Carbon steel surface treatment method based on multi-component alloy co-sherardizing

Abstract

The invention relates to the technical field of metal surface treatment and metal corrosion prevention, and provides a carbon steel surface treatment method based on multi-component alloy zinc co-penetration. Carbon steel is subjected to surface pretreatment to clean the surface and then is dispersed in a mixture of a multi-component alloy co-permeation agent and a filling agent, heating co-permeation is conducted after sealing is conducted, carbon steel with a multi-component alloy co-permeation layer is obtained, and after the carbon steel is cooled to the room temperature, cleaning and drying are conducted; wherein the heating co-permeation temperature is 380-420 DEG C, and the heat preservation time is 4-8 hours; the multicomponent alloy co-permeation agent comprises the following components in parts by mass: 65-75 parts of zinc powder, 15-25 parts of zinc-aluminum powder, 2-10 parts of aluminum-magnesium powder, 2-10 parts of ferroboron powder, 0.1-0.5 part of rare earth oxide and 1-4 parts of a permeation promoter. According to the method, a multi-component alloy co-permeation layer is formed on the surface of the carbon steel through the multi-component alloy co-permeation agent, and the multi-component alloy co-permeation layer is thick, uniform, compact, good in combination with the carbon steel and free of obvious cracks, so that the corrosion resistance and the wear resistance of the surface of the carbon steel are enhanced.

Description

Technical Field

[0001] The present invention belongs to the technical fields of metal surface treatment and metal anti-corrosion, and particularly relates to a surface treatment method for carbon steel based on multi-alloy co-permeated zinc. Background Art

[0002] As an important means for surface anti-corrosion strengthening of steel materials, the zinc permeation technology has been widely applied in fields such as machinery, automobiles, and ocean engineering. Traditional zinc permeation processes mostly use single zinc powder or zinc-based alloy powder as the permeating agent to form a zinc-iron alloy layer on the substrate surface through thermal diffusion. However, the current zinc permeation processes have the following limitations: First, insufficient performance of the permeated layer: The hardness of the permeated layer formed by conventional zinc powder zinc permeation is relatively low (usually ≤300HV), and the thickness of the permeated layer is uneven (the fluctuation range exceeds ±15%), resulting in limited wear resistance and fatigue resistance; Second, the bottleneck of corrosion resistance: The single zinc-based permeated layer is prone to pitting and peeling in harsh environments such as salt spray and damp heat, and the life of the neutral salt spray test (ASTM B117) is generally less than 300 hours; Third, inefficient utilization of rare earth elements: Although existing research has tried to introduce rare earth elements (such as lanthanum and cerium) to improve the quality of the permeated layer, most of them use single rare earth addition or mechanical mixing methods, failing to achieve the synergistic effect of rare earth and multi-alloy components (such as aluminum, magnesium, and boron), resulting in the rare earth modification effect not meeting expectations; Fourth, defects in the introduction of boron element: In the existing technology, boron element is often added in the form of elemental boron, which is easily oxidized to form B2O3 impurities during the zinc permeation process, reducing the density of the permeated layer. At the same time, the grain boundary strengthening potential of boron-iron alloy has not been effectively developed.

[0003] Currently, there is no targeted research on the co-permeation process of using multi-component composite powder to improve the corrosion resistance of the permeated layer for medium carbon steel (such as 45 steel). The existing formulations are difficult to meet the performance requirements of carbon steel under high-load working conditions in terms of the bonding force of the permeated layer, thermal stress matching, etc. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the present invention provides a surface treatment method for carbon steel based on multi-alloy co-permeated zinc, aiming to solve the problems mentioned in the background art.

[0005] The present invention provides a surface treatment method for carbon steel based on multi-alloy co-permeated zinc: After the carbon steel is subjected to surface pretreatment to clean the surface, it is dispersed in a mixture of a multi-alloy permeating agent and a filler, and then heated and co-permeated after sealing to obtain carbon steel with a multi-alloy permeated layer. After cooling to room temperature, it is washed and dried; wherein, the temperature for heating and co-permeating is 380 - 420°C, and the holding time is 4 - 8 hours; by mass, the multi-alloy permeating agent includes: 65 - 75 parts of zinc powder, 15 - 25 parts of zinc-aluminum powder, 2 - 10 parts of aluminum-magnesium powder, 2 - 10 parts of boron-iron powder, 0.1 - 0.5 parts of rare earth oxide, and 1 - 4 parts of a penetration aid.

[0006] Further, it specifically includes the following steps:

[0007] Step S1: The carbon steel is subjected to surface pretreatment, and the surface treatment includes degreasing, mechanical polishing and ultrasonic cleaning to make the surface of the carbon steel clean;

[0008] Step S2: The ground multi-alloy co-permeation agent and filler are placed in a zinc permeation tank, and then the carbon steel is dispersed in the mixture of the multi-alloy co-permeation agent and the filler. The zinc permeation tank is sealed and then the sealed zinc permeation tank is put into a rotary co-permeation furnace for co-permeation to obtain carbon steel with a multi-alloy co-permeation layer;

[0009] Among them, the rotation speed of the rotary co-permeation furnace is 2 - 12 r / min, the pressure in the furnace is 0.1 Pa, the temperature is raised to 380 - 420 °C, and the heat preservation time is 4 - 8 hours; by mass, the multi-alloy co-permeation agent includes 65 - 75 parts of zinc powder, 15 - 25 parts of zinc-aluminum powder, 2 - 10 parts of aluminum-magnesium powder, 2 - 10 parts of boron-iron powder, 0.1 - 0.5 parts of rare earth oxide, and 1 - 4 parts of a permeability aid;

[0010] Among them, by mass percentage, the zinc-aluminum powder includes: 7 - 11% Al, and the rest is Zn; the aluminum-magnesium powder includes: 45 - 55% Mg, and the rest is Al; the boron-iron powder includes: 15 - 18% B, and the rest is Fe; the rare earth oxide is lanthanum trioxide;

[0011] Step S3: After the rotary co-permeation furnace stops heating and the temperature of the rotary co-permeation furnace cools to ≤150 °C, the furnace cover of the rotary co-permeation furnace is opened. After the carbon steel with the multi-alloy co-permeation layer naturally cools to room temperature, it is taken out, ultrasonically cleaned and then dried.

[0012] Further, in step S1, the mechanical polishing is carried out with 400-mesh sandpaper, and the ultrasonic cleaning is for 10 min.

[0013] Further, in step S2, the filler is quartz sand, and the gaps of the zinc permeation tank are sealed with a mixture of refractory clay and glass water to seal the zinc permeation tank, where the mass ratio of the refractory clay to the glass water is 3:1.

[0014] Further, in step S2, the multi-alloy co-permeation agent includes 67 parts of zinc powder, 18 parts of zinc-aluminum powder, 5.3 parts of aluminum-magnesium powder, 7.4 parts of boron-iron powder, 0.3 part of rare earth oxide, and 2 parts of a permeability aid.

[0015] Further, the zinc-aluminum powder includes: 11% Al, and the rest is Zn; the aluminum-magnesium powder includes: 55% Mg, and the rest is Al; the boron-iron powder includes: 16% B, and the rest is Fe; the rare earth oxide is lanthanum trioxide with a purity ≥99.7%; the permeability aid is analytical pure NH4Cl.

[0016] Further, in step S2, the thickness of the multi-alloy co-permeation layer ≥60 μm.

[0017] Further, in step S2, during the heating-up process of the rotary co-permeation furnace, keep the temperature constant at 180 - 250°C for 30 min.

[0018] Further, in step S2, the ferroboron powder is prepared through the following steps:

[0019] Step S21: Place 15 - 18% boron by mass percentage, with the rest being iron, in an intermediate frequency induction furnace. After evacuating the air, introduce argon until it reaches a slightly positive pressure state. Heat up to 1500 - 1700°C for melting. After electromagnetic stirring for 15 - 25 min, form a uniform ferroboron alloy liquid, and then let it stand for 10 - 15 min and remove the surface scum.

[0020] Step S22: Pass the ferroboron alloy liquid through argon at 1.0 - 1.2 MPa and spray the ferroboron alloy liquid at a speed of 300 - 500 m / s. The spraying angle of the argon spraying the ferroboron alloy liquid is 85° - 95°, obtaining atomized droplets. The atomized droplets rapidly solidify under the condition that the rapid solidification cooling rate ≥ 10 3 K / s to obtain powder.

[0021] Step S23: Place the powder in a vacuum drying oven, dehydrate it at 60 - 80°C for 2 - 3 h, and then pass it through a grading sieve to obtain ferroboron powder with a particle size distribution of 250 - 350 mesh.

[0022] Further, the carbon steel is medium carbon steel.

[0023] The present invention has the following beneficial effects:

[0024] (1) A multi-element alloy co-permeation layer is formed on the surface of the carbon steel through the multi-element alloy co-permeation agent. The multi-element alloy co-permeation layer is relatively thick, uniform, dense, has good bonding with the carbon steel and no obvious cracks, strengthening the corrosion resistance and wear resistance of the carbon steel surface. After the surface of the carbon steel is treated by this method, it can be used for the manufacture of railway bridge steel structures, key equipment such as pressure vessels, pipelines, and valves, as well as the manufacture of molds with complex shapes and high precision. In addition, this method is carried out in a completely closed environment, no gas will escape, and the recovered multi-element alloy co-permeation agent can be reused, so it is environmentally friendly.

[0025] (2) The added ferroboron powder and lanthanum sesquioxide have a good synergistic effect. Lanthanum sesquioxide can inhibit the oxidation of boron in ferroboron powder, promote the uniform diffusion of boron on the surface of carbon steel, and enhance the grain boundary strengthening effect. Boron atoms form borides with iron atoms, and the dispersed distribution improves the hardness of the carburized layer. Lanthanum sesquioxide refines the grains, making the structure of the carburized layer more uniform. The two work together to significantly improve the comprehensive performance of the carburized layer. In addition, zinc powder provides the main element for zinc carburizing. Aluminum in zinc-aluminum powder improves the corrosion resistance and oxidation resistance of the carburized layer and forms a stable alloy layer in synergy with zinc powder. Magnesium in aluminum-magnesium powder reduces the surface tension of the alloy liquid, promotes the diffusion of elements, and makes the carburized layer more uniform and dense. Multiple components work together to form a unique carburized layer structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The exemplary embodiments of the present invention can be more fully understood by referring to the following drawings:

[0027] Figure 1 SEM cross-sectional view of the multi-element alloy carburized layer on the surface of carbon steel treated in Example 2 of the present invention, scale: 100μm.

[0028] Figure 2 Optical microscope image of the multi-element alloy carburized layer on the surface of carbon steel treated in Example 2 of the present invention, scale: 100μm.

[0029] Figure 3 SEM cross-sectional view of the multi-element alloy carburized layer on the surface of carbon steel treated in Comparative Example 1 of the present invention, scale: 100μm.

[0030] Figure 4 Optical microscope image of the multi-element alloy carburized layer on the surface of carbon steel treated in Comparative Example 1 of the present invention, scale: 100μm. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clear, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and do not limit the present invention.

[0033] An embodiment of the present invention provides a surface treatment method for carbon steel based on multi - element alloy co - permeated zinc: After the carbon steel is subjected to surface pretreatment to clean the surface, it is dispersed in a mixture of a multi - element alloy co - permeating agent and a filler, and then sealed and heated for co - permeation to obtain carbon steel with a multi - element alloy co - permeated layer. After cooling to room temperature, it is washed and dried; wherein, the heating temperature for co - permeation is 380 - 420 °C, and the holding time is 4 - 8 hours; by mass, the multi - element alloy co - permeating agent includes: 65 - 75 parts of zinc powder, 15 - 25 parts of zinc - aluminum powder, 2 - 10 parts of aluminum - magnesium powder, 2 - 10 parts of boron - iron powder, 0.1 - 0.5 parts of rare - earth oxide, and 1 - 4 parts of a co - permeation aid.

[0034] In some embodiments, it specifically includes the following steps:

[0035] Step S1: The carbon steel is subjected to surface pretreatment, and the surface treatment includes degreasing, mechanical polishing, and ultrasonic cleaning to clean the surface of the carbon steel;

[0036] Step S2: The ground multi - element alloy co - permeating agent and the filler are placed in a zinc - permeating tank (the grinding time is 30 - 50 min), and then the carbon steel is dispersed in the mixture of the multi - element alloy co - permeating agent and the filler. The zinc - permeating tank is sealed, and then the sealed zinc - permeating tank is placed in a rotary co - permeation furnace for co - permeation to obtain carbon steel with a multi - element alloy co - permeated layer;

[0037] Among them, the rotation speed of the rotary co - permeation furnace is 2 - 12 r / min, the pressure in the furnace is 0.1 Pa, the temperature is raised to 380 - 420 °C, and the holding time is 4 - 8 hours; by mass, the multi - element alloy co - permeating agent includes 65 - 75 parts of zinc powder, 15 - 25 parts of zinc - aluminum powder, 2 - 10 parts of aluminum - magnesium powder, 2 - 10 parts of boron - iron powder, 0.1 - 0.5 parts of rare - earth oxide, and 1 - 4 parts of a co - permeation aid;

[0038] Among them, by mass percentage, the zinc - aluminum powder includes: 7 - 11% Al, and the rest is Zn; the aluminum - magnesium powder includes: 45 - 55% Mg, and the rest is Al; the boron - iron powder includes: 15 - 18% B, and the rest is Fe; the rare - earth oxide is lanthanum trioxide;

[0039] Step S3: After the rotary co - permeation furnace stops heating and the temperature of the rotary co - permeation furnace cools to ≤150 °C, the furnace cover of the rotary co - permeation furnace is opened. The carbon steel with a multi - element alloy co - permeated layer is naturally cooled to room temperature and then taken out, and ultrasonically cleaned and dried at 60 - 70 °C.

[0040] In some embodiments, in step S1, the mechanical polishing is carried out with 400 - mesh sandpaper, and the ultrasonic cleaning is carried out for 10 min.

[0041] In some embodiments, in step S2, the filler is quartz sand, and the gaps of the zinc - permeating tank are sealed with a mixture of refractory mud (50 - 100 mesh) and glass water to seal the zinc - permeating tank, where the mass ratio of the refractory mud to the glass water is 3:1.

[0042] In some embodiments, in step S2, the multi-alloy co-permeation agent includes 67 parts of zinc powder, 18 parts of zinc-aluminum powder, 5.3 parts of aluminum-magnesium powder, 7.4 parts of boron-iron powder, 0.3 parts of rare earth oxide, and 2 parts of co-permeation aid.

[0043] In some embodiments, the zinc-aluminum powder includes: 11% Al, and the rest is Zn; the aluminum-magnesium powder includes: 55% Mg, and the rest is Al; the boron-iron powder includes: 16% B, and the rest is Fe; the rare earth oxide is lanthanum sesquioxide with a purity ≥ 99.7%; the co-permeation aid is analytical pure NH4Cl.

[0044] In some embodiments, in step S2, the thickness of the multi-alloy co-permeation layer ≥ 60 μm.

[0045] In some embodiments, in step S2, during the heating process of the rotary co-permeation furnace, it is kept at a constant temperature of 180 - 250 °C for 30 min.

[0046] In some embodiments, in step S2, the boron-iron powder is prepared by the following steps:

[0047] Step S21: Place, by mass percentage, 15 - 18% boron, and the rest is iron, in an intermediate frequency induction electric furnace. After evacuating the air, argon is introduced until it is in a slightly positive pressure state, and the temperature is raised to 1500 - 1700 °C for melting. After electromagnetic stirring for 15 - 25 min, a uniform boron-iron alloy liquid is formed, and then it is left standing for 10 - 15 min and the surface scum is removed;

[0048] Step S22: Pass the boron-iron alloy liquid through argon at 1.0 - 1.2 MPa to spray the boron-iron alloy liquid at a speed of 300 - 500 m / s. The spraying angle of the argon spraying the boron-iron alloy liquid is 85° - 95°, and atomized droplets are obtained. The atomized droplets rapidly solidify under the condition that the rapid solidification cooling rate ≥ 10 3 K / s to obtain powder;

[0049] Step S23: Place the powder in a vacuum drying oven, dehydrate it at 60 - 80 °C for 2 - 3 h, and then pass it through a grading sieve to obtain boron-iron powder with a particle size distribution of 250 - 350 mesh.

[0050] In some embodiments, the carbon steel is medium carbon steel, specifically No. 45 steel.

[0051] Experimental materials:

[0052] Zinc powder: Purchased from Changsha Tianjiu Metal Materials Co., Ltd., zinc content ≥ 99.99%, 250 - 350 mesh;

[0053] Aluminum ingot: Aluminum content ≥ 99.9%, purchased from North China Supply and Marketing Company of Nonferrous Metals Industry of China;

[0054] Zinc ingot: with zinc content ≥ 99.9%, purchased from North China Supply and Marketing Company of Nonferrous Metals Industry, China;

[0055] Magnesium ingot: with magnesium content ≥ 99.9%, purchased from Foshan Zhengxi Metal Materials Co., Ltd.;

[0056] Lanthanum sesquioxide: with purity ≥ 99.7%, from Nanjing Eprui Nano Materials Co., Ltd.;

[0057] Example 1: Preparation of multi - element alloy co - permeating agent

[0058] Mix zinc - aluminum powder, aluminum - magnesium powder, boron - iron powder, rare - earth oxide and zinc powder in ascending order of proportion. During mixing, continuously grind to obtain a uniform mixture. Grind for 40 minutes. The component ratio (by mass) of the multi - element alloy co - permeating agent is shown in Table 1 below.

[0059] Table 1 Component ratio of multi - element alloy co - permeating agent

[0060] Example 1 Example 2 Example 3 Example 4 Example 5 Zinc powder 65 69 72 75 70 Zinc-aluminum powder 18 17 15 16 25 Aluminum-magnesium powder 5.3 2 4.3 10 6.3 Ferroboron powder 9.4 10 8.5 6.5 2 Lanthanum sesquioxide 0.1 0.3 0.2 0.5 0.3 <![CDATA[Analytical pure NH4Cl]]> 1 2 2 4 3

[0061] Example 2:

[0062] (1) Perform surface pretreatment on 45 - steel. The surface treatment includes degreasing, grinding with 400 - mesh sandpaper and ultrasonic cleaning for 10 min to make the surface of 45 - steel clean;

[0063] (2) Place the ground multi - element alloy co - permeating agent and filler in a zinc - permeating tank. Then disperse 45 - steel in the mixture of the multi - element alloy co - permeating agent and quartz sand. Use a mixture of refractory mud (50 - mesh) and glass water to seal the gaps of the zinc - permeating tank to make the zinc - permeating tank airtight. The mass ratio of refractory mud to glass water is 3:1. Then place the sealed zinc - permeating tank in a rotary co - permeating furnace for co - permeation to obtain 45 - steel with a multi - element alloy co - permeating layer. The rotation speed of the rotary co - permeating furnace is 4 r / min, the pressure in the furnace is 0.1 Pa, heat up to 380 °C (during the heating process, keep constant at 250 °C for 30 min), and the holding time is 4 hours. By mass, the multi - element alloy co - permeating agent includes 65 parts of zinc powder, 18 parts of zinc - aluminum powder (11% Al, the rest is Zn), 5.3 parts of aluminum - magnesium powder (55% Mg, the rest is Al), 2 parts of boron - iron powder (16% B, the rest is Fe), 0.1 part of lanthanum sesquioxide and 1 part of analytical - grade NH4Cl;

[0064] (3) Stop heating the rotary co - permeating furnace. After the temperature of the rotary co - permeating furnace cools to ≤ 150 °C, open the furnace cover of the rotary co - permeating furnace. Take out the 45 - steel with a multi - element alloy co - permeating layer after it naturally cools to room temperature, and dry it at 70 °C after ultrasonic cleaning.

[0065] The cross - sectional scanning electron micrograph of the multi - element alloy permeating layer of 45 - steel after treatment is as Figure 1As shown, it can be seen that the multi - element alloy infiltration layer is dense and has a good bonding with the 45# steel.

[0066] The metallographic microscope image of the multi - element alloy infiltration layer of the 45# steel after treatment is as Figure 2 shown. It can be seen that the multi - element alloy infiltration layer is relatively thick and has no obvious cracks.

[0067] Example 3:

[0068] (1) The 45# steel is subjected to surface pretreatment. The surface treatment includes degreasing, grinding with 400 - mesh sandpaper, and ultrasonic cleaning for 10 min to make the surface of the 45# steel clean.

[0069] (2) The ground multi - element alloy co - permeation agent and filler are placed in a zinc - infiltration tank. Then the 45# steel is dispersed in the mixture of the multi - element alloy co - permeation agent and quartz sand. The gaps of the zinc - infiltration tank are sealed with a mixture of refractory clay (100 - mesh) and glass water to seal the zinc - infiltration tank. The mass ratio of refractory clay to glass water is 3:1. Then the sealed zinc - infiltration tank is put into a rotary co - permeation furnace for co - permeation to obtain the 45# steel with a multi - element alloy co - permeation layer. The rotation speed of the rotary co - permeation furnace is 2 r / min, the pressure in the furnace is 0.1 Pa, and it is heated to 390 °C (during the heating process, it is kept at 200 °C for 30 min), and the holding time is 5 hours. By mass, the multi - element alloy co - permeation agent includes 69 parts of zinc powder, 17 parts of zinc - aluminum powder (7% Al, the rest is Zn), 2 parts of aluminum - magnesium powder (45% Mg, the rest is Al), 10 parts of boron - iron powder (15% B, the rest is Fe), 0.3 parts of lanthanum sesquioxide, and 2 parts of analytical - grade NH4Cl.

[0070] (3) The rotary co - permeation furnace stops heating. After the temperature of the rotary co - permeation furnace cools to ≤150 °C, the furnace cover of the rotary co - permeation furnace is opened. The 45# steel with a multi - element alloy co - permeation layer is naturally cooled to room temperature and then taken out, ultrasonically cleaned, and dried at 70 °C.

[0071] Example 4:

[0072] (1) The 45# steel is subjected to surface pretreatment. The surface treatment includes degreasing, grinding with 400 - mesh sandpaper, and ultrasonic cleaning for 10 min to make the surface of the 45# steel clean.

[0073] (2) The ground multi-alloy co-permeation agent and filler are placed in a zinc permeation tank. Then, the No. 45 steel is dispersed in the mixture of the multi-alloy co-permeation agent and quartz sand. The gaps of the zinc permeation tank are sealed with a mixture of refractory clay (50 mesh) and glass water to make the zinc permeation tank airtight. The mass ratio of refractory clay to glass water is 3:1. Then, the sealed zinc permeation tank is put into a rotary co-permeation furnace for co-permeation to obtain No. 45 steel with a multi-alloy co-permeation layer. The rotation speed of the rotary co-permeation furnace is 8 r / min, the pressure inside the furnace is 0.1 Pa, and it is heated to 400 °C (during the heating process, it is kept at a constant temperature of 180 °C for 30 min), and the holding time is 6 hours. By mass, the multi-alloy co-permeation agent includes 72 parts of zinc powder, 15 parts of zinc-aluminum powder (11% Al, the rest is Zn), 4.3 parts of aluminum-magnesium powder (55% Mg, the rest is Al), 8.5 parts of boron-iron powder (16% B, the rest is Fe), 0.2 part of lanthanum sesquioxide, and 2 parts of analytical pure NH4Cl;

[0074] (3) After the rotary co-permeation furnace stops heating and the temperature of the rotary co-permeation furnace cools to 145 °C, the furnace lid of the rotary co-permeation furnace is opened. The No. 45 steel with a multi-alloy co-permeation layer is naturally cooled to room temperature and then taken out, ultrasonically cleaned, and dried at 65 °C.

[0075] Example 5:

[0076] (1) The No. 45 steel is subjected to surface pretreatment, including degreasing, grinding with 400-mesh sandpaper, and ultrasonic cleaning for 10 min to make the surface of the No. 45 steel clean;

[0077] (2) The ground multi-alloy co-permeation agent and filler are placed in a zinc permeation tank. Then, the No. 45 steel is dispersed in the mixture of the multi-alloy co-permeation agent and quartz sand. The gaps of the zinc permeation tank are sealed with a mixture of refractory clay (100 mesh) and glass water to make the zinc permeation tank airtight. The mass ratio of refractory clay to glass water is 3:1. Then, the sealed zinc permeation tank is put into a rotary co-permeation furnace for co-permeation to obtain No. 45 steel with a multi-alloy co-permeation layer. The rotation speed of the rotary co-permeation furnace is 10 r / min, the pressure inside the furnace is 0.1 Pa, and it is heated to 410 °C (during the heating process, it is kept at a constant temperature of 190 °C for 30 min), and the holding time is 7 hours. By mass, the multi-alloy co-permeation agent includes 75 parts of zinc powder, 16 parts of zinc-aluminum powder (10% Al, the rest is Zn), 10 parts of aluminum-magnesium powder (50% Mg, the rest is Al), 6.5 parts of boron-iron powder (18% B, the rest is Fe), 0.5 part of lanthanum sesquioxide, and 4 parts of analytical pure NH4Cl;

[0078] (3) After the rotary co-permeation furnace stops heating and the temperature of the rotary co-permeation furnace cools to ≤150 °C, the furnace lid of the rotary co-permeation furnace is opened. The No. 45 steel with a multi-alloy co-permeation layer is naturally cooled to room temperature and then taken out, ultrasonically cleaned, and dried at 70 °C.

[0079] Example 6:

[0080] (1) The No. 45 steel is subjected to surface pretreatment, and the surface treatment includes degreasing, grinding with 400-mesh sandpaper and ultrasonic cleaning for 10 min to make the surface of the No. 45 steel clean;

[0081] (2) The ground multi-alloy co-permeation agent and filler are placed in a zinc permeation tank, and then the No. 45 steel is dispersed in the mixture of the multi-alloy co-permeation agent and quartz sand. The gaps of the zinc permeation tank are sealed with a mixture of refractory mud (100-mesh) and glass water to make the zinc permeation tank airtight, where the mass ratio of the refractory mud to the glass water is 3:1. Then the sealed zinc permeation tank is put into a rotary co-permeation furnace for co-permeation to obtain the No. 45 steel with a multi-alloy co-permeation layer; the rotation speed of the rotary co-permeation furnace is 12 r / min, the pressure in the furnace is 0.1 Pa, and the temperature is raised to 420 °C (during the heating process, it is kept at a constant temperature of 250 °C for 30 min), and the holding time is 8 hours; by mass, the multi-alloy co-permeation agent includes 70 parts of zinc powder, 25 parts of zinc-aluminum powder (9% Al, the rest is Zn), 6.3 parts of aluminum-magnesium powder (45% Mg, the rest is Al), 2 parts of boron-iron powder (15% B, the rest is Fe), 0.3 part of lanthanum sesquioxide and 3 parts of analytical pure NH4Cl;

[0082] (3) After the rotary co-permeation furnace stops heating and the temperature of the rotary co-permeation furnace cools to ≤150 °C, the furnace cover of the rotary co-permeation furnace is opened. The No. 45 steel with a multi-alloy co-permeation layer is naturally cooled to room temperature and then taken out, and ultrasonically cleaned and dried at 60 °C.

[0083] Comparative Example 1:

[0084] Referring to Example 2, the difference is that the multi-alloy permeation agent only contains 60 parts of zinc powder and 40 parts of zinc-aluminum powder (without aluminum-magnesium powder and boron-iron powder).

[0085] The cross-sectional scanning electron microscope image of the multi-alloy permeation layer of the No. 45 steel after treatment is as shown in Figure 3 It can be seen that the multi-alloy permeation layer is not dense and has a poor bonding with the No. 45 steel.

[0086] The metallographic microscope image of the multi-alloy permeation layer of the No. 45 steel after treatment is as shown in Figure 4 It can be seen that the multi-alloy permeation layer is relatively thin and has obvious cracks.

[0087] Comparative Example 2:

[0088] Referring to Example 3, the difference is that the multi-alloy permeation agent only contains 65 parts of zinc powder and 35 parts of zinc-aluminum powder (without aluminum-magnesium powder and boron-iron powder).

[0089] Comparative Example 3:

[0090] Referring to Example 4, the difference is that the multi - element alloy penetrant only contains 70 parts of zinc powder and 30 parts of zinc - aluminum powder (without aluminum - magnesium powder and boron - iron powder).

[0091] Comparative Example 4:

[0092] Referring to Example 5, the difference is that the multi - element alloy penetrant only contains 77 parts of zinc powder and 23 parts of zinc - aluminum powder (without aluminum - magnesium powder and boron - iron powder).

[0093] Comparative Example 5:

[0094] Referring to Example 6, the difference is that the multi - element alloy penetrant only contains 80 parts of zinc powder and 20 parts of zinc - aluminum powder (without aluminum - magnesium powder and boron - iron powder).

[0095] The performance test results of Examples 2 - 6 and Comparative Examples 1 - 5 are shown in Table 2, where the micro - Vickers hardness is tested according to GB / T4340.1; the self - corrosion potential and corrosion current density are tested by an electrochemical workstation; energy - dispersive spectroscopy analysis is carried out by an energy spectrometer; and the thickness is tested according to GB / T4956.

[0096] Table 2 Performance of Examples and Comparative Examples

[0097]

[0098] The hardness of 45 steel is between 195 - 235 Hv. It can be seen from Table 2 that the hardness of Examples 2 - 6 has a significant increase compared with that of 45 steel, while the hardness of Comparative Examples 1 - 5 has no obvious increase compared with that of 45 steel; and compared with Comparative Examples 1 - 5, the self - corrosion potential of Examples 2 - 6 is significantly increased, making it more difficult to corrode. At the same time, the corrosion current density is smaller, and the corrosion rate is also lower.

[0099] (3) Based on the performance test results of Examples 2-6 and Comparative Examples 1-5, the present invention concludes that: (1) By forming a multi-element alloy co-permeation layer on the surface of carbon steel with a multi-element alloy co-permeation agent, the multi-element alloy co-permeation layer is relatively thick, uniform, dense, well-bonded to the carbon steel and has no obvious cracks, strengthening the corrosion resistance and wear resistance of the carbon steel surface. After the surface of carbon steel is treated by this method, it can be used for the manufacture of railway bridge steel structures, the manufacture of key equipment such as pressure vessels, pipelines, valves, etc., and the manufacture of molds with complex shapes and high precision. In addition, this method is carried out in a completely sealed environment, no gas will escape, and the recycled multi-element alloy co-permeation agent can be reused, so it is environmentally friendly. (2) In the prior art, boron element is often added in the form of elemental boron, which is easily oxidized to generate B2O3 impurities, reducing the density of the permeation layer, and the grain boundary strengthening potential of ferroboron alloy has not been effectively developed. However, the boron iron powder added in the present invention has a good synergistic effect with lanthanum trioxide. Lanthanum trioxide can inhibit the oxidation of boron in the boron iron powder, promote the uniform diffusion of boron on the surface of carbon steel, and enhance the grain boundary strengthening effect. Boron atoms form borides with iron atoms, and the dispersed distribution improves the hardness of the permeation layer, while lanthanum trioxide refines the grains, making the structure of the permeation layer more uniform. The two synergistically significantly improve the comprehensive performance of the permeation layer. In addition, zinc powder provides the main element for zinc permeation, aluminum in the zinc-aluminum powder improves the corrosion resistance and oxidation resistance of the permeation layer, and synergistically forms a stable alloy layer with zinc powder; magnesium in the aluminum-magnesium powder reduces the surface tension of the alloy liquid, promotes the diffusion of elements, and makes the permeation layer more uniform and dense. Multiple components synergistically form a unique permeation layer structure. (3) There are also defects in the addition of boron element in the prior art. The present invention uses boron iron powder and, with the help of the vacuum environment and the action of lanthanum trioxide during the co-permeation process, inhibits the oxidation of boron. The vacuum environment reduces the presence of oxygen and reduces the possibility of boron oxidation, and lanthanum trioxide further prevents boron oxidation, ensuring the density of the permeation layer. During heating co-permeation, boron atoms diffuse to the grain boundaries of carbon steel and form borides with iron atoms, enhancing the grain boundary bonding force and improving the strength and hardness of the material. Other alloy elements synergistically optimize the grain boundary structure with boron, improving the comprehensive performance of the permeation layer.

[0100] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A surface treatment method for carbon steel based on multi-alloy co-permeated zinc, characterized in that: After the carbon steel is subjected to surface pretreatment to clean the surface, it is dispersed in a mixture of a multi-alloy co-permeation agent and a filler, and then sealed and heated for co-permeation to obtain carbon steel with a multi-alloy co-permeation layer. After cooling to room temperature, it is washed and dried; among them, the heating temperature for co-permeation is 380-420°C, and the holding time is 4-8 hours; by mass, the multi-alloy co-permeation agent includes: 65-75 parts of zinc powder, 15-25 parts of zinc-aluminum powder, 2-10 parts of aluminum-magnesium powder, 2-10 parts of boron-iron powder, 0.1-0.5 parts of rare earth oxide, and 1-4 parts of a co-permeation aid.

2. The surface treatment method for carbon steel based on multi - element alloy co - permeated zinc as described in claim 1, wherein, Specifically, it includes the following steps: Step S1: The carbon steel is subjected to surface pretreatment, and the surface treatment includes degreasing, mechanical polishing and ultrasonic cleaning to clean the surface of the carbon steel; Step S2: The ground multi-alloy co-permeation agent and filler are placed in a zinc permeation tank, and then the carbon steel is dispersed in the mixture of the multi-alloy co-permeation agent and the filler. The zinc permeation tank is sealed, and then the sealed zinc permeation tank is placed in a rotary co-permeation furnace for co-permeation to obtain carbon steel with a multi-alloy co-permeation layer; Among them, the rotation speed of the rotary co-permeation furnace is 2-12 r / min, the pressure in the furnace is 0.1 Pa, the temperature is raised to 380-420°C, and the holding time is 4-8 hours; by mass, the multi-alloy co-permeation agent includes 65-75 parts of zinc powder, 15-25 parts of zinc-aluminum powder, 2-10 parts of aluminum-magnesium powder, 2-10 parts of boron-iron powder, 0.1-0.5 parts of rare earth oxide, and 1-4 parts of a co-permeation aid; Among them, by mass percentage, the zinc-aluminum powder includes: 7-11% Al, and the rest is Zn; the aluminum-magnesium powder includes: 45-55% Mg, and the rest is Al; the boron-iron powder includes: 15-18% B, and the rest is Fe; the rare earth oxide is lanthanum trioxide; Step S3: The rotary co-permeation furnace stops heating. After the temperature of the rotary co-permeation furnace cools to ≤150°C, the furnace cover of the rotary co-permeation furnace is opened. The carbon steel with a multi-alloy co-permeation layer is naturally cooled to room temperature and then taken out, and ultrasonically cleaned and dried at 60-70°C.

3. The surface treatment method of carbon steel based on multi - element alloy co - permeated zinc as claimed in claim 2, wherein: In step S1, the mechanical polishing is carried out with 400-mesh sandpaper, and the ultrasonic cleaning is carried out for 10 min.

4. The surface treatment method of carbon steel based on multi-alloy co-permeated zinc according to claim 3, characterized in that: In step S2, the filler is quartz sand, and the gaps of the zinc permeation tank are sealed with a mixture of refractory clay and glass water to seal the zinc permeation tank, where the mass ratio of the refractory clay to the glass water is 3:

1.

5. A surface treatment method for carbon steel based on multi-alloy co-permeated zinc as claimed in claim 4, characterized in that: In step S2, the multi-alloy co-permeation agent includes 67 parts of zinc powder, 18 parts of zinc-aluminum powder, 5.3 parts of aluminum-magnesium powder, 7.4 parts of boron-iron powder, 0.3 parts of rare earth oxide, and 2 parts of a co-permeation aid.

6. A surface treatment method for carbon steel based on multi-alloy co-permeated zinc as described in claim 5, characterized in that: The zinc-aluminum powder includes: 11% Al, and the rest is Zn; the aluminum-magnesium powder includes: 55% Mg, and the rest is Al; the boron-iron powder includes: 16% B, and the rest is Fe; the rare earth oxide is lanthanum trioxide with a purity ≥99.7%; the co-permeation aid is analytical pure NH4Cl.

7. The surface treatment method of carbon steel based on multi - element alloy co - permeated zinc as claimed in claim 6, wherein: In step S2, the thickness of the multi-alloy co-permeation layer is ≥60 μm.

8. The surface treatment method of carbon steel based on multi - element alloy co - permeated zinc as claimed in claim 7, wherein: In step S2, during the heating process of the rotary co-permeation furnace, it is held at a constant temperature of 180-250°C for 30 min.

9. The surface treatment method of carbon steel based on multi - element alloy co - permeated zinc as claimed in claim 8, characterized in that: In step S2, the boron-iron powder is prepared through the following steps: Step S21: Put 15-18% boron by mass percentage and the rest being iron into an intermediate frequency induction furnace. After evacuating the air, introduce argon until it reaches a slightly positive pressure state, heat up to 1500-1700 °C for melting, carry out electromagnetic stirring for 15-25 minutes to form a uniform ferroboron alloy liquid, then let it stand for 10-15 minutes and remove the surface scum; Step S22: Pass the ferroboron alloy liquid through argon gas at 1.0 to 1.2 MPa and spray the ferroboron alloy liquid at a speed of 300 to 500 m / s. The spraying angle of the argon gas on the ferroboron alloy liquid is 85° to 95° to obtain atomized droplets. The atomized droplets are rapidly solidified under the condition that the rapid solidification cooling rate is ≥ 10 3 K / s to obtain powder; Step S23: Place the powder in a vacuum drying oven, dehydrate it at 60-80 °C for 2-3 hours, and then pass it through a grading sieve to obtain ferroboron powder with a particle size distribution of 250-350 mesh.

10. A surface treatment method for carbon steel based on multi-alloy co-permeated zinc as described in claim 1, characterized in that: The carbon steel is medium carbon steel.

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