CN112746150A - Method for improving oxidation resistance of iron-based automobile part - Google Patents

Method for improving oxidation resistance of iron-based automobile part Download PDF

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Publication number
CN112746150A
CN112746150A CN202011553179.5A CN202011553179A CN112746150A CN 112746150 A CN112746150 A CN 112746150A CN 202011553179 A CN202011553179 A CN 202011553179A CN 112746150 A CN112746150 A CN 112746150A
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China
Prior art keywords
iron
oxidation resistance
improving
automobile part
based automobile
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CN202011553179.5A
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Chinese (zh)
Inventor
朱永福
马威
刘国军
沈涛
史惠妍
郎兴友
杨春成
金波
蒋青
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Tongling Fuxiang Copper Recycling Co ltd
Jilin University
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Tongling Fuxiang Copper Recycling Co ltd
Jilin University
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Priority to CN202011553179.5A priority Critical patent/CN112746150A/en
Publication of CN112746150A publication Critical patent/CN112746150A/en
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • 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
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
    • C23C8/12—Oxidising using elemental oxygen or ozone
    • C23C8/14—Oxidising of ferrous surfaces

Abstract

The invention relates to the technical field of metal compound antioxidant treatment, and particularly discloses a method for improving the antioxidant capacity of iron-based automobile parts2Of residual O2Reaction to form SiO2Thereby forming Fe-SiO on the surface of the FeSi alloy2The composite adhesive film is compact and stable, has high melting point, can effectively prevent the base metal from being oxidized, has simple process flow and low cost, can meet the requirement of industrial production, is environment-friendly and pollution-free, and effectively improves the quality of the composite adhesive filmThe oxidation resistance of iron and iron products solves the problem that the existing method for improving the oxidation resistance of iron-based automobile parts can not meet the requirements of industrial production and environmental protection, greatly reduces the huge loss caused by iron oxidation corrosion in industry, and has wide market prospect.

Description

Method for improving oxidation resistance of iron-based automobile part
Technical Field
The invention relates to the technical field of anti-oxidation treatment of metal compounds, in particular to a method for improving the anti-oxidation capacity of iron-based automobile parts.
Background
Corrosion is a problem that often occurs during use of metallic materials. The metal material is damaged by the action of surrounding media, so that the mechanical properties such as strength, plasticity, toughness and the like of the metal material are remarkably reduced, the physical properties such as electricity, optics and the like of a metal component are also deteriorated, and the service life of equipment is shortened. The corrosion problem is more prevalent in the automotive industry because a large number of parts are made of metal, which are susceptible to corrosion or staining from the surrounding medium. The automobile loss of every year in China reaches 1000 hundred million yuan RMB due to corrosion, wherein the corrosion of iron and products thereof, which is the most used metal, is the most serious. And as the metal yield increases and the industry develops, the economic loss tends to increase, so that research on high-temperature oxidation of iron metal is necessary to reduce the economic loss.
In view of the above problems, it is common in the current industrial production to add one or more elements such as Al, Cr, Ti, Ni, etc. to Fe to form a composite to improve the oxidation resistance of Fe and further improve the usage rate of Fe, however, the use of this process is limited due to the influence of a large amount of these alloying elements on its own properties, such as the decrease of electrical conductivity and thermal conductivity and the influence on mechanical properties, and is not suitable for the actual industrial production. For this reason, the conventional methods for preventing corrosion of metal surfaces include baking, galvanizing, and surface coating, and these methods have a good corrosion prevention effect but have many disadvantages. For example, the galvanization process causes great environmental pollution, which does not meet the environmental protection requirement; in addition, if the pretreatment before galvanization is incomplete, an oxide film workpiece appears on the surface, which can affect the normal deposition of zinc; when the temperature is too high, the coating tends to whiten and orange peel, while when the temperature is too low, the paint layer tends to flow, which adversely affects the quality of the coating on the metal surface.
Therefore, the above technical solutions have the following disadvantages in practical use: the existing method for improving the oxidation resistance of iron-based automobile parts has the problem that the method can not meet the requirements of industrial production and environmental protection at the same time.
Disclosure of Invention
The embodiment of the invention aims to provide a method for improving the oxidation resistance of iron-based automobile parts, and the method is used for solving the problem that the existing method for improving the oxidation resistance of iron-based automobile parts in the background technology cannot meet the requirements of industrial production and environmental protection at the same time. The invention develops a method for improving the oxidation resistance of iron and iron products, which has simple process flow, low cost, environmental protection and no pollution, can meet the requirements of industrial production; by the method, iron and products thereof can be effectively prevented from being oxidized at high temperature, and huge loss caused by iron oxidation corrosion in industry is greatly reduced.
In order to achieve the above purpose, the embodiments of the present invention provide the following technical solutions:
a method for improving the oxidation resistance of an iron-based automobile part comprises the following steps:
1) melting (pure) iron, and then adding (pure) silicon to carry out smelting to obtain FeSi alloy; wherein the silicon content in the FeSi alloy is 0.2-2 wt.% (mass%);
2) annealing the FeSi alloy at 600-1000 ℃ in an annealing atmosphere; wherein the annealing atmosphere is at least 1 × 102Pa-10×102Pa (preferably 5X 10)2Pa) oxygen-hydrogen mixed gas of oxygen.
Compared with the prior art, the invention has the beneficial effects that:
the method for improving the oxidation resistance of the iron-based automobile part provided by the embodiment of the invention is characterized in that the FeSi alloy is annealed in an annealing atmosphere, and Si and the annealing atmosphere H2Of residual O2Reaction to form SiO2Thereby forming Fe-SiO on the surface of the FeSi alloy2The composite adhesive film is compact and stable, has a high melting point, can effectively prevent matrix metal from being oxidized, has simple process flow and low cost, can meet the requirements of industrial production, is environment-friendly and pollution-free, effectively improves the oxidation resistance of iron and iron products, and solves the problem that the existing method for improving the oxidation resistance of iron-based automobile parts cannot meet the requirements of industrial production and environmental protection at the same time. The method can effectively prevent iron and products thereof from being oxidized at high temperature, greatly reduces huge loss caused by iron oxidation corrosion in industry, and has wide market prospect.
Drawings
FIG. 1 is a XPS etching element percentage plot of an annealed FeSi alloy in example 14 of the present invention.
FIG. 2 is an XPS analysis of the Si 2p orbital of an annealed FeSi alloy in example 14 of the present invention.
FIG. 3 is an XPS analysis of the O1 s orbital of an annealed FeSi alloy in example 14 of the present invention.
Fig. 4 is a thermogravimetric plot of an FeSi alloy provided by an embodiment of the present invention.
FIG. 5 is a surface SEM representation and elemental distribution diagram of the FeSi alloy obtained in example 12 of the present invention.
Fig. 6 is a surface SEM characterization and elemental distribution chart of the FeSi alloy obtained in example 13 of the present invention.
FIG. 7 is a surface SEM representation and elemental distribution diagram of FeSi alloy obtained in example 14 of the present invention.
FIG. 8 is a cross-sectional SEM representation and elemental distribution of FeSi alloy obtained in example 14 of the present invention.
FIG. 9 is an enlarged sectional SEM representation of the FeSi alloy of FIG. 8 obtained in example 14 of the present invention.
FIG. 10 is a diagram showing the process of oxidizing an automobile part made of FeSi alloy obtained in example 14 of the present invention at 400 ℃ for 24 hours.
Detailed Description
The invention is described in further detail below with reference to the figures and specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention. The parts not involved in the present invention can be realized by the prior art, and are not described herein.
The embodiment of the invention provides a method for improving the oxidation resistance of an iron-based automobile part, in particular to a method for improving the oxidation resistance of an iron-based automobile part based on a self-generated non-metallic oxide composite film, which comprises the following steps:
1) melting (pure) iron, and then adding (pure) silicon to carry out smelting to obtain FeSi alloy; wherein the silicon content in the FeSi alloy is 0.2-2 wt.% (mass%);
2) annealing the FeSi alloy at 600-1000 ℃ in an annealing atmosphere; wherein the annealing atmosphere is at least 1 × 102Pa-10×102Pa (preferably 5X 10)2Pa) oxygen-hydrogen mixed gas, i.e., the annealing atmosphere is hydrogen, and the amount of oxygen remaining in hydrogen is 1X 102Pa-10×102Pa (preferably 5X 10)2Pa）。
In the embodiment of the invention, the FeSi alloy is in the annealing atmosphereAnnealing at 600-1000 deg.C, according to Ehrunham diagram, the high activity of Si is firstly mixed with H of annealing atmosphere2Of residual O2Reaction to form SiO2Thereby forming Fe-SiO on the surface of the FeSi alloy2The composite adheres to the membrane, the membrane is dense, stable and high in melting point, can prevent the base metal from oxidizing effectively. And Si4+The ionic radius is 0.041nm, Fe2+The radius is 0.075nm, the oxide lattice constant formed by the Si element is small, and the diffusion of the base metal ions through the base metal ions is relatively difficult, so that the oxidation resistance of the FeSi alloy is greatly improved. The method for improving the oxidation resistance of the iron-based automobile part, provided by the invention, has the advantages of simple process flow, environmental protection and no pollution, and obviously improves the oxidation resistance of iron. Since Si is more active than Fe, the added trace element Si reacts with H under annealing conditions2Residual O in the gas2The atmosphere reacts preferentially to form a stable non-metal protective film. Fe is used as the metal with the largest consumption in industrial production, and the FeSi alloy obtained by the method can ensure that the iron product is not easily oxidized under the condition of high-temperature pure oxygen, so that the oxidation resistance of the product is improved on one hand, the reliability of related products and equipment is improved on the other hand, and the consumption caused by oxidation corrosion is reduced.
As another preferred embodiment of the invention, the annealing treatment is heating to the annealing temperature of 600-1000 ℃ in the annealing atmosphere, preserving the heat for 720-1440 min, and then cooling to the room temperature.
As another preferred embodiment of the present invention, the annealing temperature of the annealing treatment is 800-900 ℃.
As another preferred embodiment of the invention, the time of cooling is 720min-1440 min.
As another preferred embodiment of the invention, the gas flow rate of the hydrogen-oxygen mixed gas introduced during the annealing treatment is 90ml/min-150ml/min, and specifically, H is introduced during the whole annealing treatment2Gas (containing about 5X 10)2Pa oxygen).
As another preferred embodiment of the present invention, the size of the silicon is 3mm3-5mm3Particles, in particular straight cross-sectionCylindrical particles with the diameter of 3mm-5mm, large block-shaped materials are not beneficial to penetration, so that the uniformity of the alloy after smelting is poor, and the silicon size is 3-5mm3And particles are used for preventing materials from splashing during smelting and influencing the alloy composition and the alloy uniformity.
As another preferred embodiment of the invention, the smelting further comprises the step of adjusting the temperature to 1480-1490 ℃ for charged casting after the iron and the silicon are fully and uniformly mixed; and the charged pouring is pouring by adding current with power of 40kW-60kW (preferably 50 kW), cooling to room temperature after the pouring is finished, introducing gas for protection, and finishing the preparation of the FeSi alloy.
As another preferred embodiment of the present invention, the method for improving the oxidation resistance of iron-based automobile parts further comprises the step of heating the molten iron to 1510 ℃ -1550 ℃ (preferably 1520 ℃) for heat preservation before adding silicon, generally for 5 minutes for refining, and the purpose of the method is further homogenization, degassing and impurity removal of the charge. And after refining is finished, stopping power supply and reducing the temperature, so that the temperature of the furnace burden is reduced to a surface film. The film was then melted by the application of electricity, whereupon granular (pure) silicon was added to the charge. Silicon element should be added as slowly as possible in the ferrosilicon alloying process to prevent splashing and ensure the accuracy of the alloy components.
In another preferred embodiment of the present invention, the refining is repeated 3 to 5 times, and the purpose of the refining is to further homogenize the charge, remove gas and impurities, and ensure a high-purity alloy with uniform components.
As another preferred embodiment of the present invention, the method for improving the oxidation resistance of the iron-based automobile part further comprises the step of stamping the prepared FeSi alloy before the annealing treatment, specifically, the prepared FeSi alloy is made into the automobile part by stamping, and the stamped automobile part is firstly mechanically polished by sand paper to reduce the roughness of the surface of the workpiece, so as to obtain a bright and flat surface. And then, sequentially putting the polished metal sheet into acetone and ethanol for ultrasonic cleaning to remove oil stains and fine impurity particles on the surface. And then, putting the ultrasonically cleaned automobile parts into electrolyte for electrolytic polishing, and ultrasonically cleaning the automobile parts subjected to electrolytic polishing once by using ethanol. In order to facilitate subsequent annealing and carry out various experimental tests, the FeSi alloy can be pressed into a 0.5mm metal sheet, and then a metal wafer with the diameter of 4mm is manufactured by a puncher.
As another preferred embodiment of the present invention, the mechanical polishing is to polish to 3000 mesh with sand paper, or vibration polishing may be used for 1 h; the electrolyte for electrolytic polishing is a mixed solution of perchloric acid and acetic acid, and the volume ratio of the perchloric acid to the acetic acid is (1-3): (9-7).
As another preferred embodiment of the present invention, the method for improving the oxidation resistance of the iron-based automobile part further comprises a step of washing before annealing, specifically, the punched FeSi alloy is placed in a sealed environment (generally, the punched FeSi alloy is placed in a quartz boat, then, the placed quartz boat is placed in a constant temperature area of a tube furnace), the pressure is pumped to be not more than-0.1 atm, then, an inert protective gas is introduced to be normal atmospheric pressure, the operation is generally repeated for 3 to 5 times, H is introduced after the last washing and vacuum pumping, and the like2To slightly above normal atmospheric pressure to prevent suck-back during ventilation.
As another preferred embodiment of the present invention, the inert shielding gas may be helium, neon, argon, krypton, xenon, radon, etc., which are selected according to the requirement and are not limited herein. Here, preferably, the inert shielding gas is argon, the annealing temperature is 800 deg.C, the temperature reduction time is 720min, and H is introduced2The flow rate of the gas was 90 ml/min.
As another preferred embodiment of the invention, a sample obtained after annealing treatment of the FeSi alloy at 600-1000 ℃ in an annealing atmosphere is oxidized for 120min at 400 ℃ under the condition of pure oxygen, and the weight gain is 0.02733mg/cm2-0.14694mg/cm2The lowest weight gain was 0.0335%.
The embodiment of the invention also provides an iron product prepared by the method for improving the oxidation resistance of the iron-based automobile part.
The embodiment of the invention also provides application of the method for improving the oxidation resistance of the iron-based automobile part in corrosion prevention of iron products and/or iron-based alloy products. For example, it may be corrosion protection of iron-based automobile parts.
As another preferred embodiment of the invention, compared with the common use of adding one or more elements such as Al, Cr, Ti, Ni and the like into Fe to form a compound to improve the corrosion resistance and further improve the utilization rate of Fe in the current industrial production, the embodiment of the invention improves the oxidation resistance of Fe by adding Si element into Fe and improves the oxidation resistance of Fe by adding H element into H element2The pretreatment or annealing is carried out at higher temperature in the gas, so that Fe-SiO is formed on the surface of the alloy2Composite adhesion film, formed SiO2The protective film is compact and stable, has high melting point, and can effectively prevent the base metal from being oxidized. Furthermore, the electrical conductivity, thermal conductivity and mechanical properties are less affected.
The technical effect of the method for improving the oxidation resistance of an iron-based automobile part according to the present invention will be further described below by referring to specific examples.
Example 1
A method for improving the oxidation resistance of an iron-based automobile part comprises the following steps:
1) melting pure iron, and then adding pure silicon for smelting to obtain FeSi alloy; wherein the silicon content in the FeSi alloy is 0.2 wt.%.
2) Annealing the FeSi alloy at 600 ℃ in an annealing atmosphere to obtain the FeSi alloy; wherein the annealing atmosphere is 1 × 10 residue2Pa oxygen.
Example 2
A method for improving the oxidation resistance of an iron-based automobile part comprises the following steps:
1) melting pure iron, and then adding pure silicon for smelting to obtain FeSi alloy; wherein the silicon content in the FeSi alloy is 2 wt.%.
2) Annealing the FeSi alloy at 1000 ℃ in an annealing atmosphere to obtain the FeSi alloy; wherein the annealing atmosphere is 10 × 10 residues2Pa oxygen.
Example 3
Compared with example 1, except that the annealing atmosphere is 5X 102Of oxygen PaThe procedure was repeated in the same manner as in example 1 except for using hydrogen gas.
Example 4
The same as example 1 except that the silicon content in the FeSi alloy was 0.5wt.% as compared to example 1.
Example 5
The same as example 1 except that the silicon content in the FeSi alloy was 1.0wt.% compared to example 1.
Example 6
Compared with example 1, except that the annealing atmosphere contains 2X 102The rest of the atmosphere of the mixture of Pa and oxygen was the same as in example 1.
Example 7
Compared with example 1, except that the annealing atmosphere contains 8 × 102The rest of the atmosphere of the mixture of Pa and oxygen was the same as in example 1.
Example 8
A method for improving the oxidation resistance of an iron-based automobile part comprises the following steps:
1) melting pure iron, and then adding pure silicon for smelting to obtain FeSi alloy; wherein the silicon content in the FeSi alloy is 1 wt.%.
2) Annealing the FeSi alloy at 800 ℃ in an annealing atmosphere, specifically heating the FeSi alloy to 800 ℃ in the annealing atmosphere, preserving the heat for 720min, and then cooling to room temperature for 720 min; wherein the annealing atmosphere is 5 × 102Pa oxygen.
Example 9
A method for improving the oxidation resistance of an iron-based automobile part comprises the following steps:
1) melting pure iron, and then adding pure silicon for smelting to obtain FeSi alloy; wherein the silicon content in the FeSi alloy is 1 wt.%.
2) Annealing the FeSi alloy at 900 ℃ in an annealing atmosphere, specifically heating the FeSi alloy to 900 ℃ in the annealing atmosphere, preserving the heat for 1440min, and then cooling to room temperature for 1440 min; wherein the annealing atmosphere is 5 × 102Pa oxygenHydrogen gas of gas.
Example 10
A method for improving the oxidation resistance of an iron-based automobile part comprises the following steps:
1) melting pure iron, and then adding pure silicon for smelting to obtain FeSi alloy; wherein the silicon content in the FeSi alloy is 1 wt.%.
2) Annealing the FeSi alloy at 850 ℃ in an annealing atmosphere, specifically heating the FeSi alloy to the annealing temperature of 850 ℃ in the annealing atmosphere, preserving the heat for 1080min, and then cooling to room temperature for 1080 min; wherein the annealing atmosphere is 5 × 102Pa oxygen.
Example 11
A method for improving the oxidation resistance of an iron-based automobile part comprises the following steps:
a. pure Si with the purity of 99.99wt.% and pure Fe with the purity of 99.9wt.% are correspondingly placed with the mass fraction of 0.2wt.% and the mass fraction of 99.8wt.% so as to smelt FeSi alloy with the Si content of 0.2 wt.%.
b. Respectively placing pure Fe and the ingot mould at corresponding positions of a vacuum smelting furnace, then closing a furnace door, and pumping the furnace body to a low vacuum of-0.1 atm. After the furnace burden is completely melted, the temperature is raised to 1520 ℃ or so, and the refining is carried out after the heat preservation for 5 minutes, so that the aim of further homogenizing the furnace burden, degassing and removing impurities is fulfilled. And after refining is finished, stopping power supply and reducing the temperature, so that the temperature of the furnace burden is reduced to a surface film. The film was then melted by electrical conduction, at which time granular pure Si was added to the charge. The silicon element should be added as slowly as possible in the alloying process to prevent splashing and ensure the accuracy of the alloy components.
c. When the pure Si and the pure Fe are completely and uniformly added, the temperature of the molten liquid is adjusted to 1480-1490 ℃ for pouring, and 50kW of power is added for carrying out charged pouring during pouring. And after the casting is finished, cooling to room temperature, introducing gas, and finishing the preparation of the FeSi alloy.
d. And stamping the prepared FeSi alloy into an automobile part. Firstly, grinding the automobile parts to 3000 meshes by using sand paper, and mechanically polishing to reduce the surface roughness of the workpiece so as to obtain a bright and flat surface. And then, sequentially putting the polished metal sheet into acetone and ethanol for ultrasonic cleaning to remove oil stains and fine impurity particles on the surface. And then, putting the ultrasonically cleaned metal sheet into an electrolyte prepared by mixing perchloric acid and acetic acid according to a ratio of 1:9 for electrolytic polishing, and ultrasonically cleaning the electrolytically polished metal sheet by using ethanol. In order to facilitate subsequent annealing and various experimental tests, the alloy can be pressed into a 0.5mm metal sheet, and then a 4mm diameter metal disc can be made by a puncher.
e. Firstly, the punched automobile parts are placed in a quartz boat. Subsequently, the mounted quartz boat was placed in a constant temperature zone of a tube furnace. Then, gas washing is carried out, the tube furnace is pumped to-0.1 atm, then inert protective gas argon is introduced to normal atmospheric pressure, then the operation is repeated for 3-5 times, and H is introduced after the last gas washing and the vacuum pumping2To slightly above normal atmospheric pressure to prevent suck-back during ventilation. After the gas washing is finished, H is introduced into the tubular furnace according to a certain gas flow velocity2. Then heating the tube furnace to the annealing temperature 800 ℃ preset in the experiment, and keeping the temperature for 1440 min; the cooling time is 720min, and the annealing treatment is completed. H is introduced into the whole annealing process2Gas (H)2The residual oxygen amount in the reaction system is 5 x 102Pa), the gas flow rate was 90 ml/min.
Example 12
A method for improving the oxidation resistance of an iron-based automobile part comprises the following steps:
a. pure Si with the purity of 99.99wt.% and pure Fe with the purity of 99.9wt.% are correspondingly placed with the mass fraction of 0.5wt.% and the purity of 99.5wt.% in order to smelt FeSi alloy with the Si content of 0.5 wt.%.
b. Respectively placing pure Fe and the ingot mould at corresponding positions of a vacuum smelting furnace, then closing a furnace door, and pumping the furnace body to a low vacuum of-0.1 atm. After the furnace burden is completely melted, the temperature is raised to 1520 ℃ or so, and the refining is carried out after the heat preservation for 5 minutes, so that the aim of further homogenizing the furnace burden, degassing and removing impurities is fulfilled. And after refining is finished, stopping power supply and reducing the temperature, so that the temperature of the furnace burden is reduced to a surface film. The film was then melted by electrical conduction, at which time granular pure Si was added to the charge. The silicon element should be added as slowly as possible in the alloying process to prevent splashing and ensure the accuracy of the alloy components.
c. When the pure Si and the pure Fe are completely and uniformly added, the temperature of the molten liquid is adjusted to 1480-1490 ℃ for pouring, and 50kW of power is added for carrying out charged pouring during pouring. And after the casting is finished, cooling to room temperature, introducing gas, and finishing the preparation of the FeSi alloy.
d. And stamping the prepared FeSi alloy into an automobile part. Firstly, grinding the automobile parts to 3000 meshes by using sand paper, and mechanically polishing to reduce the surface roughness of the workpiece so as to obtain a bright and flat surface. And then, sequentially putting the polished metal sheet into acetone and ethanol for ultrasonic cleaning to remove oil stains and fine impurity particles on the surface. And then, putting the ultrasonically cleaned metal sheet into an electrolyte prepared by mixing perchloric acid and acetic acid according to a ratio of 1:9 for electrolytic polishing, and ultrasonically cleaning the electrolytically polished metal sheet by using ethanol. In order to facilitate subsequent annealing and various experimental tests, the alloy can be pressed into a 0.5mm metal sheet, and then a 4mm diameter metal disc can be made by a puncher.
e. Firstly, the punched automobile parts are placed in a quartz boat. Subsequently, the mounted quartz boat was placed in a constant temperature zone of a tube furnace. Then, gas washing is carried out, the tube furnace is pumped to-0.1 atm, then inert protective gas argon is introduced to normal atmospheric pressure, then the operation is repeated for 3-5 times, and H is introduced after the last gas washing and the vacuum pumping2To slightly above normal atmospheric pressure to prevent suck-back during ventilation. After the gas washing is finished, H is introduced into the tubular furnace according to a certain gas flow velocity2. Then heating the tube furnace to the annealing temperature 800 ℃ preset in the experiment, and keeping the temperature for 1440 min; the cooling time is 720min, and the annealing treatment is completed. H is introduced into the whole annealing process2Gas (H)2The residual oxygen amount in the reaction system is 5 x 102Pa), the gas flow rate was 90 ml/min.
Example 13
The procedure of example 11 was repeated, except that pure Si with a purity of 99.99wt.% in a mass fraction of 1wt.% in granular form was placed corresponding to pure Fe with a purity of 99.9wt.% in a mass fraction of 99wt.%, so as to melt a FeSi alloy with a Si content of 1 wt.%.
Example 14
The procedure of example 11 was repeated, except that pure Si having a purity of 99.99wt.% in a mass fraction of 2wt.% in granular form was placed corresponding to pure Fe having a purity of 99.9wt.% in a mass fraction of 98wt.%, so as to melt a FeSi alloy having a Si content of 2 wt.%.
Example 15
Compared with example 11, except that pure Si is 3mm in size3And the cross-sectional diameter of the cylindrical pellet was 3mm, the same as in example 11.
Example 16
Compared with example 11, except that pure Si is 5mm in size3And the same as example 11 except for the cylindrical pellets having a cross-sectional diameter of 5 mm.
Example 17
Compared with example 11, except that pure Si is 4mm in size3And the same as example 11 except for cylindrical pellets having a cross-sectional diameter of 4 mm.
Example 18
The same as example 11 except that the gas flow rate was 100ml/min, as compared with example 11.
Example 19
The same as example 11 except that the gas flow rate was 120ml/min, as compared with example 11.
Example 20
The same as example 11 except that the gas flow rate was 150ml/min, as compared with example 11.
Example 21
Compared with the embodiment 11, except that the electrolyte for electrolytic polishing is a perchloric acid and acetic acid mixed solution, the volume ratio of perchloric acid to acetic acid is 1: except for 7, the procedure was the same as in example 11.
Example 22
Compared with the embodiment 11, except that the electrolyte for electrolytic polishing is a perchloric acid and acetic acid mixed solution, the volume ratio of perchloric acid to acetic acid is 3: except for 9, the procedure was the same as in example 11.
Example 23
Compared with the embodiment 11, except that the electrolyte for electrolytic polishing is a perchloric acid and acetic acid mixed solution, the volume ratio of perchloric acid to acetic acid is 3: except for 7, the procedure was the same as in example 11.
Example 24
Compared with the embodiment 11, except that the electrolyte for electrolytic polishing is a perchloric acid and acetic acid mixed solution, the volume ratio of perchloric acid to acetic acid is 2: the procedure of example 11 was repeated except for 8.
Example 25
The annealed FeSi alloy in example 14 (i.e., the FeSi alloy with a Si content of 2 wt.%) was subjected to XPS characterization, specifically, elemental depth analysis was performed by a photoelectron spectroscopy (XPS), and the characterization results are shown in fig. 2 and 3, where fig. 2 is an XPS analysis graph of Si 2p orbital, the obtained peak value is 103.5eV, fig. 3 is an XPS analysis graph of O1 s orbital, the obtained peak value is 532.65eV, and the corresponding binding energy and SiO energy are both2The binding energy is consistent, so that SiO is considered to exist on the surface of the alloy2。
In order to further determine the composition of the alloy surface, the FeSi alloy subjected to annealing treatment in example 14 was etched 12 times, the etching speed was 9nm/s, the etching time was 25s, 50s, 100s, 150s, 200s, 300s, 450s, 600s, 900s, 1200s, 1800s, 2400s, respectively, and the element content of each etching was obtained, and a specific XPS etching element percentage chart of the FeSi alloy is shown in fig. 1. It can be seen that the etching time of 300s only contains Si element and O element, no iron element appears, and the content of the Fe element begins to increase gradually with the increase of the etching time, which shows that a layer of SiO with the thickness of about 2700nm is formed on the surface of the alloy2A film.
Example 26
Thermogravimetric analysis was performed on the FeSi alloys annealed in examples 11, 12, 13 and 14, and Pure iron (Pure Fe) was used as a control, specifically, a sample was placed at a high temperature of 400 ℃ and Pure oxygen gas was introduced, so that weight changes before and after oxidation of the sample of each component were obtained, and the obtained thermogravimetric curves are shown in fig. 4. The weight gain of pure iron after oxidation for 120min is 2.01069mg/cm2Examples 11, 12, 13 and 1314 the weight gain of the FeSi alloy is 0.14694mg/cm2、0.12597mg/cm2、0.07321mg/cm2、0.02733mg/cm2. The weight gain of the FeSi alloy obtained in example 14 is only 1.3% of the weight gain of pure iron, indicating that the oxidation resistance of the FeSi alloy obtained by the present invention is very significantly improved, and the oxidation resistance of the FeSi alloy is enhanced with the increase of the content of Si element.
Example 27
The surfaces of the FeSi alloys of examples 12 to 14, which were annealed respectively, were subjected to SEM-EDS (scanning Electron microscope and X-ray energy Dispersion spectrometer) characterization, and the results of the characterization are shown in FIGS. 5 to 7. Fig. 5 is an SEM image (upper left diagram in fig. 5) and an elemental distribution diagram obtained for the FeSi alloy with Si content of 0.5wt.% in example 12, fig. 6 is an SEM image (upper left diagram in fig. 6) and an elemental distribution diagram obtained for the FeSi alloy with Si content of 1wt.% in example 13, and fig. 7 is an SEM image (upper left diagram in fig. 7) and an elemental distribution diagram obtained for the FeSi alloy with Si content of 2wt.% in example 14.
As can be seen from fig. 5, the surface oxide film of the FeSi alloy having an Si content of 0.5wt.% is loose and porous, and has a significant exfoliation phenomenon. This is because the Si content is low and complete SiO cannot be formed2The thin film cannot prevent the oxidation reaction between oxygen and the substrate, thereby resulting in poor oxidation resistance. As can be seen from fig. 6, the oxide film formed on the surface of the FeSi alloy having the Si content of 1wt.% in example 13 is relatively intact but many particles are present. This is because, although the Si content is increased, it is not sufficient to completely form SiO on the surface2Oxide film, however Fe is hindered due to increase of Si content2+Out-diffusion of Fe2+Can only be on SiO2The defective portions, such as grain boundaries, are diffused outward, thereby forming many granular Fe oxides. As can be seen from FIG. 7, the FeSi alloy of example 14, which has an Si content of 2wt.%, has SiO formed on the surface thereof2The oxidation film is complete, continuous and compact, effectively isolates the contact of oxygen and a matrix, prevents and slows down oxidation reaction, and has lower oxidation rate and better oxidation resistance.
Example 28
The cross section of the FeSi alloy obtained in example 14 is subjected to SEM-EDS characterization, and the characterization result is shown in figure 8, and the SEM image is the upper left image in figure 8). FIG. 9 is an enlarged sectional SEM representation of the FeSi alloy of FIG. 8 obtained in example 14 of the present invention. According to the element distribution at the section, the obvious aggregation of Si element and O element on the alloy surface can be seen, and continuous and compact SiO is formed2And (5) oxidizing the film.
Example 29
The process of stamping the FeSi alloy obtained in example 14 into a shoe shaped axle damper automotive part and oxidizing at 400 c for 24h and 400 c for 24h is shown in fig. 10. In fig. 10, fig. b is a picture of the shoe-shaped shaft baffle automobile part stamped from the FeSi alloy obtained in example 14, and fig. a is a picture of the shoe-shaped shaft baffle automobile part stamped from pure iron under the same conditions after oxidation in air at 400 ℃ for 24 hours; FIG. c is a photograph of an automobile component stamped into a shoe shaped axle shield from the FeSi alloy of example 14 after oxidation in air at 400 ℃ for 24 hours. The pure iron automobile parts are obviously blackened and oxidized, the treated FeSi alloy automobile parts are not obviously changed after being oxidized, and the oxidation resistance is obviously improved.
In the above embodiments of the present invention, in order to solve the problems in the background art, a method for improving the oxidation resistance of an iron-based automobile part is provided, in which a trace element Si is added to Fe based on the Wanger theory to form a composite oxide film on the surface of Fe, thereby improving the oxidation resistance of Fe. The method comprises the steps of repeatedly smelting trace Si and Fe in a vacuum smelting furnace according to a certain proportion to obtain FeSi alloy; the prepared sample is placed in a tube furnace, and H is introduced2The atmosphere is used as a protective gas, annealing treatment is carried out at 800-1000 ℃, the activity of Si is high, and the Si and the annealing atmosphere are firstly H2Of residual O2Reaction to form SiO2Thereby forming Fe-SiO on the surface of the FeSi alloy2The composite is attached to the film, so that the iron and the iron product can be effectively prevented from being oxidized at high temperature, and huge loss caused by iron oxidation corrosion in industry is greatly reduced.
Moreover, the Si element is very rich in the earth crust,the method for improving the oxidation resistance of the iron-based automobile part provided by the invention meets the requirement of reducing the cost in industrial production and can meet the requirement of industrial production development only after the content of the O element, the yield is rich and the cost is low. The iron-silicon alloy is an important magnetic material for manufacturing generators, transformers, relays, motors and other electrical equipment, has good magnetic performance, small saturated magnetostriction coefficient and small sensitivity of magnetism to temperature change, vibration, stress and the like. Namely, the iron-silicon alloy provided by the invention has higher performance stability, is suitable for being used in special environments, and is improved by being used in H2The pretreatment or annealing is carried out at higher temperature in the gas, so that Fe-SiO is formed on the surface of the alloy2Composite adhesion film, formed SiO2The protective film is compact and stable, has high melting point, and can effectively prevent the base metal from being oxidized. And Si4+The ionic radius is 0.041nm, Fe2+The radius is 0.075nm, the oxide lattice constant formed by the Si element is small, and the diffusion of the base metal ions through the oxide lattice constant is relatively difficult, so that the oxidation resistance of the iron-silicon alloy is greatly improved.
While the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the knowledge of those skilled in the art. In particular, the various features of the embodiments disclosed herein may be used in any combination as long as there is no conflict, and the failure to exhaustively describe such combinations in this specification is merely for brevity and resource saving, and not necessarily for all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.

Claims (9)

1. A method for improving the oxidation resistance of an iron-based automobile part is characterized by comprising the following steps:
1) melting iron, and then adding silicon to carry out smelting to obtain FeSi alloy; wherein the silicon content in the FeSi alloy is 0.2-2 wt.%;
2) annealing the FeSi alloy at 600-1000 ℃ in an annealing atmosphere; wherein the annealing atmosphere is at least 1 × 102Pa-10×102Pa oxygen and hydrogen mixed gas.
2. The method for improving the oxidation resistance of an iron-based automobile part according to claim 1, wherein in the method for improving the oxidation resistance of the iron-based automobile part, the annealing treatment is heating to an annealing temperature of 600-1000 ℃ in an annealing atmosphere, keeping the temperature for 720-1440 min, and then cooling to room temperature.
3. The method for improving the oxidation resistance of the iron-based automobile part as claimed in claim 1, wherein in the method for improving the oxidation resistance of the iron-based automobile part, the gas flow rate of the hydrogen-oxygen mixed gas introduced during the annealing treatment is 90ml/min to 150 ml/min.
4. The method for improving the oxidation resistance of an iron-based automobile part as claimed in claim 1, wherein in the method for improving the oxidation resistance of an iron-based automobile part, the silicon is 3mm3-5mm3The granules have a cross-sectional diameter of 3-5 mm.
5. The method for improving the oxidation resistance of an iron-based automobile part according to claim 1, wherein the smelting further comprises the step of adjusting the temperature to 1480-1490 ℃ for hot-line casting after uniformly mixing iron and silicon in the method for improving the oxidation resistance of an iron-based automobile part.
6. The method for improving the oxidation resistance of an iron-based automobile part as claimed in claim 1, further comprising the step of heating the molten iron to 1510 ℃ -1550 ℃ for heat preservation before adding the silicon.
7. The method for improving the oxidation resistance of an iron-based automobile part as claimed in claim 1, further comprising the step of stamping the FeSi alloy before the annealing treatment.
8. The method for improving the oxidation resistance of the iron-based automobile part as claimed in claim 7, further comprising a step of performing gas washing before the annealing treatment, specifically, placing the stamped FeSi alloy in a sealed environment, pumping to a pressure of not more than-0.1 atm, and introducing an inert protective gas.
9. The method for improving the oxidation resistance of the iron-based automobile part as claimed in claim 1, wherein the weight gain of a sample obtained after annealing treatment of the FeSi alloy at 600-1000 ℃ in an annealing atmosphere after oxidation at 400 ℃ for 120min under pure oxygen condition is 0.02733mg/cm2-0.14694mg/cm2。
CN202011553179.5A 2020-12-24 2020-12-24 Method for improving oxidation resistance of iron-based automobile part Pending CN112746150A (en)

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CN105051231A (en) * 2013-03-29 2015-11-11 株式会社神户制钢所 Steel material having excellent corrosion resistance and excellent magnetic properties and production method therefor
CN105950960A (en) * 2016-05-04 2016-09-21 武汉钢铁股份有限公司 Non-oriented silicon steel for drive motor of electric automobile and preparation method thereof
CN108286021A (en) * 2018-03-27 2018-07-17 东北大学 A kind of preparation method of non-oriented silicon steel with high magnetic induction plate
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CN1288070A (en) * 2000-08-31 2001-03-21 武汉钢铁(集团)公司 Series electrical steel used for high efficiency motor iron core
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