Cobalt-based amorphous soft magnetic alloy for precise current detection and preparation method thereof
Technical Field
The invention belongs to the field of soft magnetic alloy materials, and particularly relates to a cobalt-based amorphous soft magnetic alloy for precise current detection and a preparation method thereof.
Background
The control circuit of the switching power supply is shown in fig. 1, wherein SL1 and SL2 are two iron cores with rectangular hysteresis loops, which are respectively operated and demagnetized in positive and negative half cycles. Taking SL1 as an example, during the positive half cycle, the main transformer secondary ui is applied to the output via SL1, D1, L, while SL1 is magnetized to saturation; during the negative half cycle the control current demagnetizes SL1 from the feedback system via D3.
Fig. 2 (a) shows an input waveform of the circuit voltage. (b) The schematic diagram of rectification and voltage stabilization shows that the waveform areas of the magnetization part and the demagnetization part are equal. When the output voltage u0 rises, the control current of the feedback system increases to demagnetize the SL1 and deepen, so that (c) the pulse width Ton of the output pulse in the output voltage waveform diagram becomes narrow, the rectified output voltage drops, and the voltage stabilization process is realized. When no feedback is applied to the circuit of fig. 1, the cores SL1 and SL2 only operate between Bs and Br without demagnetization, when the cores are magnetized from Br to Bs with the desired pulse width TDReferred to as dead space. In order to obtain the highest possible output voltage and the widest possible adjustment range, it is desirable to keep the dead angle as small as possible. This requires a material with a high squareness ratio to control the sensitivity and amplification of the material; and meanwhile, the coercive force and loss of the material are required to be low so as to reduce the control power.
The precise current detection switch is a device which utilizes the nonlinear characteristic of the magnetization curve of a ferromagnetic material to realize the control action, and the iron core material of the precise current detection switch is the key for determining the performance of the switch. The current soft magnetic materials for current detection iron core mainly comprise silicon steel sheet, permalloy and ironFerrite, amorphous alloy, and the like. The working power of the equipment is improved at present, and the working frequency of many switching power supplies is above 100kHz and even 200 kHz. At such high frequencies, permalloy suffers from too low a resistivity (about 60 μ Ω wcm), resulting in too large eddy current losses, resulting in increased temperatures and low efficiency; the use of ultra thin and ultra thin tapes can be improved, but the cost will rise dramatically. Ferrite has very high resistivity (more than 10)5μ Ω wcm), but its Bs is too low and the curie point is too low, which also makes it difficult to apply to a precision current detection switch. In many cases, the stress sensitivity, thermal stability, etc. of the material are strictly required due to the severe working environment, and the material is difficult to meet the requirements.
Therefore, how to obtain a soft magnetic alloy material with high squareness ratio, low coercive force and low loss has become a focus of great attention of many researchers in the industry.
Disclosure of Invention
Aiming at the defects and shortcomings of the prior art, the invention mainly aims to provide the cobalt-based amorphous soft magnetic alloy for precise current detection. The cobalt-based amorphous soft magnetic alloy has the characteristics of low coercive force, extremely low loss and the like while keeping a high squareness ratio. The sensitivity of the power switch can be greatly improved, the control power is reduced, and the magnetic core material is an ideal magnetic core material for a precise current switch.
The invention also aims to provide a preparation method of the cobalt-based amorphous soft magnetic alloy for precise current detection. The method has simple preparation process and is suitable for large-scale industrial production.
The purpose of the invention is realized by the following technical scheme:
a cobalt-based amorphous soft magnetic alloy for precision current detection has a general formula shown in formula (I):
CoxFeyMozSinBm(I);
wherein x is more than or equal to 67.0 and less than or equal to 74.5, y is more than or equal to 0.5 and less than or equal to 1.5, z is more than or equal to 0 and less than or equal to 1.5, n is more than or equal to 12.0 and less than or equal to 14.0, and m is more than or equal to 13.0 and less than or equal to 16.0; x, y, z, n, m refer to the mass percent of each element, and x + y + z + n + m is 100.
Preferably, 68.4. ltoreq. x.ltoreq.71.0, 0.9. ltoreq. y.ltoreq.1.1, 0.5. ltoreq. z.ltoreq.1.0, 12.5. ltoreq. n.ltoreq.13.5, 14. ltoreq. m.ltoreq.14.9.
The preparation method of the cobalt-based amorphous soft magnetic alloy for precise current detection comprises the following steps:
A) mixing and smelting cobalt, iron, silicon, boron and molybdenum to obtain an alloy ingot;
B) crushing the alloy ingot obtained in the step A), and then throwing to obtain an amorphous alloy strip;
C) and C), under the condition of vacuum or protective atmosphere, carrying out heat treatment on the amorphous alloy strip obtained in the step B) to obtain the cobalt-based amorphous soft magnetic alloy for precise current detection.
Further, the smelting temperature in the step A) is 1300-1450 ℃, and the smelting time is 1-5 min.
Further, the smelting in the step A) is a plurality of times of smelting, and the smelting times are not less than 3 times.
Further, the smelting in the step A) specifically comprises the following steps: firstly, cobalt is put into a smelting device for smelting, and then iron, silicon, boron and molybdenum are put into the smelting device for smelting.
Further, the step B) of cleaning by using at least one of ethanol and acetone after the alloy ingot is crushed.
Further, the melt-spinning in the step B) is single-roller quenching melt-spinning; the linear speed of the cold roll of the melt-spun belt is 45-55 m/s.
Further, the width of the amorphous alloy strip in the step B) is 2-3 mm, and the thickness of the amorphous alloy strip is 18-35 mu m.
Further, the heat treatment in the step C) is longitudinal magnetic field heat treatment, the longitudinal magnetic field intensity is 600-1000 Gs, the heat treatment temperature is 430-450 ℃, and the time is 10-60 min. Preferably, the longitudinal magnetic field intensity is 650-950 Gs, the heat treatment temperature is 435-445 ℃, and the time is 20-50 min. More preferably, the longitudinal magnetic field intensity is 700-900 Gs, the heat treatment temperature is 438-442 ℃, and the time is 30-40 min.
Further, the temperature rise rate of the heat treatment in the step C) is 10-20 ℃/min. More preferably 12 to 18 ℃/min, and most preferably 14 to 16 ℃/min.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) according to the invention, specific elements are added and corresponding proportions are supplemented to obtain the cobalt-based amorphous soft magnetic alloy with a high rectangular ratio, the alloy has excellent soft magnetic properties such as a high rectangular ratio and a low coercive force, a magnetic ring made of the cobalt-based amorphous soft magnetic alloy can be rapidly saturated under a small current, the problem of low response sensitivity of the existing amorphous nanocrystalline soft magnetic alloy is effectively solved, and the novel cobalt-based amorphous soft magnetic alloy has the characteristic of low loss, greatly reduces energy loss in circuit application, improves working efficiency, and has the advantages of energy conservation and environmental protection while improving sensitivity.
(2) The cobalt-based amorphous soft magnetic alloy prepared by the invention has high squareness ratio which can reach more than 96%, low coercive force which can reach 0.2A/m, low loss which can reach 45w/kg (100kHz, 0.4T), and effectively overcomes the defects of low squareness ratio and high loss of the existing amorphous soft magnetic alloy.
Drawings
Fig. 1 is a control circuit diagram of a switching power supply.
In fig. 2, (a) is a circuit voltage input waveform diagram, (b) is a rectification voltage stabilization diagram, and (c) is an output voltage waveform diagram.
Detailed Description
The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto. All of the starting materials of the present invention, without particular limitation as to their source, may be purchased commercially or prepared according to conventional methods well known to those skilled in the art. All the raw materials of the present invention are not particularly limited in their purity, and the present invention preferably adopts analytical purity or conventional purity used in the art.
Example 1
Weighing 50g of the raw materials according to the mixture ratio of table 1:
TABLE 1
Raw materials
|
Purity (%)
|
Proportioning (mass fraction)
|
Co
|
≥99.5
|
70.7
|
Fe
|
≥99.8
|
1
|
Mo
|
≥94.6
|
0.8
|
Si
|
≥99.5
|
13
|
B
|
≥94.5
|
14.5 |
(1) And (3) putting the raw materials weighed according to the proportion into a vacuum melting furnace for melting for multiple times (not less than 3 times), wherein the melting temperature is 1380 ℃, the melting time is 4min, and cooling to obtain an alloy ingot.
(2) Crushing the alloy ingot, cleaning with acetone, and performing melt spinning by a single-roll quenching method, wherein the linear velocity of a cold roll of the melt spinning is 50m/s, so as to obtain the strip-shaped amorphous alloy with the width of 3mm and the thickness of 25 mu m.
(3) And (3) carrying out longitudinal magnetic field heat treatment on the strip-shaped amorphous alloy, wherein the longitudinal magnetic field intensity is 800Gs, the heat treatment temperature is 440 ℃, and the time is 35 min. The heating rate of the heat treatment was 15 ℃/min.
The cobalt-based amorphous soft magnetic alloy obtained in the embodiment has a squareness ratio of 97.3%, a coercive force Hc of 0.15A/m, and a loss Ps of 35w/kg (100kHz, 0.4T).
Example 2
Weighing 50g of the raw materials according to the mixture ratio of table 2:
TABLE 2
Raw materials
|
Purity (%)
|
Proportioning (mass fraction)
|
Co
|
≥99.5
|
67
|
Fe
|
≥99.8
|
1.5
|
Mo
|
≥94.6
|
1.5
|
Si
|
≥99.5
|
14
|
B
|
≥94.5
|
16 |
(1) And (3) putting the raw materials weighed according to the proportion into a vacuum melting furnace for melting for multiple times (not less than 3 times), wherein the melting temperature is 1380 ℃, the melting time is 4min, and cooling to obtain an alloy ingot.
(2) Crushing the alloy ingot, cleaning with acetone, and performing melt spinning by a single-roll quenching method, wherein the linear velocity of a cold roll of the melt spinning is 50m/s, so as to obtain the strip-shaped amorphous alloy with the width of 3mm and the thickness of 25 mu m.
(3) And (3) carrying out longitudinal magnetic field heat treatment on the strip-shaped amorphous alloy, wherein the longitudinal magnetic field intensity is 800Gs, the heat treatment temperature is 440 ℃, and the time is 35 min. The heating rate of the heat treatment was 15 ℃/min.
The cobalt-based amorphous soft magnetic alloy obtained in the embodiment has a squareness ratio of 96.2%, a coercive force Hc of 0.2A/m, and a loss Ps of 43w/kg (100kHz, 0.4T).
Example 3
Weighing 50g of the raw materials according to the mixture ratio of table 3:
TABLE 3
(1) And (3) putting the raw materials weighed according to the proportion into a vacuum melting furnace for melting for multiple times (not less than 3 times), wherein the melting temperature is 1380 ℃, the melting time is 4min, and cooling to obtain an alloy ingot.
(2) Crushing the alloy ingot, cleaning with acetone, and performing melt spinning by a single-roll quenching method, wherein the linear velocity of a cold roll of the melt spinning is 50m/s, so as to obtain the strip-shaped amorphous alloy with the width of 3mm and the thickness of 25 mu m.
(3) And (3) carrying out longitudinal magnetic field heat treatment on the strip-shaped amorphous alloy, wherein the longitudinal magnetic field intensity is 800Gs, the heat treatment temperature is 440 ℃, and the time is 35 min. The heating rate of the heat treatment was 15 ℃/min.
The cobalt-based amorphous soft magnetic alloy obtained in the embodiment has a squareness ratio of 96.5%, a coercive force Hc of 0.18A/m, and a loss Ps of 40w/kg (100kHz, 0.4T).
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.