Ferrite sintered magnet

Abstract

Provided is a ferrite sintered magnet comprising Sr ferrite having a hexagonal magnetoplumbite structure as a main phase, the ferrite sintered magnet containing: 0.1 mass% to 1.2 mass% of MnO; 0.1 mass% to 2.8 mass% of R2O3 (R is at least one rare earth element and essentially includes La), and 0.06 mass% to 0.7 mass% of AO (A is Zn and / or Ni).

Description

Ferrite sintered magnet

[0001] This disclosure relates to ferrite sintered magnets.

[0002] Ferrite sintered magnets offer excellent cost performance due to their inexpensive iron oxide main raw material and the ability to be manufactured in air. They are also extremely chemically stable and are used in a wide range of applications, including motors and speakers. Because ferrite sintered magnets have higher resistivity than metallic magnets, they also contribute to suppressing the decrease in motor efficiency due to eddy current losses. A typical ferrite sintered magnet is Sr ferrite with a magnetoplanbite structure, and its basic composition is SrFe. １２ O １９ It is represented as follows.

[0003] Iron oxide, the main raw material for ferrite sintered magnets, inevitably contains manganese (Mn) as an impurity. In recent years, the demand for ultra-high-tensile steel sheets has increased due to the social need for carbon neutrality and safety in the automotive industry, and the Mn content in automotive thin sheets has been increasing year by year. Since the iron oxide used in the manufacture of ferrite sintered magnets is mainly produced by roasting waste acid generated during the pickling of thin sheets, the amount of Mn in the iron oxide is also increasing in proportion to the Mn content in automotive thin sheets.

[0004] When the amount of Mn in iron oxide, the main raw material of ferrite sintered magnets, increases, the amount of Mn contained as an unavoidable impurity in the ferrite sintered magnet increases, and the residual magnetic flux density B ｒ (Hereafter, simply referred to as "B") ｒ In some cases, this can lead to a decrease in the magnet's performance. While it is possible to perform a de-Mn treatment to reduce the amount of Mn in the iron oxide, it is difficult to completely remove Mn, and the price of iron oxide increases with the de-Mn treatment, thus undermining the cost-effectiveness of ferrite sintered magnets.

[0005] Methods for improving magnetic properties include, for example, the following: Patent Document 1 describes how to improve magnetic properties by incorporating B (boron) and Zn into an Sr ferrite sintered magnet. ｒ It is disclosed that this can be improved. Patent Document 2 describes Sr ferrite in which Sr is replaced with La and Fe is replaced with Zn. １－ｘ Laｘ Fe １２－ｘ Zn ｘ O １９ A ferrite sintered magnet consisting of the above is disclosed. Patent Document 2 describes that high properties can be obtained when x is in the range of 0.1 to 0.4 (0.1 to 0.4 in molar ratio) (see Paragraph 0073 and Figure 4 of Patent Document 2).

[0006] Japanese Patent Application Laid-Open No. 2020-161657 Japanese Patent Application Laid-Open No. 9-115715

[0007] However, in Sr ferrite sintered magnets, increasing the Mn content reduces B ｒ Even if Zn is added to improve the decrease in B, or La and Zn are contained in an equimolar ratio at a molar ratio of x≧0.1 as shown in Patent Document 2, the B ｒ can be recovered, but the coercive force H ｃＪ (hereinafter may be simply referred to as "H ｃＪ ") decreases to a greater extent, and it has been found that there is a problem in that the performance required for application to various motors and the like cannot be obtained. Note: there is an extra "ある" in the original Japanese text, which is retained in the sense of the original as a double "there is".

[0008] Embodiments of the present disclosure maintain the advantages of ferrite magnets such as cost performance and high specific resistance, while avoiding a large decrease in H ｃＪ and suppressing the decrease in B associated with an increase in Mn content in iron oxide ｒ It enables the provision of a ferrite sintered magnet capable of suppressing the above decrease.

[0009] As a result of intensive studies by the present inventor, it was found that when iron oxide with an extremely low Mn content is used as a raw material, the specific resistance becomes extremely low, that is, Mn is an element effective for increasing the specific resistance. The present inventor found that, in a Sr ferrite sintered magnet having a relatively high Mn content, containing a small amount of La can suppress the decrease in B ｒ and improve the H ｃＪ It has been found that H can be improved. However, a new problem has arisen that the electrical resistance decreases significantly with the inclusion of La. Therefore, the inventors found that by containing a small amount of Zn together with a small amount of La, excellent B can be obtained without causing a decrease in electrical resistance ｒ and H ｃＪWe found that an Sr ferrite sintered magnet possessing [a certain characteristic] can be obtained.

[0010] A ferrite sintered magnet of an exemplary embodiment, not limited to the present disclosure, is a ferrite sintered magnet having a hexagonal magnetoplanbite structure as its main phase, wherein MnO is present in an amount of 0.1 mass% to 1.2 mass%, R ２ O ３ It contains 0.1 mass% to 2.8 mass% of (R is at least one rare earth element, and La is essential) and 0.06 mass% to 0.7 mass% of AO (A is Zn and / or Ni).

[0011] A ferrite sintered magnet of another exemplary embodiment, not limited to this disclosure, is given by the general formula: Sr, R, Fe, Mn, and A, where R is at least one rare earth element and essentially contains La, and A is Zn and / or Ni, with the atomic ratio of these elements being Sr, R, Fe, Mn, and A. １－ｘ R ｘ Fe ２ｎ－ｙ－ｚ Mn ｙ A ｚ In this equation, x, y, z, and n (where 2n is a molar ratio and is expressed as 2n = (Fe + Mn + A) / (Sr + R)) satisfy the following conditions: 0.05 ≤ x ≤ 0.2, 0.05 ≤ y ≤ 0.15, 0 < z < 0.1, x ≥ z, y ≥ z, and 11 ≤ 2n - y - z ≤ 12.

[0012] In one embodiment, 0.05 ≤ x ≤ 0.15.

[0013] In one embodiment, y > z.

[0014] In one embodiment, x > z.

[0015] In one embodiment, x = y.

[0016] In one embodiment, the resistivity is 1.0 × 10⁻⁶ ５ It is greater than or equal to Ω·cm.

[0017] According to the embodiments of this disclosure, while maintaining the advantages of ferrite magnets such as cost performance and high resistivity, a large H ｃＪ Without causing a decrease in B, the amount of Mn in iron oxide increases.ｒ This makes it possible to provide ferrite sintered magnets that can suppress the decrease in performance.

[0018] H associated with an increase in MnO content in iron oxide ｃＪ and B ｒ This figure shows the relationship between the MnO content in iron oxide and its resistivity. This figure shows the relationship between H in Sr ferrite sintered magnets with a relatively high Mn content and changes in La and Zn content. ｃＪ and B ｒ This figure shows the relationship between the amount of La and resistivity in a Sr ferrite sintered magnet with a relatively high amount of Mn. This figure shows the relationship between H and resistivity as La and Zn amounts change in a Sr ferrite sintered magnet with a relatively low amount of Mn. ｃＪ and B ｒ This figure shows the relationship between the amount of La and resistivity in a Sr ferrite sintered magnet with a relatively low amount of Mn.

[0019] In one non-limiting embodiment, the ferrite sintered magnet of the present disclosure is a ferrite sintered magnet mainly composed of Sr ferrite having a hexagonal magnetoplanbite structure, wherein MnO is present in an amount of 0.1 mass% to 1.2 mass%, R ２ O ３ It contains 0.1 mass% to 2.8 mass% of (R is at least one rare earth element, and La is essential) and 0.06 mass% to 0.7 mass% of AO (A is Zn and / or Ni).

[0020] The main phase constituting the ferrite sintered magnet of the embodiment of this disclosure is Sr ferrite having a hexagonal magnetoplumbite (M-type) structure. Generally, magnetic materials, especially sintered magnets, may contain grain boundary phases and multiple compounds (other phases, etc.) in addition to the main phase, but the compound that determines the properties (physical properties, magnetic properties, etc.) of the magnetic material is defined as the "main phase." In the ferrite sintered magnet of the embodiment of this disclosure, Sr ferrite having a hexagonal magnetoplumbite (M-type) structure is the main phase. In the ferrite sintered magnet of the embodiment of this disclosure, the proportion of the main phase to the entire ferrite sintered magnet (phase ratio) is 50 mass% or more, preferably 70 mass% or more, more preferably 90 mass% or more, and even more preferably 95 mass% or more. The phase ratio can be determined by performing X-ray diffraction using an X-ray diffractometer and analyzing the obtained X-ray pattern using Rietveld analysis.

[0021] "Having a hexagonal magnetoplanvite (M-type) structure" means that when the X-ray diffraction of a ferrite sintered magnet is measured under general conditions, the X-ray diffraction pattern mainly observed is that of a hexagonal magnetoplanvite (M-type) structure.

[0022] In the ferrite sintered magnet according to the embodiment of this disclosure, Mn is contained as an unavoidable impurity in the iron oxide raw material, and the effects of the embodiment of this disclosure can be obtained if the content is in the range of 0.1 mass% to 1.2 mass% in terms of MnO. If the MnO content is less than 0.1 mass%, the electrical resistance of the ferrite sintered magnet is low, and if it exceeds 1.2 mass%, the R described later will be obtained. ２ O ３ B by ｒ The effect of suppressing the decline was not sufficiently obtained, B ｒ The concentration decreases. The Mn content is preferably in the range of 0.1 mass% to 1.0 mass% in terms of MnO.

[0023] In the ferrite sintered magnet of the embodiment of the present disclosure, R ２ O ３ The content is 0.1 mass% to 2.8 mass%. R is at least one rare earth element and must contain La. ２ O３ is typically La ２ O ３ That is. R ２ O ３ If the content is less than 0.1 mass%, then B ｒ The effect of suppressing the decrease and H ｃＪ If no improvement is obtained and the R content exceeds 2.8 mass%, it leads to an increase in the cost of ferrite sintered magnets. ２ O ３ Preferably, the conversion rate is in the range of 0.9 mass% to 2.0 mass%.

[0024] In the ferrite sintered magnet of the embodiment of this disclosure, the AO content is 0.06 mass% to 0.7 mass%. A is Zn and / or Ni. That is, AO is ZnO and / or NiO. AO is typically ZnO. If the AO content is less than 0.06 mass%, the effect of suppressing the decrease in electrical resistance is not obtained, and if it exceeds 0.7 mass%, H ｃＪ The amount of A decreases. Preferably, the content of A is in the range of 0.06 mass% to 0.5 mass% in terms of AO equivalent.

[0025] In other embodiments, the ferrite sintered magnets of the present disclosure are provided by a general formula that expresses the atomic ratio of the metallic elements Sr, R, Fe, Mn, and A (wherein R is at least one rare earth element and essentially contains La, and A is Zn and / or Ni): Sr １－ｘ R ｘ Fe ２ｎ－ｙ－ｚ Mn ｙ A ｚ In this equation, x, y, and z, as well as n (where 2n is a molar ratio and is expressed as 2n = (Fe + Mn + A) / (Sr + R)), satisfy the following: 0.05 ≤ x ≤ 0.2, 0.05 ≤ y ≤ 0.15, 0 < z < 0.1, x ≥ z, y ≥ z, and 11 ≤ 2n - y - z ≤ 12.

[0026] The ferrite sintered magnet of this embodiment, like the previously described embodiment, has Sr ferrite having a hexagonal magnetoplumbite structure as its main phase, and the explanation of the parts common to the previously described embodiment will be omitted.

[0027] In the above general formula, the atomic ratio x (content of R) is 0.05 ≤ x ≤ 0.2. R is typically La. If x is less than 0.05, B ｒ The effect of suppressing the decrease and H ｃＪ If the improvement effect is not obtained and the value exceeds 0.2, it will lead to an increase in the cost of ferrite sintered magnets, which is undesirable. The preferred range is 0.05 ≤ x ≤ 0.15.

[0028] In the above general formula, the atomic ratio y (Mn content) is 0.05 ≤ y ≤ 0.15. A value of y less than 0.05 is undesirable because it results in a low electrical resistance of the ferrite sintered magnet. Furthermore, if y exceeds 0.15, the B ratio according to the atomic ratio x... ｒ The effect of suppressing the decline could not be obtained, B ｒ This is undesirable because it reduces the B. A particularly preferred range is 0.06 < y ≤ 0.15, and when the amount of Mn is large, by simultaneously including a small amount of La and a small amount of Zn, it is possible to achieve excellent B without causing a decrease in electrical resistance. ｒ and H ｃＪ The effect of having this characteristic is clearly obtained.

[0029] In the above general formula, the atomic ratio z (content of A) is 0 < z < 0.1. A is Zn and / or Ni. A is typically Zn. When x is 0, the effect of suppressing the decrease in electrical resistance is not obtained, and when it is 0.1 or more, H ｃＪ This is undesirable because it reduces the value. The preferred range is 0 < z ≤ 0.06.

[0030] In the above general formula, it is preferable that the atomic ratio x and atomic ratio z satisfy the relationship x ≥ z, and more preferably x > z. In particular, when the Mn content is relatively high (for example, when x exceeds 0.06), it is preferable that it is greater than the A content (x > z). If x < z, then H ｃＪ This is undesirable because it reduces [the value]. It is preferable that the relationship x:z = 1:1 to 2:1 is satisfied.

[0031] In the above general formula, it is preferable that the atomic ratio y and atomic ratio z satisfy the relationship y ≥ z, and more preferably that y > z. If the relationship y < z, then H ｃＪ This is undesirable because it reduces [the value]. It is preferable that the relationship y:z = 1:1 to 2:1 is satisfied.

[0032] The atomic ratio 2n-y-z (Fe content) is preferably 11 ≤ 2n-y-z ≤ 12. If 2n-y-z is less than 11 or greater than 12, B ｒ and H ｃＪ This is undesirable because it reduces [something].

[0033] In the above general formula, it is more preferable that the atomic ratios x and y satisfy the relationship x = y. That is, it is preferable that the R content and the Mn content are equal in amount (equomoles). Note that x = y means that x:y can range from 0.9:1.1 to 1.1:0.9.

[0034] The above general formula is shown in terms of the atomic ratio of metal elements, but the composition containing oxygen (O) is shown in the general formula: Sr １－ｘ R ｘ Fe ２ｎ－ｙ－ｚ Mn ｙ A ｚ O α It is expressed as follows. The number of moles of oxygen α is basically α = 19, but it varies depending on the valencies of Fe and Mn, the values ​​of x, y and z, and n. In addition, the ratio of oxygen to metal elements changes due to oxygen vacancies (vacancies) when calcined in a reducing atmosphere, changes in the valency of Fe in the ferrite phase, etc. Therefore, the actual number of moles of oxygen α may deviate from 19. For this reason, in the embodiments of this disclosure, the composition is expressed in terms of the atomic ratio of metal elements, which is the easiest to identify.

[0035] An example of a method for manufacturing a ferrite sintered magnet according to the embodiments of the present disclosure described above is explained below.

[0036] The raw material powder can be any oxide, carbonate, hydroxide, nitrate, chloride, etc., of the respective metal, regardless of its valency. A solution of the raw material powder may also be used. Examples of compounds of each metal element used as raw material powder are listed below. Sr is SrCO ３ , R is R ２ O ３ , R(OH) ３ And typically La ２ O ３ , La(OH) ３ Fe contains 0.1 mass% to 1.2 mass% of MnO as an unavoidable impurity, iron oxide (Fe２ O ３ ), A is AO, typically ZnO.

[0037] The raw material powders are mixed to satisfy the components and composition of the ferrite sintered magnet according to the embodiment of the present disclosure described above, thereby obtaining a mixed raw material powder. Compounding and mixing of the raw material powders may be performed by either a wet process or a dry process. Stirring together with a medium such as steel balls allows more uniform mixing of the raw material powders. In the case of a wet process, it is preferable to use water as the dispersion medium. A known dispersant such as ammonium polycarboxylate or calcium gluconate may be used for the purpose of improving the dispersibility of the raw material powders. The mixed raw material slurry may be calcined as it is, or may be calcined after dehydrating the raw material slurry.

[0038] The mixed raw material powder obtained by dry mixing or wet mixing is heated using an electric furnace, a gas furnace or the like, thereby forming a ferrite compound having a hexagonal magnetoplumbite (M-type) structure through a solid-phase reaction. This process is referred to as "calcination", and the obtained compound is referred to as a "calcined body".

[0039] In the calcination step, a solid-phase reaction in which a ferrite phase is formed proceeds as the temperature increases. If the calcination temperature is lower than 1100°C, unreacted hematite (iron oxide) remains, resulting in low magnet properties. On the other hand, if the calcination temperature exceeds 1450°C, crystal grains grow excessively, so that pulverization may require a great amount of time in the pulverization step. Therefore, the calcination temperature is preferably from 1100°C to 1450°C. The calcination time is preferably from 0.5 hours to 5 hours. It is preferable that the calcined body after calcination is coarsely pulverized by a hammer mill or the like.

[0040] In order to promote the reaction during calcination, if necessary, B ２ O ３ , H ３ BO ３ and other boron (B)-containing compounds, and SiO ２ and the like may be added in an amount up to about 1 mass%. In particular, H ３ BO ３ addition is effective for improving magnet properties. The addition amount of H ３ BO ３ is preferably 0.3 mass% or less. H３ BO ３ and SiO ２ also have the effect of controlling the shape and size of crystal grains during firing, so they may be added after calcination (before fine pulverization or before firing), or may be added both before and after calcination.

[0041] The calcined body or coarsely pulverized powder of the calcined body is pulverized (finely pulverized) by a vibration mill, jet mill, ball mill, attritor, or the like to obtain calcined body powder (finely pulverized powder). The average particle diameter of the calcined body powder is preferably about 0.4 µm to 1.2 µm. In the embodiments of the present disclosure, a value measured by the air permeation method using a powder specific surface area analyzer (e.g., SS-100 manufactured by Shimadzu Corporation) is referred to as the average particle diameter (average particle size) of the powder. The pulverization step may be either dry pulverization or wet pulverization, or a combination of both. In the case of wet pulverization, water and / or a non-aqueous solvent (an organic solvent such as acetone, ethanol, xylene, etc.) is used as a dispersion medium. Typically, a slurry containing water (dispersion medium) and the calcined body is produced. A known dispersant and / or surfactant may be added to the slurry in an amount of 0.2 mass% to 2 mass% based on the solid content ratio. After wet pulverization, the slurry may be concentrated.

[0042] In the molding step, the slurry after the pulverization step is press-molded in a magnetic field or in the absence of a magnetic field while removing the dispersion medium. By press molding in a magnetic field, the crystal orientation of the powder particles can be aligned (oriented), and the magnetic properties can be dramatically improved. Furthermore, in order to improve the orientation, 0.1 mass% to 1 mass% each of a dispersant and a lubricant may be added to the slurry before molding. The slurry may also be concentrated as necessary before molding. The concentration is preferably performed by centrifugation, filter press, or the like.

[0043] After the calcination step and before the molding step, the shrinkage ratio and B are added to the calcined body or the powder of the calcined body (coarsely pulverized powder or finely pulverized powder) ｒ / H ｃＪ to adjust the balance of SiO ２ , CaCO ３ , SrCO ３ , Cr ２ O ３ , Al ２ O３ Other substances may be added. The amount of each of these additives may be 2 mass% or less.

[0044] In the embodiments of this disclosure, CaCO ３ All amounts added are expressed in terms of CaO equivalent. From the amount added in terms of CaO equivalent, CaCO ３ The amount to add is given by the formula: (CaCO2) ３ It can be calculated by (molecular weight of [the substance] × amount added in terms of CaO) / molecular weight of CaO. For example, 0.5 mass% CaCO2 in terms of CaO. ３ When adding, {(40.08 [atomic weight of Ca] + 12.01 [atomic weight of C] + 48.00 [atomic weight of O × 3] = 100.09 [CaCO2] ３ [Molecular weight of Calcium] × 0.5 mass% [Amount added in terms of CaO]} / (40.08 [atomic weight of Ca] + 16.00 [atomic weight of O] = 56.08 [molecular weight of CaO]) = 0.892 mass% [CaCO] ３ The amount to be added is as follows:

[0045] The molded body obtained by press molding is degreased as necessary and then fired (sintered). The firing is carried out using an electric furnace, gas furnace, etc. It is preferable to fire the body in an atmosphere with an oxygen concentration of 10% by volume or more. More preferably, it is 20% by volume or more, and most preferably 100% by volume. The firing temperature is preferably around 1150°C to 1250°C. The firing time is preferably 0 hours (no holding at firing temperature) to about 4 hours.

[0046] After the firing process, the ferrite sintered magnet is finally produced through known manufacturing processes such as processing, cleaning, and inspection.

[0047] The ferrite sintered magnet of the embodiment of this disclosure obtained by applying the above manufacturing method has a large H ｃＪ B increases with the increase in the amount of Mn in iron oxide without causing a decrease. ｒ This can suppress the decrease in resistivity, and in a preferred embodiment, the resistivity is 1.0 × 10 ５ It shows a high value of Ω·cm or more.

[0048] Embodiments of the present disclosure will be described in further detail by reference to examples, but the embodiments of the present disclosure are not limited thereto.

[0049] Experimental Example 1 Experimental Example 1 shows that the amount of Mn in Sr ferrite sintered magnets increases as the amount of Mn increases with the amount of Mn in iron oxide, and B ｒ , H ｃＪ This is a reference example that verifies the change in resistivity.

[0050] General formula SrFe ２ｎ－ｙ Mn ｙ In this case, y=0, y=0.06 (0.46 mass%) in terms of MnO equivalent, y=0.09 (0.69 mass%) in terms of MnO equivalent, y=0.12 (0.92 mass%) in terms of MnO equivalent, and n=5.85, SrCO ３ powder, Fe ２ O ３ The powder was weighed. The amount of Mn was adjusted using high-purity iron oxide powder (y=0) and three types of iron oxide powder containing different amounts of Mn as an unavoidable impurity.

[0051] SiO₂ per 100 mass% of the total powder after weighing ２ Powder at 0.2 mass%, H ３ BO ３ After adding 0.1 mass% of the powder, each mixture was mixed in a wet ball mill for 4 hours, then dried and granulated to obtain four types of mixed raw material powders. Each of the obtained mixed raw material powders was calcined in air at 1300°C for 3 hours to obtain four types of calcined bodies.

[0052] After coarsely grinding each of the obtained calcined materials in a vibratory mill to obtain coarsely ground powder, SrCO4 is added to 100 mass% of each coarsely ground powder. ３ 0.5% by mass, CaCO ３ (Amount added is equivalent to CaO) 0.4% by mass, SiO ２ Each of the following was added at 0.2% by mass and finely ground for 18 hours in a wet ball mill using water as the dispersion medium to obtain four types of finely ground slurries.

[0053] Each finely ground slurry was molded using a parallel magnetic field molding machine (vertical magnetic field molding machine) where the pressure direction and magnetic field direction were parallel, while removing the dispersion medium. The molded material was then subjected to a magnetic field of approximately 1 T and a pressure of approximately 2.4 MPa, producing multiple molded bodies of four different types. Each of the obtained molded bodies was placed in a sintering furnace and fired in air at 1190°C, 1200°C, and 1210°C for 1 hour to obtain 12 types of Sr ferrite sintered magnets.

[0054] B of the obtained Sr ferrite sintered magnet ｒ , H ｃＪ The resistivity was also measured. The measurement results are shown in Table 1, Figure 1, and Figure 2. B ｒ , H ｃＪ The coercivity was measured using a BH tracer, and the resistivity was measured using a Mitsubishi Chemical Corporation Hi-Resta. The same procedure was followed for the following experimental examples. In Table 1, ** next to the sample number indicates that it is a reference example. In Figure 1, the horizontal axis represents coercivity H. ｃＪ (kA / m), vertical axis is B ｒ (T) is shown. In Figure 2, the horizontal axis shows the amount of MnO in iron oxide (mass%), and the vertical axis shows the resistivity (Ω·cm). As shown in Table 1 and Figure 1, B increases with increasing amount of Mn in iron oxide. ｒ It can be seen that the resistivity tends to decrease. Also, as shown in Table 1 and Figure 2, it can be seen that the resistivity increases with increasing Mn content.

[0055] Note that the atomic ratios in Table 1 represent the atomic ratios (composition) of the raw material powders at the time of mixing. The atomic ratios (composition of the sintered magnet) in the sintered body (ferrite sintered magnet) after firing are based on the atomic ratios at the time of mixing, for example, the additives (H) added before the calcination process. ３ BO ３ The amount of additives (such as CaCO3) added, and additives added after the calcination process and before the molding process. ３ or SiO ２ The amount of additives (such as) can be considered and calculated, and the calculated value will be basically the same as the result of analyzing ferrite sintered magnets with an ICP emission spectrometer (for example, Shimadzu ICPV-1017). The same applies to the following experimental examples.

[0056]

[0057] Experimental Example 2 Experimental Example 2 is an experimental example according to the present disclosure, in which a small amount of Zn is included together with a small amount of La in a Sr ferrite sintered magnet with a relatively large amount of Mn.

[0058] General formula Sr １－ｘ La ｘ Fe ２ｎ－ｙ－ｚ Mn ｙ Zn ｚ In this process, the atomic ratios are set to 1-x, x, 2n-y-z, y, z as shown in Table 2 for each sample No. 5-1 to 12-3, using SrCO ３ Powder, La(OH) ３ powder, Fe ２ O ３ The powder and ZnO powder were weighed in predetermined proportions. ２ O ３ The powder used was iron oxide powder containing Mn as an unavoidable impurity, where y = 0.12 (0.92 mass%) in the general formula mentioned above. A sintered magnet was fabricated in the same manner as in Experimental Example 1, except that the fine grinding time was set to 19 hours.

[0059] B of the obtained Sr ferrite sintered magnet ｒ , H ｃＪ The resistivity was also measured. The measurement results are shown in Table 2, Figure 3, and Figure 4. In Table 2, samples without an asterisk (*) next to the sample number are experimental examples based on the embodiments of this disclosure, while samples with an asterisk (*) are experimental examples (comparative examples) that do not satisfy the embodiments of this disclosure. Also, Figure 3 is H ｃＪ and B ｒ This diagram shows the relationship, with the horizontal axis being H ｃＪ (kA / m), vertical axis is B ｒ (T) is shown. Figure 4 shows the relationship between La content (x) and resistivity when fired at 1210°C, with the horizontal axis representing La content (x) and the vertical axis representing resistivity (Ω・cm).

[0060]

[0061] As shown in Table 2, Figure 3, and Figure 4, in an iron oxide powder containing a large amount of Mn as an unavoidable impurity, and in a Sr ferrite sintered magnet containing 0.92 mass% Mn in terms of MnO, by including a small amount of La as shown in samples No. 5-1 to 7-3, B ｒand H ｃＪ The performance has improved. However, with the increase in La content, the resistivity has decreased significantly.

[0062] Furthermore, as shown in samples No. 8-1 to 8-3, when a small amount of Zn (z = 0.06) is included without La, B ｒ H improves ｃＪ The amount of is significantly reduced (compared to samples No. 5-1 to 5-3). However, as shown in samples No. 9-1 to 10-3, by simultaneously including small amounts of La (x = 0.06, 0.12) and small amounts of Zn (z = 0.06), B ｒ H does not decrease ｃＪ This improves. In the case of x = 0.06, z = 0.06 (x = z), excellent B is achieved without causing a decrease in resistivity. ｒ and H ｃＪ An Sr ferrite sintered magnet is obtained, and when x = 0.12 and z = 0.06 (x > z), the resistivity decreases slightly (still 1.0 × 10⁻¹⁰). ５ Although it shows a high value of Ω·cm or more, the superior B ｒ and H ｃＪ A Sr ferrite sintered magnet having the following characteristics can be obtained. That is, in a Sr ferrite sintered magnet with a relatively large amount of Mn, it is better to have a smaller Zn content (z) than La content (x) (x > z) than to have equimolar La content (x) and Zn content (z) (x = z). ｒ , H ｃＪ Both will improve.

[0063] On the other hand, if the Zn content is too high (z = 0.12), as shown in samples No. 11-1 to 12-3, there is no decrease in resistivity, but when there is no La content (x = 0), B ｒ H improves ｃＪ H decreased significantly, and when combined with a small amount of La (x = 0.06), H was lower compared to when La was not included. ｃＪ Although it improves, B ｒ It will decrease significantly.

[0064] Furthermore, as shown in Figure 4, when no Zn is present (z=0), the resistivity decreases significantly when the amount of La (x) is 0.06, whereas when a small amount of Zn (z=0.06, 0.12) is present, the resistivity hardly decreases when the amount of La (x) is 0.06. On the other hand, when the amount of La (x) is 0.12, the resistivity decreases in both the case of no Zn present (z=0) and the case of a small amount of Zn present (z=0.06).

[0065] These experimental results suggest that it is possible to achieve excellent B while suppressing the decrease in resistivity. ｒ and H ｃＪ To obtain an Sr ferrite sintered magnet having the following, it is preferable to satisfy (1) to (4) below. (1) MnO is 0.1 mass% to 1.2 mass%, La ２ O ３ It contains 0.1 mass% to 2.8 mass% of and 0.06 mass% to 0.7 mass% of ZnO. Alternatively, Sr １－ｘ R ｘ Fe ２ｎ－ｙ－ｚ Mn ｙ A ｚ In this case, the following conditions are satisfied: 0.05 ≤ x ≤ 0.2, 0.05 ≤ y ≤ 0.15, 0 < z < 0.1, x ≥ z, y ≥ z, and 11 ≤ 2n - y - z ≤ 12. (2) Make the Zn content (z) less than the Mn content (y). That is, y > z. (3) Make the Zn content (z) less than the La content (x). That is, x > z. (4) Make the La content (x) and Mn content (y) equal (equomoles). That is, x = y.

[0066] Experimental Example 3 Experimental Example 3 is an experimental example according to the present disclosure, in which a small amount of Zn is included together with a small amount of La in a Sr ferrite sintered magnet with a relatively small amount of Mn.

[0067] General formula Sr １－ｘ La ｘ Fe ２ｎ－ｙ－ｚ Mn ｙ Zn ｚ In this process, the atomic ratios are set to 1-x, x, 2n-y-z, y, z as shown in Table 3 for each sample No. 13-1 to 20-3, using SrCO ３ Powder, La(OH) ３ powder, Fe２ O ３ The powder and ZnO powder were weighed in predetermined proportions. ２ O ３ The powder used was iron oxide powder containing Mn as an unavoidable impurity, where y = 0.06 (0.46 mass%) in the general formula mentioned above, and a sintered magnet was fabricated in the same manner as in Experimental Example 2.

[0068] B of the obtained Sr ferrite sintered magnet ｒ , H ｃＪ The resistivity was also measured. The measurement results are shown in Table 3, Figure 5, and Figure 6. In Table 3, samples without an asterisk (*) next to the sample number are experimental examples based on the embodiments of this disclosure, while samples with an asterisk (*) are experimental examples (comparative examples) that do not satisfy the embodiments of this disclosure. Also, Figure 5 is H ｃＪ and B ｒ This diagram shows the relationship, with the horizontal axis being H ｃＪ (kA / m), vertical axis is B ｒ (T) is shown. Figure 6 shows the relationship between La content (x) and resistivity when fired at 1210°C, with the horizontal axis representing La content (x) and the vertical axis representing resistivity (Ω・cm).

[0069]

[0070] As shown in Table 3, Figure 5, and Figure 6, in an iron oxide powder containing a relatively small amount of Mn as an unavoidable impurity, and in a Sr ferrite sintered magnet containing 0.46 mass% Mn in terms of MnO, as shown in samples No. 13-1 to 15-3, by including a small amount of La, H ｃＪ B remained almost unchanged. ｒ The resistivity has improved slightly. Also, the resistivity has decreased significantly with the increase in La content.

[0071] Furthermore, as shown in samples No. 16-1 to 16-3, when a small amount of Zn (z = 0.06) is included without La, B ｒ H improves ｃＪ The amount of is significantly reduced (compared to samples No. 13-1 to 13-3). However, as shown in samples No. 17-1 to 17-3, by simultaneously including a small amount of La (x = 0.06) and a small amount of Zn (z = 0.06), B ｒAlthough H decreases slightly ｃＪ This improves. Although the resistivity decreases slightly, it is 1.0 × 10 ５ It shows high values ​​of Ω·cm or more. As shown in samples No. 18-1 to 18-3, when x = 0.12 and z = 0.06 (x > z), B is higher compared to when x = 0.06 and z = 0.06 (x = z). ｒ , H ｃＪ And the resistivity decreases.

[0072] On the other hand, if the Zn content is too high (z = 0.12), as shown in samples No. 19-1 to 20-3, there is no decrease in resistivity, but when there is no La content (x = 0), B ｒ H improves ｃＪ H decreased significantly, and when combined with a small amount of La (x = 0.06), H was lower compared to when La was not included. ｃＪ Although it improves, B ｒ It will decrease significantly.

[0073] Furthermore, as shown in Figure 6, in the case of no Zn content (z=0), the resistivity decreases significantly as the amount of La (x) increases. This is almost the same trend as the result shown in Figure 4 of Experimental Example 2. On the other hand, when the Zn content is 0.06, the resistivity also decreases significantly as the amount of La (x) increases. This is significantly different from the trend shown in Figure 4 of Experimental Example 2. When the Zn content is 0.12, the resistivity hardly decreases even when the amount of La (x) becomes 0.06. However, as shown in Table 3 and Figure 5, B ｒ It will decrease significantly.

[0074] These experimental results show that even when the same amounts of La(x) and Zn(z) are added, the properties obtained differ between a Sr ferrite sintered magnet with a high Mn content (Experimental Example 2), which uses iron oxide powder containing a relatively high amount of Mn as an unavoidable impurity, and a Sr ferrite sintered magnet with a low Mn content (Experimental Example 3), which uses iron oxide powder containing a relatively low amount of Mn as an unavoidable impurity. This is dependent on the amount of Mn, and by simultaneously including small amounts of La and Zn, it is possible to obtain excellent B without causing a decrease in electrical resistance. ｒ and H ｃＪThe effect of having [specific characteristic] is clearly observed when the amount of Mn is high (y > 0.06 or MnO > 0.46 mass%).

[0075] The ferrite sintered magnet according to the embodiments of this disclosure has a large H ｃＪ B increases with the increase in the amount of Mn in iron oxide without causing a decrease. ｒ Since it can suppress the decrease in both power and electrical resistance, it can be suitably used in various motors and the like.

Claims

1. A ferrite sintered magnet having a hexagonal magnetoprumbite structure with Sr ferrite as the main phase, wherein MnO is present in an amount of 0.1 mass% to 1.2 mass%, R ２ O ３ A ferrite sintered magnet containing 0.1 mass% to 2.8 mass% of (where R is at least one rare earth element, and La is essential) and 0.06 mass% to 0.7 mass% of AO (where A is Zn and / or Ni).

2. General formula showing the atomic ratios of metallic elements Sr, R, Fe, Mn, and A (where R is at least one rare earth element and must contain La, and A is Zn and / or Ni): Sr １－ｘ R ｘ Fe ２ｎ－ｙ－ｚ Mn ｙ A ｚ A ferrite sintered magnet in which x, y, and z, as well as n (where 2n is a molar ratio and is expressed as 2n = (Fe + Mn + A) / (Sr + R)) satisfy the following conditions: 0.05 ≤ x ≤ 0.2, 0.05 ≤ y ≤ 0.15, 0 < z < 0.1, x ≥ z, y ≥ z, and 11 ≤ 2n - y - z ≤ 12.

3. The ferrite sintered magnet according to claim 2, wherein 0.05 ≤ x ≤ 0.

15.

4. The ferrite sintered magnet according to claim 2, wherein y > z.

5. The ferrite sintered magnet according to claim 2, wherein x > z.

6. The ferrite sintered magnet according to claim 2, wherein x = y.

7. Resistivity is 1.0 × 10 ５ A ferrite sintered magnet according to claim 1 or 2, having a diameter of Ω·cm or more.

Images