MnCoZn ferrite and production method for same

[0116] Example 1

[0117] Convert all the iron, zinc, cobalt and manganese contained into Fe 2 O 3 In the case of ZnO, CoO and MnO, weigh Fe according to the ratio shown in Table 1. 2 O 3 The amount of ZnO, CoO and MnO, the raw material powders were mixed for 16 hours using a ball mill, and then calcined in the air at 925°C for 3 hours. Then, weigh the equivalent of 150 and 700 ppm by mass of SiO 2 After adding CaO, it was added to the calcined powder and pulverized with a ball mill for 12 hours. Next, polyvinyl alcohol was added to the obtained pulverized slurry, spray-dried and granulated at an exhaust temperature of 250°C, the coarse powder was removed through a sieve with a mesh size of 350μm, and then a pressure of 118MPa was applied to form the annular core and Rectangular core. In addition, since high-purity raw materials are used, and media such as ball mills are thoroughly cleaned before use to reduce the mixing of ingredients derived from other materials, the impurities P, B, S, Cl, Bi, and Zr contained in the ring core and rectangular core The amount of is 5 mass ppm, the particle size distribution d90 of the granulated powder used for molding is 230 μm, and the crushing strength is 1.29 MPa. In addition, the contents of P, B, S, Cl, Bi, and Zr were quantified in accordance with JIS K 0102 (IPC mass analysis method).

[0118] Then, the compact was charged into a sintering furnace, and fired in a flow of appropriately mixed nitrogen and air at a maximum temperature of 1350°C for 2 hours to obtain a sintered body with an outer diameter: 25mm, an inner diameter: 15mm, and a height: 5mm. Ring core and 5 sintered cylindrical cores with diameter: 10mm and height: 10mm.

[0119] The obtained sample was based on JIS C 2560-2, and the sintered density of the annular core was measured by the Archimedes method at 23° C., and the resistivity was measured by the 4-terminal method.

[0120] The initial magnetic permeability of the toroidal core was calculated from the inductance value obtained by winding 10 turns on the toroidal core and measuring at 100°C using an LCR measuring instrument (4980A manufactured by Keito Corporation). In addition, the initial permeability of some samples was also measured at 23°C.

[0121] The Curie temperature is calculated from the measurement result of the temperature characteristic of the inductance value.

[0122] The abrasion value is measured according to the method specified in JPMA P11-1992.

[0123] The squareness ratio is calculated by dividing the residual magnetic flux density Br measured at 100°C based on JIS C 2560-2 by the saturation magnetic flux density Bs. In addition, the squareness ratio of some samples was also measured at 23°C.

[0124] The results obtained are summarized in Table 1.

[0125] [Table 1]

[0126]

[0127] As shown in the table, in Examples 1-1 to 1-8, which are examples of the present invention, a MnCoZn ferrite can be obtained that has both high strength with a wear value of less than 0.85% and high strength at 23°C. The electrical resistivity is above 30Ω·m, the squareness ratio at 100℃ is below 0.35, and the Curie temperature is above 170℃.

[0128] On the contrary, it contains more than 50.0mol% Fe 2 O 3 In Comparative Examples 1-1 and 1-2, with Fe 2+ The generation resistivity is greatly reduced. On the other hand, in Fe 2 O 3 In Comparative Examples 1-3 in which the amount of is less than 45.0 mol%, an increase in squareness ratio at 100°C and a decrease in Curie temperature were observed.

[0129] In addition, in Comparative Examples 1-4 in which the amount of ZnO exceeded the appropriate range, a decrease in the Curie temperature was observed. On the other hand, in Comparative Examples 1-5 in which the amount of ZnO did not reach the appropriate range, the squareness ratio was increased, and good magnetic characteristics could not be achieved.

[0130] In addition, in Comparative Examples 1-6 in which the amount of CoO did not reach the proper range, the squareness ratio was high due to insufficient positive magnetic anisotropy, while in Comparative Examples 1-7 in which the amount of CoO exceeded the proper range, excessive positive magnetic The increase in anisotropy leads to an increase in the squareness ratio and a deviation from the preferred range.

[0131] In addition, in Comparative Examples 1-8 in which the amount of ZnO exceeded the appropriate range, no satisfactory Curie temperature was obtained.

[0132] Example 2

[0133] Convert all the iron, zinc, cobalt and manganese contained into Fe 2 O 3 , ZnO, CoO and MnO, according to Fe 2 O 3 The amount is 49.0 mol%, the amount of ZnO is 10.0 mol%, the amount of CoO is 2.0 mol%, and the balance of MnO. The raw materials are weighed, mixed with a ball mill for 16 hours, and then calcined in air at 925°C for 3 hours. Then, the amount of SiO shown in Table 2 was added to the calcined powder 2 And CaO, and use a ball mill to grind for 12 hours. Next, polyvinyl alcohol was added to the crushed slurry obtained, spray-dried and granulated at an exhaust temperature of 250°C, the coarse powder was removed through a sieve with a mesh size of 350μm, and then a pressure of 118MPa was applied to form a ring core and Cylindrical core. In addition, the contents of P, B, S, Cl, Bi, and Zr in the annular core and the cylindrical core are all 5 mass ppm, the particle size distribution d90 of the granulated powder used for molding is 230 μm, and the crushing strength is 1.29 MPa.

[0134] Then, the compact was charged into a sintering furnace, and fired in a flow of appropriately mixed nitrogen and air at a maximum temperature of 1350°C for 2 hours to obtain a sintered body with an outer diameter: 25mm, an inner diameter: 15mm, and a height: 5mm. Ring core and 5 cylindrical cores with diameter: 10mm and height: 10mm.

[0135] For each of these samples, the same method and apparatus as in Example 1 were used to evaluate various characteristics.

[0136] The results obtained are summarized in Table 2.

[0137] [Table 2]

[0138]

[0139] As shown in the table, the SiO 2 In Examples 2-1 to 2-4 in which the amount of CaO and the amount of CaO are within the appropriate range, a MnCoZn ferrite can be obtained that has both high strength with a wear value of less than 0.85% and resistivity at 23°C. It has excellent magnetic properties at 30Ω·m or more, squareness ratio at 100°C of 0.35 or less, and Curie temperature of 170°C or more.

[0140] In contrast, even SiO 2 In Comparative Examples 2-1 and 2-3 in which one of CaO and CaO does not reach the appropriate range, the size of the grain size is uneven due to insufficient formation of grain boundaries, so the abrasion value is higher than 0.85%, and due to the thickness of the grain boundary It is also insufficient, so the resistivity is less than 30 Ω·m.

[0141] In addition, in the levels of Comparative Examples 2-2, 2-4, and 2-5 where any one of the above-mentioned components was excessive, abnormal particles appeared, which hindered sintering and reduced the sintered density, and the abrasion value was also increased. In addition, due to insufficient formation of grain boundaries, the resistivity is reduced, the initial permeability is also reduced, and the squareness ratio is also increased.

[0142] Example 3

[0143] According to the methods shown in Examples 1 and 2, the basic components and auxiliary components are in the same composition ratio as in Example 1-2, but raw materials with different amounts of impurities are used, or ingredients are intentionally added to produce the outer diameter: A sintered annular core of 25mm, inner diameter: 15mm, height: 5mm, and 5 cylindrical cores with a diameter: 10mm, height: 10mm. The characteristics were evaluated using the same method and device as in Example 1, and the results obtained are shown in Table 3. In addition, the particle size distribution d90 of the granulated powder used for molding was 230 μm, and the crushing strength was 1.29 MPa.

[0144] [table 3]

[0145]

[0146] As shown in the table, in Example 3-1 where the contents of P, B, S, Cl, Bi, and Zr are below the specified value, the strength expressed by the abrasion value and the squareness ratio at 100°C can be obtained , Resistivity and Curie temperature show good magnetic properties.

[0147] In contrast, in each of Comparative Examples 3-1 to 3-8 in which one or more of the six content levels exceeded the specified value, abnormal particles appeared, and the sintering density was reduced due to the hindrance of sintering, so the abrasion value was increased. And due to insufficient formation of grain boundaries, the resistivity decreases, the initial permeability also decreases, and the squareness ratio increases as the residual magnetic flux density increases.