CN118675832A - Modified metal magnetic powder and preparation method and application thereof - Google Patents
Modified metal magnetic powder and preparation method and application thereof Download PDFInfo
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- CN118675832A CN118675832A CN202410662174.8A CN202410662174A CN118675832A CN 118675832 A CN118675832 A CN 118675832A CN 202410662174 A CN202410662174 A CN 202410662174A CN 118675832 A CN118675832 A CN 118675832A
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Abstract
The invention relates to the technical field of magnetic materials, and discloses modified metal magnetic powder, a preparation method and application thereof. According to the invention, a polysiloxane layer is formed on the surface of metal magnetic powder by using a T unit siloxane raw material; then, through drying treatment, the polysiloxane layer is in a state of low moisture content, the condensation of silicon hydroxyl is promoted, and organic groups of the T unit siloxane are orderly arranged to form a uniform polysiloxane layer; finally, the organic groups of the T unit siloxane are removed through calcination treatment, so that the uniform polysiloxane layer is converted into a compact siloxane compound layer. The modified metal magnetic powder thus obtained has excellent properties of low water content after being left to stand.
Description
Technical Field
The invention relates to the technical field of magnetic materials, in particular to modified metal magnetic powder and a preparation method and application thereof.
Background
With the rapid development of microelectronics and communication technology, electronic components are increasingly developed towards miniaturization, energy saving, high frequency and the like, which puts higher requirements on the electrical performance, magnetic performance, stability and the like of the electronic components, and the loss at high frequency is a great obstacle to restrict the application of the electronic components.
The magnetic powder core is generally modified by insulating the powder surface to reduce eddy current loss. The insulating modification of the surface of the magnetic powder is mainly used for reducing the phenomenon that charges are concentrated on the surface of the magnetic powder particles, so that eddy currents are generated inside the magnetic powder particles under a high-frequency magnetic field, the magnetic powder particles are conducted (regarded as short circuits), eddy current loss among the magnetic powder particles is increased sharply, power loss of an inductor is large, and even the problem that the electric circuit is burnt occurs is solved.
The existing magnetic powder surface insulation modification method mainly comprises organic insulation coating and inorganic insulation coating. In the organic insulating coating, an organic insulating coating agent such as epoxy resin, phenolic resin, organic silicon resin and the like is used as an adhesive, so that the inductance device after powder pressing has the required shape, size and strength, and the adhesive of the organic coating agent is good, but the heat resistance is poor, the internal stress of a magnetic core is difficult to eliminate, and the heat treatment temperature of the magnetic powder core is limited. In the inorganic insulating coating process, mineral powder with high resistivity, silicate and various oxides are mainly used as inorganic coating agents, and the inorganic coating agents are widely used in insulating coating modified magnetic powder due to the advantages of high heat treatment temperature, high resistivity, low cost and the like.
At present, inorganic coated magnetic powder is subjected to insulation modification on the surface of the magnetic powder, so that the magnetic powder is difficult to uniformly coat, and the risk of conduction exists among magnetic powder particles under high frequency due to incomplete coating.
For example, patent CN110181036a discloses a composite soft magnetic metal powder, which is prepared by dissolving phosphoric acid in volatile organic solvents (such as acetone, alcohol, etc.), mixing the soft magnetic powder with phosphoric acid solution to generate a phosphating reaction, forming a phosphating film on the surface of the soft magnetic powder, passivating the soft magnetic powder, and then adding an insulating agent and a binder to perform powder insulation coating. The insulating coating layer formed by the method is easy to have incomplete and uneven problems, the resistivity of the inductor is reduced, and the conducting risk exists under high frequency; meanwhile, due to solvent reaction, more moisture is easily introduced into the soft magnetic powder, and the moisture content of a soft magnetic powder product is higher, so that the conduction risk in the operation process of the electronic element is greatly increased.
And then, as a method for insulating and modifying the surface of the silicon dioxide coated magnetic powder by adopting silicon dioxide with high resistivity and excellent thermal stability, patent CN110767441A discloses a preparation method of a FeSiBCr/SiO 2 nanocrystalline soft magnetic composite iron core, which controls the hydrolysis polycondensation reaction rate of Tetraethoxysilane (TEOS) by controlling the technological parameters such as the dropping amount of a silicon source, the reaction temperature, the water content, the ammonia water content and the like in a chemical liquid phase in-situ deposition process so as to form a SiO 2 insulating shell layer with good uniformity and continuity. However, the insulating shell layer prepared by the method has the problem of high water content, and meanwhile, the patent has long reaction time and is not suitable for industrial quantitative production.
Disclosure of Invention
In order to solve the technical problem of surface insulation modification of the metal magnetic powder, the invention provides modified metal magnetic powder and a preparation method and application thereof.
Firstly, the invention provides a modified metal magnetic powder which has a core-shell structure with metal magnetic powder as a core and silicone compound as a shell layer, and the surface of the modified metal magnetic powder is insulated by utilizing the high resistivity property of the silicone compound; the ratio of peak integral area of-80 ppm to-120 ppm and +20ppm to-120 ppm in solid 29 Si-NMR spectrum chart is 50-99.5:100, and the modified metal magnetic powder can have lower water absorption when being placed for a long time in the semiconductor field, can have lower water content after being placed for a long time, and avoids the risk of conduction between the modified metal magnetic powder particles due to the existence of water.
Secondly, the invention provides a preparation method of the modified metal magnetic powder, and the siloxane compound formed on the surface of the metal magnetic powder is more continuous and more compact through optimizing raw materials and a preparation process, and the water content is low after long-time standing.
Again, the invention provides the use of the modified metal magnetic powder as a filler in the preparation of packaging materials or inductance materials in the semiconductor field.
The specific technical scheme of the invention is as follows:
In a first aspect, the present invention provides a modified metal magnetic powder. The modified metal magnetic powder provided by the invention is characterized in that: the magnetic powder core-shell structure takes metal magnetic powder as a core and silicone compound as a shell; in the solid 29 Si-NMR spectrum chart, the ratio of the peak integral area of the modified metal magnetic powder ranging from-80 ppm to-120 ppm to the peak integral area ranging from +20ppm to-120 ppm is 50-99.5:100.
In the field of semiconductors, in order to reduce eddy current loss of a magnetic powder core, insulation modification is required to be performed on the surface of magnetic powder, so that eddy current generated in the interior of magnetic powder particles under a high-frequency magnetic field is avoided.
Accordingly, in view of the above problems, the present invention provides a modified metal magnetic powder having a core-shell structure in which a metal magnetic powder is used as a core and a silicone compound is used as a shell, and by virtue of the high resistivity characteristic of the silicone compound, the modified metal magnetic powder can reduce the concentration of charges on the surface of magnetic powder particles, and the modified metal magnetic powder can be prevented from being conducted at high frequencies.
In the solid 29 Si-NMR spectrum diagram, the ratio of the peak integral area of the range of-80 ppm to-120 ppm to the range of +20ppm to-120 ppm is 50-99.5:100.
In the field of semiconductors, in the practical application process of the filler, the filler is generally not directly used after being prepared, and the shelf life exists, so that the filler absorbs water in the placing process. The modified metal magnetic powder provided by the invention has less water absorption after being placed, and has great advantages for reducing the conduction risk caused by high water content.
In the modified metal magnetic powder of the present invention, in order to uniformly coat the surface of the metal magnetic powder with the silicone compound, it is necessary to make the amount of the specific silicone compound within a certain range. If the amount of the siloxane compound is too small, the siloxane compound cannot completely wrap the surface of the metal magnetic powder, the shell layer is discontinuous and has high porosity, the problem of water absorption in the later period can exist, the problem of ion precipitation can exist when the water content of the modified metal magnetic powder is too large, the risk of conducting magnetic powder particles can be increased, and the operation of an electronic device is influenced; if the amount of the siloxane compound is too large, the modified metal magnetic powder can have agglomeration phenomenon, and is difficult to uniformly mix with the resin, and the mixed filler formed by the product and the resin can have stripping phenomenon, and the formation of pores in the mixed filler of the metal magnetic powder and the resin can be increased, so that the water absorption problem is caused. Accordingly, the present invention provides a modified metal magnetic powder having a ratio of peak integration area in the range of-80 ppm to-120 ppm to the range of +20ppm to-120 ppm in a solid 29 Si-NMR spectrum chart of 50 to 99.5:100.
Preferably, the siloxane compound is prepared from a siloxane containing 90% by weight or more of T units. Wherein T unit = R 1SiO3 -, R1 is a hydrogen atom or an independently selectable hydrocarbyl group of carbon atoms 1 to 16.
The inorganic coating magnetic powder is used for insulating and modifying the surface of the magnetic powder, so that the magnetic powder is difficult to uniformly coat, and the risk of conduction exists between the magnetic powder particles under high frequency due to incomplete coating. The siloxane compound shell layer of the modified metal magnetic powder provided by the invention has higher density and better continuity. The siloxane compound film prepared by taking polysiloxane containing more than 90%wt of T units as a raw material has higher density and better continuity. In order to coat the metal magnetic powder, a layer of polysiloxane film is formed on the surface of the metal magnetic powder by condensation of silicon hydroxyl groups of siloxane, and then the siloxane compound is obtained by heat treatment, and in the process of forming the polysiloxane film, since the free rotation of molecules of T units is easier than that of Q units, the film of the modified metal magnetic powder is prepared by using polysiloxane containing more than 90% wt of T units as a raw material, so that the modified metal magnetic powder has the advantage of small water absorption after being placed.
Further preferably, the T unit siloxane is selected from the group consisting of hydrocarbyl trialkoxysilanes and hydrocarbyl trichlorosilane.
Preferably, the thickness of the shell layer is 0.5nm to 300nm.
Preferably, the modified metal magnetic powder provided by the invention is placed for 48 hours under the environmental conditions of 25 ℃ and 50% RH, and the Karl Fischer water content of the modified metal magnetic powder at 200 ℃ is not higher than 150ppm/m 2.
The metal magnetic powder is communicated with water, so that the conduction risk exists, and meanwhile, due to the existence of water, the problem of metal ion precipitation exists, and the operation of an electronic device is influenced.
The modified metal magnetic powder provided by the invention has a compact and continuous siloxane compound shell layer, so that the modified metal magnetic powder has the excellent characteristic of small water absorption after being placed, the water absorption of the metal magnetic powder in the shelf life can be reduced, the modified metal magnetic powder is used as a filler of an electronic device, the modified metal magnetic powder has lower conduction risk during operation, and meanwhile, the surface insulation of the modified metal magnetic powder can play a role in reducing eddy current loss.
In a second aspect, the present invention provides a method for preparing the modified metal magnetic powder, comprising the steps of:
S1, adding T unit siloxane into metal magnetic powder, and reacting to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor;
s2, drying treatment is carried out to enable the precursor to be in a low-moisture content state;
Step S3, calcining to densify the surface of the precursor to obtain modified metal magnetic powder;
wherein T unit = R 1SiO3 -, R1 is a hydrogen atom or an independently selectable hydrocarbyl group of carbon atoms 1 to 16, the modified metal magnetic powder having a dense siloxane compound shell layer.
In order to reduce the loss of the magnetic powder core, the surface of the metal magnetic powder is generally subjected to insulation modification, and the most common method in the prior art is to carry out coating modification by adopting an inorganic insulation coating agent. However, the existing inorganic coated magnetic powder is difficult to uniformly coat the magnetic powder by insulating modification on the surface of the magnetic powder, and the risk of conduction exists between magnetic powder particles under high frequency due to incomplete coating. In addition, the coating modification in the prior art generally does not consider the problems of water absorption and water content, but in the field of semiconductors, no filler or inductance material is generally used directly after preparation, and the shelf life exists, so that the problems of water absorption and water content after placement in the placing process are required to be paid attention.
In order to improve the compactness of the siloxane compound film layer of the metal magnetic powder and reduce the water absorption of a product after being placed, the invention provides the preparation method of the modified metal magnetic powder, and a uniform and compact siloxane compound film layer is formed on the surface of the metal magnetic powder. Firstly, forming a polysiloxane layer on the surface of metal magnetic powder by using a T unit siloxane raw material; then, through drying treatment, the polysiloxane layer is in a low-moisture state, the condensation of silicon hydroxyl is promoted, organic groups of the T unit siloxane are orderly arranged, a uniform polysiloxane layer is formed, and the formation of a compact siloxane compound is facilitated; finally, through calcination treatment, part of organic groups of the T unit siloxane are removed, so that the uniform polysiloxane layer is converted into a compact siloxane compound shell layer.
The conditions for forming the compact siloxane compound shell layer on the surface of the metal magnetic powder comprise the following three aspects:
① Since the T-unit siloxane has polarity, it can be rapidly adsorbed on the surface of the metal magnetic powder when mixed with the metal magnetic powder to form a polysiloxane film layer, and thus the first condition of the preparation method of the present invention is to use the T-unit siloxane as a raw material. Since the free rotation of the molecules of the T units is easier, the first condition is that the siloxane of the T units is used as a raw material, which is a precondition for optimizing the arrangement of the siloxane by making the polysiloxane film layer in a low moisture content state in step S2 of the present invention.
② The second condition of the preparation method is that the polysiloxane layer is in a low moisture content state by drying, so that the organic groups of the T unit siloxane are promoted to rotate and orderly arranged, and a uniform polysiloxane layer is formed. A uniform polysiloxane layer, facilitates the formation of a uniform and dense layer of silicone compound,
③ The third condition is that the organic groups of the polysiloxane layer are removed by calcination to densify it, under which conditions the uniform polysiloxane layer is transformed into a uniform, dense shell of the siloxane compound.
As a preferable mode of the above preparation method, in the step S1, the particle diameter of the metal magnetic powder is 0.05 to 40. Mu.m.
In order to form a uniform shell layer of the silicone compound on the surface of the metal magnetic powder, it is necessary to have a particle size of the metal magnetic powder in the range of 0.05 to 40 μm. If the particle size of the metal magnetic powder is too small, agglomeration is easy, and the T unit siloxane is difficult to uniformly adsorb on the surface of the metal magnetic powder, so that a uniform polysiloxane film layer is difficult to form on the metal magnetic powder, the coating is incomplete, and the coating effect is poor; because the thickness of the siloxane compound needing to be coated is smaller, the added T unit siloxane raw material is less, if the particle size of the metal magnetic powder is too large, siloxane can also have the problem that the siloxane is difficult to uniformly adsorb on the surface of the metal magnetic powder, so that the problem of uneven coating and higher porosity is brought, at the moment, if the coating thickness is increased and the amount of the added siloxane raw material is increased to promote uniform coating, the obtained metal magnetic powder has an agglomeration phenomenon, the agglomeration phenomenon can lead the modified metal magnetic powder to be difficult to uniformly mix with the resin, the mixed filler formed by a product and the resin can have a stripping phenomenon, and the problem of water absorption can be caused by the formation of pores in the mixed filler of the metal magnetic powder and the resin.
Preferably, in the step S1, the mass ratio of the metal magnetic powder to the added T unit siloxane is 100:0.2-10.
As a preferred embodiment of the above preparation method, in step S1, an alkaline aqueous solution is added to carry out the reaction.
Step S1 is a reaction that T unit siloxane is adsorbed on the surface of metal magnetic powder to form a polysiloxane film layer, and an alkaline aqueous solution is added for reaction, so that condensation of silicon hydroxyl groups can be promoted. The alkaline aqueous solution can be one or more of ammonia water, tetramethyl ammonium hydroxide, choline, ethylenediamine, isopropylamine and ethanolamine.
Further preferably, step S1 is performed by adding silica powder.
Further preferably, the particle size of the silica powder is 10 to 100nm.
In order to further improve the compactness of the silicone compound shell, the invention also adds nano silicon dioxide powder when the silicone shell is formed in the step S1. The siloxane compound coated on the surface of the metal magnetic powder can be prepared from a great majority of siloxane raw materials derived from T units, and a small part of siloxane raw materials are directly added nano silicon dioxide powder. When siloxane is condensed to generate polysiloxane, the polysiloxane is not compact, a small amount of silicon dioxide powder is added to disperse in a polysiloxane skeleton in the reaction process, and when polysiloxane organic groups are removed by calcining in the step S3, the silicon dioxide powder can fill the positions of the organic groups, so that the porosity of the shell layer of the siloxane compound coated on the surface of the metal magnetic powder is reduced. Wherein, the particle size of the silicon dioxide powder is preferably 10-100 nm, and the added amount is preferably 0.5-1.2% of the mass of the siloxane raw material of the unit T.
In step S2, the precursor is preferably dried to have a water content of 0.1 to 1%.
The polysiloxane layer is in a low-moisture state, organic groups of the T-unit siloxane are promoted to rotate and are orderly arranged, so that a uniform polysiloxane layer is formed, the obtained siloxane compound shell is more compact and uniform, finally, the water absorption of the product after the product is placed is less, and the water content of the product after the product is placed is low. When the water content of the precursor is 0.1-1%, the density of the siloxane compound shell layer formed on the surface of the metal magnetic powder is highest.
As a preferable example of the above preparation method, the drying treatment method is as follows: heating to 50-200 deg.c and drying for 6-24 hr.
In step S3, the calcination treatment is preferably performed under an inert gas atmosphere.
As a preferable mode of the above preparation method, in the step S3, the calcination treatment is carried out at 600 to 1200℃for 6 to 72 hours.
The calcination treatment serves to remove the organic groups of the T unit siloxane, converting the uniform polysiloxane layer into a dense siloxane compound layer. The calcination treatment is carried out in an inert gas atmosphere, has a better densification effect, and the treatment temperature is preferably 600-1200 ℃ and the time is preferably 6-72 hours.
In a third aspect, the invention also provides an application of the modified metal magnetic powder in preparing a semiconductor packaging material or an inductance material.
In the semiconductor field, when passive elements, semiconductor elements, electroacoustic devices, display devices, optical devices, radio frequency devices, and the like are assembled into devices, circuit board substrate materials such as high-density interconnection boards, high-frequency high-speed boards, and mother boards are required. These substrate materials are generally mainly composed of organic polymers such as fillers and resins. The modified metal magnetic powder provided by the invention is applied to the preparation of semiconductor packaging materials or substrate materials, and can effectively meet the heat dissipation requirement of the semiconductor packaging materials or substrate materials.
Compared with the prior art, the invention has the following technical effects:
(1) The invention provides a modified metal magnetic powder with a core-shell structure taking metal magnetic powder as a core and taking a siloxane compound as a shell, wherein in a solid 29 Si-NMR spectrum chart, the ratio of peak integral area of the modified metal magnetic powder in the range of-80 ppm to-120 ppm to the range of +20ppm to-120 ppm is 50-99.5:100. The modified metal magnetic powder can insulate and modify the surface of the metal magnetic powder through the siloxane compound, so that the eddy current loss of the magnetic powder core is reduced. Furthermore, the modified metal magnetic powder has the excellent characteristic of small water absorption after being placed, so that the water absorption of the modified metal magnetic powder in shelf life can be reduced, and the conduction risk brought by high water content under high frequency can be reduced.
(2) According to the invention, a polysiloxane layer is formed on the surface of metal magnetic powder by using a T unit siloxane raw material; then, through drying treatment, the polysiloxane layer is in a state of low moisture content, the condensation of silicon hydroxyl is promoted, and organic groups of the T unit siloxane are orderly arranged to form a uniform polysiloxane layer; finally, through calcination treatment, part of organic groups of the T unit siloxane are removed to convert the T unit siloxane into Q units, so that the uniform polysiloxane layer is converted into a compact siloxane compound shell layer. Thus, the present invention provides a metallic magnetic powder having a continuous, dense shell of silicone compound that has a low water absorption after placement.
Detailed Description
The invention is further described below with reference to examples. Those of ordinary skill in the art will be able to implement the invention based on these descriptions. In addition, the embodiments of the present invention referred to in the following description are typically only some, but not all, embodiments of the present invention. Therefore, all other embodiments, which can be made by one of ordinary skill in the art without undue burden, are intended to be within the scope of the present invention, based on the embodiments of the present invention.
The water content of the particles is 200 ℃ and is tested by a Karl Fischer moisture meter, the meter is CA-310 of Mitsubishi chemical, and the measuring method is a coulomb method. Wherein, in the performance test, the water content is calculated as ppm/m 2, which is the measured water content divided by the geometric external surface area of the test article particles (calculated as the measured average particle size).
The average particle size, herein referred to as the volume average diameter of the particles, was determined using a Beckman Coulter laser particle size distribution apparatus LS-13320, the solvent being deionized water.
In 29 Si-NMR spectrum of siloxane compound, the total content of Si-bonded groups was represented by a peak integration area ranging from +20ppm to-120 ppm, and the content of Q unit was represented by a peak integration area ranging from-80 ppm to-120 ppm. The ratio of the peak integral area of the modified metal magnetic powder particles in the range of-80 ppm to-120 ppm to the peak integral area of the modified metal magnetic powder particles in the range of +20ppm to-120 ppm is 50-99.5:100.
The coating thickness of the modified metal magnetic powder siloxane compound, namely the thickness of the shell layer of the modified metal magnetic powder, is obtained through high-resolution transmission electron microscope test.
Example 1
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 0.5 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5%, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 50:1:1.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 750 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound is 2.0nm.
Example 2
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 0.5 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5%, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 50:1:1.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.2%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 750 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 2.3nm.
Example 3
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 0.5 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5%, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 50:1:1.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the water content of 1%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 750 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound is 2.0nm.
Example 4
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 1 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5%, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 50:1:1.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 750 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 7.0nm.
Example 5
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 1.8 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5%, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 50:1:1.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 750 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 24.0nm.
Example 6
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle diameter of 0.05 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5%, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 50:1:1.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 750 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound is 0.5nm.
Example 7
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
And S1, adding methyltrimethoxysilane (MTMS) into 40 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5%, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 50:1:1.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 750 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 260.1nm.
Example 8
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 40 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5%, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 45:1:1.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 750 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 300.0nm.
Example 9
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 10 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5% and nano silicon dioxide powder, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein, the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5 percent to the nano silicon dioxide powder is 50:3:3:0.01. Wherein the average particle diameter of the nano silicon dioxide powder is 30nm.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 650 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 127.1nm.
Example 10
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 10 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5% and nano silicon dioxide powder, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein, the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5 percent to the nano silicon dioxide powder is 50:3:3:0.01. Wherein the average particle diameter of the nano silicon dioxide powder is 10nm.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 650 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 118.0nm.
Example 11
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 10 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5% and nano silicon dioxide powder, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein, the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5 percent to the nano silicon dioxide powder is 50:3:3:0.01. Wherein the average particle diameter of the nano silicon dioxide powder is 100nm.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 650 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound is 135.6nm.
Example 12
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 10 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5% and nano silicon dioxide powder, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein, the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5 percent to the nano silicon dioxide powder is 50:3:3:0.01. Wherein the average particle diameter of the nano silicon dioxide powder is 7nm.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 650 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 109.9nm.
Example 13
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 10 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5% and nano silicon dioxide powder, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein, the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5 percent to the nano silicon dioxide powder is 50:3:3:0.01. Wherein the average particle diameter of the nano silicon dioxide powder is 120nm.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 70 ℃ and keeping the temperature for 24 hours for drying treatment, so that the precursor is in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 650 ℃ at a heating rate of 5 ℃/min, preserving heat for 6 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 137.7nm.
Example 14
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 10 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5% and nano silicon dioxide powder, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein, the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5 percent to the nano silicon dioxide powder is 50:3:3:0.019. Wherein the average particle diameter of the nano silicon dioxide powder is 30nm.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 50 ℃ and keeping the temperature for 10 hours, and drying to enable the precursor to be in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 1000 ℃ at a heating rate of 5 ℃/min, preserving heat for 10 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 125.5nm.
Example 15
A modified metal magnetic powder having a continuous, dense silicone compound shell layer is provided, prepared as follows:
Step S1, adding methyltrimethoxysilane (MTMS) into metal magnetic powder with the average particle size of 10 mu m, uniformly mixing, adding ammonia water with the volume concentration of 5% and nano silicon dioxide powder, and reacting at 25 ℃ to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor. Wherein, the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5 percent to the nano silicon dioxide powder is 100:6:6:0.01. Wherein the average particle diameter of the nano silicon dioxide powder is 30nm.
And S2, placing the precursor obtained in the step S1 into a muffle furnace, heating to 200 ℃ and keeping the temperature for 6 hours, and drying to enable the precursor to be in a low-moisture content state with the moisture content of 0.8%.
And S3, introducing nitrogen into the muffle furnace to ensure that the interior of the furnace is in a nitrogen atmosphere, then heating to 1200 ℃ at a heating rate of 5 ℃/min, preserving heat for 24 hours, calcining to densify the surface of the precursor, and then cooling to room temperature along with the furnace to obtain the modified metal magnetic powder with the continuous and compact siloxane compound coated on the surface. Wherein the coating thickness of the silicone compound was 115.6nm.
Comparative example 1
The main difference from example 1 is that: the average particle diameter of the metal magnetic powder in step S1 was 0.02. Mu.m. Otherwise, the same as in example 1 was used.
The coating thickness of the silicone compound was 1.2nm as measured in this comparative example.
Comparative example 2
The main difference from example 1 is that: the average particle diameter of the metal magnetic powder in step S1 was 46 μm. Otherwise, the same as in example 1 was used.
The coating thickness of the silicone compound was measured to be 320.2nm in this comparative example.
Comparative example 3
The main difference from example 1 is that: the average particle diameter of the metal magnetic powder in the step S1 is 46 mu m; in the step S1, the mass ratio of the metal magnetic powder to the MTMS to the ammonia water with the volume concentration of 5% is 40:1:1. Otherwise, the same as in example 1 was used.
The coating thickness of the silicone compound was measured to be 450.4nm in this comparative example.
Comparative example 4
The main difference from example 1 is that: the moisture content of the precursor in step S2 was 0.01%. Otherwise, the same as in example 1 was used.
The coating thickness of the silicone compound was measured to be 2.4nm in this comparative example.
Comparative example 5
The main difference from example 1 is that: the moisture content of the precursor in step S2 was 1.2%. Otherwise, the same as in example 1 was used.
The coating thickness of the silicone compound was measured to be 2.1nm in this comparative example.
Comparative example 6
The main difference from example 1 is that: the gas atmosphere for calcination in step S3 is air. Otherwise, the same as in example 1 was used.
The coating thickness of the silicone compound was measured to be 2.3nm in this comparative example.
Comparative example 7
The main difference from example 1 is that: the calcination temperature in the step S3 is 600 ℃, and the temperature is kept for 5 hours. Otherwise, the same as in example 1 was used.
The coating thickness of the silicone compound was measured to be 2.2nm in this comparative example.
Comparative example 8
The main difference from example 1 is that: the calcination temperature in the step S3 is 550 ℃, and the temperature is kept for 6 hours. Otherwise, the same as in example 1 was used.
The coating thickness of the silicone compound was measured to be 2.3nm in this comparative example.
Characterization of Performance
The modified metal magnetic powders prepared in examples 1 to 15 and comparative examples 1 to 8 were subjected to tests of particle diameter, Q unit content, and water content after standing, and the analysis results are shown in Table 1. Wherein the water content after standing is the water content test performed by standing for 48 hours at 25 ℃ and 50% RH environment condition from the preparation. Q unit content is the ratio of the peak integral area in the range of-80 ppm to-120 ppm to the peak integral area in the range of +20ppm to-120 ppm in the solid 29 Si-NMR spectrum of the modified metal magnetic powder.
TABLE 1
As can be seen from table 1:
(1) As is clear from examples 1 to 15, the present invention forms a polysiloxane layer on the surface of a metal magnetic powder by using a T unit siloxane raw material; then, through drying treatment, the polysiloxane layer is in a low-moisture state, the condensation of silicon hydroxyl is promoted, organic groups of the T unit siloxane are orderly arranged, a uniform polysiloxane layer is formed, and the formation of a compact siloxane compound is facilitated; finally, the organic groups of part of the T unit siloxane are removed through calcination treatment and converted into Q units, so that the uniform polysiloxane layer is converted into a compact siloxane compound layer. The modified metal magnetic powder thus obtained has excellent properties of having a small water content after leaving. Because the modified metal magnetic powder is applied to the semiconductor filler, the modified metal magnetic powder has a compact siloxane compound shell layer, the water absorption capacity of the metal magnetic powder in the shelf life can be reduced, the eddy current loss of the magnetic powder core during the operation of an electronic device can be reduced, and the risk of easy conduction among magnetic powder particles caused by high water content is reduced.
(2) In the preparation method of the modified metal magnetic powder, the selection condition analysis of the particle size is as follows:
As is clear from the comparative analysis of comparative examples 1 to 2 and example 1, the particle diameters of the metal magnetic powder of comparative examples 1 to 2 are 0.02 μm and 46 μm, respectively, and the water content thereof is greatly increased compared with example 1, and the analysis is because if the particle diameter of the metal magnetic powder is too small, agglomeration is easy, T unit siloxane is difficult to uniformly adsorb on the surface of the metal magnetic powder, so that a uniform polysiloxane film layer is difficult to form on the surface of the metal magnetic powder, and the coating effect is poor; because the thickness of the siloxane compound to be coated is smaller, the raw material of the added T unit siloxane is less, if the particle size of the metal magnetic powder is too large, the siloxane is difficult to uniformly adsorb on the surface of the metal magnetic powder, the problem of uneven coating is caused, and the water absorption of the product after the product is placed is increased due to uneven coating, so that the particle size of the metal magnetic powder needs to be controlled within a proper range when the method is used for preparing the modified metal magnetic powder.
Further, as is clear from comparative analysis of the water content characterization data of examples 1, examples 6 to 7, and comparative examples 1 to 2, the particle size of the metal magnetic powder of the present invention is preferably 0.05 to 40. Mu.m.
As can be seen from comparative analysis of example 8 with example 7 and example 1, the particle size of the metal magnetic powder of example 7 is larger than that of example 1, and in order to increase the coating amount of example 7 to increase the uniformity of the coating film layer, to increase the film layer compactness, it can be achieved by increasing the amount of added T unit siloxane, and the coating uniformity is better than that of example 7 (as shown by lower water absorption of example 8) by increasing the amount of added siloxane. However, when the particle diameter of the metal magnetic powder of comparative example 2 is increased to 46 μm by comparing comparative example 3 with comparative example 2, although the siloxane is added in addition to comparative example 3, the water absorption amount of comparative example 3 is more than that of comparative example 2, and agglomeration phenomenon of the metal magnetic powder is found in the preparation process, it is presumed that too much addition of the siloxane per unit of T increases the viscosity of the metal magnetic powder, the siloxane is not uniformly adsorbed on the surface of the metal magnetic powder to form a polysiloxane film layer, and the density of the film layer of the calcined siloxane compound is finally decreased. Therefore, it is further presumed that the method requires controlling the particle size of the metal magnetic powder within a certain range in order to form a uniform and dense shell layer of the silicone compound and to reduce the water content of the product.
(3) In the preparation method of the modified metal magnetic powder, the condition analysis of the water content of the precursor is as follows:
from comparative analysis of comparative examples 4 to 5 and example 1, it is understood that the moisture contents of the precursors after drying of comparative examples 4 and 5 are 0.01% and 1.2%, respectively, and the moisture contents of the obtained modified metal magnetic powder products after being left to stand are greatly increased as compared with example 1. Therefore, the water content of the precursor is controlled within a certain range, which is favorable for forming the compact siloxane compound, and the water content of the precursor is preferably in a low-water content state of 0.1% -1%. The reason for this is that the polysiloxane layer is in a state of 0.1% -1% low moisture content, and the organic groups of the T unit siloxane can be promoted to rotate and orderly arrange, so that a uniform polysiloxane layer is formed, and the obtained siloxane compound shell layer is more compact and has lower porosity.
(4) In the preparation method of the modified metal magnetic powder, the condition analysis of the precursor calcination gas atmosphere is as follows:
As is clear from the comparative analysis of comparative example 6 and example 1, the calcination treatment in step S3 of comparative example 6 was conducted in the atmosphere of air, and the water content of comparative example 6 was greatly increased after the calcination treatment. The reason is analyzed that in the air, the oxygen contains active gas oxygen, the oxygen can react with carbon formed by decomposing organic groups, and defects can be formed at carbon sites after carbon is taken away, so that the porosity is higher, a shell layer is not compact, and the water absorption capacity of the product is large. When calcination is carried out in an inert atmosphere, although the moisture discharged by condensation of silicon hydroxyl groups reacts with carbon to take away carbon, the moisture content is low, so that the carbon taking rate is low, the defect sites can be repaired by continuous condensation of the silicon hydroxyl groups in the film layer, the porosity is low, and the final appearance is that the water content of the product is low.
(5) In the preparation method of the modified metal magnetic powder, the condition analysis of the unit content of the product Q:
As is clear from comparative analyses of comparative examples 7 to 8 and example 1, comparative examples 7 and 8 were each greatly increased in water content by adjusting the temperature and time of the calcination step to reduce the conversion of T units to Q units so that the Q unit contents of the products of comparative examples 7 and 8 were 47.0% and 42.1%, respectively, and the obtained modified metal magnetic powders were each 195.4ppm/m 2、274.6ppm/m2 in water content after being left to stand. Therefore, the content of the Q unit of the modified metal magnetic powder is controlled within a certain range, so that the water content of the obtained modified metal magnetic powder after being placed is low.
(6) In the preparation method of the modified metal magnetic powder, the condition analysis of the addition of the nano silicon dioxide in the preparation process is as follows: as can be seen from comparative analysis of examples 9 to 11 and example 1, nano silica with different particle sizes and contents is added in the preparation process of examples 9 to 11, and the water content is reduced to different degrees after the nano silica is placed, which indicates that the addition of the nano silica can improve the compactness of the prepared siloxane compound film layer. The reason for this analysis is: when siloxane is condensed to generate polysiloxane, the polysiloxane is not compact, a small amount of silicon dioxide powder is added to be dispersed in a polysiloxane skeleton in the reaction process, and when polysiloxane organic groups are removed by calcining in the step S3, the silicon dioxide powder can well fill the positions of the organic groups, so that the compactness of the shell layer of the silicone compound coated on the surface of the metal magnetic powder is improved. Further, as is clear from comparative examples 12 to 13 of examples 9 to 11, the particle size of the nano silica powder is 10 to 100nm, otherwise, the nano silica powder cannot be filled in the polysiloxane skeleton, the water content of the nano silica powder cannot be reduced as compared with example 1, and the continuity of the shell layer is damaged due to the excessively large particle size of the silica added in example 13, which finally results in a large water content.
The raw material metal magnetic powder used in the embodiment of the invention is purchased from Shenzhen platinum family New materials Co.Ltd.
The raw materials and equipment used in the invention are common raw materials and equipment in the field unless specified otherwise; the methods used in the present invention are conventional in the art unless otherwise specified.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and any simple modification, variation and equivalent transformation of the above embodiment according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.
Claims (16)
1. A modified metal magnetic powder characterized in that: the modified metal magnetic powder has a core-shell structure with metal magnetic powder as a core and silicone compound as a shell;
in the solid 29 Si-NMR spectrum chart, the ratio of the peak integral area of the modified metal magnetic powder ranging from-80 ppm to-120 ppm to the peak integral area ranging from +20ppm to-120 ppm is 50.0-99.5:100.
2. A modified metal magnetic powder as defined in claim 1, wherein: the modified metal magnetic powder is placed for 48 hours under the environmental condition of 25 ℃ and 50% RH, and the Karl Fischer water content of the modified metal magnetic powder at 200 ℃ is not higher than 150ppm/m 2.
3. A modified metal magnetic powder as defined in claim 1, wherein: the siloxane compound is prepared from siloxane containing more than 90%wt of T units as a raw material;
wherein T unit = R 1SiO3 -, R1 is a hydrogen atom or an independently selectable hydrocarbyl group of carbon atoms 1 to 16.
4. A modified metal magnetic powder as claimed in claim 3, wherein: the unit siloxane is selected from alkyl trialkoxysilane and alkyl trichlorosilane.
5. A modified metal magnetic powder as defined in claim 1, wherein: the thickness of the shell layer is 0.5 nm-300 nm.
6. The method for preparing modified metal magnetic powder according to any one of claims 1 to 5, characterized by comprising the steps of: the method comprises the following steps:
S1, adding T unit siloxane into metal magnetic powder, and reacting to form polysiloxane on the surface of the metal magnetic powder to obtain a precursor;
s2, drying treatment is carried out to enable the precursor to be in a low-moisture content state;
Step S3, calcining to densify the surface of the precursor to obtain modified metal magnetic powder;
wherein T unit = R 1SiO3 -, R1 is a hydrogen atom or an independently selectable hydrocarbyl group of carbon atoms 1 to 16, the modified metal magnetic powder having a dense siloxane compound shell layer.
7. A method for producing a modified metal magnetic powder as defined in claim 6, wherein: in step S1, an alkaline aqueous solution is added to carry out a reaction.
8. A method for producing a modified metal magnetic powder as defined in claim 7, wherein: silica powder was also added to carry out the reaction.
9. A method for producing a modified metal magnetic powder as defined in claim 8, wherein: the particle size of the silicon dioxide powder is 10-100 nm.
10. A method for producing a modified metal magnetic powder as defined in claim 6, wherein: in the step S1, the particle size of the metal magnetic powder is 0.05-40 μm.
11. A method for producing a modified metal magnetic powder as defined in claim 6, wherein: in the step S2, the precursor is dried to have a water content of 0.1-1%.
12. A method for producing a modified metal magnetic powder as defined in claim 6 or 11, characterized in that: the drying treatment method comprises the following steps: heating to 50-200 ℃, and drying for 6-24 hours.
13. A method for producing a modified metal magnetic powder as defined in claim 6, wherein: in step S3, the calcination treatment is performed under an inert gas atmosphere.
14. A method for producing a modified metal magnetic powder as defined in claim 6, wherein: in the step S3, the temperature of the calcination treatment is 600-1200 ℃.
15. A method for producing a modified metal magnetic powder as defined in claim 14, wherein: in the step S3, the calcination treatment time is 6-72 hours.
16. The modified metal magnetic powder according to any one of claims 1 to 5, or the modified metal magnetic powder prepared by the preparation method according to any one of claims 6 to 15, for use in preparing semiconductor packaging materials or inductance materials.
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