TWI437590B - Wide temperature type and low hysteresis coefficient of the magnetic core manufacturing methods - Google Patents

Description

Method for manufacturing magnetic core with wide temperature type and low hysteresis coefficient

The present invention relates to a method for manufacturing a magnetic core, and more particularly to a method for manufacturing a magnetic core having a wide temperature type and a low hysteresis coefficient.

Asymmetric Digital Subscriber Line (ADSL) is the mainstream of existing information transmission. Among them, the broadband transformer for transmission is a necessary equipment for ADSL. Therefore, the demand for magnetic core for broadband transmission is greatly increased.

However, since the use area of ADSL is spread all over the world, the magnetic core used for broadband transmission is required to achieve the permeability (μ) of the magnetic core at room temperature (25 ° C), even at -40 ° C to 100 ° C. At ambient temperature, the magnetic permeability (μi _{-40 ° C ~ 100 ° C} ) should be maintained as much as possible, so that the smaller the rate of change of magnetic permeability with temperature (that is, the temperature coefficient of magnetic permeability), the more stable the control of the magnetic circuit. Furthermore, as the transmission distance of ADSL is longer and longer, it is necessary to reduce the hysteresis coefficient (ηB) of the magnetic core for broadband transmission, so as to achieve high separation, no distortion and good stability in transmission.

Referring to Figures 1 and 2, the magnetic permeability of the existing low hysteresis coefficient Mn-Zn soft magnetic powder between 25 °C and 100 °C is between 3100 and 3600, and the relative hysteresis coefficient is between 0.29×10 ^-6 and 0.32×10. Between ^-6 , however, the existing low hysteresis coefficient Mn-Zn soft magnetic powder is only 1907 when the magnetic permeability is low at -40 °C, and the hysteresis coefficient between -40 °C and 10 °C is as high as 0.44×10 ^{- 6} ~ 1.16 × 10 ^-6 .

At the same time, the absolute value of the magnetic permeability temperature coefficient (α _{-20 ° C ~ 25 ° C} ) of the existing low hysteresis coefficient Mn - Zn soft magnetic powder between -20 ° C and 25 ° C is as high as 3 × 10 ^-6 , which is also likely to cause signal transmission distortion. Therefore, the existing low hysteresis coefficient manganese-zinc soft magnetic powder is not suitable for the cold zone.

In order to improve the above-mentioned shortcomings of the existing low hysteresis coefficient Mn-Zn soft magnetic magnetic powder, the related art has developed a patent application for a wide temperature, high magnetic permeability and low distortion soft ferrite as disclosed in the Chinese Patent Publication No. CN101894650A, the main component of which is The percentage of moles is calculated as oxides: 52.7 to 53.5 mol% of iron oxide (Fe ₂ O ₃ ), 22.5 to 24 mol% of zinc oxide (ZnO), and the remaining manganese oxide (MnO); The oxide is calculated as: 0.08 to 0.2 wt% of tin oxide (SnO ₂ ), 0.04 to 0.06 wt% of calcium oxide (CaO), and 0.04 to 0.06 wt% of vanadium oxide (V ₂ O ₅ ).

The magnetic permeability of the wide temperature, high magnetic permeability and low distortion soft ferrite at 10KHz, -55°C to 85°C (μi _{10KHz, -55°C to 85°C} ) is greater than 5000, and the hysteresis coefficient at room temperature (ηB _25°C ) is less than 0.3. ×10 ^- 6/mT.

From the above, it has been found that the use of a change in the distribution ratio of the material to develop a magnetic core having a high magnetic permeability and a low hysteresis coefficient suitable for a wide temperature range is indeed an objective of the related art.

Accordingly, it is an object of the present invention to provide a method of manufacturing a magnetic core having a wide temperature type and a low hysteresis coefficient.

Therefore, the method for producing a wide-temperature and low hysteresis magnetic core of the present invention comprises the following steps: (A) calcining a main raw material containing 100 mol% of iron oxide and manganese oxide in total And zinc oxide, wherein the iron oxide is 52.35mol%~52.55 mol%, and the ratio of the molar percentage of manganese oxide to zinc oxide is between 1.35 and 1.38; (B) adding a raw material to the main raw material to become a a mixture, wherein the auxiliary material contains 0.04% by weight of calcium oxide of the mixture, and 0.02% by weight of zirconia; (C) grinding the mixture and adding a binder to form particles; (D) The mold is used to form the pellet into a green embryo; (E) the green embryo is sintered into a magnetic core.

The beneficial effects of the invention are: using the distribution ratio of the main raw material, the auxiliary raw material and the bonding agent, and sintering into a magnetic core after being calcined, mixed, ground, granulated, formed, etc., so that the magnetic core is in- The magnetic permeability of 40 ° C ~ 100 ° C is between 3200 ~ 4800, and the absolute value of the temperature coefficient of permeability of -20 ° C ~ 25 ° C is less than 7.0 × 10 ^-7 , and the absolute temperature coefficient of magnetic permeability of 25 ° C ~ 60 ° C The value is less than 0.45×10 ^-7 , the hysteresis coefficient of -40°C~100°C is less than 0.75×10 ^-6 , and the hysteresis coefficient of 25°C is less than 0.6×10 ^-6 .

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to FIG. 3, in a preferred embodiment of the method for manufacturing a wide-temperature and low hysteresis magnetic core of the present invention, first, as shown in step 21, a main raw material is calcined at 900 ° C, and the main raw material contains a total of It is 100 mol% of iron oxide (Fe ₂ O ₃ ), manganese oxide (MnO) and zinc oxide (ZnO), wherein iron oxide is 52.35 mol% to 52.55 mol%, and the percentage of molybdenum oxide and zinc oxide is The ratio is between 1.35 and 1.38.

Next, as shown in step 22, a raw material is added to the main raw material to form a mixture, wherein the auxiliary raw material contains 0.04% by weight of calcium oxide (CaO) of the mixture, and 0.02% by weight of the mixture. Zirconium oxide (ZrO ₂ ), 0.02 wt% to 0.08 wt% of titanium oxide (TiO ₂ ), and 0.02 wt% to 0.05 wt% of cobalt oxide (CoO) based on the mixture.

Among them, the addition of calcium oxide and zirconia can increase the grain boundary resistance, while the addition of titanium oxide and cobalt oxide is used to improve the magnetic permeability and hysteresis coefficient of low temperature.

Then, as shown in step 23, the mixture was wet-milled and 1 wt% of polyvinyl alcohol (Polyvinyl Alcohol) was added as a binder, and manually sieved to form particles having a particle diameter of between 80 μm and 240 μm.

Next, as shown in step 24, the granules are formed into green embryos using a mold. Finally, as shown in step 25, the green embryo is sintered into a magnetic core, wherein the oxygen content during sintering is adjusted according to the equilibrium oxygen partial pressure theory: AP=log(PO ₂ )+14540/(T+273), wherein AP is the atmospheric parameter, PO ₂ represents the equilibrium oxygen partial pressure, and T represents the operating temperature, wherein the high permeability MnZn soft magnetic AP is 8.0, and the equilibrium oxygen partial pressure is reduced from 21% to 4% after heating to 900 °C. ~8%.

In this embodiment, the green body is first heated to 500 ° C at a heating rate of 100 ° C per hour, and then the raw embryo is heated from 500 ° C to 900 ° C at a heating rate of 200 ° C per hour, and then hourly. The heating rate of 250 ° C heats the green embryo from 900 ° C to 1350 ° C, then holds the temperature for 2 to 4 hours, then cools the raw embryo to 1100 ° C at a cooling rate of 200 ° C per hour, and finally cools at 240 ° C per hour. The raw embryos cooled to 1100 ° C were cooled to room temperature (25 ° C).

In order to verify the efficacy of the present invention, the inventors respectively produced the three magnetic cores according to the distribution ratios of the first embodiment, the second embodiment and the third embodiment, and the equilibrium oxygen partial pressure in accordance with the manufacturing method in FIG. The magnetic core was detected at 100 KHz using a magnetic permeability measuring device Agilent-4284A (LCR meter), and the results are shown in Table 2.

The comparative example in Table 2 is the measurement result of the existing low hysteresis coefficient Mn-Zn soft magnetic magnetic powder, and the first embodiment, the second embodiment and the third embodiment represent the embodiment 1 in the first embodiment. 2, the distribution ratio of Example 3 and the balance of oxygen partial pressure, μi _{-40 ° C ~ 100 ° C} is -40 ° C ~ 100 ° C permeability, μi _{25 ° C} is 25 ° C permeability, α _{-20 ° C ~ 25 ° C} is -20 ° C ~ 25 ° C magnetic permeability temperature coefficient, α _{25 ° C ~ 60 ° C} is 25 ° C ~ 60 ° C magnetic permeability temperature coefficient, ηB _{-40 ° C ~ 100 ° C} is -40 ° C ~ 100 The hysteresis coefficient of °C, and ηB _{25 °C} is the room temperature hysteresis coefficient.

As can be seen from Table 2, the magnetic cores produced by the manufacturing method of the present invention (i.e., Example 1, Example 2 and Example 3), whether at a magnetic permeability of -40 ° C to 100 ° C or 25 ° C, The magnetic permeability coefficients of -20 ° C ~ 25 ° C and 25 ° C ~ 60 ° C are better than the existing low hysteresis coefficient Mn - Zn soft magnetic powder.

Although the magnetic core produced by the manufacturing method of the present invention is slightly larger than the conventional low hysteresis coefficient manganese zinc soft magnetic powder in terms of the room temperature hysteresis coefficient, the magnetic core produced by the manufacturing method of the present invention is - The rate of change of hysteresis coefficient from 40 °C to 100 °C is significantly smaller than that of the existing low hysteresis coefficient manganese-zinc soft magnetic powder.

As apparent from the above, according to the production method of the present invention, it is possible to manufacture a magnetic core which is more widely applicable than the conventional low hysteresis coefficient manganese-zinc soft magnetic powder and which is more stable in transmission efficiency.

In summary, the method for manufacturing a magnetic core having a wide temperature type and a low hysteresis coefficient according to the present invention utilizes a process ratio of a main raw material, an auxiliary material, and a binder, and is subjected to processes such as calcination, mixing, grinding, granulation, and the like. After sintering into magnetic core, the magnetic permeability of the magnetic core between -40 ° C ~ 100 ° C is between 3200 ~ 4800, and the absolute value of the magnetic permeability temperature coefficient of -20 ° C ~ 25 ° C is less than 7.0 × 10 ^-7 , The absolute value of the magnetic permeability coefficient of 25 ° C ~ 60 ° C is less than 0.45 × 10 ^-7 , the hysteresis coefficient of -40 ° C ~ 100 ° C is less than 0.75 × 10 ^-6 , and the hysteresis coefficient of 25 ° C is less than 0.6 × 10 ^-6 Therefore, the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

twenty one. . . Burning a main raw material

twenty two. . . Adding a pair of raw materials to the main raw material to form a mixture

twenty three. . . Grinding and granulating the mixture

twenty four. . . Forming the granule into a green embryo

25. . . Sintering the raw embryo into a magnetic core

1 is a relational diagram showing the relationship between the magnetic permeability and the temperature of a conventional low hysteresis coefficient manganese-zinc soft magnetic powder;

2 is another relationship diagram illustrating the relationship between hysteresis coefficient and temperature of a conventional low hysteresis coefficient manganese-zinc soft magnetic powder;

Fig. 3 is a flow chart showing a preferred embodiment of the method for producing a wide-temperature and low hysteresis magnetic core of the present invention.

twenty one. . . Burning a main raw material

twenty two. . . Adding a pair of raw materials to the main raw material to form a mixture

twenty three. . . Grinding and granulating the mixture

twenty four. . . Forming the granule into a green embryo

25. . . Sintering the raw embryo into a magnetic core

Claims (10)

A method for producing a magnetic core having a wide temperature type and a low hysteresis coefficient, comprising: (A) calcining a main raw material containing a total of 100 mol% of iron oxide, manganese oxide and zinc oxide, wherein The iron oxide is 52.35 mol% to 52.55 mol%, and the ratio of the molar percentage of manganese oxide to zinc oxide is between 1.35 and 1.38; (B) adding a raw material to the main raw material to form a mixture, wherein The auxiliary material contains 0.04% by weight of calcium oxide of the mixture, and 0.02% by weight of zirconia of the mixture; (C) grinding the mixture and adding 1% by weight of a binder to form particles; (D) using a mold Forming the granule into a green embryo; and (E) sintering the green blast into a magnetic core. The method for producing a magnetic core having a wide temperature type and a low hysteresis coefficient according to the first aspect of the patent application, wherein the step (E) is heating the green body to 1350 ° C, holding the temperature for 2 to 4 hours, and then cooling to Room temperature. The method for manufacturing a magnetic core having a wide temperature type and a low hysteresis coefficient according to the second aspect of the patent application, wherein the step (E) is to first heat the green embryo to 500 ° C at a heating rate of 100 ° C per hour. The raw embryos were heated from 500 ° C to 900 ° C at a heating rate of 200 ° C per hour, and the green embryos were heated from 900 ° C to 1350 ° C at a heating rate of 250 ° C per hour, and held at a temperature of 2 to 4 hours. The method for manufacturing a magnetic core of a wide temperature type and a low hysteresis coefficient according to claim 3, wherein the step (E) cools the green embryo to 1100 ° C at a cooling rate of 200 ° C per hour, and finally The green embryos that had reached 1100 ° C were cooled to room temperature at a cooling rate of 240 ° C per hour. The method for producing a magnetic core of a wide temperature type and a low hysteresis coefficient according to any one of claims 1 to 4, wherein the oxygen content in the step (E) is based on the equilibrium oxygen partial pressure theory: AP =log(PO ₂ )+14540/(T+273) adjustment, where AP is the atmospheric parameter, PO ₂ represents the equilibrium oxygen partial pressure, and T represents the operating temperature. The method for manufacturing a magnetic core of a wide temperature type and a low hysteresis coefficient according to the sixth aspect of the patent application, wherein the step (E) reduces the partial pressure of oxygen from 21% to 4% to 8 after heating to 900 ° C. %. The method for producing a magnetic core of a wide temperature type and a low hysteresis coefficient according to the first aspect of the invention, wherein the auxiliary material of the step (B) further comprises 0.02 wt% to 0.08 wt% of titanium oxide of the mixture. Cobalt oxide is present in an amount of from 0.02 wt% to 0.05 wt% of the mixture. A method for producing a magnetic core having a wide temperature type and a low hysteresis coefficient according to the first aspect of the invention, wherein in the step (C), wet grinding is employed, and 1 wt% of polyvinyl alcohol is added as a binder. A method for producing a magnetic core having a wide temperature type and a low hysteresis coefficient according to the first aspect of the invention, wherein the particle diameter in the step (C) is between 80 μm and 240 μm. A method for producing a magnetic core having a wide temperature type and a low hysteresis coefficient according to the first aspect of the invention, wherein the main raw material in the step (A) is calcined at 900 °C.