Temperature-sensitive magnetic materials, powders, compacts and composites

Abstract

To provide a temperature-sensitive magnetic material, a powder, a compact, and a composite that have a large rate of decrease in magnetic attractive force as temperature increases.SOLUTION: A thermosensitive magnetic material that contains iron and silicon and has a first phase with a crystal structure belonging to the space group P213, and in the cross section of the thermosensitive magnetic material, the area-based percentage of the first phase is 85% or more, and the percentage is measured using a scanning electron microscope equipped with an energy dispersive X-ray analyzer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a temperature-sensitive magnetic material, a powder, a compact, and a composite. [Background technology]

[0002] Thermosensitive magnetic materials are used in temperature control of motors in home appliances and automobiles, optical and magnetic storage devices, etc. For example, Patent Document 1 discloses a thermosensitive switch that combines a thermosensitive magnetic material with a permanent magnet. A thermosensitive switch switches on and off in response to changes in the external temperature.

[0003] Various compositions of temperature-sensitive magnetic materials have been proposed, one of which is an Fe—Si alloy (Non-Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-31274 [Non-patent literature]

[0005] [Non-Patent Document 1] Osawa et al. (1940), Study on Fe-Si alloys, Journal of the Japan Institute of Metals, Vol. 4, No. 8, 228-242 Summary of the Invention [Problem to be solved by the invention]

[0006] To improve the performance of a thermosensitive switch, it is preferable to use a thermosensitive magnetic material that exhibits a large rate of decrease in magnetic attractive force with increasing temperature. The use of such a thermosensitive magnetic material can, for example, increase the distance between the contacts of the thermosensitive switch when it is in the OFF state, improving insulation resistance. Therefore, this thermosensitive magnetic material can be used for applications such as fuses capable of reversible operation.

[0007] The Fe—Si alloy described in Non-Patent Document 1 has an insufficient rate of decrease in magnetic attractive force with increasing temperature, and further improvement is desired.

[0008] Therefore, an object of the present disclosure is to provide a temperature-sensitive magnetic material, powder, compact, and composite that exhibits a large rate of decrease in magnetic attractive force with increasing temperature. [Means for solving the problem]

[0009] The temperature-sensitive magnetic material of the present disclosure is A temperature-sensitive magnetic material comprising a first phase containing iron and silicon and having a crystal structure belonging to the space group P213, In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the first phase is 85% or more, The percentages are temperature sensitive magnetic materials measured using a scanning electron microscope with an energy dispersive X-ray analyzer. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a temperature-sensitive magnetic material, powder, compact, and composite that exhibit a large rate of decrease in magnetic attractive force with increasing temperature. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a graph showing the change in magnetic attractive force with respect to the temperature change of the compacts of Sample 11 and Sample 1-3. [Figure 2] FIG. 2 is a scanning electron microscope (SEM) image (magnification: 200 times) of a cross section of the molded body of Sample 11. [Figure 3] FIG. 3 is a scanning electron microscope (SEM) image (magnification: 200 times) of the cross section of the molded body of Sample 1-3. [Figure 4] FIG. 4 is a graph showing the change in magnetic attractive force with respect to the temperature change of the molded body of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described. (1) The temperature-sensitive magnetic material of the present disclosure is A temperature-sensitive magnetic material comprising a first phase containing iron and silicon and having a crystal structure belonging to the space group P213, In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the first phase is 85% or more, The percentages are temperature sensitive magnetic materials measured using a scanning electron microscope with an energy dispersive X-ray analyzer.

[0013] According to the present disclosure, it is possible to provide a temperature-sensitive magnetic material in which the rate of decrease in magnetic attractive force with respect to an increase in temperature is large.

[0014] In this disclosure, the rate of decrease in magnetic attractive force with increasing temperature (unit: kg / °C) is defined as a value calculated using the following procedure. The relationship between the temperature and magnetic attractive force of a temperature-sensitive magnetic material is shown in a coordinate system with the X-axis representing temperature (°C) and the Y-axis representing magnetic attractive force (kg). The magnetic attractive force M1 of the temperature-sensitive magnetic material at 50°C is identified. The magnetic attractive force M2 is 80% of the magnetic attractive force M1 at 50°C, and point A2 is identified, which represents the temperature T2 at magnetic attractive force M2. The magnetic attractive force M3 is 20% of the magnetic attractive force M1 of the temperature-sensitive magnetic material at 50°C, and point A3 is identified, which represents the temperature T3 at magnetic attractive force M3. A straight line is drawn connecting points A2 and A3. The rate of decrease in magnetic attractive force per 1°C of temperature is calculated based on this straight line.

[0015] In this specification, an increase in the rate of decrease in magnetic attractive force with increasing temperature is also referred to as improved magnetic properties.

[0016] (2) In the above (1), the first phase may contain manganese, thereby increasing the content of the first phase in the temperature-sensitive magnetic material.

[0017] (3) In the above (1) or (2), the first phase may contain 85 mass% or more of iron, silicon, and manganese in total. When the magnetic attractive force is measured under the same conditions, the magnetic attractive force of the temperature-sensitive magnetic material at 25°C is improved compared to a temperature-sensitive magnetic material in which the total content of iron, silicon, and manganese in the first phase is less than 85 mass%.

[0018] (4) In the above (2) or (3), the manganese content of the first phase may be 10% by mass or less. When the magnetic attractive force of the temperature-sensitive magnetic material is measured under the same conditions, the magnetic attractive force at 25°C is less likely to decrease than that of a temperature-sensitive magnetic material having a manganese content of more than 10% by mass.

[0019] (5) In any of the above (1) to (4), the first phase may be composed of 23% by mass or more and 27% by mass or less of silicon, 10% by mass or less of manganese, and the remainder being iron. This increases the content of the first phase in the temperature-sensitive magnetic material.

[0020] (6) In the above (1), the first phase may be composed of 23% by mass to 27% by mass of silicon, the remainder being iron. This can increase the rate at which the magnetic attractive force decreases with increasing temperature.

[0021] (7) In any one of the above (1) to (6), the temperature-sensitive magnetic material has a second phase, the second phase includes at least one selected from the group consisting of a first alloy, a second alloy, and a third alloy; the first alloy contains iron and silicon and has a crystal structure belonging to the space group P-3m1; the second alloy contains iron and silicon and has a crystal structure belonging to the space group Fm-3m; the third alloy contains iron and silicon and has a crystal structure belonging to the space group P63 / mcm; In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the second phase may be 15% or less.

[0022] This makes it difficult for lattice distortion to occur in the first phase, and prevents a decrease in the rate of decrease in magnetic attractive force with increasing temperature.

[0023] (8) In any of the above (1) to (7), the saturation magnetization J at 150°C s Saturation magnetization J at 50°C vs. 150 s 50% J s 50 / J s 150 may be equal to or greater than 10. This further improves the magnetic properties of the temperature-sensitive magnetic material.

[0024] (9) In the above (8), the J s 50 / J s 150 may be equal to or greater than 15. This further improves the magnetic properties of the temperature-sensitive magnetic material.

[0025] (10) In (8) or (9) above, J s 50 is 0.3Wb / m 2 This further improves the magnetic properties of the temperature-sensitive magnetic material.

[0026] (11) The powder of the present disclosure is a powder made of a temperature-sensitive magnetic material containing iron and silicon and having a first phase having a crystal structure belonging to the space group P213, In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the first phase is 85% or more, The percentage is measured using a scanning electron microscope equipped with an energy dispersive X-ray analyzer; It is a powder with an average particle size of 1.0 μm or more and 100 μm or less.

[0027] According to the present disclosure, it is possible to provide a powder with a large rate of decrease in magnetic attractive force with increasing temperature. Furthermore, the specific surface area of ​​the powder made of the temperature-sensitive magnetic material is small, and the saturation magnetization J of the powder at 50°C is s 50 is high and the proportion of phase 1 is large.

[0028] (12) The molded article of the present disclosure is a molded article made of particles of the temperature-sensitive magnetic material according to any one of (1) to (10), The molded body has voids formed inside.

[0029] According to the present disclosure, it is possible to provide a molded body in which the rate of decrease in magnetic attractive force with respect to an increase in temperature is large.

[0030] (13) In the above (12), the porosity of the compact may be 30% by volume or less, thereby improving the magnetic properties of the compact.

[0031] (14) In the above (12) or (13), the average particle size of the particles may be 1.0 μm or more and 100 μm or less. According to this, the specific surface area of ​​the particles made of the temperature-sensitive magnetic material is small, and the molded body has a large saturation magnetization J at 50° C. s 50, and a high ratio of the first phase can coexist with low porosity.

[0032] (15) The composite of the present disclosure is a composite comprising a plurality of particles made of the thermosensitive magnetic material of any one of (1) to (10) above, and a filler filling the spaces between the particles.

[0033] According to the present disclosure, it is possible to provide a composite body in which the rate of decrease in magnetic attractive force with increasing temperature is large.

[0034] (16) In the above (15), the content of the particles may be 70% by volume or more. According to this, the relative density of the particles made of the temperature-sensitive magnetic material in the composite is high, and the composite has a large saturation magnetization J at 50°C. s 50, the variation in the internal demagnetizing field in the composite is small, and the rate of decrease in the magnetic attractive force with increasing temperature of the composite is large.

[0035] (17) In the above (15) or (16), the filler may be a resin, which makes the material less susceptible to damage even when subjected to shocks during switching or internal stress caused by thermal expansion of the temperature-sensitive magnetic material.

[0036] (18) In any of the above (15) to (17), the particles may have an average particle size of 1.0 μm or more and 100 μm or less. According to this, the specific surface area of ​​the particles made of the temperature-sensitive magnetic material is small, and the composite has a large saturation magnetization J at 50° C. s 50 and also has a high proportion of first phase.

[0037] [Details of the embodiments of the present disclosure] In this specification, the expression "A to B" means the upper and lower limits of a range (i.e., A or more and B or less), and when no unit is specified for A and a unit is specified only for B, the unit of A and the unit of B are the same.

[0038] In the present specification, when a compound or the like is represented by a chemical formula, unless the atomic ratio is particularly limited, it is understood to include any conventionally known atomic ratio, and is not necessarily limited to only those within the stoichiometric range, but includes any conventionally known atomic ratio.

[0039] In this specification, unless otherwise specified, high temperature means 150°C and low temperature means 50°C.

[0040] In the present disclosure, when one or more numerical values ​​are recited as the lower limit and the upper limit of a numerical range, a combination of any one numerical value recited as the lower limit and any one numerical value recited as the upper limit is also considered to be disclosed. For example, when a1 or more, b1 or more, and c1 or more are recited as the lower limit and a2 or less, b2 or less, and c2 or less are recited as the upper limit, a1 or more and a2 or less, a1 or more and b2 or less, a1 or more and c2 or less, b1 or more and a2 or less, b1 or more and b2 or less, b1 or more and c2 or less, c1 or more and a2 or less, c1 or more and b2 or less, and c1 or more and c2 or less are considered to be disclosed.

[0041] To investigate the reason why the rate of decrease in magnetic attractive force with increasing temperature in conventional Fe-Si alloys is insufficient, the inventors first produced Fe-Si alloys under the annealing conditions described in Non-Patent Document 1 and observed their structures. Specifically, the raw material (a mixed powder of Fe powder and Si powder) was annealed at 950°C for 88 hours in a vacuum and then slowly cooled to produce an Fe-Si alloy (page 231, left column, V. Magnetic Analysis, lines 1-4), and the cross section was observed using a scanning electron microscope (SEM-EDX) equipped with an energy dispersive X-ray analyzer.

[0042] As a result, the inventors newly discovered that in the Fe-Si alloy, FeSi and Fe3Si exist as two largely separated phases. Here, FeSi refers to an alloy having a crystalline structure belonging to the space group P213, and Fe3Si refers to an alloy having a crystalline structure belonging to the space group Fm-3m. The inventors hypothesized that the magnetic properties of the Fe-Si alloy deteriorate due to the alloy structure containing FeSi and Fe3Si, which exist as two largely separated phases. Based on this new discovery and assumption, the inventors conducted extensive research and developed the temperature-sensitive magnetic material, powder, compact, and composite of the present disclosure. Specific examples of the temperature-sensitive magnetic material, powder, compact, and composite of the present disclosure are described below with reference to the drawings.

[0043] [Embodiment 1: Temperature-sensitive magnetic material] A temperature-sensitive magnetic material according to one embodiment of the present disclosure (hereinafter also referred to as "embodiment 1") comprises: A temperature-sensitive magnetic material comprising a first phase containing iron and silicon and having a crystal structure belonging to the space group P213, In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the first phase is 85% or more, The percentage is the temperature sensitive magnetic material as measured using a scanning electron microscope with an energy dispersive X-ray analyzer.

[0044] The temperature-sensitive magnetic material of embodiment 1 exhibits a large decrease in magnetic attractive force with increasing temperature. The reason for this is not clear, but is presumed to be as follows.

[0045] The first phase of the temperature-sensitive magnetic material of embodiment 1 contains iron (Fe) and silicon (Si) and has a crystal structure belonging to the space group P213. The first phase exhibits a large decrease in magnetic attractive force with increasing temperature. Furthermore, the temperature-sensitive magnetic material of embodiment 1 contains 85% or more of the first phase by area in its cross section, and in terms of magnetic properties, the first phase behaves as a substantially single phase. Therefore, the temperature-sensitive magnetic material of embodiment 1 exhibits a large decrease in magnetic attractive force with increasing temperature.

[0046] <Phase 1> The first phase of the first embodiment contains iron (Fe) and silicon (Si) and has a crystal structure belonging to the space group P213. Examples of constituent components of the first phase include FeSi and alloys in which a portion of the iron in FeSi is substituted with an element X, such as chromium (Cr), cobalt (Co), manganese (Mn), or nickel (Ni), which has an atomic radius similar to that of iron. Hereinafter, chromium (Cr), cobalt (Co), manganese (Mn), and nickel (Ni) will also be collectively referred to as element X. In the present disclosure, FeSi refers to an alloy containing Fe and Si in an atomic ratio of Fe:Si=43:57 to 57:43 and having a crystal structure belonging to the space group P213. FeSi is also called fersilicite and has an FeSi-type crystal structure. In this disclosure, an alloy in which a portion of the iron in FeSi is replaced by an element X, such as chromium, cobalt, manganese, or nickel, with an atomic radius similar to that of iron, refers to an alloy containing the element X in an atomic ratio of (Fe + X):Si = 43:57 to 57:43 and having a crystal structure belonging to the space group P213. The crystal structure of the first phase belonging to the space group P213 can be confirmed by acquiring a diffraction pattern using an X-ray diffractometer (SmartLab manufactured by Rigaku) ​​and identifying it using the database analysis software (SmartLab Studio II) provided with the diffractometer. Identification may also be performed using the JCPDS database published by the International Centre for Diffraction Data (ICDD). The X-ray diffraction conditions are Cu-Kα radiation (45 kV / 200 mA, 0.8 mm slit, 0.5 mm mask), and measurement conditions are 2θ-θ scan (5 to 90°, step width 0.03°, scan speed 2° / min). The crystal structure described below can be confirmed by the same method.

[0047] In the cross section of the temperature-sensitive magnetic material of the first embodiment, the area-based percentage of the first phase is 85% or more. This means that the first phase exists in a substantially single phase in the temperature-sensitive magnetic material, and the difference (M L -M H) is large, and the rate of decrease in magnetic attractive force with increasing temperature is large. The lower limit of the area-based percentage of the first phase is 85% or more, more preferably 90% or more, and even more preferably 95% or more. The upper limit of the area-based percentage of the first phase is not particularly limited, and is preferably, for example, 100% or less. The area-based percentage of the first phase is more preferably 85% or more and 100% or less, more preferably 90% or more and 100% or less, and even more preferably 95% or more and 100% or less.

[0048] The area-based percentage of the first phase in the cross section of the temperature-sensitive magnetic material is measured using a scanning electron microscope equipped with an energy dispersive X-ray analyzer. Specifically, the measurement is performed by the following steps.

[0049] Step A1: If the thermosensitive magnetic material is a molded body or composite, the cross section is exposed by cutting it using a method that does not easily cause grain shedding from the processed surface of the object to be cut, such as a diamond abrasive cutter or an electric discharge machine. If the thermosensitive magnetic material is a powder, the cross section is exposed by focused ion beam processing (FIB processing, device: Quanta 3D 200i (trademark) manufactured by Thermo Fisher Scientific) while observing it under an optical microscope at 100x or 200x magnification. At this time, FIB processing is performed so that the cross section including the approximate center of the particles that make up the powder is exposed.

[0050] Step B1: Surface analysis is performed on the cross section using FESEM (Field Emission Scanning Electron Microscope, JEOL JSM-7800F)-EDX (AMETEK EDAX, analysis software: GENESIS Spectrum). The acceleration voltage during surface analysis is 10 kV, the irradiation current is 5 nm, and the observation magnification is 5000 times. The measurement field is a rectangle of 10 μm × 10 μm. In the measurement field, the atomic abundance ratio A of Fe atoms is Fe (atomic%), atomic abundance ratio A of Si atoms Si (atomic%), and the total atomic abundance ratio A of element X (Cr, Co, Mn, and Ni) x (atomic%) of A Fe +ASi +A x Identify region A where the atomic percentage is 80 atomic % or more. Region A corresponds to the region that has thermo-sensitive magnetic properties. In this case, adjust the position of the measurement field so that the area percentage of region A in the measurement field is 50% or more. Region A corresponds to the region where the thermo-sensitive magnetic material is present. In the case of powder, arrange the powder so that the area percentage of region A in the measurement field is 50% or more. If the powder is too fine and difficult to measure, the measurement field may be changed to 1 μm x 1 μm.

[0051] When the temperature-sensitive magnetic material is a molded body or composite, identifying the above-mentioned region A corresponds to a process of distinguishing between the temperature-sensitive magnetic material and voids or fillers, and extracting the region in the temperature-sensitive magnetic material that has the characteristics of temperature-sensitive magnetism.

[0052] Step C1: Within region A, a region B is identified where the atomic ratio of Fe, Si, and element X (Cr, Co, Mn, and Ni) is (Fe+X):Si=43:57 to 57:43. Region B corresponds to the region where the first phase exists.

[0053] Step D1. Using image analysis software ("ImageJ" (trademark), https: / / imagej.nih.gov / ij / index.html), calculate the area percentage C of region B relative to region A ((region B / region A) x 100) (%).

[0054] Step E1: The area percentage C is measured at 10 different measurement fields. In the case of powder, one measurement field is set for each of the 10 different particles that make up the powder. The average D (%) of the area percentages C (%) at the 10 locations is calculated. This average D (%) corresponds to the area-based percentage of the first phase in the cross section of the temperature-sensitive magnetic material of embodiment 1.

[0055] It has been confirmed that as long as measurements are made on the same temperature-sensitive magnetic material, there is no variation in the measurement results even if the measurement field of view is set arbitrarily.It has been confirmed that as long as measurements are made on the same temperature-sensitive magnetic material, there is no variation in the measurement results even if the measurement cross section is changed.

[0056] The first phase preferably contains manganese. This increases the content of the first phase in the temperature-sensitive magnetic material. The higher the manganese content of the first phase, the more the magnetic attractive force tends to decrease to near 0 kgf / cm2 at lower temperatures. From the viewpoint of decreasing the magnetic attractive force to near 0 kgf / cm2 at lower temperatures, the lower limit of the manganese content of the first phase is preferably greater than 0 mass%, more preferably 2 mass% or more, preferably 4 mass% or more, more preferably 6 mass% or more, and even more preferably 8 mass% or more. From the viewpoint of avoiding a decrease in saturation magnetization, the upper limit of the manganese content of the first phase is preferably 10 mass% or less. The manganese content of the first phase is preferably greater than 0 mass% and 10 mass% or less, more preferably 2 mass% or more and 10 mass% or less, more preferably 4 mass% or more and 10 mass% or less, even more preferably 8 mass% or more and 10 mass% or less. It is presumed that manganese exists in the first phase as a substitutional solid solution in FeSi.

[0057] The first phase preferably contains iron, silicon, and manganese in a total content of 85% by mass or more. This improves the rate of decrease in magnetic attractive force with increasing temperature of the temperature-sensitive magnetic material. The lower limit of the total content of iron, silicon, and manganese in the first phase is preferably 85% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. The upper limit of the total content of iron, silicon, and manganese in the first phase is not particularly limited and can be set to 100% by mass or less. The total content of iron, silicon, and manganese in the first phase is preferably 85% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less.

[0058] The first phase preferably contains a total of 90% by mass or more of iron and silicon. This improves the rate of decrease in magnetic attractive force with increasing temperature of the temperature-sensitive magnetic material. The lower limit of the total content of iron and silicon in the first phase is preferably 90% by mass or more, and more preferably 95% by mass or more. The upper limit of the total content of iron and silicon in the first phase is not particularly limited and can be set to 100% by mass or less. The total content of iron and silicon in the first phase is preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less.

[0059] The iron, silicon and manganese contents of the first phase are measured by the following steps.

[0060] Step A2: Region B is identified using the same procedure as steps A1 to C1 above.

[0061] Step B2: Point analysis is performed using EDX within region B to derive the Fe:Mn:Si mass ratio. Point analysis is performed at five points per measurement field, and the average of the Fe:Mn:Si mass ratios is derived. This average is the Fe:Mn:Si mass ratio for that measurement field. The accelerating voltage during analysis is 10 keV.

[0062] Step C2: The point analysis is performed at 10 different measurement fields. In the case of powder, one measurement field is set for each of the 10 different particles that make up the powder. The average of the Fe:Mn:Si mass ratios at the 10 points is calculated. Based on this average, the content of iron in the first phase, the content of silicon in the first phase, and the content of manganese in the first phase are calculated.

[0063] It has been confirmed that as long as measurements are made on the same temperature-sensitive magnetic material, there is no variation in the measurement results even if the measurement field of view is set arbitrarily.It has been confirmed that as long as measurements are made on the same temperature-sensitive magnetic material, there is no variation in the measurement results even if the measurement cross section is changed.

[0064] The first phase preferably comprises 23% to 27% by mass of silicon, 10% to 10% by mass of manganese, and the remainder being iron. The silicon content of the first phase is more preferably 23% to 25% by mass. The manganese content of the first phase is preferably greater than 0% by mass and less than or equal to 10% by mass, more preferably 2% to 10% by mass, even more preferably 4% to 10% by mass, and even more preferably 8% to 10% by mass.

[0065] The first phase preferably contains 23 to 27 mass % silicon, the remainder being iron, and the silicon content of the first phase is preferably 23 to 25 mass %.

[0066] The first phase may contain impurities as long as the effects of the present disclosure are not impaired. Examples of such impurities include oxygen, nitrogen, carbon, magnesium, aluminum, phosphorus, and sulfur. The content of such impurities may be 15% by mass or less. The first phase preferably contains 23% by mass or more and 27% by mass or less of silicon, 10% by mass or less of manganese, and the balance being iron and impurities. The first phase preferably contains 23% by mass or more and 27% by mass or less of silicon, and the balance being iron and impurities.

[0067] <Phase 2> The temperature-sensitive magnetic material of the first embodiment may have a second phase. In the present disclosure, the second phase refers to a phase in which, when a cross section of the temperature-sensitive magnetic material is subjected to area analysis in accordance with steps A1 and B1 of the method for measuring the area-based percentage of the first phase in the cross section of the temperature-sensitive magnetic material, the atomic abundance ratio A of Fe atoms is 0.05 to 0.05. Fe (atomic%), atomic abundance ratio A of Si atoms Si (atomic%), and the total atomic abundance ratio A of element X (Cr, Co, Mn, and Ni) x (atomic%) of A Fe +A Si +A x is 80 atomic % or more, and has a crystal structure different from that of the first phase (a crystal structure belonging to the space group P213).

[0068] In the cross section of the temperature-sensitive magnetic material of embodiment 1, the area-based percentage of the second phase is preferably 15% or less, more preferably 10% or less, and even more preferably 5% or less. When the temperature-sensitive magnetic material of embodiment 1 has a second phase, the area-based percentage of the second phase is preferably more than 0% and less than 15%, more preferably more than 0% and less than 10%, and even more preferably more than 0% and less than 5%.

[0069] The area-based percentage of the second phase in the cross section of the temperature-sensitive magnetic material is measured by the following steps. Regions A and B are identified according to steps A1 to C1 of the method for measuring the area-based percentage of the first phase in the cross section of the temperature-sensitive magnetic material. Within region A, region G, which is the portion other than region B, is identified. Region G corresponds to the region where the second phase exists. Image analysis software ("ImageJ" (trademark), https: / / imagej.nih.gov / ij / index.html) is used to calculate the area percentage H ((region G / region A) × 100) (%) of region G relative to region A.

[0070] The area percentage H is measured at 10 different measurement fields. In the case of powder, one measurement field is set for each of the 10 different particles that make up the powder. The average I (%) of the area percentages H (%) at the 10 locations is calculated. This average I (%) corresponds to the area-based percentage of the second phase in the cross section of the temperature-sensitive magnetic material of embodiment 1.

[0071] It has been confirmed that as long as measurements are made on the same temperature-sensitive magnetic material, there is no variation in the measurement results even if the measurement field of view is set arbitrarily.It has been confirmed that as long as measurements are made on the same temperature-sensitive magnetic material, there is no variation in the measurement results even if the measurement cross section is changed.

[0072] The second phase preferably comprises at least one alloy selected from the group consisting of a first alloy, a second alloy, and a third alloy, wherein the first alloy comprises iron and silicon and has a crystal structure belonging to the space group P-3m1, the second alloy comprises iron and silicon and has a crystal structure belonging to the space group Fm-3m, and the third alloy comprises iron and silicon and has a crystal structure belonging to the space group P63 / mcm. The area-based percentage of the second phase in the cross section of the thermosensitive magnetic material is preferably 15% or less. The second phase is a by-product generated during the manufacturing process of the thermosensitive magnetic material of this embodiment. The thermosensitive magnetic material containing the second phase is less likely to experience lattice distortion in the first phase, preventing a decrease in the rate of decrease in magnetic attractive force with increasing temperature.

[0073] Examples of the first alloy include Fe2Si and alloys in which part of the iron in Fe2Si is substituted with at least one of Cr, Co, Mn, and Ni. Examples of the second alloy include Fe3Si and alloys in which part of the iron in Fe3Si is substituted with at least one of Cr, Co, Mn, and Ni. Examples of the third alloy include Fe5Si3 and alloys in which part of the iron in Fe5Si3 is substituted with at least one of Cr, Co, Mn, and Ni.

[0074] The second phase is composed of the first, second and third alloys, as well as Fe 0.67 Si 0.33 , Fe 0.8 Si 0.2 , Fe 0.92 Si 0.08 , Fe 0.92 Si2, Fe 1.5 Si 0.5 and FeSi2 (including FeSi2 structure and CaF2 structure), as well as alloys in which a portion of the iron in these iron-containing alloys is substituted with at least one of Cr, Co, Mn, and Ni, such as FeSi2, Si, MnSi, and MnSi2. The composition of the alloy contained in the second phase can be confirmed by X-ray diffraction.

[0075] In the cross section of the thermosensitive magnetic material of the present disclosure, the total area percentage of the first alloy, second alloy and third alloy in the second phase is preferably 0.5% to 15%, more preferably 0.5% to 10%.

[0076] The temperature-sensitive magnetic material of the first embodiment can be composed of a first phase and a second phase. The temperature-sensitive magnetic material of the first embodiment can include a third phase in addition to the first and second phases, as long as the effects of the present disclosure are not impaired. In the present disclosure, the third phase refers to a phase in which the atomic abundance ratio A of Fe atoms is 0.01 to 0.01 when the cross section of the temperature-sensitive magnetic material is subjected to area analysis according to steps A1 and B1 of the method for measuring the area-based percentage of the first phase in the cross section of the temperature-sensitive magnetic material. Fe (atomic%) is 50 atomic% or more, and the atomic abundance ratio A of Fe atoms is Fe (atomic%), atomic abundance ratio A of Si atomsSi (atomic%), and the total atomic abundance ratio A of element X (Cr, Co, Mn, and Ni) x (atomic%) of A Fe +A Si +A x The third phase corresponds to a region of the temperature-sensitive magnetic material that does not have the temperature-sensitive magnetic properties.

[0077] <Saturation magnetization> The saturation magnetization J of the temperature-sensitive magnetic material of embodiment 1 at 150°C s Saturation magnetization J at 50°C vs. 150 s 50% J s 50 / J s It is preferable that the ratio J is 10 or more. This further improves the magnetic properties of the temperature-sensitive magnetic material. s 50 / J s The lower limit of 150 is preferably 12 or more, more preferably 14 or more, more preferably 15 or more, and even more preferably 25 or more. s 50 / J s There is no particular upper limit to 150, but for example, 10 5 The ratio J can be s 50 / J s 150 is 10 over 10 5 Less than or equal to 12 is preferred, and 10 is preferred 5 Less than 10 is preferable, 14 or more is preferable 5 Less than 15 is preferable, and 10 is preferable. 5 Less than 10 is more preferable, and 25 or more is more preferable. 5 The following is even more preferred:

[0078] The saturation magnetization J of the temperature-sensitive magnetic material of embodiment 1 at 50 ° C. s 50 is 0.20Wb / m 2 The above is preferable. This further improves the magnetic properties of the temperature-sensitive magnetic material. s The lower limit of 50 is 0.25Wb / m 2 More than 0.3Wb / m is more preferable. 2 The above is more preferable. s The upper limit of J is not particularly limited, but can be set to, for example, 2 Wb / m or less.s 50 is 0.20Wb / m 2 More than 2Wb / m 2 Less than 0.25Wb / m is preferable 2 More than 2Wb / m 2 Less than 0.3Wb / m is preferable. 2 More than 2Wb / m 2 The following is even more preferred:

[0079] In this disclosure, the saturation magnetization of the temperature-sensitive magnetic material is measured using a BH loop tracer (JIS C2501) for compacts and composites, and a vibrating sample magnetometer (VSM) (JIS C2500) for powders. The saturation magnetization is measured at an applied magnetic field of 0.8 MA / m for compacts and composites, and 1.6 MA / m for powders.

[0080] <Manufacturing method> The following describes an example of a method for producing the temperature-sensitive magnetic material of embodiment 1. The production method may include a material melting step and a powdering step.

[0081] ≪Material melting process≫ Iron (Fe) raw material and silicon (Si) raw material are prepared and weighed to a predetermined mass ratio. The mixing ratio (mass ratio) of the Fe raw material and the Si raw material is Fe raw material:Si raw material = 40:60 to 60:40. Manganese (Mn) raw material, chromium (Cr) raw material, cobalt (Co) raw material, nickel (Ni) raw material, etc. can also be added. When at least one of the Mn raw material, Cr raw material, Co raw material, and Ni raw material is included, the total content of these raw materials is 10 mass% or less of the total raw material. Each of the above main raw materials may be in any form such as plate, granule, chip, or powder.

[0082] The weighed raw materials are placed in a magnesium oxide (MgO) crucible with a diameter of 80 mm and heated to 1600°C using high-frequency heating to obtain molten Fe-Si, Fe-Si-Mn, Fe-Si-Cr, Fe-Si-Co, Fe-Si-Ni, or other melts. The melts are cast into stainless steel molds and cooled. A 10 mm section is removed from the top surface of the casting, where oxides and other inclusions remain, and the casting is then crushed to obtain fragments of approximately 10 mm. Other heating methods, such as arc melting and plasma melting, may also be used for melting.

[0083] ≪Powdering process≫ The obtained fragments are placed in a φ25 mm quartz crucible equipped with a nozzle, and melted by high-frequency heating to 1550°C. The melt is then sprayed from the nozzle onto a rotating copper roll and pulverized while being rapidly cooled, thereby obtaining the thermosensitive magnetic material of embodiment 1. In other words, the obtained powder is a powder consisting of the thermosensitive magnetic material of embodiment 1.

[0084] The above powdering step makes it possible to obtain a thermosensitive magnetic material in which the area ratio of the first phase in the cross section of the thermosensitive magnetic material is 85% or more. The powdering step is a step newly discovered by the present inventors.

[0085] <Application> The temperature-sensitive magnetic material of embodiment 1 can be used in a temperature-sensitive switch. In particular, for applications such as detecting temperature rises in water-cooled systems, etc., there is a demand for improved magnetic properties of the temperature-sensitive switch in the temperature range of 50 to 150°C. Therefore, a temperature-sensitive switch using the temperature-sensitive magnetic material of embodiment 1 can exhibit excellent magnetic properties in these applications.

[0086] The temperature-sensitive magnetic material of the first embodiment can also be used as a countermeasure against demagnetization in permanent magnet motors.

[0087] [Embodiment 2: Powder] A powder according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 2") is a powder made of a thermosensitive magnetic material containing iron and silicon and having a first phase with a crystal structure belonging to the space group P213, wherein the area-based percentage of the first phase in a cross section of the thermosensitive magnetic material is 85% or more, and the percentage is measured using a scanning electron microscope equipped with an energy dispersive X-ray analyzer, and the powder has an average particle size of 1.0 μm or more and 100 μm or less. This powder corresponds to the powder obtained by the powdering step of the method for producing a thermosensitive magnetic material of Embodiment 1. This powder exhibits a greater rate of decrease in magnetic attractive force with increasing temperature than conventional Fe-Si alloys.

[0088] <Average particle size> The powder of the second embodiment has an average particle size of 1.0 μm or more and 100 μm or less. The specific surface area of ​​the powder made of the temperature-sensitive magnetic material is small, and the saturation magnetization J of the powder at 50° C. s 50 is high and the ratio of the first phase is large. The lower limit of the average particle size of the powder is preferably 10 μm or more, more preferably 30 μm or more. The upper limit of the average particle size of the powder is preferably 50 μm or less. The average particle size of the powder is preferably 10 μm or more and 100 μm or less, more preferably 30 μm or more and 100 μm or less, and even more preferably 30 μm or more and 50 μm or less.

[0089] In this disclosure, the average particle size of a powder refers to the number-based area-equivalent diameter D50 of the particles constituting the powder. The area-equivalent diameter is measured in accordance with JIS Z 8827-1:2018. The area-equivalent diameters of 100 or more particles are measured. Based on these results, the area-equivalent diameter D50 at which the cumulative number-based frequency is 50% is determined.

[0090] [Embodiment 3: Molded body] A molded body according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 3") is a molded body made of particles of the temperature-sensitive magnetic material described in Embodiment 1, in which voids are formed inside the molded body. The molded body exhibits a greater rate of decrease in magnetic attractive force with increasing temperature than conventional Fe-Si alloys.

[0091] <Porosity> The porosity of the molded body of embodiment 3 is preferably 30% by volume or less. This improves the magnetic properties of the molded body. From the viewpoint of improving the magnetic properties, the upper limit of the porosity of the molded body is preferably 30% by volume or less, more preferably 20% by volume or less, and even more preferably 10% by volume or less. The porosity of the molded body may be 0% by volume, i.e., the molded body may have no voids. The molded body may be made of the temperature-sensitive magnetic material described in embodiment 1 and may contain no voids. The porosity of the molded body is preferably 0% by volume or more and 30% by volume or less, more preferably 0% by volume or more and 20% by volume or less, and even more preferably 0% by volume or more and 10% by volume or less.

[0092] The porosity of the molded body is measured by the following steps.

[0093] Step A4: The molded body is cut to expose the cross section in the same manner as in step A1. At this time, the molded body is cut so that three mutually orthogonal cross sections (X cross section, Y cross section, and Z cross section) can be obtained, and a rectangular parallelepiped sample is obtained.

[0094] Step B4: The surface of the sample is subjected to area analysis using SEM-EDX under the same conditions as in step B1. The void region is defined as the region where the detected amount of atoms is 1 / 20 or less of the detected amount of atoms in the region where the total atomic abundance ratio of Fe, Mn, and Si exceeds 80 atomic% (corresponding to region A).

[0095] Step C4. Using image analysis software ("ImageJ"), calculate the void ratio Sv_x (%) in the X cross section, the void ratio Sv_y (%) in the Y cross section, and the void ratio Sv_z (%) in the Z cross section, and calculate the void ratio Sv (volume %) according to the following formula: Sv=(Lx*(Sv_x) 1.5 +Ly*(Sv_y) 1.5 +Lz*(Sv_z) 1.5 ) / (Lx+Ly+Lz) In the above formula, Lx is the area of ​​the analysis region of the X cross section of the sample (unit: m 2 ), and Ly is the area of ​​the analysis region of the Y cross section of the sample (unit: m 2), and Lz is the area of ​​the analysis region of the Z cross section of the sample (unit: m 2 ) is shown.

[0096] It has been confirmed that as long as measurements are made on the same molded body, there is no variation in the measurement results even if the measurement field is set arbitrarily.It has been confirmed that as long as measurements are made on the same molded body, there is no variation in the measurement results even if the measurement cross section is changed.

[0097] <Average particle size> In the molded body of the third embodiment, the average particle size of the particles is preferably 1.0 μm or more and 100 μm or less. According to this, the specific surface area of ​​the particles made of the temperature-sensitive magnetic material is small, and the molded body has a large saturation magnetization J at 50° C. s 50, and a high ratio of the first phase can coexist with low porosity. The lower limit of the average particle size of the particles is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. The upper limit of the average particle size of the particles is preferably 50 μm or less. The average particle size of the particles is preferably 10 μm or more and 100 μm or less, more preferably 30 μm or more and 100 μm or less, and even more preferably 30 μm or more and 50 μm or less.

[0098] In this disclosure, the average particle size of particles refers to the number-based equivalent area diameter D50 of the particles. The equivalent area diameter of particles in a compact is measured in accordance with JIS Z 8827-1:2018, with the area surrounded by the boundaries between particles and voids counted as one particle, and the compact considered to be a powder. The equivalent area diameters of 100 or more particles are measured. Based on these results, the equivalent area diameter D50 is determined, at which the cumulative number-based frequency is 50%. The average particle size of particles in the composite described below is also measured in a similar manner.

[0099] The breaking strength of the molded article of embodiment 3 is preferably 10 MPa or more, more preferably 50 MPa or more, and even more preferably 100 MPa or more. There is no particular upper limit to the breaking strength of the molded article, but it can be, for example, 1500 MPa or less. The breaking strength of the molded article is preferably 10 MPa or more and 1500 MPa or less, more preferably 50 MPa or more and 1500 MPa or less, and even more preferably 100 MPa or more and 1500 MPa or less.

[0100] The breaking strength of the molded body is measured as follows: The molded body is cut into a square bar of 3 mm x 4 mm x 30 mm to prepare a measurement sample. The measurement sample is subjected to a test using a three-point bending tester with a span of 20 mm and a stroke speed of 1 mm / min to measure the breaking strength.

[0101] It has been confirmed that the fracture strength of the alloy produced under the annealing conditions described in Reference 1 is less than 10 MPa. This is presumably because in this alloy, FeSi and Fe3Si are largely separated into two phases, and therefore the highly brittle FeSi is prone to fracture.

[0102] <Manufacturing method> An example of a method for producing the molded body of embodiment 3 is described below. The method can include a raw material melting step, a powdering step, and a molding step. The raw material melting step and the powdering step can be the same steps as those of embodiment 1.

[0103] ≪Molding process≫ The powder obtained in the powdering step is filled into a molding die and heated and pressurized at 800 to 1000° C. and 10 to 500 MPa for 1 to 120 minutes, thereby obtaining the molded body of embodiment 3.

[0104] [Embodiment 4: Composite] A composite according to one embodiment of the present disclosure (hereinafter also referred to as "Embodiment 4") is a composite comprising a plurality of particles made of the temperature-sensitive magnetic material described in Embodiment 1 and a filler filling the spaces between the particles. Compared to conventional Fe-Si alloys, this composite has a larger difference between the magnetic attractive force at low temperatures and the magnetic attractive force at high temperatures, and the rate of decrease in magnetic attractive force with increasing temperature is larger.

[0105] The particle content of the composite of embodiment 4 is preferably 60% by volume or more, more preferably 70% by volume or more. This improves the magnetic properties of the composite. From the viewpoint of ensuring the strength of the composite, the upper limit of the particle content of the composite is preferably 85% by volume or less, more preferably 75% by volume or less. The particle content of the composite is preferably 60% by volume or more and 85% by volume or less, more preferably 70% by volume or more and 85% by volume or less, and even more preferably 70% by volume or more and 75% by volume or less.

[0106] The particle content of the composite is measured by the following steps.

[0107] Step A5: The complex is cut in the same manner as in step A4 above to obtain a rectangular parallelepiped sample.

[0108] Step B5: The surface of the sample is subjected to area analysis using SEM-EDX under the same conditions as in step B1. The area in the measurement field where the total atomic ratio of Fe, Mn, and Si exceeds 80% is defined as the particle presence area.

[0109] Step C5. Using image analysis software ("ImageJ"), calculate the particle area percentage Sg_x (area%) in the X cross section, the particle area percentage Sg_y (area%) in the Y cross section, and the particle area percentage Sg_z (area%) in the Z cross section, and calculate the particle content Sg (volume%) based on the following formula: Sg=(Lx*(Sg_x) 1.5 +Ly*(Sg_y) 1.5 +Lz*(Sg_z) 1.5 ) / (Lx+Ly+Lz) In the above formula, Lx is the area of ​​the analysis region of the X cross section of the sample (unit: m 2), and Ly is the area of ​​the analysis region of the Y cross section of the sample (unit: m 2 ), and Lz is the area of ​​the analysis region of the Z cross section of the sample (unit: m 2 ) is shown.

[0110] It has been confirmed that as long as measurements are made on the same complex, there is no variation in the measurement results even if the measurement field is set arbitrarily.

[0111] <Filler> The filler in embodiment 4 is preferably a resin that has high adhesion to the temperature-sensitive magnetic powder, which improves the strength of the composite material.

[0112] Examples of the resin used in the fourth embodiment include a thermosetting epoxy resin and a thermosetting acrylic resin.

[0113] <Average particle size> In the composite of embodiment 4, the average particle size of the particles is preferably 1.0 μm or more and 100 μm or less. According to this, the specific surface area of ​​the particles made of the temperature-sensitive magnetic material is small, and the composite has a large saturation magnetization J at 50° C. s 50, and a high ratio of the first phase can coexist with low porosity. The lower limit of the average particle size of the particles is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. The upper limit of the average particle size of the particles is preferably 50 μm or less. The average particle size of the particles is preferably 10 μm or more and 100 μm or less, more preferably 30 μm or more and 100 μm or less, and even more preferably 30 μm or more and 50 μm or less.

[0114] The breaking strength of the composite of embodiment 4 is preferably 10 MPa or more, more preferably 20 MPa or more, and even more preferably 100 MPa or more. There is no particular upper limit to the breaking strength of the composite, but it can be, for example, 500 MPa or less. The breaking strength of the composite is preferably 10 MPa or more and 500 MPa or less, more preferably 20 MPa or more and 500 MPa or less, and even more preferably 100 MPa or more and 500 MPa or less. The method for measuring the breaking strength of the composite is the same as the method for measuring the breaking strength of the molded body of embodiment 3.

[0115] <Manufacturing method> An example of a method for producing the composite of embodiment 4 is described below. The production method may include a material dissolving step, a powdering step, and a composite forming step. The material dissolving step and the powdering step may be the same steps as those in embodiment 1.

[0116] ≪Composite process≫ The powder obtained in the powdering step is mixed with the raw powder of the filler to obtain a mixed powder. The mixed powder is filled into a mold and heated and pressurized at 100 to 180°C and 0.5 to 20 MPa for 1 to 120 minutes. This gives the composite of embodiment 4.

[0117] [Appendix 1] A temperature-sensitive magnetic material comprising a first phase containing iron and silicon and having a crystal structure belonging to the space group P213, In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the first phase is 85% or more, The percentage is measured using a scanning electron microscope equipped with an energy dispersive X-ray analyzer. [Appendix 2] 2. The temperature-sensitive magnetic material according to claim 1, wherein the first phase contains manganese. [Appendix 3] 3. The temperature-sensitive magnetic material according to claim 1, wherein the first phase contains iron, silicon, and manganese in a total amount of 85 mass % or more. [Appendix 4] The temperature-sensitive magnetic material according to claim 2 or 3, wherein the manganese content of the first phase is 10 mass % or less. [Appendix 5] 5. The temperature-sensitive magnetic material according to any one of claims 1 to 4, wherein the first phase is composed of 23 mass % to 27 mass % silicon, 10 mass % or less manganese, and the remainder iron. [Appendix 6] 2. The temperature-sensitive magnetic material according to claim 1, wherein the first phase is composed of 23 mass % to 27 mass % silicon, and the remainder is iron. [Appendix 7] the temperature-sensitive magnetic material has a second phase; the second phase includes at least one selected from the group consisting of a first alloy, a second alloy, and a third alloy; the first alloy contains iron and silicon and has a crystal structure belonging to the space group P-3m1; the second alloy contains iron and silicon and has a crystal structure belonging to the space group Fm-3m; the third alloy contains iron and silicon and has a crystal structure belonging to the space group P63 / mcm; 7. The temperature-sensitive magnetic material according to any one of claims 1 to 6, wherein the area-based percentage of the second phase in a cross section of the temperature-sensitive magnetic material is 15% or less. [Appendix 8] Saturation magnetization J at 150°C s Saturation magnetization J at 50°C vs. 150 s 50% J s 50 / J s 8. The temperature-sensitive magnetic material according to any one of Supplementary Notes 1 to 7, wherein 150 is 10 or more. [Appendix 9] Said J s 50 / J s 9. The temperature-sensitive magnetic material according to claim 8, wherein 150 is 15 or more. [Appendix 10] Said J s 50 is 0.3Wb / m 2 The temperature-sensitive magnetic material according to Supplementary Note 8 or Supplementary Note 9, wherein: [Appendix 11] A powder made of a temperature-sensitive magnetic material containing iron and silicon and having a first phase having a crystal structure belonging to the space group P213, In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the first phase is 85% or more, The percentage is measured using a scanning electron microscope equipped with an energy dispersive X-ray analyzer; A powder having an average particle size of 1.0 μm or more and 100 μm or less. [Appendix 12] A molded body made of particles of the temperature-sensitive magnetic material according to any one of Supplementary Note 1 to Supplementary Note 10, A molded body, wherein voids are formed inside the molded body. [Appendix 13] 13. The molded body according to claim 12, wherein the molded body has a porosity of 30% by volume or less. [Appendix 14] 14. The molded article according to claim 12 or 13, wherein the particles have an average particle size of 1.0 μm or more and 100 μm or less. [Appendix 15] A composite comprising a plurality of particles made of the temperature-sensitive magnetic material according to any one of Supplementary Note 1 to Supplementary Note 10, and a filler filling the spaces between the particles. [Appendix 16] 16. The composite of claim 15, wherein the particle content is 70% by volume or more. [Appendix 17] 17. The composite of claim 15 or 16, wherein the filler is a resin. [Appendix 18] 18. The complex according to any one of claims 15 to 17, wherein the particles have an average particle size of 1.0 μm or more and 100 μm or less. [Example]

[0118] The present embodiment will be described in more detail with reference to examples, although the present embodiment is not limited to these examples.

[0119] Example 1: Powder and compact <Samples 1 to 18, Sample 1-4, Sample 1-5> Powders of Samples 1 to 18, 1-4, and 1-5 were prepared by the following process.

[0120] ≪Material melting process≫ The Fe raw material, the Si raw material, and the element X raw material (X is Mn, Cr, Co, or Ni) were weighed. The percentage (mass%) of each raw material when the total of the raw materials (all raw materials) was taken as 100 mass% is shown in the manufacturing method column in Table 1.

[0121] The weighed raw materials were placed in a magnesium oxide (MgO) crucible with a diameter of 80 mm and heated to 1600°C by high-frequency heating to obtain molten Fe-Si or Fe-Si-X. The molten metal was poured into a mold and cooled. After that, 10 mm was removed from the surface of the upper part of the casting, and the casting was crushed to obtain pieces of approximately 10 mm.

[0122] ≪Powdering process≫ The resulting fragments were placed in a 25mm diameter quartz crucible equipped with a nozzle, and melted by high-frequency heating to 1550°C. The melt was then sprayed from the nozzle onto a copper roll rotating at 1000-3000 rpm, where it was rapidly cooled and powdered, yielding a powder of the temperature-sensitive magnetic material for each sample. The rotation speed of the copper roll for each sample was as shown in the "Rotational Speed" column of the "Powdering Step" in Table 1. This step is referred to as "Quick-Cooled Powdering" in Table 1.

[0123] The average particle size of the powder obtained by quenching and pulverization for each sample was adjusted to the average particle size listed in the "Average particle size" column of "Powder" in Table 1 using the following procedure. The powder obtained by quenching and pulverization was sieved using a test sieve (diameter 200 mm) with mesh sizes of 180 μm, 125 μm, 63 μm, or 32 μm. This sieving yielded powders with D50 values ​​of 150 μm, 100 μm, 50 μm, or 20 μm. The sieving was performed in accordance with JIS Z 8815-1994. The test sieve diameter was 200 mm. The powder with D50 = 20 μm was milled using a Fritsch planetary ball mill P-5 classic line (φ8 mm SUS balls). A powder with D50 = 1.5 μm was obtained by rotating at 150 rpm and milling for 20 minutes. A powder with D50=0.8 μm was obtained by rotating at 150 rpm for 300 minutes.

[0124] <Samples 1-1 to 1-3> Powders of Samples 1-1 to 1-3 were prepared by the following process.

[0125] The Fe raw material, Si raw material, and Mn raw material were weighed. The percentage (mass %) of each raw material when the total of the raw materials (all raw materials) was 100 mass % is shown in the production method column in Table 1.

[0126] The weighed raw materials were placed in a φ80 mm magnesium oxide (MgO) crucible and heated to 1600°C using high-frequency heating to obtain molten Fe-Si or Fe-Si-Mn. The molten metal was poured into a mold and cooled. After cooling, 10 mm was removed from the top surface of the casting, and the casting was crushed to obtain fragments of approximately 10 mm. These fragments were then heat-treated in a vacuum at 950°C for 88 hours, and then slowly cooled after heating to obtain fragments of the temperature-sensitive magnetic material.

[0127] [Table 1]

[0128] <Measurement of powder> The obtained powder was measured for the area-based percentages of the first and second phases in the cross section, the atomic contents of the first phase (Fe content, Si content, element X content), the composition of the second phase, and the average particle size of the powder. Specific measurement methods were as described in Embodiments 1 and 2. The results are shown in Table 2.

[0129] [Table 2]

[0130] <Preparation of molded body> The powder of each sample obtained above was filled into a mold and heated and pressed at 1000°C and 30 MPa for 60 minutes to obtain a compact of each sample. The size of the compact was φ40 mm x 5 mm.

[0131] <Measurement of molded body> The obtained compacts were measured for porosity, average particle size, and saturation magnetization J at 150°C. s Saturation magnetization J at 50°C vs. 150 s 50% J s 50 / J s 150, Js The specific measurement methods are as described in the first and third embodiments. The results are shown in Table 2, in the "Porosity" and "Average particle size" columns of "Molded body", in the "J" column of "Saturation magnetization" of "Evaluation", and in the "J" column of "Saturation magnetization". s 50 / J s 150," "J s The results are shown in the "50" and "Breaking Strength" columns.

[0132] <Evaluation of magnetic properties> The resulting compacts were measured for the rate of decrease in magnetic attractive force with increasing temperature (the amount of decrease in magnetic attractive force per 1°C of temperature when the magnetic attractive force decreases from 80% at 50°C to 20%). The specific method for measuring magnetic attractive force is as follows: The compact to be measured was cut to a size of φ15mm x 2mm and fixed to a hot plate with Kapton tape. A weighing scale with a φ15mm x 5mm SmCo magnet attached to the tip was attached to the measurement sample by magnetic attractive force. The weighing scale was then lifted vertically, and the support value of the weighing scale when the magnet separated from the measurement sample was taken as the magnetic attractive force. The measurement temperature was set to include the temperature from 50°C until the magnetic attractive force decreased to 20% of its original value at 50°C. The results are shown in the "Decrease in magnetic attractive force" column under "Evaluation" in Table 2.

[0133] <Consideration> The compacts of Samples 1 to 18 correspond to Examples, and the compacts of Samples 1-1 to 1-5 correspond to Comparative Examples. It was confirmed that the compacts of Samples 1 to 18 had a larger rate of decrease in magnetic attractive force with increasing temperature than the compacts of Samples 1-1 to 1-5.

[0134] The change in magnetic attractive force with respect to temperature changes of the compacts of Sample 11 (Example) and Sample 1-3 (Comparative Example) will be explained using Figure 1. Figure 1 is a graph showing the change in magnetic attractive force with respect to temperature changes of the compacts of Sample 11 and Sample 1-3. In Figure 1, the horizontal axis represents temperature, and the vertical axis represents magnetic attractive force.

[0135] As shown in Figure 1, Sample 11 exhibited a greater rate of decrease in magnetic attractive force with increasing temperature than Samples 1-3. The magnetic attractive force of Sample 11 became 0 kg at temperatures above approximately 118°C. On the other hand, the magnetic attractive force of Sample 1-3 did not become 0 kg even at approximately 115°C.

[0136] Scanning electron microscope (SEM) images (magnification 200x) of the cross sections of Sample 11 and Sample 1-3 shown in Figure 1 are shown in Figures 2 and 3, respectively. In Figures 2 and 3, reference numeral 1 indicates the first phase, reference numeral 2 indicates the second phase, and reference numeral 3 indicates voids. As shown in Figure 2, the second phase was hardly observed in the structure of Sample 11, and it was confirmed that the first phase existed as a nearly single phase in the regions other than the voids. On the other hand, as shown in Figure 3, it was confirmed that the structure of Sample 1-3 consisted of the first phase and the second phase, largely separated into two phases.

[0137] The change in magnetic attractive force versus temperature for the compacts of Samples 8, 9, 10, and 11 will be examined using Figure 4. Figure 4 is a graph showing the change in magnetic attractive force versus temperature for the compacts. In Figure 4, the horizontal axis represents temperature, and the vertical axis represents magnetic attractive force.

[0138] As shown in Figure 4, it was confirmed that the magnetic attractive force of all samples became 0 kg at temperatures above 130°C. Furthermore, it was confirmed that the higher the manganese content, the more likely the magnetic attractive force to decrease at low temperatures, and the temperature at which the magnetic attractive force becomes 0 kg decreases.

[0139] [Example 2: Molded body] In Example 2, compacts were produced using the powders of Sample 8, Sample 11, Sample 1-1, and Sample 1-3 from Example 1. The powders were filled into a mold and heated and pressed at the temperature, pressure, and time shown in Table 3 to obtain compacts of each sample. The size of the compacts was φ40 mm × 5 mm.

[0140] <Measurement of molded body> The obtained compacts were measured for porosity, average particle size, and saturation magnetization J at 150°C. s Saturation magnetization J at 50°C vs. 150s 50% J s 50 / J s 150, J s The tensile strength, tensile strength, and breaking strength were measured. The specific measurement methods are as described in Embodiments 1 and 3. The results are shown in Table 3.

[0141] <Evaluation of magnetic properties> The rate of decrease in magnetic attractive force with increasing temperature of the obtained molded body was measured. The specific measurement method was as described in Example 1. The results are shown in Table 3.

[0142] [Table 3]

[0143] <Consideration> Samples 21 to 24 correspond to Examples, and Samples 2-1 to 2-4 correspond to Comparative Examples. It was confirmed that Samples 21 to 24 had a greater rate of decrease in magnetic attractive force with increasing temperature than Samples 2-1 to 2-4.

[0144] Example 3: Complex In Example 3, a composite was produced using the powder of Sample 8, Sample 11, Sample 1-1, or Sample 1-3 of Example 1. Specifically, the above powder was mixed with a filler raw material powder (UIP-R, polyimide powder, manufactured by UBE Corporation) in the mass ratio shown in Table 4 to obtain a mixed powder. The mixed powder was filled into a mold and heated and pressurized at 190°C and 0.2 MPa for 5 minutes to obtain a composite.

[0145] <Measurement of complex> The particle content, average particle size, and saturation magnetization J at 150°C were measured for the obtained composite. s Saturation magnetization J at 50°C vs. 150 s 50% J s 50 / J s 150, J s The tensile strength, tensile strength, and breaking strength were measured. The specific measurement methods are as described in Embodiments 1 and 4. The results are shown in Table 4.

[0146] <Evaluation of magnetic properties> The resulting composite was measured for the rate of decrease in magnetic attractive force with increasing temperature. The specific measurement method was as described in Example 1. The results are shown in Table 4.

[0147] [Table 4]

[0148] <Consideration> Samples 31 to 34 correspond to Examples, and Samples 3-1 to 3-4 correspond to Comparative Examples. It was confirmed that Samples 31 to 34 had a greater rate of decrease in magnetic attractive force with increasing temperature than Samples 3-1 to 3-4. The rate of decrease in magnetic attractive force of the composite of Sample 3-2 was equal to or greater than the rate of decrease in magnetic attractive force of the compacts of Samples 1, 3, 5, and 13. This is presumably because the compacts have a smaller internal demagnetizing field than the powder or composite state, and the magnetic attractive force at high temperatures (which is more susceptible to the influence of the internal demagnetizing field) is relatively high, resulting in a lower rate of decrease in magnetic attractive force.

[0149] Although the embodiments and examples of the present disclosure have been described above, it is originally intended that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways. The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims rather than the above-described embodiments and examples, and it is intended to include any modifications within the scope of the claims that are equivalent to the claims. [Explanation of symbols]

[0150] 1 Phase 1 2 Phase 2 3 void

Claims

1. containing iron and silicon and belonging to the space group P2 １ A temperature-sensitive magnetic material having a first phase having a crystal structure belonging to No. 3, In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the first phase is 85% or more, The percentage is measured using a scanning electron microscope equipped with an energy dispersive X-ray analyzer.

2. The temperature-sensitive magnetic material according to claim 1 , wherein the first phase contains manganese.

3. The temperature-sensitive magnetic material according to claim 1 , wherein the first phase contains iron, silicon, and manganese in a total amount of 85 mass % or more.

4. The temperature-sensitive magnetic material according to claim 2 or 3, wherein the manganese content of the first phase is 10 mass % or less.

5. 3. The temperature-sensitive magnetic material according to claim 1, wherein the first phase is composed of 23 mass % to 27 mass % of silicon, 10 mass % or less of manganese, and the balance being iron.

6. 2. The temperature-sensitive magnetic material according to claim 1, wherein the first phase is composed of 23 mass % to 27 mass % silicon and the remainder iron.

7. the temperature-sensitive magnetic material has a second phase; the second phase includes at least one selected from the group consisting of a first alloy, a second alloy, and a third alloy; the first alloy contains iron and silicon and has a crystal structure belonging to the space group P-3m1; the second alloy contains iron and silicon and has a crystal structure belonging to the space group Fm-3m; The third alloy contains iron and silicon and is in the space group P6 ３ / mcm, 3. The temperature-sensitive magnetic material according to claim 1, wherein the area-based percentage of the second phase in a cross section of the temperature-sensitive magnetic material is 15% or less.

8. Saturation magnetization J at 150°C ｓ Saturation magnetization J at 50°C relative to 150 ｓ 50% J ｓ 50 / J ｓ 3. The temperature-sensitive magnetic material according to claim 1, wherein 150 is 10 or more.

9. Said J ｓ 50 / J ｓ The temperature-sensitive magnetic material according to claim 8, wherein 150 is 15 or more.

10. Said J ｓ 50 is 0.3 Wb / m ２ The temperature-sensitive magnetic material according to claim 8 .

11. containing iron and silicon and belonging to the space group P2 １ A powder made of a temperature-sensitive magnetic material having a first phase having a crystal structure belonging to No. 3, In a cross section of the temperature-sensitive magnetic material, the area-based percentage of the first phase is 85% or more, The percentage is measured using a scanning electron microscope equipped with an energy dispersive X-ray analyzer; A powder having an average particle size of 1.0 μm or more and 100 μm or less.

12. A molded body made of particles of the temperature-sensitive magnetic material according to claim 1 or 2, A molded body, wherein voids are formed inside the molded body.

13. The molded body according to claim 12, wherein the molded body has a porosity of 30% by volume or less.

14. The molded article according to claim 12, wherein the particles have an average particle size of 1.0 μm or more and 100 μm or less.

15. A composite comprising a plurality of particles made of the temperature-sensitive magnetic material according to claim 1 or 2 and a filler filling spaces between the particles.

16. The composite of claim 15, wherein the particle content is 70% by volume or more.

17. 16. The composite of claim 15, wherein the filler is a resin.

18. The composite according to claim 15, wherein the particles have an average particle size of 1.0 μm or more and 100 μm or less.

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