JP2002164239A5 - - Google Patents

Description

[Claims]
1. A the R-T-B-based (R is at least one of rare earth elements including Y, Pr occupying in R is 50 atomic% or more, T is a Fe or Fe and Co) rare earth The alloy coarse powder for a sintered magnet is pulverized in a non-oxidizing atmosphere to an average particle size of 1 to 10 μm, and the obtained fine powder is mixed with at least one oil selected from mineral oil, synthetic oil and vegetable oil, and one of fatty acids. hydric alcohols esters, multi monohydric alcohol esters of polybasic acid, polyhydric alcohol fatty acid esters and the slurry was collected in a non-oxidizing liquid consisting of lubricant and comprising at least one selected from among the derivatives thereof prepared, then molded by the slurry, the resulting molded body is sintered after deoiling method for producing a rare earth sintered magnet characterized by heat-treating the obtained sintered body.
2. The amount of the lubricant to be added is in the range of (RTB based alloy fine powder) :( lubricant) = 99.99 to 99.5 parts by weight: 0.01 to 0.5 part by weight. Of manufacturing rare earth sintered magnets.
3. In% by weight, R (R is at least one kind of rare earth element including Y and Pr occupies at least 50 atomic%): 28 to 33% , B: 0.8 to 1.5% , Co: 5% or less (including 0) , Cu: 0.3% or less (including 0) and the balance: a main component of Fe, and an RTB system containing unavoidable impurities (T is Fe or Fe and Co An arc segment magnet comprising a sintered magnet,
The amount of oxygen inevitably contained is 0.3% or less with respect to the total weight of the arc segment magnet, is formed into a thin shape having a thickness of 1 to 4 mm, and has a density of 7.50 Mg / m ³ (g / cm ³ ) or more. An arc segment magnet having a coercive force iHc of 1.1 MA / m (14 kOe) or more at room temperature and a degree of orientation (Br / 4πI _max ) of 96% or more in an anisotropic direction at room temperature.
4. The arc segment magnet according to claim 3, which has a parallel anisotropy.
5. The arc segment magnet according to claim 3, wherein the arc segment magnet is formed in a long shape having a length of 40 to 100 mm.
6. The ratio of the X-ray diffraction peak intensity from the (105) plane: I (105) to the X-ray diffraction peak intensity from the (006) plane: I (006) is I (105) / I ( 006) = 0.5 to 0.8, the arc segment magnet according to any one of claims 3 to 5.
7. In% by weight, R (R is at least one kind of rare earth element including Y and Pr occupies at least 50 atomic%): 28 to 33% , B: 0.8 to 1.5% , Co: 5% or less (including 0) , Cu: 0.3% or less (including 0) and the balance: a main component of Fe, and an RTB system containing unavoidable impurities (T is Fe or Fe and Co An arc segment magnet comprising a sintered magnet,
The amount of oxygen inevitably contained relative to the total weight of the arc segment magnets Ri Ah at 0.3% or less, and said arc segment magnets is formed in an arc sectional shape radial anisotropy imparted, inner diameter less than 100mm The density is 7.50 Mg / m ³ (g / cm ³ ) or more, the coercive force iHc at room temperature is 1.1 MA / m (14 kOe) or more, and the residual magnetic flux density in the radial direction (Br //) at room temperature And the degree of orientation defined by the residual magnetic flux density (Br⊥) in the length direction perpendicular to the radial direction: [(Br //) / (Br // + Br⊥) × 100 (%)] is 85.5% or more. An arc segment magnet characterized in that:
8. The arc segment magnet according to claim 7 , wherein the arc segment magnet is formed in a thin shape having a thickness of 1 to 4 mm.
Arc segment magnets according to claim 9 according to claim 7 or 8 length is formed in a long shape of 40 to 100 mm.
10. In% by weight, R (R is at least one kind of rare earth element including Y, and Pr occupies 50 atomic% or more in R): 28 to 33%, B: 0.8 to 1.5%, Co: 5% or less (including 0), Cu: 0.3% or less (including 0) and the balance: a main component of Fe, and an RTB system containing unavoidable impurities (T is Fe or Fe and Co A) ring magnet comprising a sintered magnet,
The amount of oxygen inevitably contained is 0.3% or less based on the total weight of the ring magnet, and the ring magnet has an inner diameter of 100 mm or less, has radial anisotropy, and has a density of 7.50 Mg / m ^3. (G / cm ³ ) or more, the coercive force iHc at room temperature is 1.1 MA / m (14 kOe) or more, the residual magnetic flux density (Br //) in the radial direction at room temperature and the length in the length direction perpendicular to the radial direction. A ring magnet, wherein the degree of orientation defined by residual magnetic flux density (Br⊥): [(Br //) / (Br // + Br⊥) × 100 (%)] is 85.5% or more.

[0002]
[Prior art]
(At least one rare earth element R containing Y, T is a transition metal) the R-T-B-based sintered magnet, coarsely crushed an R-T-B type alloy having a predetermined composition, and then such as N ₂ non It is manufactured by pulverizing in an active gas and molding the obtained fine powder having an average particle size of 1 to 10 μm in a magnetic field, followed by sintering and heat treatment. Further, as described in JP-A-10-303008, an RTB-based alloy using 50 atomic% or more of Pr as an element of R is high without exhibiting spin rearrangement near a liquid nitrogen cooling temperature. are known to be capable of retaining the magnetic properties, the fluid machinery and machine tools requiring high speed rotation, is Rukoto have use in the power storage apparatus that stores and converts the excess power into kinetic energy of the flywheel Are being considered.
In these applications, reduction of the oxygen content is extremely important to increase the residual magnetic flux density Br and the maximum energy product (BH) max. For this reason, the present applicant has discovered mineral oil or synthetic oil having a remarkable effect of inhibiting the progress of the oxidation of the fine powder, recovering the fine powder in the oil to form a slurry, molding the slurry, and then obtaining the slurry. Proposed a manufacturing process to obtain a high-performance, high-density type RTB-based sintered magnet with low oxygen content and high density by deoiling, sintering and heat-treating the compact (Patent No. 2731337, etc.). reference). This manufacturing process has a feature that the progress of oxidation can be substantially suppressed by coating the fine powder and the molded body with the oil and shielding the air from the atmosphere. The oxygen content of the TB-based sintered body is maintained at a low level corresponding to the RTB-based alloy coarse powder before fine pulverization. Therefore, the R element in the RTB-based sintered body is oxidized, and the reduction in the amount of effective rare earth caused by substantial loss is suppressed, and the rare earth rich phase forming the grain boundary phase is kept sound. You. Since the R content can be set lower by the amount that the substantial loss of the effective rare earth is small, the excess R-rich phase and rare earth oxide can be reduced as compared with the prior art, and at the same time, the R ₂ Fe ₁₄ B type crystal grains of the ferromagnetic phase Since the volume ratio of the (main phase) can be increased, Br and (BH) max are significantly improved.

[0005]
[Means for Solving the Problems]
Method for producing a rare earth sintered magnet of the present invention which solves the above-mentioned problems, R-T-B system (R is at least one of rare earth elements including Y, Pr occupying the R is at least 50 atom%, T is finely ground to an average particle size of 1~10μm rare earth sintered alloy coarse powder for a magnet and is) Fe or Fe and Co in a non-oxidizing atmosphere, select a resultant fine mineral, synthetic oils and vegetable oils at least one oil, monohydric alcohol esters of fatty acids, monohydric alcohol esters of polybasic acids, a lubricant consisting of at least one selected from among polyhydric alcohol fatty acid esters and their derivatives made and collected in a non-oxidizing liquid slurry prepared, then molded by the slurry, the resulting molded body is sintered after deoiling, characterized by heat-treating the obtained sintered body.
The amount of the lubricant added is preferably in the range of (R-T-B-based alloy fine powder) :( lubricant) = 99.99 to 99.5 parts by weight: 0.01 to 0.5 part by weight. FIG. 6 shows the temperature dependence of the amount of magnetic flux in the case where R is Pr-based and in the case of Nd-based. In the case of the Nd-based RTB-based rare earth sintered magnet, the magnetic flux amount decreases when the temperature is reduced to about 130K or less. On the other hand, in the Pr system, the amount of magnetic flux continues to increase even if the environmental temperature is lowered to around 80K, and the fluid machinery and machine tools that require high-speed rotation and the surplus power that is converted into kinetic energy of the flywheel and stored Even if it is applied to a storage device or the like, it is possible to obtain a product with high characteristics.

The arc segment magnet of the present invention has a weight percentage of R (R is at least one kind of rare earth element including Y and Pr occupying 50 at% or more in R): 28 to 33% , B: 0.8 to 1.5% , Co: 5% or less (including 0) , Cu: 0.3% or less (including 0) and the balance: a main component of Fe, and an RTB system containing unavoidable impurities (T is An arc segment magnet comprising a sintered magnet ( which is Fe or Fe and Co) , wherein the amount of oxygen inevitably contained is 0.3% or less with respect to the total weight of the arc segment magnet, and the thickness is 1 to 4 mm. It is formed in a thin shape, has a density of 7.50 Mg / m ³ (g / cm ³ ) or more, and has a coercive force iHc of 1.1 MA / m (14 kOe) or more at room temperature and an orientation degree of 96% or more in the anisotropic direction. (Br / 4πI _max ).
The arc segment magnet can have parallel anisotropy, and can be manufactured in a long shape having a length of 40 to 100 mm. In this arc segment magnet having good orientation, the ratio of the X-ray diffraction peak intensity from the (105) plane: I (105) to the X-ray diffraction peak intensity from the (006) plane: I (006) is It has a feature that I (105) / I (006) = 0.5 to 0.8.

Further, the other arc segment magnet of the present invention is, by weight%, R (R is at least one kind of rare earth element including Y and Pr occupying at least 50 atomic%): 28 to 33%, B: 0.8~1.5%, Co: 5 % or less (including 0), Cu: 0.3% or less (including 0), and the balance: principal component, and the R-T-B-based containing unavoidable impurities Fe ( T is Fe or Fe and Co) a arc segment magnet made of a sintered magnet, the amount of oxygen inevitably contained relative to the total weight of the arc segment magnets Ri Ah at 0.3% or less, and said arc The segment magnet is formed in an arc cross-sectional shape provided with radial anisotropy, has an inner diameter of 100 mm or less, has a density of 7.50 Mg / m ³ (g / cm ³ ) or more, and has a coercive force iHc of 1.1 MA at room temperature. / m (14 kOe) or more, residual magnetic flux in the radial direction at room temperature The degree of orientation defined by the density (Br //) and the residual magnetic flux density (Br⊥) in the length direction perpendicular to the radial direction: [(Br //) / (Br // + Br ×) × 100 (%) ] Is 85.5% or more.
The arc segment magnet can be formed in a thin shape having a thickness of 1 to 4 mm and further in a long shape having a length of 40 to 100 mm.

In the ring magnet of the present invention, R (R is at least one kind of rare earth element including Y and Pr occupies at least 50 atomic%) is 28 to 33%, and B is 0.8 to 0.8% by weight. R-T-B system containing 1.5%, Co: 5% or less (including 0), Cu: 0.3% or less (including 0) and the balance: a main component of Fe, and inevitable impurities (T is Fe or A ring magnet comprising a sintered magnet ( Fe and Co) , wherein the amount of oxygen inevitably contained is 0.3% or less with respect to the total weight of the ring magnet, and the ring magnet has an inner diameter of 100 mm or less. Has a radial anisotropy, a density of 7.50 Mg / m ³ (g / cm ³ ) or more, a coercive force iHc at room temperature of 1.1 MA / m (14 kOe) or more, and a radial residual at room temperature. Degree of orientation defined by magnetic flux density (Br //) and residual magnetic flux density (Br⊥) in the length direction perpendicular to the radial direction: [(Br //) / (Br // + Br⊥) × 100 (%)] is not less than 85.5% .

In a rare earth sintered magnet mainly containing Pr as an R element, an R ₂ Fe ₁₄ B intermetallic compound (R is at least one rare earth element including Y and Pr in R is 50 atomic% or more) is used. When the main phase is used, the composition of the main component is represented by R: 28 to 33%. B: 0.8 to 1.5%, M ₁ : 0 to 0.6% (M ₁ is at least one selected from Nb, Mo, W, V, Ta, Cr, Ti, Zr and Hf), M ₂ : 0 to 0.6% _{(M 2} is Al, at least one selected from Ga and Cu), and the balance Fe (However, when the _{R + B + Fe + M 1} + M 2 = 100 wt%) preferably with. Hereinafter, simply writing% means weight%.
The amount of R is preferably 28 to 33%. In order to provide good corrosion resistance, the R amount is more preferably from 28 to 32%, particularly preferably from 28 to 31%. If the amount of R is less than 28%, a predetermined iHc cannot be obtained, and if it exceeds 33%, Br is remarkably reduced. In order to obtain a predetermined Br and orientation degree, R is preferably composed of Pr, or Pr and Dy, or Nd, Dy, Pr, and an unavoidable R component. That is, it is preferable that the ratio of Pr to R be 50 atomic% or more and the Dy content be 0.3 to 10%. Further, it is more preferable that the ratio of Pr in R is 90 atomic% or more and the Dy content is 0.5 to 8%. When Pr occupying less than 50 atomic% of R, spin rearrangement becomes remarkable near the temperature of liquid nitrogen, and the magnetic properties are greatly reduced. If the Dy content is less than 0.3%, the effect of containing Dy cannot be obtained, and if it exceeds 10%, Br decreases and the predetermined degree of orientation cannot be obtained.
The B content is preferably from 0.8 to 1.5%, more preferably from 0.85 to 1.2%. If the amount of B is less than 0.8%, it is difficult to obtain iHc of 1.1 MA / m (14 kOe) or more, and if the amount of B exceeds 1.5%, Br is significantly reduced.
Nb, Mo, W, V, Ta, Cr, Ti, it is preferable to enhance the magnetic properties of the refractory metal element _{M 1} consisting of at least one of Zr and Hf containing 0.01 to 0.6%. By containing M ₁ 0.01 to 0.6%, is suppressed main phase crystal grains of excessive grain growth in the sintering process, can be obtained stably 1.1MA / m (14kOe) or more iHc. However, normal grain growth of the reverse main phase crystal grains when the M ₁ ultra containing 0.6% is inhibited, leading to reduction in Br. The M ₁ content can not be obtained the effect of improving the magnetic properties is less than 0.01%.
The content of M ₂ element (Al, at least one of Ga and Cu) is preferably 0.01 to 0.6%. The content of Al improves iHc and improves corrosion resistance. However, when the Al content exceeds 0.6%, Br is greatly reduced, and when the Al content is less than 0.01%, the effect of increasing iHc and corrosion resistance cannot be obtained. A more preferred Al content is 0.05 to 0.3%. The content of Ga significantly improves iHc, but when the content of Ga exceeds 0.6%, Br is greatly reduced, and when the content of Ga is less than 0.01%, the effect of increasing iHc cannot be obtained. A more preferable Ga content is 0.05 to 0.2%. The addition of a small amount of Cu contributes to the improvement of corrosion resistance and iHc, but when the Cu content exceeds 0.3%, Br is greatly reduced, and when the Cu content is less than 0.01%, the effect of increasing corrosion resistance and iHc cannot be obtained. A more preferred Cu content is 0.05 to 0.3%.
The content of Co improves the corrosion resistance, raises the Curie point, and improves the heat resistance of the rare earth sintered magnet. However, if the Co content exceeds 5%, a Fe—Co phase harmful to magnetic properties is formed, or R ₂ (Fe, Co) ₁₄ B phase is formed and Br and iHc are greatly reduced. Therefore, the Co content is preferably 5% or less. On the other hand, if the Co content is less than 0.5%, the effect of improving corrosion resistance and heat resistance cannot be obtained. Therefore, the Co content is preferably 0.5 to 5%.
When 0.5 to 5% of Co and 0.01 to 0.3% of Cu are contained, the allowable temperature of the second heat treatment for obtaining iHc at room temperature of 1.1 MA / m (14 kOe) or more is obtained, which is particularly preferable.
When Al is contained in an amount of 0.01 to 0.3%, it contributes to the improvement of the coercive force, and it is possible to reduce the variation of the coercive force due to the variation of the heat treatment temperature. When Nb is contained in an amount of 0.01 to 0.08%, crystal grain growth during the sintering process is suppressed, and formation of coarse grains can be suppressed.
The amount of oxygen inevitably contained is preferably 0.3% or less, more preferably 0.2% or less, and particularly preferably 0.18% or less. By reducing the oxygen content to 0.3% or less, the density of the sintered body can be increased to approximately the theoretical density. When the R ₂ Fe ₁₄ B intermetallic compound is used as the main phase, the sintered body density is 7.50 g / cm ³ or more, which is close to the theoretical density (7.54 g / cm ³ ) of the Pr ₂ Fe ₁₄ B intermetallic compound.
Further, the unavoidable carbon content is preferably 0.10% or less, more preferably 0.07% or less. The reduction of the carbon content suppresses the formation of rare earth carbides, increases the effective rare earth amount, and can increase iHc and (BH) max.
The amount of nitrogen unavoidably contained is preferably 0.15% or less . When the amount of nitrogen exceeds 0.15%, Br is greatly reduced. The magnet of the present invention is coated with a known surface treatment film (Ni plating or the like) and put to practical use. However, when the R amount is 28 to 32% and the nitrogen amount is 0.002 to 0.15%, good corrosion resistance is obtained. It is more preferable because it is provided.
When the magnet of the present invention was manufactured using a material alloy manufactured by a reduction diffusion method using Ca as a reducing agent, the total weight of the magnet was reduced to 100% by weight in order to obtain a predetermined iHc and orientation degree. The Ca content is preferably suppressed to 0.1% by weight or less (excluding 0), and more preferably 0.03% by weight or less (excluding 0).

As a mineral oil , a synthetic oil or a vegetable oil, those having a fractionation point of 350 ° C. or lower are preferred from the viewpoint of deoiling and moldability. The kinematic viscosity at room temperature is preferably 10 cSt or less, more preferably 5 cSt or less.

An example in which an RTB based sintered ring magnet having polar anisotropy is manufactured and evaluated will be described below.
(Example 11)
By weight, the main component composition is Pr: 29.5%, Dy: 1.0%, B: 1.05%, Ga: 0.08%, Nb: 0.2%, Al: 0.05%, Cu: 0.13%, Co: 2.0% and the balance Fe RTB-based raw material alloy coarse powder (320 mesh under) consisting of the following was milled by a jet mill in a nitrogen atmosphere having an oxygen concentration of less than 1 ppm (volume ratio), and the obtained fine powder having an average particle diameter of 3.8 µm was used. A slurry was prepared in the same manner as in Example 1 except for the above. The resulting slurry, after filling the cavity 59 of the molding machine shown in FIG. 2, the molding pressure: 78.4MPa (0.8ton / cm ²⁾ and polar anisotropy in a pulse magnetic field of 100V is molded in a magnetic field to be applied To obtain a molded product. The compact was heated at 200 ° C. for 1 hour at a degree of vacuum of about 66.5 Pa (5 × 10 ⁻¹ Torr), and after deoiling, subsequently, about 4.0 × 10 ⁻³ Pa (3 × 10 ⁻⁵ Torr), 1060 After sintering at a temperature of 2 ° C. for 2 hours, the mixture was cooled to room temperature to obtain a sintered body. Next, heat treatment was performed in an argon atmosphere at 900 ° C. for 1 hour, followed by cooling to 550 ° C., and then heating at 550 ° C. for 2 hours and further cooling to room temperature. Then after processing into a predetermined size, by coating the epoxy resin film having an average thickness of 12μm by electrodeposition, to obtain an outer diameter 48 mm, the 8-pole pole anisotropic ring having an inner diameter of 30mm and height 11 mm.
Then cut the sample for X-ray diffraction from the inter-pole center portion in the radially outer surface of the pole anisotropic ring, sets its sample X-ray diffraction apparatus manufactured by Rigaku Denki (Ltd.) (RU-200BH) X-ray diffraction was performed by a 2θ-θ scanning method. A CuKα1 ray (λ = 0.15405 nm) was used as an X-ray source, and noise (background) was removed by software built in the apparatus. The main diffraction peaks are the (004) plane at 2θ = 29.08 °, the (105) plane at 38.06 °, the (006) plane at 44.34 °, and the (006) plane of the R2T14B type intermetallic compound as the main phase. X-ray diffraction peak intensity: I (004) / I (006) = 0.33 and I (105) / I (006) = 0.63, where I (006) was 100%. Table 6 shows the results. Bo in the table indicates the surface magnetic flux density measured at the magnetic pole portion.
(Comparative Example 11)
Instead of the slurry of Example 11, polar anisotropic properties except molded in a magnetic field to be applied to produce a polar anisotropic ring of the comparative example in the same manner as in Example 11 by a slurry of Comparative Example 1. Thereafter it was subjected to X-ray diffraction of the polar anisotropic property ring of Comparative Example 11 in the same manner as in Example 11. Table 6 shows the results. The main diffraction peaks were the same as in Example 11, but I (004) / I (006) = 0.32 and I (105) / I (006) = 0.96. The oxygen content of the polar anisotropic property ring is 0.13 wt%, the carbon content is 0.05 wt%, nitrogen content was 0.003 wt%.

From the results of Example 11 and Comparative Example 11 in Table 4, according to the present invention, the material has polar anisotropy, has a density of 7.50 Mg / m ³ (g / cm ³ ) or more, and has a ring outer diameter surface. The ratio between the X-ray diffraction peak intensity from the (105) plane: I (105) and the X-ray diffraction peak intensity from the (006) plane: I (006) measured at the surface position of the center between the magnetic poles is I ( 105) / I (006) = 0.5~0.8 a polar anisotropic ring it can be seen that can provide.

[0036]
【The invention's effect】
As described above , according to the present invention , there is provided a manufacturing method capable of obtaining a high-performance rare-earth sintered magnet having a low oxygen content, a high sintered body density, and a higher degree of orientation than in the past. it is Ru can be.
In addition, it has low oxygen content, high sintered body density, high degree of orientation compared to conventional, high performance with parallel or radial anisotropy of thin or thin, long shape. Ru can provide the R-T-B based sintered arc segment magnets.
Also, a high performance R-T-B sintered ring magnet having a low oxygen content, a high sintered body density, and a higher degree of radial orientation than before, and having a radial anisotropy. Ru can provide.

[Explanation of symbols]
1 die, 2 lower punches, 3 cavities, 4 cylinders, 6 slurry supply pipe, 9 supply head, 10 pumps, 11 piping, 13 tanks, 15 slurry supply device, 30, 40 arc segment magnet, 51 die ferromagnetic section, 52 Dies, 53 cores, 59 cavities, 70 radial rings.

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