Hot galvanizing liquid as well as preparation method and application thereof

Abstract

The invention relates to the technical field of hot galvanizing, and particularly discloses hot galvanizing liquid as well as a preparation method and application thereof. The hot galvanizing liquid comprises the following raw materials in parts by weight: 55-60 parts of zinc; 30 to 35 parts of aluminum; 0.8 to 2 parts of silicon; 0.1 to 0.5 part of lead; 0.15-0.2 part of a rare earth element mixture; the rare earth element mixture is composed of rhenium, cobalt and antimony, and the weight part ratio of rhenium to cobalt to antimony is 1: (1.4-1.8): (0.9-1.3). The preparation method comprises the following steps: melting the aluminum in a production container, then adding the zinc for uniformly melting, then adding the silicon and the lead for uniformly melting, and finally adding the rare earth element mixture for uniformly melting to obtain the hot galvanizing liquid. After the hot galvanizing liquid is applied, adverse effects caused by other factors can be well made up, and a good binding force is shown between a plating layer and a base body.

Description

Technical Field

[0001] The present application relates to the technical field of hot-dip galvanizing, and more specifically, to a hot-dip galvanizing solution and a preparation method and application thereof. Background Art

[0002] Hot-dip galvanizing, also known as hot-dip galvanizing, is a process in which a cleaned and activated steel product is immersed in molten zinc liquid to form a zinc alloy coating with good adhesion on the steel surface through the reaction and diffusion between iron and zinc. Hot-dip galvanizing has the advantages of uniform coating, strong adhesion and long service life. It is one of the effective means to delay environmental corrosion of steel materials. The hot-dip galvanizing process generally includes the following steps: pickling, cleaning, plating assistance, hot-dip galvanizing, cooling and passivation.

[0003] The composition of hot-dip galvanizing liquid mainly includes zinc and flux. Zinc is the main component of the galvanized layer and has good corrosion resistance; the flux is used to lower the melting point of zinc, improve the fluidity and wettability of the galvanizing liquid, and ensure that the galvanized layer can be evenly and tightly attached to the surface of the steel pipe. The components of hot-dip galvanizing liquid usually include zinc and aluminum. For example, the invention patent application with patent publication number CN108179369A discloses a twin-induced plasticity high-strength steel hot-dip galvanizing liquid and its preparation method and application. The hot-dip galvanizing liquid includes 0.1-35wt% aluminum and 65-99.9wt% zinc. The hot-dip galvanizing process has a galvanizing melt temperature of 630-690℃ and a hot-dip time of 60-240 seconds. Among them, the addition of aluminum can improve the appearance and corrosion resistance of the coating. Aluminum and zinc form an alloy, which can improve the hardness and wear resistance of the coating.

[0004] With regard to the above-mentioned related technologies, the inventors believe that in the actual operation process of the hot-dip galvanizing process, there are inevitably factors such as insufficient surface treatment of the steel plate, uniform distribution of the components of the galvanizing solution, and changes in the fluidity of the galvanizing solution, which result in the bonding force between the coating and the substrate being not strong enough and unable to achieve the expected result, thus adversely affecting the service life of the coating.

[0005] Therefore, it is urgent to propose a solution to solve the above technical problems. Summary of the invention

[0006] In order to improve the bonding strength between the coating and the substrate and further compensate for the adverse effects of other factors, the present application provides a hot-dip galvanizing solution and a preparation method and application thereof.

[0007] In a first aspect, the present application provides a hot-dip galvanizing solution, which adopts the following technical solution: A hot-dip galvanizing solution is composed of the following raw materials in parts by weight: Zinc 55-60 parts; Aluminum 30-35 parts; Silicon 0.8-2 parts; Lead 0.1-0.5 parts; Rare earth element mixture 0.15-0.2 parts; The rare earth element mixture consists of rhenium, cobalt and antimony, and the weight ratio of rhenium, cobalt and antimony is 1:(1.4-1.8):(0.9-1.3).

[0008] By adopting the above technical scheme, zinc reacts chemically with the surface of steel to form a solid zinc alloy protective layer, which can effectively prevent the intrusion of moisture and oxygen, significantly improve the corrosion resistance of the metal and extend its service life; aluminum will form a Zn-Al alloy layer with zinc in the hot-dip galvanizing liquid, which can significantly improve the corrosion resistance of the coating. Compared with the pure zinc coating, the Zn-Al alloy layer will not cause uniform corrosion when the coating is damaged, but will cause local corrosion, thereby protecting the substrate; silicon can significantly reduce the surface tension of the hot-dip galvanizing liquid, making it easier to spread and flow on the metal surface. In addition, silicon can also react with zinc to form a dense silicide layer, which can effectively prevent the formation of zinc oxide in the zinc liquid, keep the zinc liquid clean and active, and further improve the quality of the coating; lead can improve the fluidity and operating convenience of the hot-dip galvanizing liquid, and can make the surface of the coating smoother, reducing defects and bubbles on the surface of the coating; and the combination of zinc, aluminum, silicon and lead can form a relatively balanced mixed matrix in the hot-dip galvanizing liquid.

[0009] In the rare earth element mixture, rhenium can improve the fluidity of the hot-dip galvanizing liquid at a higher temperature, purify the hot-dip galvanizing liquid, hinder the formation of the brittle phase of the zinc-iron alloy, and improve the uniformity and density of the coating; the use of cobalt can form a cobalt-rich layer in the coating, which can not only improve the corrosion resistance of the coating, but also form an alloy with zinc. This alloy layer can enhance the bonding force between the coating and the substrate, making the coating more firmly attached to the substrate; antimony can improve the coating formed by the application of hot-dip galvanizing liquid, making the coating structure denser than that of pure zinc coating, reducing cracks and strengthening interface bonding; and when the rare earth element mixture composed of rhenium, cobalt and antimony is applied to the hot-dip galvanizing liquid, the three can play an excellent composite synergistic role, so that the bonding force between the coating and the substrate is significantly improved, and can make up for the adverse effects caused by other unfavorable factors in the hot-dip galvanizing process operation, thereby improving the overall application quality of the hot-dip galvanizing liquid.

[0010] Preferably, the weight ratio of rhenium, cobalt and antimony in the rare earth element mixture is 1:1.6:1.

[0011] By adopting the above technical scheme, rhenium, cobalt and antimony in the above weight ratio are used in combination, and the composite synergistic effect between them is better, and they can fully play their role in the mixed matrix formed by the combination of zinc, aluminum, silicon and lead, so that the obtained hot-dip galvanizing liquid can better compensate for the adverse effects brought by other factors after application, and make the coating and the substrate show better bonding strength.

[0012] Preferably, the weight ratio of zinc, aluminum, silicon and lead in the hot-dip galvanizing solution is 57:32:1:0.3.

[0013] By adopting the above technical scheme, when zinc, aluminum, silicon and lead in the above weight ratio are used in combination, the mixed matrix formed is easier to exert a more sufficient bonding effect between the rare earth element mixture, thereby making the coating formed by the application of hot-dip galvanizing liquid have a stronger bonding force with the substrate.

[0014] Preferably, the rare earth element mixture accounts for 0.18% of the total mass of the hot-dip galvanizing liquid.

[0015] By adopting the above technical scheme, the dosage of the above rare earth element mixture makes it play a better overall role in the hot-dip galvanizing solution, can play a better regulatory role in the growth of the coating, ensure that the various component raw materials are fully combined, and the formed organizational structure is relatively uniform and dense, and can better compensate for the adverse effects of other factors, so that the coating and the substrate are tightly combined.

[0016] Preferably, 0.06-0.1 parts by weight of a functional auxiliary agent is further added to the raw materials of the hot-dip galvanizing solution, and the functional auxiliary agent consists of lanthanum and nickel, and the weight ratio of lanthanum to nickel is 1:(5-7).

[0017] By adopting the above technical scheme, the use of lanthanum can significantly improve the corrosion resistance of the coating, reduce surface cracks, and improve the density and uniformity of the coating; the addition of nickel effectively controls the grain size inside the coating, thereby greatly enhancing the corrosion resistance and adhesion of the coating; and when lanthanum and nickel are used as functional auxiliary agents, it can not only assist the rare earth element mixture to play a better role, but also significantly reduce the surface tension of the hot-dip galvanizing solution and improve the wettability to the surface of the steel substrate, thereby significantly improving the bonding force between the coating and the substrate, and improving the practical applicability of the hot-dip galvanizing solution, and the ability to compensate for the adverse effects of other factors is stronger.

[0018] Preferably, the functional auxiliary agent consists of lanthanum and nickel, and the weight ratio of lanthanum to nickel is 1:6.

[0019] By adopting the above technical scheme, when lanthanum and nickel in the above weight ratio are used in combination, the compounding effect between them is better, and the coordination and enhancement effect between the functional auxiliary agent and the rare earth element mixture is also better, so that the coating formed by the application of hot-dip galvanizing liquid has better bonding performance with the substrate, and the overall application quality is better.

[0020] In a second aspect, the present application provides a method for preparing a hot-dip galvanizing solution, using the following technical solution: A method for preparing a hot-dip galvanizing solution comprises the following steps: (1) preparing a raw material mixture containing zinc, aluminum, silicon, lead and rare earth elements according to a proportion; (2) Aluminum is melted in a production container, and then zinc is added to melt evenly, silicon and lead are added to melt evenly, and finally a rare earth element mixture is added to melt evenly to obtain a hot-dip galvanizing liquid.

[0021] By adopting the above technical scheme, the above operation is relatively simple and convenient, and each raw material is added and used in steps, which is also conducive to quality control during the process. It can also make the raw materials fully combined and play a better coordination role, thereby obtaining a hot-dip galvanizing liquid with excellent and stable application quality, which is also suitable for large-scale industrial production as a whole.

[0022] Preferably, the method for preparing hot-dip galvanizing liquid comprises the following steps: (1) preparing a raw material mixture containing zinc, aluminum, silicon, lead and rare earth elements according to a proportion; (2) Aluminum is melted at 600°C-680°C in a production container, and then zinc is added at 420°C-480°C for uniform melting, and then silicon and lead are added at 1400°C-1450°C for uniform melting, and finally a rare earth element mixture is added at 1500°C-1560°C for uniform melting to obtain a hot-dip galvanizing liquid.

[0023] By adopting the above technical scheme, in the preparation operation of hot-dip galvanizing liquid, the above temperature control is adopted when each raw material is added and used, so that a more uniform mixing state and a more compact combination state can be formed, and the actual application effect of the hot-dip galvanizing liquid is better.

[0024] In a third aspect, the present application provides an application of hot-dip galvanizing liquid in hot-dip galvanizing of steel surfaces, using the following technical solution: The invention discloses an application of hot-dip galvanizing liquid in hot-dip galvanizing of steel surface.

[0025] Preferably, the hot-dip galvanizing temperature is 450-470°C and the hot-dip galvanizing time is 1-2 minutes.

[0026] By adopting the above technical scheme, in the hot-dip galvanizing of the steel surface, the selection of the above hot-dip galvanizing temperature and hot-dip galvanizing time can enable the hot-dip galvanizing liquid to form a coating with a better organizational structure during the application process, and can have excellent and stable bonding performance with the steel substrate.

[0027] In summary, this application has the following beneficial effects: 1. The present application applies a rare earth element mixture composed of rhenium, cobalt and antimony to the hot-dip galvanizing solution, which can significantly enhance the bonding force between the coating and the substrate, and compensate for the adverse effects caused by other unfavorable factors in the hot-dip galvanizing process operation, so that the hot-dip galvanizing solution as a whole has excellent applicability; 2. The present application uses a functional auxiliary agent composed of lanthanum and nickel, which can not only assist the rare earth element mixture to exert a better effect, but also significantly reduce the surface tension of the hot-dip galvanizing solution, improve the wettability of the steel substrate surface, and thus significantly improve the bonding strength between the coating and the substrate, and has a stronger ability to compensate for the adverse effects of other factors. DETAILED DESCRIPTION

[0028] The present application is further described in detail below with reference to examples and comparative examples. Example

[0029] Example 1 A hot-dip galvanizing solution, the raw materials and their corresponding weights of which are shown in Table 1, is prepared by the following steps: (1) preparing a raw material containing a mixture of zinc, aluminum, silicon, lead and rare earth elements according to a proportion; (2) Aluminum is melted at 640°C in a production container, zinc is then added at 450°C for uniform melting, silicon and lead are then added at 1425°C for uniform melting, and finally a rare earth element mixture is added at 1530°C for uniform melting to obtain a hot-dip galvanizing solution.

[0030] Note: In the above operation, the rare earth element mixture consists of rhenium, cobalt and antimony, and the weight ratio of rhenium, cobalt and antimony is 1:1.6:1.

[0031] Example 2-3 A hot-dip galvanizing solution, which is different from Example 1 in that its preparation raw materials and their corresponding weights are shown in Table 1.

[0032] Table 1 Raw materials for preparing hot-dip galvanizing solution in Examples 1-3 and their weight portions (kg / portion) raw material Example 1 Example 2 Example 3 Zinc 57.5 55 60 aluminum 32.5 30 35 silicon 1.4 0.8 2 lead 0.3 0.1 0.5 Rare earth element mixture 0.175 0.15 0.2 Example 4 A hot-dip galvanizing solution, which is different from that in Example 1, is prepared by the following steps: (1) preparing a raw material containing a mixture of zinc, aluminum, silicon, lead and rare earth elements according to a proportion; (2) Aluminum is melted at 600°C in a production container, zinc is then added at 420°C for uniform melting, silicon and lead are then added at 1400°C for uniform melting, and finally a rare earth element mixture is added at 1500°C for uniform melting to obtain a hot-dip galvanizing solution.

[0033] Example 5 A hot-dip galvanizing solution, which is different from that in Example 1, is prepared by the following steps: (1) preparing a raw material containing a mixture of zinc, aluminum, silicon, lead and rare earth elements according to a proportion; (2) Aluminum is melted at 680°C in a production container, zinc is then added at 480°C for uniform melting, silicon and lead are then added at 1450°C for uniform melting, and finally a rare earth element mixture is added at 1560°C for uniform melting to obtain a hot-dip galvanizing liquid.

[0034] Example 6 A hot-dip galvanizing solution is different from Example 1 in that the rare earth element mixture consists of rhenium, cobalt and antimony, and the weight ratio of rhenium, cobalt and antimony is 1:1.6:1.1.

[0035] Example 7 A hot-dip galvanizing solution is different from Example 1 in that the rare earth element mixture consists of rhenium, cobalt and antimony, and the weight ratio of rhenium, cobalt and antimony is 1:1.4:0.9.

[0036] Example 8 A hot-dip galvanizing solution is different from Example 1 in that the rare earth element mixture consists of rhenium, cobalt and antimony, and the weight ratio of rhenium, cobalt and antimony is 1:1.8:1.3.

[0037] Example 9 A hot-dip galvanizing solution, which is different from Example 1 in that the total weight of zinc, aluminum, silicon and lead in the hot-dip galvanizing solution remains unchanged, and the weight ratio of the four is adjusted to 57:32:1:0.3.

[0038] Example 10 A hot-dip galvanizing solution, which is different from Example 1 in that the total weight of zinc, aluminum, silicon and lead in the hot-dip galvanizing solution remains unchanged, and the rare earth element mixture is adjusted to account for 0.18% of the total mass of the hot-dip galvanizing solution.

[0039] Embodiment 11 A hot-dip galvanizing liquid is different from Example 1 in that 0.08 parts by weight of a functional auxiliary agent is further added to the raw materials of the hot-dip galvanizing liquid, the functional auxiliary agent is composed of lanthanum and nickel in a weight ratio of 1:6, and the functional auxiliary agent is added together with the rare earth element mixture.

[0040] Example 12 A hot-dip galvanizing solution, which is different from Example 11 in that the weight portion of the functional auxiliary agent is 0.06 parts.

[0041] Embodiment 13 A hot-dip galvanizing solution, which is different from Example 11 in that the weight portion of the functional auxiliary agent is 0.1 part.

[0042] Embodiment 14 A hot-dip galvanizing solution, which is different from Example 11 in that the functional auxiliary agent consists of lanthanum and nickel in a weight ratio of 1:5.

[0043] Embodiment 15 A hot-dip galvanizing solution, which is different from Example 11 in that the functional auxiliary agent consists of lanthanum and nickel in a weight ratio of 1:7.

[0044] Example 16 A hot-dip galvanizing solution, which is different from Example 11 in that no lanthanum is used in the preparation of raw materials.

[0045] Embodiment 17 A hot-dip galvanizing solution, which is different from Example 11 in that no nickel is used in the preparation of raw materials.

[0046] Comparative Example Comparative Example 1 A hot-dip galvanizing solution, which is different from Example 1 in that rhenium is not used in the preparation raw materials.

[0047] Comparative Example 2 A hot-dip galvanizing solution, which is different from Example 1 in that no cobalt is used in the preparation of raw materials.

[0048] Comparative Example 3 A hot-dip galvanizing solution, which is different from Example 1 in that no antimony is used in the preparation of raw materials.

[0049] Comparative Example 4 A hot-dip galvanizing solution, which is different from Example 1 in that rhenium and cobalt are not used in the preparation raw materials.

[0050] Comparative Example 5 A hot-dip galvanizing solution, which is different from Example 1 in that rhenium and antimony are not used in the preparation raw materials.

[0051] Comparative Example 6 A hot-dip galvanizing solution, which is different from Example 1 in that no cobalt or antimony is used in the preparation of raw materials.

[0052] Comparative Example 7 A hot-dip galvanizing solution, which is different from Example 1 in that no rare earth element mixture is used in the preparation of raw materials.

[0053] Comparative Example 8 A hot-dip galvanizing solution, which is different from Example 11 in that no rare earth element mixture is used in the preparation of raw materials.

[0054] Performance test test samples: The hot-dip galvanizing solution obtained in Examples 1-17 was used as test samples 1-17, and the hot-dip galvanizing solution obtained in Comparative Examples 1-8 was used as control samples 1-8.

[0055] Test method: The substrate for plating is Q235 industrial steel, which is cut into small square pieces of 10mm×10mm×3mm, and then surface polished → alkaline washing and degreasing (15% NaOH, 80℃, 2min) → water washing → acid washing and derusting (15% HCl, 25℃, 1.5min) → water washing → plating treatment (mixed aqueous solution with mass ratio of NH4Cl:ZnCl2=1.2:1, concentration of 330g / L, 80℃, 3min) → drying to obtain a pretreated substrate; then the pretreated substrate is hot-dip galvanized using hot-dip galvanizing liquid, the hot-dip galvanizing temperature is 450℃, and the hot-dip galvanizing time is 1.5min to obtain a hot-dip galvanized finished product.

[0056] Select a tape with a bonding strength of 10N, take the hot-dip galvanized product, use a sharp blade to score on its surface, the depth of the score only penetrates the coating, and the distance between two adjacent scores is 0.1mm. After completing the longitudinal and transverse cross-scoring, stick the above tape to the surface of the hot-dip galvanized product so that it fits tightly without generating bubbles, then peel off the tape, and calculate the proportion of the adhered coating to the adhesive area of ​​the tape; the higher the proportion, the worse the bonding performance between the coating formed by the hot-dip galvanizing liquid and the substrate.

[0057] After completing the above tests on test samples 1-17 and control samples 1-8 in sequence, the corresponding results are recorded in Table 2.

[0058] Table 2 Test results of test samples 1-17 and control samples 1-8 It can be seen from the combination of Examples 1-5 and Comparative Examples 1-7 and Table 2 that the present application applies the rare earth element mixture composed of rhenium, cobalt and antimony to the hot-dip galvanizing liquid, which can significantly enhance the bonding force between the coating and the substrate, and to a certain extent can greatly compensate for the adverse effects caused by other unfavorable factors in the hot-dip galvanizing process operation; and when any one or two of rhenium, cobalt and antimony are applied to the hot-dip galvanizing liquid, although the bonding force between the coating and the substrate can be improved, and the corresponding ratio obtained by the test is also significantly reduced, the actual effect is extremely limited, and the effects are only simply superimposed on each other. Only when rhenium, cobalt and antimony are compounded and applied, can a more significant enhancement effect be achieved. It can be seen from Examples 6-8 and Table 2 that when the weight ratio of rhenium, cobalt and antimony in the rare earth element mixture is 1:1.6:1, the corresponding effect brought by the application of the rare earth element mixture in the hot-dip galvanizing liquid is better.

[0059] It can be seen from Examples 1-5 and Example 9 and Table 2 that when the weight ratio of zinc, aluminum, silicon and lead in the hot-dip galvanizing solution is 57:32:1:0.3, the mixed matrix formed is easier for the rare earth element mixture to exert a more sufficient bonding effect, so that the coating formed by the hot-dip galvanizing solution has a stronger bonding force with the substrate.

[0060] Combining Examples 1-5 and Example 10 with Table 2, it can be seen that when the rare earth element mixture accounts for 0.18% of the total mass of the hot-dip galvanizing liquid, its overall effect in the hot-dip galvanizing liquid is better, and the bonding force between the coating formed by the hot-dip galvanizing liquid and the substrate is also better.

[0061] Combining Example 1 and Example 11-15 and Table 2, it can be seen that by adding and using a functional auxiliary agent composed of lanthanum and nickel, the bonding force between the coating and the substrate can be further improved, and the corresponding ratio value obtained by the above test is also significantly reduced; if lanthanum and nickel are used alone, it is found that the corresponding effects brought are limited, and the sum of the improvement effects brought by the use of each of them alone is far less than the excellent combination of the two. It can be seen that lanthanum and nickel can bring a significant improvement effect of 1+1>2 in the application of the hot-dip galvanizing liquid of the present application. Combining Comparative Examples 7-8 and Table 2, it can be seen that if the hot-dip galvanizing liquid lacks the use of a rare earth element mixture, it is found that the corresponding effect brought by the application of the functional auxiliary agent in the hot-dip galvanizing liquid will be greatly discounted, indicating that the excellent effect of the functional auxiliary agent cannot be achieved without the rare earth element mixture, and the two have a complementary effect, thereby obtaining a hot-dip galvanizing liquid with better application quality.

[0062] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A hot-dip galvanizing solution, characterized in that: The invention is composed of the following raw materials in parts by weight: Zinc 55-60 parts; Aluminum 30-35 parts; Silicon 0.8-2 parts; Lead 0.1-0.5 parts; Rare earth element mixture 0.15-0.2 parts; The rare earth element mixture consists of rhenium, cobalt and antimony, and the weight ratio of rhenium, cobalt and antimony is 1:(1.4-1.8):(0.9-1.3).

2. The hot-dip galvanizing solution according to claim 1, characterized in that: The weight ratio of rhenium, cobalt and antimony in the rare earth element mixture is 1:1.6:

1.

3. The hot-dip galvanizing solution according to claim 1, characterized in that: The weight ratio of zinc, aluminum, silicon and lead in the hot-dip galvanizing solution is 57:32:1:0.

3.

4. The hot-dip galvanizing solution according to claim 1, characterized in that: The rare earth element mixture accounts for 0.18% of the total mass of the hot-dip galvanizing liquid.

5. The hot-dip galvanizing solution according to claim 1, characterized in that: 0.06-0.1 parts by weight of a functional auxiliary agent is also added to the raw materials of the hot-dip galvanizing liquid. The functional auxiliary agent is composed of lanthanum and nickel, and the weight ratio of lanthanum to nickel is 1: (5-7).

6. The hot-dip galvanizing solution according to claim 5, characterized in that: The functional auxiliary agent consists of lanthanum and nickel, and the weight ratio of lanthanum to nickel is 1:

6.

7. The method for preparing hot-dip galvanizing liquid according to claim 1, characterized in that: The following steps are involved: (1) preparing raw materials containing a mixture of zinc, aluminum, silicon, lead and rare earth elements according to a proportion; (2) Aluminum is melted in a production container, and then zinc is added to melt evenly, silicon and lead are added to melt evenly, and finally a rare earth element mixture is added to melt evenly to obtain a hot-dip galvanizing liquid.

8. The method for preparing hot-dip galvanizing liquid according to claim 7, characterized in that: The following steps are involved: (1) preparing raw materials containing a mixture of zinc, aluminum, silicon, lead and rare earth elements according to a proportion; (2) Aluminum is melted at 600°C-680°C in a production container, and then zinc is added at 420°C-480°C for uniform melting, and then silicon and lead are added at 1400°C-1450°C for uniform melting, and finally a rare earth element mixture is added at 1500°C-1560°C for uniform melting to obtain a hot-dip galvanizing liquid.

9. Use of the hot-dip galvanizing liquid according to any one of claims 1 to 6 in hot-dip galvanizing of steel surfaces.

10. Application of the hot-dip galvanizing solution according to claim 9 in hot-dip galvanizing of steel surfaces, characterized in that: The hot-dip galvanizing temperature is 450-470℃, and the hot-dip galvanizing time is 1-2min.

Images