A zinc alloy for zinc bath iron hot dip

Abstract

The present invention provides a zinc alloy for hot-dip zinc bath iron control. The zinc alloy contains 0.005-0.02 wt.% of Ga and 0.01-1.2 wt.% of Si, with the remainder being Zn, Al, and unavoidable impurities, based on the total mass of the zinc alloy. Appropriate amounts of Ga and Si are added to a zinc bath of a zinc-aluminum alloy. A trace amount of Ga promotes better binding of Si with free Fe in the zinc bath into a slag phase, thereby achieving the purpose of zinc bath iron control. The zinc alloy for hot-dip zinc bath iron control is suitable for various steel materials with complex compositions and shapes. During the hot-dip process, the iron content in the zinc bath can be effectively controlled to remain at a low level, thereby improving the fluidity of the zinc bath, reducing the thickness of the coating, and increasing the adhesion of the coating, resulting in a high coating quality.

Description

Technical Field

[0001] The invention belongs to the technical field of hot-dip galvanizing and relates to a zinc alloy for hot-dip galvanizing in a zinc bath. Background Art

[0002] With the rapid development of industries such as communications, electricity, automobiles, home appliances, and construction, the demand for hot-dip galvanized products is increasing year by year, and the demand for product quality is constantly improving. The principle of hot-dip galvanizing is to clean rust from the surface of steel parts through pickling or atmospheric reduction, then dry them with solvents before immersing them in a zinc alloy solution or directly immersing them in the zinc alloy solution. The iron on the steel surface reacts with the molten zinc to form an alloy coating on the surface of the steel structure. During the hot-dip galvanizing process, as the steel parts are immersed in the molten zinc bath, iron (Fe) on the surface of the steel parts will seep into the zinc bath, increasing the Fe content in the zinc bath. This can lead to galvanizing problems such as reduced bath fluidity, thickened coatings, and poor adhesion. To reduce the Fe content in the zinc bath and improve the adhesion of hot-dip galvanized products, the hot-dip galvanizing alloy technology market is experiencing new development demands: Fe content in the hot-dip galvanizing bath for structural parts is below 0.015%, and Fe content in the galvanized zinc bath for strip steel is below 0.005%.

[0003] For example, in the current hot-dip galvanizing industry, both domestically and internationally, alloy coatings created by adding trace alloying elements such as Ni and RE exhibit excellent surface quality, superior corrosion resistance, excellent bonding and mechanical properties, and robust zinc bath purification capabilities. However, with advancements in steel production processes, steel composition has become increasingly complex. This change has led to quality issues with traditional hot-dip galvanizing, such as a rapid increase in Fe content in the zinc bath, excessively thick coating thickness, and poor adhesion. Furthermore, the structures and shapes of the components being plated are complex, such as large pipe tower components, which often utilize steel with high silicon and manganese content. These structures are more complex than those of simple angle steel, plate, flat steel, pipe, or strip steel of varying sizes. This structure affects heat transfer and zinc bath flow during galvanizing, hindering coating adhesion and placing higher demands on hot-dip galvanizing alloys. The prolonged pickling time for large and complex steel components can lead to over-pickling in some areas. Over-pickling introduces more iron particles into the flux and zinc alloy bath, increasing the amount of impure iron in the zinc alloy bath during the galvanizing process and generating more zinc slag. At the same time, the hot-dip galvanizing requirements for such structural parts are high, requiring extended galvanizing times. This is primarily due to poor heat transfer and fluidity in the zinc bath during the galvanizing process, which results in more iron dissolving from the steel parts into the zinc alloy solution. This leads to quality issues such as thicker coatings, poor adhesion, particles, and an uneven finish. In the prior art, commonly used zinc alloys for hot-dip galvanizing include Zn-Al-RE alloys and Zn-Ni alloys. These alloys are not suitable for hot-dip galvanizing processes on surfaces of complex steel materials and cannot effectively address the problem of increased zinc slag caused by excessive iron particles entering the zinc alloy solution. When Zn-Ni alloy is used for hot-dip galvanizing of structural parts for more than three minutes, the iron particle concentration reaches 0.032% or even above 0.04% for six consecutive months, resulting in brittle coatings and poor local adhesion on the plated parts. When a Zn-Al-RE alloy zinc bath is used for strip steel, the iron particle concentration reaches 0.01% for six consecutive months, leading to surface particles.

[0004] CN113881911A discloses a silicon-tin alloy in a hot-dip galvanizing bath. This alloy improves the fluidity of the zinc bath by changing the surface tension of the zinc alloy, thereby achieving the effects of slowing down iron dissolution, controlling the thickness of the coating, improving the adhesion of the coating, and improving other qualities of the coating. However, when the iron content of the coating reaches a certain concentration, the fluidity of the zinc bath inevitably deteriorates, resulting in coating quality problems such as thick coating thickness, poor coating adhesion, possible particles in the coating, and uneven coating. These quality problems are more obvious when galvanizing complex parts. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a zinc alloy for hot-dip zinc bath control iron.

[0006] In response to the above technical problems, the following solutions are proposed:

[0007] The present invention provides a zinc alloy for hot-dip zinc bath iron control. Based on the total mass of the zinc alloy for hot-dip zinc bath iron control, the zinc alloy for hot-dip zinc bath iron control contains 0.005-0.02wt% of Ga, 0.01-1.2wt% of Si, and the remainder is Zn, Al and unavoidable impurities of the zinc alloy.

[0008] Preferably, the Al content is 5-30 wt.%.

[0009] Preferably, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron-control contains 0.008 wt.% Ga, 0.3 wt.% Si, and the remainder is Zn, Al and unavoidable impurities.

[0010] Preferably, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron control contains 0.01 wt.% Ga, 0.5 wt.% Si, and the remainder is Zn, Al and unavoidable impurities.

[0011] Preferably, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron-control contains 0.015 wt.% Ga, 0.8 wt.% Si, and the remainder is Zn, Al and inevitable impurities of the zinc alloy.

[0012] Preferably, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron control contains 0.02 wt.% Ga, 1.2 wt.% Si, and the remainder is Zn, Al and inevitable impurities of the zinc alloy.

[0013] Preferably, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron control contains 0.005wt.% Ga, 0.01wt.% Si, and the remainder is Zn, Al and inevitable impurities of the zinc alloy.

[0014] The present invention also provides a hot-dip galvanizing method, which comprises placing a substrate to be plated in the molten hot-dip zinc alloy to form a coating on the surface of the substrate to be plated.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] In the present invention, the zinc alloy for hot-dip coating provided by the present invention is obtained by adding appropriate amounts of Ga and Si elements to a zinc bath of a zinc-aluminum alloy. Through the synergistic effect of Ga and Si, a trace amount of Ga promotes better combination of Si with free Fe in the zinc bath and enters the slag phase, thereby achieving the purpose of controlling iron in the zinc bath. The zinc alloy for hot-dip coating with iron control in the zinc bath is suitable for steel materials with various complex compositions and complex shapes. During the hot-dip coating process, the iron content in the zinc bath can be effectively controlled to remain at a low level, thereby improving the fluidity of the zinc bath, reducing the thickness of the coating, and increasing the adhesion of the coating, thereby having a high coating quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 This is the backscattered image of the hot-dip galvanizing slag sample produced in Example 3.

[0019] Figure 2 This is the backscattered image of the hot-dip galvanizing slag sample produced in Comparative Example 1. DETAILED DESCRIPTION

[0020] The present invention provides a zinc alloy for hot-dip zinc bath iron control. Based on the total mass of the zinc alloy for hot-dip zinc bath iron control, the zinc alloy for hot-dip zinc bath iron control contains 0.005-0.02wt% of Ga, 0.01-1.2wt% of Si, and the remainder is Zn, Al and unavoidable impurities of the zinc alloy.

[0021] After extensive research, the applicant found that by adding appropriate amounts of Ga and Si trace elements to the zinc bath, the resulting hot-dip zinc alloy is suitable for steel materials with various complex compositions and shapes. During the hot-dip process, the iron content in the zinc bath can be effectively controlled to remain at a low level, while also increasing the adhesion of the coating and achieving higher coating quality.

[0022] In a zinc alloy for hot-dip zinc bath iron control provided by the present invention, a trace amount of Ga promotes better combination of Si with free Fe in the zinc bath through the synergistic effect of Ga and Si, and enters the slag phase, thereby achieving the purpose of zinc bath iron control. When a structural part is hot-dip-galvanized for more than 3 minutes and continuously galvanized for more than six months, the iron content in the zinc bath is maintained below 0.015%. When a steel strip is continuously galvanized for more than six months, the iron content in the zinc bath is maintained below 0.005%. The coating has good adhesion and there is no particle defect problem on the plate surface.

[0023] As is common knowledge among those skilled in the art, the hot-dip zinc alloy provided by the present invention also contains inevitable impurities, which are present in normal amounts and for which the present invention has no special requirements.

[0024] In some preferred embodiments, the Al content is 5-30 wt.%.

[0025] In some preferred embodiments, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron control contains 0.008 wt.% Ga, 0.3 wt.% Si, and the remainder is Zn, Al and unavoidable impurities.

[0026] In some preferred embodiments, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron control contains 0.01 wt.% Ga, 0.5 wt.% Si, and the remainder is Zn, Al and unavoidable impurities.

[0027] In some preferred embodiments, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron control contains 0.015 wt.% Ga, 0.8 wt.% Si, and the remainder is Zn, Al and unavoidable impurities of the zinc alloy.

[0028] In some preferred embodiments, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron control contains 0.02 wt.% Ga, 1.2 wt.% Si, and the remainder is Zn, Al and unavoidable impurities of the zinc alloy.

[0029] In some preferred embodiments, based on the total mass of the hot-dip zinc alloy, the zinc alloy for hot-dip zinc bath iron control contains 0.005 wt.% Ga, 0.01 wt.% Si, and the remainder is Zn, Al and unavoidable impurities of the zinc alloy.

[0030] The present invention also provides a hot-dip galvanizing method, which comprises placing a substrate to be plated in the molten hot-dip zinc alloy to form a coating on the surface of the substrate to be plated.

[0031] In some optional specific embodiments, the substrate to be plated can be conventional substrates such as angle steel, plate, flat steel, steel pipe, strip steel, etc., or it can be a complex-shaped steel component such as a large pipe tower, and the components of the substrate to be plated can also be diversified.

[0032] The hot-dip galvanizing alloy provided by the present invention is suitable for hot-dip galvanizing treatment of the surface of steel materials with various complex compositions and complex shapes by appropriately selecting the components of the hot-dip zinc alloy. Therefore, the hot-dip galvanizing method provided by the present invention is suitable for substrates to be plated with various complex shapes.

[0033] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the scope of protection of the present invention is not limited to the following specific embodiments.

[0034] Example 1

[0035] A zinc alloy S1 for hot-dip zinc bath control iron, based on the total mass of the hot-dip zinc alloy, contains 0.008wt% Ga, 0.3wt% Si, 10wt% Al, and the remainder is Zn and unavoidable impurities of the zinc alloy.

[0036] The hot-dip zinc alloy S1 of this embodiment was used to hot-dip zinc alloy S1 on angle steel and steel pipes for 1.5 minutes. After continuous use for six months, the iron content in the zinc bath was maintained below 0.015%, and the coating adhesion test was good.

[0037] Example 2

[0038] A zinc alloy S2 for hot-dip zinc bath control iron coating, based on the total mass of the zinc alloy for hot-dip zinc bath control iron coating, contains 0.01wt% Ga, 0.5wt% Si, 15wt% Al, and the remainder is Zn and unavoidable impurities of the zinc alloy.

[0039] The hot-dip zinc alloy S2 of this embodiment was used for hot-dip coating of steel strips and steel wire ropes. After nine consecutive months of use, the iron content in the zinc bath was maintained below 0.0030%. The coating adhesion test was good, and the coating was bright and smooth without surface defects.

[0040] Example 3

[0041] A zinc alloy S3 for hot-dip zinc bath control iron, based on the total mass of the hot-dip zinc alloy, contains 0.015wt% Ga, 0.8wt% Si, 15wt% Al, and the remainder is Zn and unavoidable impurities of the zinc alloy.

[0042] A high-silicon, high-manganese steel large pipe tower component with discs at both ends was hot-dip-coated with the hot-dip zinc alloy S3 of this embodiment for 3 minutes. After continuous use for one year, the iron content in the zinc bath was maintained at 0.012%. The coating adhesion test was good and there were no surface defects.

[0043] The hot dip galvanizing slag sample produced in this embodiment was tested, and its backscattering pattern was as follows: Figure 1 As shown, spectrum 1 corresponds to the impurity phase, spectrum 3 corresponds to the part excluding impurities, and the EDS composition is shown in Table 1.

[0044] Table 1 EDS composition of zinc slag sample produced in Example 3

[0045]

[0046] Example 4

[0047] A zinc alloy S4 for hot-dip zinc bath control iron, based on the total mass of the hot-dip zinc alloy, contains 0.02wt% of Ga, 1.2wt% of Si, 20wt% of Al, and the remainder is Zn and unavoidable impurities of the zinc alloy.

[0048] The photovoltaic bracket was hot-dip plated with the hot-dip zinc alloy S4 of this embodiment for 2 minutes and used continuously for one year. The iron content in the zinc bath was maintained at 0.013%, the coating adhesion test was good, and the coating had no surface defects.

[0049] Comparative Example 1

[0050] A hot-dip zinc alloy S5 contains, based on the total mass of the hot-dip zinc alloy, 0.8wt% Si, 15wt% Al, and the remainder Zn and unavoidable impurities of the zinc alloy.

[0051] The square high-silicon and high-manganese steel large pipe tower component was hot-dip coated with the hot-dip zinc alloy S5 of the comparative example for 3 minutes. After continuous use for six months, the iron content in the zinc bath was maintained at 0.029%. The coating adhesion test was good, with fewer particles and more obvious flow marks on the surface.

[0052] Take the hot dip galvanizing slag sample produced in this comparative example for testing, and its backscattering pattern is as follows Figure 2 As shown, spectrum 1 corresponds to the impurity phase, spectrum 4 corresponds to the part excluding impurities, and the EDS composition is shown in Table 2.

[0053] Table 2 EDS composition of zinc slag produced in Comparative Example 1

[0054]

[0055] Comparison of the backscattered patterns and EDS composition analysis of the hot-dip galvanizing slag of Example 3 and this comparative example shows that the hot-dip galvanizing slag in Example 3 has a higher Fe content. This shows that the zinc slag produced by the zinc bath of the present invention has a significant Fe enrichment effect and a better Fe control effect in the zinc bath. It is speculated that the possible reason for this phenomenon is that a trace amount of Ga promotes a better combination of Si and free Fe in the zinc bath, thereby achieving the purpose of controlling iron in the zinc bath, thereby reducing the harmful impurity iron element in the zinc bath of the galvanizing pot and eliminating the reduction in the quality of the galvanized coating caused by a high iron content.

[0056] Comparative Example 2

[0057] A hot-dip zinc alloy S6, based on the total mass of the hot-dip zinc alloy, contains 0.01wt% of Ga, 15wt% of Al, and the remainder is Zn and unavoidable impurities of the zinc alloy.

[0058] The square high-silicon and high-manganese steel large pipe tower components were hot-dip coated with the hot-dip zinc alloy S6 of the comparative example for 3 minutes. After continuous use for six months, the iron content in the zinc bath was maintained at 0.029-0.038%. The coating adhesion test was good, with fewer particles and more obvious flow marks on the surface.

[0059] Comparative Example 3

[0060] A hot-dip zinc alloy S7 comprises 5 wt% Al, 1.0 wt% Ni, and the remainder Zn and inevitable impurities of the zinc alloy.

[0061] The hot-dip zinc alloy S7 of the comparative example was used to hot-dip coat ordinary angle steel for 2 minutes. After continuous use for one year, the iron content in the zinc bath was maintained at 0.032%. The coating adhesion test was good, and more particles and more obvious flow marks appeared on the surface.

[0062] Comparative Example 4

[0063] A hot-dip zinc alloy S8 comprises 5 wt% Al, 0.072 wt% RE, and the remainder Zn and inevitable impurities of the zinc alloy.

[0064] The hot-dip zinc alloy S8 of the comparative example was used to galvanize the steel strip and the steel wire rope. After six months of continuous use, the iron content in the zinc bath was maintained at 0.0089%. The coating adhesion test was good, with few particles on the surface of the steel strip and obvious particles on the surface of the steel wire rope.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A zinc alloy for hot-dip zinc bath iron coating, characterized in that: Based on the total mass of the zinc alloy for hot-dip zinc bath iron coating, it contains 0.005-0.02 wt.% of Ga, 0.3-1.2 wt.% of Si, 10-30 wt.% of Al, and the balance is Zn and unavoidable impurities.

2. The zinc alloy for hot-dip zinc bath ironing according to claim 1, wherein: Based on the total mass of the zinc alloy for hot-dip zinc bath iron coating, it contains 0.008 wt.% of Ga, 0.3 wt.% of Si, 10-30 wt.% of Al, and the balance is Zn and unavoidable impurities.

3. The zinc alloy for hot-dip zinc bath ironing according to claim 1, wherein: Based on the total mass of the zinc alloy for hot-dip zinc bath iron coating, it contains 0.01 wt.% of Ga, 0.5 wt.% of Si, 10-30 wt.% of Al, and the balance is Zn and unavoidable impurities.

4. The zinc alloy for hot-dip zinc bath ironing according to claim 1, wherein: Based on the total mass of the zinc alloy for hot-dip zinc bath iron coating, it contains 0.015 wt.% of Ga, 0.8 wt.% of Si, 10-30 wt.% of Al, and the remainder is Zn and inevitable impurities of the zinc alloy.

5. The zinc alloy for hot-dip zinc bath iron coating according to claim 1, wherein: Based on the total mass of the zinc alloy for hot-dip zinc bath control iron, it contains 0.02wt.% Ga, 1.2wt.% Si, 10-30wt.% Al, and the remainder is Zn and inevitable impurities of the zinc alloy.

6. A hot dip galvanizing method, characterized in that: The method comprises placing a substrate to be plated in the molten zinc alloy for hot-dip zinc bath ironing according to any one of claims 1 to 5, and forming a plating layer on the surface of the substrate to be plated.

Images