti, the content of Ti is 0 to 0.2 mas% and not 0, where mas% is the mass percentage of each component in the sintered magnet material; And / or, when M includes Zr, the content of Zr is 0 to 0.3 mas% and not 0, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Co content is 0 to 2 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Al content is 0 to 0.5 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Fe content is 64 mas% to 70 mas%, where mas% is the mass percentage of each component in the sintered magnet material.

8. The material for sintered magnets as described in claim 7, characterized in that, The content of R is 29.5 mas% to 32 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the R further includes the heavy rare earth element RH; And / or, the content of B is 0.99mas%, 0.88mas% or 0.95mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Ga content is 0.05 mas%, 0.5 mas% or 0.25 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Cu content is 0.36 mas%, 0.4 mas% or 0.16 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the content of M is 0.2 mas%, 0.28 mas% or 0.3 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, when M includes Ti, the content of Ti is 0.18 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Co content is 0 to 1.5 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Al content is 0.3 mas%, where mas% is the mass percentage of each component in the sintered magnet material.

9. The material for sintered magnets as described in claim 8, characterized in that, The content of R is 31 mas%, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the RH includes one or more of Tb, Dy, Ho, and Gd; And / or, the RH content is 0 to 2.5 mas% and not 0, where mas% is the mass percentage of each component in the sintered magnet material; And / or, the Co content is 0.5 mas% or 1 mas%, where mas% is the mass percentage of each component in the sintered magnet material.

10. The material for sintered magnets as described in claim 9, characterized in that, The RH content is 1.5 mas%, where mas% is the mass percentage of each component in the sintered magnet material.

11. The material for sintered magnets as described in any one of claims 5-10, characterized in that, The sintered magnet material, by mass percentage, comprises the following components: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 30 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, by mass percentage, the sintered magnet material comprises the following components: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 60 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 10 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, by mass percentage, the sintered magnet material comprises the following components: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 40 mas%, butyl oleate 10 mas%, fatty acid methyl ester 10 mas%, and solvent oil 40 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, by mass percentage, the sintered magnet material comprises the following components: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 15 mas%, and solvent oil 25 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, by mass percentage, the sintered magnet material comprises the following components: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 30 mas%, butyl oleate 30 mas%, fatty acid methyl ester 20 mas%, and solvent oil 20 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, by mass percentage, the sintered magnet material comprises the following components: Nd 29.5 mas%, Cu 0.36 mas%, Ga 0.05 mas%, Nb 0.1 mas%, Ti 0.18 mas%, B 0.99 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 45 mas%, butyl oleate 20 mas%, fatty acid methyl ester 5 mas%, and solvent oil 30 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, by mass percentage, the sintered magnet material comprises the following components: PrNd 31 mas%, Co 0.5 mas%, Cu 0.4 mas%, Ga 0.5 mas%, Ti 0.2 mas%, B 0.88 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 30 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, by mass percentage, the sintered magnet material comprises the following components: PrNd 29.5 mas%, Dy 2.5 mas%, Co 1.5 mas%, Cu 0.16 mas%, Ga 0.25 mas%, Al 0.3 mas%, Zr 0.3 mas%, B 0.95 mas%, and an antioxidant composition 0.2 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 30 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition; Alternatively, by mass percentage, the sintered magnet material comprises the following components: PrNd 31 mas%, Co 0.5 mas%, Cu 0.4 mas%, Ga 0.5 mas%, Ti 0.2 mas%, B 0.88 mas%, and an antioxidant composition 0.4 mas%, with the balance being iron; wherein the antioxidant composition comprises the following components: polyalphaolefin 40 mas%, butyl oleate 20 mas%, fatty acid methyl ester 10 mas%, and solvent oil 30 mas%, where mas% refers to the mass percentage of each component in the antioxidant composition.

12. A method for preparing a sintered magnet, characterized in that, The preparation method includes the following steps: The components of the sintered magnet material as described in any one of claims 5-11, excluding the antioxidant composition, are melted and coarsely pulverized to obtain coarse powder; the coarse powder is then finely pulverized with a mixture of 40% to 60% of the antioxidant composition to obtain fine powder; the fine powder is then shaped and sintered with the remaining mixture of the antioxidant composition to obtain the final product.

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