Method for improving corrosion resistance of iron-based metal

Abstract

A method for improving corrosion resistance of iron-based metal relates to the field of corrosion resistance of industrial metal consumables, and comprises the following steps: placing pure iron particles in a vacuum melting furnace, vacuumizing, introducing argon, introducing circulating cooling water, repeatedly melting Ti ingots to remove oxygen before melting the pure iron particles, and melting the pure iron particles to obtain pure iron; then pure iron with a smooth surface is obtained through rolling, grinding and polishing treatment; the method comprises the steps that pure iron is mixed with a zinc-aluminum impregnation agent and a dispersing agent, the mixture is placed in a rotary furnace to be subjected to rotary thermal diffusion zinc-aluminum impregnation, after slow cooling is conducted, a corrosion-resistant metal product containing a zinc-aluminum impregnation layer is obtained, argon is introduced in the rotary thermal diffusion zinc-aluminum impregnation process to serve as shielding gas, and the introduced shielding gas is purified through a deoxidizing device. According to the method, the problems that an embedding method in an existing powder zinc impregnation technology is low in zinc impregnation efficiency, poor in infiltrated layer quality and single in anti-corrosion mechanism are solved, and the thermal diffusion zinc impregnation efficiency, the thermal diffusion infiltrated layer quality and the corrosion resistance of metal products are improved.

Description

Technical Field

[0001] The invention relates to the technical field of anti-corrosion of industrial metal consumables, and in particular to a method for improving the corrosion resistance of iron-based metals. Background Art

[0002] In modern industry, steel materials are widely used. During service, metals will fail under the influence of the surrounding environment. There are three common forms of failure: fracture, corrosion and wear. Among them, corrosion and wear often occur together, and fracture often occurs at the same time as corrosion, which is difficult to distinguish. Among several common forms of damage, corrosion is an important form of damage that affects the service life of metals. When metals are corroded in the natural environment, chemical or electrochemical multiphase reactions will occur on the metal surface or interface, resulting in the oxidation of metal atoms into ionic states. Under natural conditions, metal materials and products will be corroded due to the influence of the environmental media in which they are located, thus causing direct or indirect economic losses to the national economy. The damage caused by corrosion is widespread in all fields, from daily life to industrial and agricultural production, from cutting-edge high-tech to practical engineering applications. Wherever metals exist, corrosion problems are always inevitable, and the economic losses caused are huge, and in engineering applications, the destructive consequences are particularly serious.

[0003] Powder zincizing technology uses the principle of metal atom diffusion during heat treatment to immerse steel parts in zinc powder. During the heat treatment process, a continuous and dense zinc-iron alloy protective layer is formed by the thermal diffusion movement of zinc atoms and iron atoms, thereby playing a corrosion-resistant role. However, the traditional embedding method has technical problems such as low zincizing efficiency, poor quality of the zinc layer, and a single anti-corrosion mechanism. Summary of the invention

[0004] In order to solve the problems of low sherardizing efficiency, poor sherardizing layer quality and single anti-corrosion mechanism in the embedding method in the existing powder sherardizing technology, the present invention provides a method for improving the corrosion resistance of iron-based metals.

[0005] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0006] The present invention provides a method for improving the corrosion resistance of iron-based metals, which mainly comprises the following steps:

[0007] Step 1, weighing pure iron particles and zinc-aluminum infiltration agent;

[0008] Step 2: placing the pure iron particles in a vacuum melting furnace, evacuating the furnace, passing argon gas, and circulating cooling water;

[0009] Step 3: Before smelting the pure iron particles, repeatedly smelt the Ti ingots to deoxidize, and then smelt the pure iron particles to obtain pure iron ingots;

[0010] Step 4: rolling, grinding, polishing, cleaning and drying the pure iron ingot to obtain pure iron with a smooth surface;

[0011] Step 5: After mixing pure iron, zinc-aluminum infiltrant and dispersant, place the mixture in a rotary furnace for rotary thermal diffusion zinc-aluminum infiltration, and obtain a corrosion-resistant metal product containing a zinc-aluminum layer after cooling; during the rotary thermal diffusion zinc-aluminum infiltration process, argon gas is introduced as a protective gas and the introduced argon gas is purified.

[0012] As a preferred implementation, in step 1, in the zinc-aluminum infiltrant, the mass fraction of Zn is 75wt%, and the mass fraction of Al is 25wt%.

[0013] As a preferred embodiment, in step 2, the vacuum melting furnace is first evacuated to 10 -1 Pa low vacuum environment, introduce high-purity argon gas, and repeat the purge operation for more than 5 times to minimize the oxygen concentration; then evacuate the vacuum melting furnace to 10 - 4 Pa high vacuum environment is used to exhaust all oxygen in the vacuum melting furnace; finally, argon gas is introduced to balance the atmospheric pressure so that the argon gas protects the environment throughout the melting process.

[0014] As a preferred embodiment, in step three, when the pure iron particles are smelted, each surface of each sample is smelted 3 to 5 times, each time for 45 seconds to 1 minute.

[0015] As a preferred embodiment, in step 4, the pure iron ingot is first made into an iron sheet with a thickness of 7mm-8mm, and then sanded with 240-5000 mesh sandpaper.

[0016] Mechanical grinding and polishing were performed, and finally ultrasonic cleaning was performed with alcohol.

[0017] As a preferred embodiment, in step five, the dispersant is aluminum oxide powder.

[0018] As a preferred embodiment, in step five, when rotary thermal diffusion zinc-aluminum is performed, the rotation speed of the rotary kiln is 700 rpm-900 rpm, the thermal diffusion temperature is 380°C-440°C, and the thermal diffusion insulation time is 220min-260min.

[0019] As a preferred embodiment, in step five, when cooling, the cooling rate is 1°C / min-2°C / min, and the cooling rate is 5°C / min-8°C / min.

[0020] As a preferred embodiment, in step 5, the specific operation steps for purifying the introduced argon gas are as follows: firstly, the argon gas is introduced into a tubular furnace filled with oil-free graphite particles, and then the purified high-purity argon gas is introduced into a rotary furnace; the gas flow rate when introducing the argon gas is 250 cm 3 / min-350cm 3 / min; the insulation temperature of the tubular furnace is 500°C-700°C, and the insulation time is 500min-700min.

[0021] Beneficial effects of the present invention:

[0022] The present invention places pure iron particles in a vacuum smelting furnace, performs vacuuming, argon gas passing, circulating cooling water treatment, repeatedly melts Ti ingots to deoxidize before smelting the pure iron particles, and then smelts the pure iron particles to obtain pure iron; then, pure iron with a smooth surface is obtained through rolling, grinding, and polishing treatment; then, the pure iron is mixed with a zinc-aluminum infiltrant and a dispersant and placed in a rotary furnace for rotary thermal diffusion zinc-aluminum infiltration, and after slowly cooling, a corrosion-resistant metal product containing a zinc-aluminum infiltration layer is obtained, and argon gas is introduced as a protective gas during the rotary thermal diffusion zinc-aluminum infiltration process, and the introduced protective gas is purified by a deoxygenation device.

[0023] The present invention adopts a mechanical energy rotational thermal diffusion aluminizing method and introduces argon as a protective gas to improve the efficiency of thermal diffusion zinc infiltration and the quality of the thermal diffusion infiltration layer, and adopts a Zn-Al co-infiltration method to form a dense Al2O3 film on the surface of a pure iron substrate on the basis of a traditional single zinc infiltration layer, which effectively hinders the occurrence of corrosion, improves corrosion resistance, and is conducive to expanding its scope of application.

[0024] In addition, the present invention also provides the best thermal diffusion temperature (440°C) under the method, and prepares a metal product with high quality zinc-aluminum infiltration layer, good corrosion resistance and smooth microscopic surface. The thermal diffusion infiltration layer of the metal product prepared by the present invention is composed of an Al2O3 film with high corrosion resistance on the surface and a Fe-Zn infiltration layer, which effectively enriches the anti-corrosion mechanism in the corrosion process and effectively improves the corrosion resistance of the metal product. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The high-magnification surface morphology image and EDS image of the iron-based thermal diffusion zinc-aluminum metal at 440°C in Example 1 of the present invention;

[0026] Figure 2 The high-magnification surface morphology image and EDS image of the iron-based thermal diffusion zinc-aluminum metal at 380°C in Comparative Example 1 of the present invention;

[0027] Figure 3 This is a high-magnification surface morphology image and EDS image of the iron-based thermal diffusion zinc-aluminum metal at 400°C in Comparative Example 1 of the present invention;

[0028] Figure 4 The high-magnification surface morphology image and EDS image of the iron-based thermal diffusion zinc-aluminum metal at 420°C in Comparative Example 1 of the present invention;

[0029] Figure 5 The SEM cross-sectional characterization image of the iron-based thermal diffusion zinc-plated aluminum metal obtained in Comparative Examples 1-3 and Example 1 of the present invention;

[0030] Figure 6 The surface morphology of the iron-based thermal diffusion zinc-plated aluminum metal obtained in Comparative Examples 1-3 and Example 1 of the present invention after corrosion for 3 days;

[0031] Figure 7 The AC impedance spectra of the iron-based thermal diffusion zinc-plated aluminum metals obtained in Comparative Examples 1-3 and Example 1 of the present invention after corrosion for 3 days;

[0032] Figure 8 The AC impedance spectra of the iron-based thermal diffusion zinc-plated aluminum metals obtained in Comparative Examples 1-3 and Example 1 of the present invention after 14 days of corrosion;

[0033] Fig. 9 The XRD patterns of the iron-based thermal diffusion zinc-aluminum metals after corrosion obtained in Comparative Examples 1-3 and Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The present invention provides a method for improving the corrosion resistance of iron-based metals, and the specific implementation process is as follows:

[0035] Step 1: Weigh a certain mass of pure iron particles and zinc-aluminum infiltrant; wherein, in the zinc-aluminum infiltrant, the mass fraction of Zn is preferably 75wt%, and the mass fraction of Al is preferably 25wt%, but not limited thereto. wherein, the particle size of the zinc-aluminum infiltrant is preferably 250-350 meshes.

[0036] Step 2: Place the pure iron particles in a vacuum melting furnace, evacuate the furnace, pass argon gas, and circulate cooling water; specifically, first evacuate the furnace to 10 -1 Pa low vacuum environment, introduce high-purity argon gas, and repeat the purge operation for more than 5 times to minimize the oxygen concentration; then evacuate the vacuum melting furnace to 10 -4 Pa high vacuum environment is used to exhaust all oxygen in the vacuum melting furnace; finally, argon gas is introduced to balance the atmospheric pressure so that the argon gas protects the environment throughout the melting process.

[0037] Step 3: Before smelting the pure iron particles, repeatedly smelt the Ti ingot to deoxidize, and then smelt the pure iron particles to obtain pure iron ingots; wherein, when smelting the pure iron particles, each surface of each sample is smelted 3 to 5 times, each time for 45 seconds to 1 minute.

[0038] Step 4: rolling, grinding, polishing, cleaning and drying the pure iron ingot obtained in step 3 to obtain pure iron with a smooth surface; specifically, firstly making the pure iron ingot into an iron sheet with a thickness of 7mm-8mm, then mechanically grinding and polishing it with 240-5000 mesh sandpaper, and finally ultrasonically cleaning it with alcohol.

[0039] Step 5: After mixing the pure iron, zinc-aluminum infiltrant and dispersant (aluminum oxide powder, the particle size of which is preferably 250 mesh-350 mesh) obtained in step 4, place the mixture in a rotary furnace with a rotation speed of 700-900 rpm for rotary thermal diffusion zinc-aluminum infiltration, the thermal diffusion temperature is 380°C-440°C, the thermal diffusion insulation time is 220min-260min, and the corrosion-resistant metal product containing zinc-aluminum infiltration layer is obtained after slow cooling, the cooling rate is 1°C / min-2°C / min, and the cooling rate is 5°C / min-8°C / min; during the rotary thermal diffusion zinc-aluminum infiltration process, argon gas is introduced as a protective gas, and the introduced argon gas is purified by a deoxidation device; specifically, the argon gas is first introduced into a tubular furnace filled with oil-free graphite particles, and then the purified high-purity argon gas is introduced into the rotary furnace; the gas flow rate when the argon gas is introduced is 250cm 3 / min-350cm 3 / min; the insulation temperature of the tubular furnace is 500°C-700°C, and the insulation time is 500min-700min.

[0040] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] Example 1

[0042] A method for preparing a 440°C iron-based thermal diffusion zinc-aluminum metal product, the specific implementation process is as follows:

[0043] (1) Weigh a certain mass of pure iron particles and zinc-aluminum infiltrant (300 mesh); the mass fraction of Zn in the zinc-aluminum infiltrant is 75wt%, and the mass fraction of Al is 25wt%.

[0044] (2) Place the pure iron particles in a vacuum melting furnace and first pump the vacuum melting furnace to 10 -1 Pa low vacuum environment, introduce high-purity argon gas, and repeat the purge operation 5 times to make the oxygen concentration reach the lowest; then evacuate the vacuum melting furnace to 10 -4Pa high vacuum environment is used to exhaust all oxygen in the vacuum melting furnace; finally, argon gas is introduced to balance the atmospheric pressure so that the argon gas protects the environment throughout the melting process.

[0045] (3) Before smelting the pure iron particles, the Ti ingots were repeatedly smelted to deoxidize, and then the pure iron particles were smelted. Each surface of each sample was smelted 4 times, each time for 1 min, to obtain a pure iron ingot.

[0046] (4) The pure iron ingot is first rolled into an iron sheet with a thickness of 8 mm, then mechanically polished with sandpaper of 240-5000 mesh, and finally ultrasonically cleaned with alcohol and blown dry to obtain pure iron with a smooth surface.

[0047] (5) After pure iron, zinc-aluminum infiltrant and alumina powder (300 mesh) are mixed, the mixture is placed in a rotary furnace at a rotation speed of 800 rpm for rotary thermal diffusion zinc-aluminum infiltration. The thermal diffusion temperature is 440°C and the thermal diffusion holding time is 240 min. After slowly cooling, a corrosion-resistant metal product containing a zinc-aluminum infiltration layer is obtained. The cooling rate is 1.5°C / min and the cooling rate is 6.5°C / min. During the rotary thermal diffusion zinc-aluminum infiltration process, argon is introduced as a protective gas. The argon is first introduced into a tubular furnace filled with oil-free graphite particles, and then the purified high-purity argon is introduced into the rotary furnace. The gas flow rate when introducing argon is 300 cm / min. 3 / min; the holding temperature of the tube furnace is 600℃ and the holding time is 600min.

[0048] Example 2

[0049] A method for preparing a 380°C iron-based thermal diffusion zinc-aluminum metal product, the specific implementation process is as follows:

[0050] (1) Weigh a certain mass of pure iron particles and zinc-aluminum infiltrant (300 mesh); the mass fraction of Zn in the zinc-aluminum infiltrant is 75wt%, and the mass fraction of Al is 25wt%.

[0051] (2) Place the pure iron particles in a vacuum melting furnace and first pump the vacuum melting furnace to 10 -1 Pa low vacuum environment, introduce high-purity argon gas, and repeat the purge operation 5 times to make the oxygen concentration reach the lowest; then evacuate the vacuum melting furnace to 10 -4 Pa high vacuum environment is used to exhaust all oxygen in the vacuum melting furnace; finally, argon gas is introduced to balance the atmospheric pressure so that the argon gas protects the environment throughout the melting process.

[0052] (3) Before smelting the pure iron particles, the Ti ingots were repeatedly smelted to deoxidize, and then the pure iron particles were smelted. Each surface of each sample was smelted 4 times, each time for 1 min, to obtain a pure iron ingot.

[0053] (4) The pure iron ingot is first rolled into an iron sheet with a thickness of 8 mm, then mechanically polished with sandpaper of 240-5000 mesh, and finally ultrasonically cleaned with alcohol and blown dry to obtain pure iron with a smooth surface.

[0054] (5) After pure iron, zinc-aluminum infiltrant and alumina powder (300 mesh) are mixed, the mixture is placed in a rotary furnace at a rotation speed of 800 rpm for rotary thermal diffusion zinc-aluminum infiltration. The thermal diffusion temperature is 380°C and the thermal diffusion holding time is 240 min. After slowly cooling, a corrosion-resistant metal product containing a zinc-aluminum infiltration layer is obtained. The cooling rate is 1.5°C / min and the cooling rate is 6.5°C / min. During the rotary thermal diffusion zinc-aluminum infiltration process, argon is introduced as a protective gas. The argon is first introduced into a tubular furnace filled with oil-free graphite particles, and then the purified high-purity argon is introduced into the rotary furnace. The gas flow rate when introducing argon is 300 cm / min. 3 / min; the holding temperature of the tube furnace is 600℃ and the holding time is 600min.

[0055] Example 3

[0056] A method for preparing a 400°C iron-based thermal diffusion zinc-aluminum metal product, the specific implementation process is as follows:

[0057] (1) Weigh a certain mass of pure iron particles and zinc-aluminum infiltrant (300 mesh); the mass fraction of Zn in the zinc-aluminum infiltrant is 75wt%, and the mass fraction of Al is 25wt%.

[0058] (2) Place the pure iron particles in a vacuum melting furnace and first pump the vacuum melting furnace to 10 -1 Pa low vacuum environment, introduce high-purity argon gas, and repeat the purge operation 5 times to make the oxygen concentration reach the lowest; then evacuate the vacuum melting furnace to 10 -4 Pa high vacuum environment is used to exhaust all oxygen in the vacuum melting furnace; finally, argon gas is introduced to balance the atmospheric pressure so that the argon gas protects the environment throughout the melting process.

[0059] (3) Before smelting the pure iron particles, the Ti ingots were repeatedly smelted to deoxidize, and then the pure iron particles were smelted. Each surface of each sample was smelted 4 times, each time for 1 min, to obtain a pure iron ingot.

[0060] (4) The pure iron ingot is first rolled into an iron sheet with a thickness of 8 mm, then mechanically polished with sandpaper of 240-5000 mesh, and finally ultrasonically cleaned with alcohol and blown dry to obtain pure iron with a smooth surface.

[0061] (5) After pure iron, zinc-aluminum infiltrant and alumina powder (300 mesh) are mixed, the mixture is placed in a rotary furnace at a rotation speed of 800 rpm for rotary thermal diffusion zinc-aluminum infiltration. The thermal diffusion temperature is 400°C and the thermal diffusion holding time is 240 min. After slowly cooling, a corrosion-resistant metal product containing a zinc-aluminum infiltration layer is obtained. The cooling rate is 1.5°C / min and the cooling rate is 6.5°C / min. During the rotary thermal diffusion zinc-aluminum infiltration process, argon is introduced as a protective gas. The argon is first introduced into a tubular furnace filled with oil-free graphite particles, and then the purified high-purity argon is introduced into the rotary furnace. The gas flow rate when introducing argon is 300 cm / min. 3 / min; the holding temperature of the tube furnace is 600℃ and the holding time is 600min.

[0062] Example 4

[0063] A method for preparing a 420°C iron-based thermal diffusion zinc-aluminum metal product, the specific implementation process is as follows:

[0064] (1) Weigh a certain mass of pure iron particles and zinc-aluminum infiltrant (300 mesh); the mass fraction of Zn in the zinc-aluminum infiltrant is 75wt%, and the mass fraction of Al is 25wt%.

[0065] (2) Place the pure iron particles in a vacuum melting furnace and first pump the vacuum melting furnace to 10 -1 Pa low vacuum environment, introduce high-purity argon gas, and repeat the purge operation 5 times to make the oxygen concentration reach the lowest; then evacuate the vacuum melting furnace to 10 -4 Pa high vacuum environment is used to exhaust all oxygen in the vacuum melting furnace; finally, argon gas is introduced to balance the atmospheric pressure so that the argon gas protects the environment throughout the melting process.

[0066] (3) Before smelting the pure iron particles, the Ti ingots were repeatedly smelted to deoxidize, and then the pure iron particles were smelted. Each surface of each sample was smelted 4 times, each time for 1 min, to obtain a pure iron ingot.

[0067] (4) The pure iron ingot is first rolled into an iron sheet with a thickness of 8 mm, then mechanically polished with sandpaper of 240-5000 mesh, and finally ultrasonically cleaned with alcohol and blown dry to obtain pure iron with a smooth surface.

[0068] (5) After pure iron, zinc-aluminum infiltrant, and alumina powder (300 mesh) were mixed, the mixture was placed in a rotary furnace at a rotation speed of 800 rpm for rotary thermal diffusion zinc-aluminum infiltration. The thermal diffusion temperature was 420°C and the thermal diffusion holding time was 240 min. After slowly cooling, a corrosion-resistant metal product containing a zinc-aluminum infiltration layer was obtained. The cooling rate was 1.5°C / min and the cooling rate was 6.5°C / min. During the rotary thermal diffusion zinc-aluminum infiltration process, argon gas was introduced as a protective gas. The argon gas was first introduced into a tubular furnace filled with oil-free graphite particles, and then the purified high-purity argon gas was introduced into the rotary furnace. The gas flow rate when introducing argon gas was 300 cm / min. 3 / min; the holding temperature of the tube furnace is 600℃ and the holding time is 600min.

[0069] The following experimental analysis is conducted on the above-mentioned embodiments 1-4, and the following conclusions are drawn:

[0070] See also Figure 1 As shown, the high-magnification surface morphology and EDS images of the metal product obtained in Example 1, wherein a is a high-magnification surface morphology image, and b, c, d and e are EDS images of Fe, Zn, Al and O elements respectively. Figure 1 It can be seen that the element distribution on the surface of the metal product obtained in Example 1 is relatively uniform.

[0071] See also Figure 2-4 As shown, the high-magnification surface morphology and EDS images of the metal products obtained in Examples 2-4, wherein a is a high-magnification surface morphology image, and b, c, d and e are EDS images of Fe, Zn, Al and O elements, respectively. Figure 2 It can be seen that the element distribution on the surface of the metal products obtained in Examples 2-4 is uneven, and there is an obvious segregation phenomenon among the Fe element, the Zn element and the Al element.

[0072] See also Figure 5 As shown, the SEM cross-sectional characterization diagram of the metal products obtained in Examples 1-4, wherein a, b, c, and d are the SEM cross-sectional characterization diagrams of the metal products obtained in Examples 1-4, respectively. Figure 5 It can be seen that the zinc-aluminum infiltrated layer on the surface of the metal product is composed from the outside to the inside: the surface is a relatively dense and complete Al2O3 film formed by sintering the Al element in the zinc-aluminum infiltrant on the surface of the Fe substrate during the thermal diffusion process; inward, it is the Fe-Zn thermal diffusion layer; and finally, it is the Fe substrate. The thickness of the zinc-aluminum infiltrated layer on the surface of the metal product obtained in Examples 1-4 is 63μm, 36μm, 30μm, and 15μm, respectively. It can be seen that the thickness of the zinc-aluminum infiltrated layer on the surface of the metal product obtained in Example 1 is the thickest, and the thickness of the zinc-aluminum infiltrated layer on the surface of the metal product obtained in Example 4 is the thinnest.

[0073] See also Figure 6 As shown, the high-magnification surface morphology images of the metal products obtained in Examples 1-4, wherein a, b, and c are the surface morphology images of the metal products obtained in Examples 2-4 after immersion corrosion for 3 days, and d is the surface morphology image of the metal product obtained in Example 1 after immersion corrosion for 3 days. Figure 6 It can be seen that after 3 days of immersion corrosion, the surfaces of the metal products obtained in Examples 2-4 all showed obvious corrosion phenomena, among which the surface corrosion of the metal product obtained in Example 2 was the most serious, with obvious pitting corrosion, which destroyed the integrity of the surface zinc-diffused layer. The surfaces of the metal products obtained in Examples 3 and 4 also showed obvious corrosion phenomena, but the corrosion was relatively uniform, so that the zinc-diffused aluminum layer still had good corrosion resistance. The surface of the metal product obtained in Example 1 was relatively smooth after 3 days of immersion corrosion, indicating that the zinc-diffused aluminum layer on the surface of the metal product obtained in Example 1 was relatively dense, and the element distribution before corrosion was also relatively uniform, with the best corrosion resistance.

[0074] See also Figure 7 and Figure 8 As shown in Figure 1, the AC impedance spectra of the metal products obtained in Examples 1-4 after corrosion for 3 days and 14 days. Figure 7 and Figure 8 It can be seen that the capacitance arc radius of the metal products obtained in Examples 1-4 gradually increases during the immersion corrosion process, indicating that a corrosion product film is formed on the surface of the substrate during the corrosion process, which hinders the further occurrence of corrosion. Among them, Example 1 has a larger capacitance arc radius, indicating that it has the best corrosion resistance.

[0075] See also Fig. 9 As shown in FIG. 1 , the XRD patterns of the metal products obtained in Examples 1-4 after corrosion. Fig. 9 It can be seen that the main phase of Example 1 is FeZn 10.89 , the main phase of Examples 2-4 is FeZn 15 .

[0076] The present invention discloses a method for improving the corrosion resistance of iron-based metals. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the method. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in the present invention. The products of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the products described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

Claims

1. A method for improving the corrosion resistance of iron-based metals, characterized in that: The following steps are involved: Step 1, weighing pure iron particles and zinc-aluminum infiltration agent; Step 2: placing pure iron particles in a vacuum melting furnace, evacuating the furnace, passing argon gas, and circulating cooling water; Step 3: Before smelting the pure iron particles, repeatedly smelt the Ti ingots to deoxidize, and then smelt the pure iron particles to obtain pure iron ingots; Step 4: rolling, grinding, polishing, cleaning and drying the pure iron ingot to obtain pure iron with a smooth surface; Step 5: After mixing pure iron, zinc-aluminum infiltrant and dispersant, place the mixture in a rotary furnace for rotary thermal diffusion zinc-aluminum infiltration, and obtain a corrosion-resistant metal product containing a zinc-aluminum layer after cooling; during the rotary thermal diffusion zinc-aluminum infiltration process, argon gas is introduced as a protective gas and the introduced argon gas is purified.

2. A method for improving the corrosion resistance of iron-based metals according to claim 1, characterized in that: In step 1, in the zinc-aluminum infiltrant, the mass fraction of Zn is 75wt%, and the mass fraction of Al is 25wt%.

3. A method for improving the corrosion resistance of iron-based metals according to claim 1, characterized in that: In step 2, first evacuate the vacuum melting furnace to 10 -1 Pa low vacuum environment, introduce high-purity argon gas, and repeat the purge operation for more than 5 times to minimize the oxygen concentration; then evacuate the vacuum melting furnace to 10 -4 Pa high vacuum environment is used to exhaust all oxygen in the vacuum melting furnace; finally, argon gas is introduced to balance the atmospheric pressure so that the argon gas protects the environment throughout the melting process.

4. A method for improving the corrosion resistance of iron-based metals according to claim 1, characterized in that: In step 3, when the pure iron particles are melted, each surface of each sample is melted 3 to 5 times, each time for 45 seconds to 1 minute.

5. The method for improving the corrosion resistance of iron-based metals according to claim 1, characterized in that: In step 4, the pure iron ingot is first made into an iron sheet with a thickness of 7mm-8mm, then mechanically polished with sandpaper of 240-5000 mesh, and finally ultrasonically cleaned with alcohol.

6. A method for improving the corrosion resistance of iron-based metals according to claim 1, characterized in that: In step five, the dispersant is alumina powder.

7. A method for improving the corrosion resistance of iron-based metals according to claim 1, characterized in that: In step five, when rotary thermal diffusion zinc-aluminum is performed, the rotation speed of the rotary furnace is 700 rpm-900 rpm, the thermal diffusion temperature is 380° C.-440° C., and the thermal diffusion insulation time is 220 min-260 min.

8. The method for improving the corrosion resistance of iron-based metals according to claim 1, characterized in that: In step 5, when cooling, the cooling rate is 1°C / min-2°C / min, and the cooling rate is 5°C / min-8°C / min.

9. A method for improving the corrosion resistance of iron-based metals according to claim 1, characterized in that: In step 5, the specific operation steps for purifying the introduced argon gas are as follows: first, the argon gas is introduced into a tubular furnace filled with oil-free graphite particles, and then the purified high-purity argon gas is introduced into a rotary furnace; the gas flow rate when introducing the argon gas is 250 cm 3 / min-350cm 3 / min; the insulation temperature of the tubular furnace is 500°C-700°C, and the insulation time is 500min-700min.

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