CN114247881A - Method for realizing in-situ passivation on surface of FeSiAl powder - Google Patents
Method for realizing in-situ passivation on surface of FeSiAl powder Download PDFInfo
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- 229910052681 coesite Inorganic materials 0.000 description 10
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
Abstract
The invention relates to the technical field of surface passivation of Fe alloy powder, and particularly discloses a method for realizing in-situ passivation of the surface of FeSiAl powder, which comprises the following steps: selecting FeSiAl flaky particles, and performing in-situ passivation treatment on the powder by using air heat treatment and reduction heat treatment to obtain FeSiAl flattened powder; weighing quantitative FeSiAl flattened powder, performing oxidation treatment and reduction treatment, and then pulping to obtain slurry; coating the slurry on a coating machine to form a base band with a preset thickness in a scraping mode and drying the base band; and (4) putting the dried base band on a flat vulcanizing machine for hot-press curing to obtain a finished product with a preset thickness to be tested. Thereby solving the problems that the FeSiAl flattened powder improves the surface resistance and does not reduce the magnetic permeability as much as possible.
Description
Technical Field
The invention relates to the technical field of surface passivation of Fe alloy powder, in particular to a method for realizing in-situ passivation of the surface of FeSiAl powder.
Background
The magnetostriction coefficient and the magnetocrystalline anisotropy constant of the FeSiAl alloy can be close to 0 through component regulation, and the FeSiAl alloy has low resistivity and low price and is widely applied to two aspects: the soft magnetic powder core is used for a magnetic core of an inductor in a switching power supply and a magnetic core of a transformer in a flyback converter; the second is an electromagnetic wave absorbing material.
With the trend of high frequency, the metallic soft magnetic powder core needs to further reduce its eddy current loss and ensure its high real part permeability (μ) in a higher frequency range′). The eddy current loss of the metal soft magnetic powder core is divided into inter-particle loss and intra-particle loss, and for the FeSiAl soft magnetic powder core, the inter-particle resistivity is mainly improved so as to reduce the eddy current loss. For the wave-absorbing material, firstly, to improve the electromagnetic wave absorption rate and reduce the reflectivity, the complex magnetic permeability (mu) and the complex dielectric constant (epsilon) must be matched, namely, mu′＝ε′，μ″＝ε″So as to ensure that the electromagnetic wave enters the material as much as possible and is not reflected. FeSiAl in<Within the frequency range of 8GHz, has the characteristic of epsilon > mu.
FeSiAl is applied as a magnetic powder core or a wave-absorbing material, and mu of the FeSiAl is improved to reduce epsilon. The FeSiAl magnetic powder is subjected to flattening treatment, and the flaky FeSiAl is oriented to enable magnetic moments to be distributed in the grain surface to form an easily magnetized surface, so that the Snack limit is broken through, and the magnetic moments have higher mu. However, the FeSiAl magnetic powder after flaking increases the specific surface area, causes local leakage, and lowers the resistivity thereof, and epsilon is also greatly increased. Therefore, the sheet FeSiAl as the wave-absorbing material has too low resistivity, cannot perform impedance matching and blocks the absorption of electromagnetic waves; as a magnetic powder core, low resistivity will result in increased inter-particle eddy current losses.
In conclusion, the surface of the flaky FeSiAl is improvedThe surface resistivity can reduce the eddy current loss of the magnetic powder core and improve the impedance matching characteristic of the magnetic powder core as a wave-absorbing material. The surface modification of FeSiAl can be carried out by various methods (1) passivating in acidic medium such as phosphoric acid or nitric acid; (2) coating of high resistivity insulating ceramic Al by wet chemical method2O3Or SiO2Etc.; (3) the surface oxidation treatment is carried out in an oxidizing medium such as air. The methods (1) and (2) can form an insulating layer on the surface of the particles, but have great environmental pollution due to the requirement of a large amount of chemical reagents and complex treatment; the method (3) is to form Al on the surface of the oxidized FeSiAl particles by heat treatment in air or oxygen-containing gas medium2O3、SiO2And FeOxThe oxide layer does not cause pollution. However, obtaining a dense oxide layer with a certain thickness will cause Fe, which is a magnetic source, to be oxidized, resulting in a decrease in permeability. Selection of H2/N2The mixed gas is subjected to surface treatment, and a part of Al, Si and Fe can be oxidized by trace oxygen in the mixed gas, so that FeO is realizedxReducing and selectively oxidizing to improve the resistivity to a certain extent. In fact, O in the mixed gas2The content determines the thickness and uniformity of the surface oxide layer, but has problems in that the oxygen concentration in the mixed gas is very low and large variation occurs in mass production, which easily results in insufficient thickness of the oxide layer, non-uniform coating and poor product stability.
Considering the standard gibbs free energy change trend of the oxidation of three elements of Al, Si, Fe: the simple substance element is easy to oxidize in sequence of Al>Si > Fe, the order of easy reduction of its oxide being FeOx＞＞SiO2>Al2O3. Therefore, if the oxidation treatment is performed at a relatively low temperature, the FeSiAl surface is mainly Al2O3、SiO2And contains a certain amount of FeOx(ii) a Reducing FeO in the thermodynamically oxidized layer at a relatively high temperaturexCan be replaced by H2Reduced to Fe simple substance, Al2O3And SiO2Can not be covered by H2And (4) reducing. In addition, above 650 ℃, the Al element in FeSiAl and FeOx will have replacement reaction, 2xAl +3FeOx→xAl2O3+3Fe to elemental Fe and Al2O3. Therefore, it is important to solve the problems of FeSiAl flattened powder that the surface resistance is improved and the magnetic permeability is not reduced as much as possible.
Disclosure of Invention
The invention aims to provide a method for realizing in-situ passivation on the surface of FeSiAl powder, which not only can repair magnetic conductivity, but also can generate a passivation layer with high resistivity in situ on the surface of FeSiAl.
In order to achieve the purpose, the method for realizing in-situ passivation on the surface of the FeSiAl powder comprises the following steps:
selecting FeSiAl flaky particles, and performing in-situ passivation treatment on the powder by using air heat treatment and reduction heat treatment to obtain FeSiAl flattened powder;
weighing a certain amount of FeSiAl flattened powder, carrying out oxidation treatment and reduction treatment, and then pulping to obtain slurry;
scraping the slurry on a coating machine to form a base band with a preset thickness and drying the base band;
and (4) putting the dried base band on a flat vulcanizing machine for hot-press curing to obtain a finished product with a preset thickness to be tested.
Wherein, in the step of selecting FeSiAl flaky particles:
the diameter of the FeSiAl flaky particles is 40-110um, the thickness is 1-2um, the Fe content is 85%, the Al content is 5.4%, and the Si content is 9.6%.
Wherein, the air heat treatment step comprises the following steps:
the oxidation temperature is 300-700 ℃, and the oxidation time is 0.5-3 h.
Wherein, in the reduction heat treatment step:
by the introduction of a gas containing H2The inert gas of (1) is Ar or N2，H2The content is more than 5 percent, the reduction temperature is 500-800 ℃, and the reduction time is 0.5-3 h.
Wherein, in the step of weighing and quantifying the FeSiAl flattened powder:
the FeSiAl flattened powder is weighed by 100g and directly placed into a sintering dish after weighing.
Weighing and quantifying the FeSiAl flattened powder, and performing oxidation treatment and reduction treatment, wherein the oxidation treatment specifically comprises the following steps:
putting the sintering dish into an air heat treatment furnace, oxidizing for 2h under the air atmosphere at the temperature of 300 ℃, and raising the temperature and reducing the temperature at the speed of 5 ℃/min;
heat treatment is carried out for 2h in a vacuum environment at 700 ℃, and the heating and cooling rate is 5 ℃/min.
Weighing and quantifying the FeSiAl flattened powder, and performing oxidation treatment and reduction treatment, wherein the reduction treatment specifically comprises the following steps:
in the presence of 10% H2In Ar inert gas, the reduction time is 2h, the temperature is 700 ℃, and the heating and cooling rate is 5 ℃/min;
in Ar inert gas, the reduction time is 2h, the temperature is 700 ℃, and the heating and cooling rate is 5 ℃/min.
Wherein, pulping to obtain the pulp specifically comprises the following steps:
adding the passivation powder obtained by oxidation treatment and reduction treatment, water, a water-based colloid, a dispersant, a curing agent and a thickening agent according to a preset proportion, and stirring and mixing to obtain uniform and stable slurry.
Wherein, the water is pure water or deionized water, the mass ratio of the water is 40-65%, and the passivation powder is 20-40%.
The water-based colloid is one or a mixture of more of water-based acrylic emulsion, water-based polyurethane emulsion, water-based nitrile emulsion, water-based SBS emulsion and water-based silicone rubber emulsion, and the mass percentage of the water-based colloid is 10-15%.
The invention discloses a method for realizing in-situ passivation on the surface of FeSiAl powder, which aims to solve the problems that the surface resistance of FeSiAl flat powder is improved and the magnetic conductivity is not reduced as much as possible2O3And SiO2Oxide layer of (2). The oxidation process is finished under the atmosphere of low temperature atmosphere or high temperature low vacuum atmosphere, so that the defects of insufficient oxygen partial pressure and oxide layer thickness in the inert gas can be effectively avoidedFoot and unevenness. Then, the FeSiAl coated with a certain thickness of oxide layer contains H2Treating under inert mixed gas, reducing to above 800K, and treating with H2And the reducing capability of Al, part of FeO in the surface passivation layerxReduction to Fe and obtaining SiO2And Al2O3Of (3) a passivation layer. Therefore, the magnetic permeability can be repaired, and a passivation layer with high resistivity can be generated on the surface of the FeSiAl in situ.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 shows the original powder of FeSiAl flakes, the powder of the original powder after heat treatment at 300 ℃ for 2H in air atmosphere, and the powder after air heat treatment at 10% H2SEM pictures of the powder after 2h reduction treatment under the atmosphere of/Ar at 700 ℃ and EDS results of the surfaces of the flaky particles.
FIG. 2 is a flow chart of the steps of the method for realizing in-situ passivation of the surface of FeSiAl powder according to the invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention. Further, in the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
Referring to fig. 1 and fig. 2, the present invention provides a method for in-situ passivation of a surface of FeSiAl powder, comprising the following steps:
s1: selecting FeSiAl flaky particles, and performing in-situ passivation treatment on the powder by using air heat treatment and reduction heat treatment to obtain FeSiAl flattened powder;
s2: weighing a certain amount of FeSiAl flattened powder, carrying out oxidation treatment and reduction treatment, and then pulping to obtain slurry;
s3: scraping the slurry on a coating machine to form a base band with a preset thickness and drying the base band;
s4: and (4) putting the dried base band on a flat vulcanizing machine for hot-press curing to obtain a finished product with a preset thickness to be tested.
The method comprises the following steps of selecting FeSiAl flaky particles:
the diameter of the FeSiAl flaky particles is 40-110um, the thickness is 1-2um, the Fe content is 85%, the Al content is 5.4%, and the Si content is 9.6%.
The air heat treatment step comprises:
the oxidation temperature is 300-700 ℃, and the oxidation time is 0.5-3 h.
In the reduction heat treatment step:
by the introduction of a gas containing H2The inert gas of (1) is Ar or N2，H2The content is more than 5 percent, the reduction temperature is 500-800 ℃, and the reduction time is 0.5-3 h.
Weighing and quantifying the FeSiAl flattened powder:
the FeSiAl flattened powder is weighed by 100g and directly placed into a sintering dish after weighing.
Weighing and quantifying the FeSiAl flattened powder, and performing oxidation treatment and reduction treatment, wherein the oxidation treatment specifically comprises the following steps:
putting the sintering dish into an air heat treatment furnace, oxidizing for 2h under the air atmosphere at the temperature of 300 ℃, and raising the temperature and reducing the temperature at the speed of 5 ℃/min;
heat treatment is carried out for 2h in a vacuum environment at 700 ℃, and the heating and cooling rate is 5 ℃/min.
Weighing and quantifying the FeSiAl flattened powder, and performing oxidation treatment and reduction treatment, wherein the reduction treatment specifically comprises the following steps:
in the presence of 10% H2In Ar inert gas for a reduction time of 2h, the temperature is 700 ℃, and the heating and cooling rate is 5 ℃/min;
in Ar inert gas, the reduction time is 2h, the temperature is 700 ℃, and the heating and cooling rate is 5 ℃/min.
Pulping to obtain a pulp specifically comprising:
adding the passivation powder obtained by oxidation treatment and reduction treatment, water, a water-based colloid, a dispersant, a curing agent and a thickening agent according to a preset proportion, and stirring and mixing to obtain uniform and stable slurry.
The water is pure water or deionized water, the mass ratio of the water is 40-65%, and the passivation powder is 20-40%.
The water-based colloid is one or a mixture of more of water-based acrylic emulsion, water-based polyurethane emulsion, water-based nitrile emulsion, water-based SBS emulsion and water-based silicone rubber emulsion, and the mass percentage of the water-based colloid is 10-15%.
The dispersant is acrylate polymer or silane coupling agent in 0.5-2 wt%.
The curing agent is high-temperature blocked isocyanate curing agent or low-temperature aziridine curing agent, and accounts for 0.5-2%.
The thickener is inorganic bentonite, polyurethane thickener or alkali swelling thickener, and accounts for 1-3%.
The viscosity of the pulping system is controlled within the range of 3000-.
In the step of blade-coating the slurry on a coating machine into a base band with a preset thickness and drying the base band: the thickness of the base band is 0.1-0.2mm, the drying temperature is 100 ℃, and the drying time is 10 min.
Putting the dried base band on a flat vulcanizing machine for hot-press curing to obtain a finished product with a preset thickness to be tested:
the hot pressing condition is 180 ℃ and 200 ℃, the time is 2min, the thickness of a single layer is 0.05mm, the thickness of the four layers is 0.1mm by laminating the two layers, the thickness of the four layers is 0.2mm by laminating the four layers, and the like.
In this embodiment, the process for preparing the soft magnetic wave absorbing material includes: the method comprises four processes of powder in-situ passivation treatment, magnetic particle slurry preparation, tape casting coating and hot-press forming.
Firstly, powder in-situ passivation treatment:
selecting FeSiAl flaky particles with the diameter of 40-110um and the thickness of 1-2 um; the Fe content is 85%, the Al content is 5.4%, and the Si content is 9.6%.
In the air heat treatment process, the pressure is normal pressure, the oxidation temperature is 300-700 ℃, the oxidation time is 0.5-3H, in the reduction heat treatment, inert gas containing H2 is adopted, the inert gas can be Ar or N2, and the like, H2The content is more than 5 percent, the reduction temperature is 500-800 ℃, and the reduction time is 0.5-3 h.
Preparation of magnetic particle slurry
1. 100g of FeSiAl flattened powder was weighed and directly placed in a sintering dish.
2. Oxidation treatment: the sintering vessel is put into an air heat treatment furnace,
(1) oxidizing for 2h in air atmosphere at 300 ℃, and heating and cooling at the rate of 5 ℃/min
(2) Heat treatment is carried out for 2h under the vacuum environment of 700 ℃ (0.1 MPa, 1325Pa), and the heating and cooling rate is 5 ℃/min.
3. Reduction treatment:
(1)10％H2ar, 2h, 700 ℃, and the heating and cooling rate is 5 ℃/min
(2) Ar, 2h, 700 ℃, and the heating and cooling rate is 5 ℃/min
4. Pulping:
the passivation powder, water colloid, dispersant, curing agent and thickening agent are added according to a certain proportion and stirred to be mixed into uniform and stable slurry. Wherein the water can be pure water and deionized water, the mass ratio of the water is 40-65%, and the deionized water is preferably selected, and the water content is 60%; the powder accounts for 20-40%, and the preferred powder mass is 30%; the colloid is one or a mixture of more of aqueous acrylic emulsion, aqueous polyurethane emulsion, aqueous nitrile emulsion, aqueous SBS emulsion and aqueous silicone rubber emulsion, the mass percentage of the colloid is 10-15%, and the aqueous acrylic emulsion is preferably 8%; the dispersant comprises acrylate polymer, silane coupling agent, etc., and accounts for 0.5-2%, preferably dispersant acrylate polymer, the addition amount is 1%; the curing agent comprises high-temperature blocked isocyanate curing agent and low-temperature aziridine curing agent, the addition amount is 0.5-2%, and the high-temperature blocked isocyanate curing agent is preferably selected and accounts for 0.5%; the thickener includes inorganic bentonite, polyurethane thickener, and alkali swelling thickener, and is added in an amount of 1-3%, preferably polyurethane thickener, and the addition amount is 2%. The viscosity of the system is controlled within the range of 3000-.
Third, coating
And (3) blade-coating the prepared stable slurry on a coating machine to form a base band with a certain thickness and drying at a certain temperature. The thickness of the coated base band is generally 0.1-0.2mm, the drying parameter is 100 ℃, and the time is 10 min.
Fourthly, hot press forming
And (4) putting the dried base band on a flat vulcanizing machine for hot-press curing to obtain a finished product with a certain thickness to be tested. The hot pressing condition is 180 ℃ and 200 ℃ for 2 min. Typically a single layer of thickness 0.05mm, by two layers laminated to give 0.1mm, four layers laminated to give 0.2mm, and so on.
FIG. 1 shows the original powder of FeSiAl flakes, the powder of the original powder after heat treatment at 300 ℃ for 2 hours in air atmosphere, and the powder after heat treatment in air at 10% H2SEM pictures of the powder after 2h reduction treatment under the atmosphere of/Ar at 700 ℃ and EDS results of the surfaces of the flaky particles.
Firstly, comparing SEM pictures of the powder obtained under three different conditions, the appearance of the powder is not affected by heat treatment, the powder is in a flaky structure with a smooth and flat surface, and obvious cracks and holes are observed. EDS results show the O: al: si: fe ═ 2.34: 9.83: 14.81: 73.02, which is changed into O: al: si: fe ═ 4.41: 10.20: 18.06: 67.33. obviously, after air oxidation, the contents of three elements of O, Al and Si are increased, and the content of Fe is reduced. Illustrating that low temperature oxidation results in the formation of mainly Al on the surface2O3And SiO2. O: al: si: fe ═ 4.66: 11.94:18.37:65.02, the O, Si content on the surface of the material is slightly increased, the Al content is more obviously increased, and the Fe content is further reduced. This indicates that the oxidation is weak in a reducing atmosphere and Al and FeO occurxReplacement of (5) and FeOxReduction of (2).
FIG. 1(a) SEM picture and EDS results of flaky FeSiAl raw powder; (b) SEM picture and EDS result of the powder of the original powder (a) after heat treatment at 300 ℃ for 2h under air atmosphere; (c) air heat treated powder (b) at 10% H2SEM pictures and EDS results of the powder after 2h reduction at 700 ℃ under the atmosphere of/Ar.
The results of the experiments were compared between 7 groups of samples and are shown in the following table. Wherein, the high and low density indicates that the FeSiAl content in the product fluctuates. Generally, the higher the fesai content, i.e., the higher the density, the lower the resistivity, and the higher the permeability. The density of the 7 samples varied by about 13% from 2.41 to 2.73. The initial powder (sample 1) after 2h of air heat treatment at 300 deg.C (sample 2) and 700 deg.C, -0.1MPa/1325Pa (sample 3), 2h at 100MHz gave permeability values of 146.2 and 147.9, resistivity values of 108-109. Compared with the original sample, the magnetic permeability is obviously reduced by 18 percent, and the resistivity is increased by 10 percent4-105. At 700 ℃ 10% H2After reduction treatment under the condition of 2 h/Ar (sample 7 and sample 8), the resistivity was 107-108And 108-109However, the permeability was increased to 160.8 and 168.5, which were reduced by 12% and 7% compared to the original sample (sample 1). At the same time, the temperature in the experiment was 700 ℃, Ar, 2H (sample 5) and 700 ℃, 10% H2The original sample was heat treated under the conditions of/Ar, 2h (sample 6). The results showed that the resistivity was only increased to 105-106The magnetic permeability was 171.8 and 173.2, and the improvement effect of the resistivity was insignificant and the magnetic permeability was slightly decreased as compared with the original sample. It is demonstrated that effective passivation is difficult to achieve purely by virtue of the trace oxygen partial pressure in the reducing atmosphere, and the significant effect of distributed redox is also demonstrated.
In addition, the oxidation temperature and time can be controlled to further adjust the thickness of the oxide layer according to the product requirements, and the resistivity and the magnetic permeability of FeSiAl can be changed. Wherein the oxidation treatment temperature is 200-700 ℃, and the time is 0.5-12 h; the reduction temperature is 500-900 ℃, and the reduction treatment time is 0.5-12 h. The preferred oxidation temperature is 300 ℃, and the oxidation time is 2 h; preferably the reduction temperatureThe degree is 700 ℃ and the reduction time is 2 h. The reducing atmosphere may be H2/N2、H2Ar and pure H2The hydrogen concentration was 2% minimum.
In table 1, the density, resistivity, and permeability of the FeSiAl ribbon obtained by tape casting after preparing the powder under different conditions. The testing frequency is 1MHz, the testing temperature is room temperature, the thickness of the thin strip is 0.1mm, and the FeSiAl comprises the following components in percentage by mass:
TABLE 1
In summary, according to the above experimental results and the thermodynamic theory, in order to solve the problems of the FeSiAl flattened powder that the surface resistance is improved and the magnetic permeability is not reduced as much as possible, the invention develops the step-by-step redox technology to selectively generate Al on the surface of the FeSiAl2O3And SiO2Oxide layer of (2). The oxidation process is completed under the atmosphere of low temperature atmosphere or high temperature low vacuum atmosphere, so that the problems of insufficient oxygen partial pressure and insufficient and uneven oxide layer thickness in the inert gas can be effectively avoided. Then, the FeSiAl coated with a certain thickness of oxide layer contains H2Treating under inert mixed gas, reducing to above 800K, and treating with H2And the reducing capability of Al, part of FeO in the surface passivation layerxReduction to Fe and obtaining SiO2And Al2O3Of (3) a passivation layer. Therefore, the magnetic permeability can be repaired, and a passivation layer with high resistivity can be generated on the surface of the FeSiAl in situ.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A method for realizing in-situ passivation on the surface of FeSiAl powder is characterized by comprising the following steps:
selecting FeSiAl flaky particles, and performing in-situ passivation treatment on the powder by using air heat treatment and reduction heat treatment to obtain FeSiAl flattened powder;
weighing a certain amount of FeSiAl flattened powder, carrying out oxidation treatment and reduction treatment, and then pulping to obtain slurry;
scraping the slurry on a coating machine to form a base band with a preset thickness and drying the base band;
and (4) putting the dried base band on a flat vulcanizing machine for hot-press curing to obtain a finished product with a preset thickness to be tested.
2. The method for realizing in-situ passivation of the surface of FeSiAl powder according to claim 1, wherein in the step of selecting FeSiAl flaky particles:
the diameter of the FeSiAl flaky particles is 40-110um, the thickness is 1-2um, the Fe content is 85%, the Al content is 5.4%, and the Si content is 9.6%.
3. The method for realizing in-situ passivation on the surface of FeSiAl powder according to claim 1, wherein in the air heat treatment step:
the oxidation temperature is 300-700 ℃, and the oxidation time is 0.5-3 h.
4. The method for realizing in-situ passivation of the surface of FeSiAl powder according to claim 1, wherein in the step of reducing heat treatment:
by the introduction of a gas containing H2The inert gas of (1) is Ar or N2，H2The content is more than 5 percent, the reduction temperature is 500-800 ℃, and the reduction time is 0.5-3 h.
5. The method for realizing in-situ passivation of the surface of the FeSiAl powder body as claimed in claim 1, wherein the step of weighing and quantifying the FeSiAl flattened powder comprises the steps of:
the FeSiAl flattened powder is weighed by 100g and directly placed into a sintering dish after weighing.
6. The method for realizing in-situ passivation of the surface of the FeSiAl powder body according to claim 5, wherein the step of weighing and quantifying the FeSiAl flattened powder and performing oxidation treatment and reduction treatment specifically comprises the following steps:
putting the sintering dish into an air heat treatment furnace, oxidizing for 2h under the air atmosphere at the temperature of 300 ℃, and raising the temperature and reducing the temperature at the speed of 5 ℃/min;
heat treatment is carried out for 2h in a vacuum environment at 700 ℃, and the heating and cooling rate is 5 ℃/min.
7. The method for realizing in-situ passivation of the surface of the FeSiAl powder body as claimed in claim 6, wherein the step of weighing and quantifying the FeSiAl flattened powder and carrying out oxidation treatment and reduction treatment specifically comprises the following steps:
in the presence of 10% H2In Ar inert gas, the reduction time is 2h, the temperature is 700 ℃, and the heating and cooling rate is 5 ℃/min;
in Ar inert gas, the reduction time is 2h, the temperature is 700 ℃, and the heating and cooling rate is 5 ℃/min.
8. The method for realizing in-situ passivation of the surface of FeSiAl powder according to claim 1, wherein the slurry is prepared by the following steps:
adding the passivation powder obtained by oxidation treatment and reduction treatment, water, a water-based colloid, a dispersant, a curing agent and a thickening agent according to a preset proportion, and stirring and mixing to obtain uniform and stable slurry.
9. The method for realizing in-situ passivation on the surface of FeSiAl powder according to claim 8, wherein the water is pure water or deionized water, the mass ratio of the water is 40-65%, and the mass ratio of the passivation powder is 20-40%.
10. The method for realizing in-situ passivation on the surface of FeSiAl powder according to claim 9,
the water-based colloid is one or a mixture of more of water-based acrylic emulsion, water-based polyurethane emulsion, water-based nitrile emulsion, water-based SBS emulsion and water-based silicone rubber emulsion, and the mass percentage of the water-based colloid is 10-15%.
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