目的 热镀锌批量镀工艺在生产中存在镀层结合力差、缺陷多、铝镁含量无法把控等问题。因此,采用批量镀工艺方法,借助于自主研发的无铵助镀剂和助镀处理工艺,旨在研究锌浴中Al、Mg元素含量对批量热浸镀锌铝镁镀层组织及性能的影响。方法 采用批量镀方法制备了不同Al、Mg含量的锌铝镁合金镀层,通过扫描电子显微镜（SEM）结合能谱分析（EDS）对镀层的微观组织结构和化学成分进行了系统表征;通过电化学极化曲线测试、中性盐雾腐蚀试验（NSS）以及全浸腐蚀实验等方法,全面评估了镀层的耐腐蚀性能;采用XRD分析了镀层的腐蚀产物。结果 结果表明：在锌浴中添加Al和Mg元素后,镀层微观结构主要由富Zn相、Zn/Al/MgZn2三元共晶相、Zn/MgZn2二元共晶相以及Fe2Al5Zn0.8金属间化合物相组成;随着Mg含量的增加,镀层中的Zn/Al/MgZn2三元共晶相和Zn/MgZn2二元共晶相增多;随着Al含量的增加,镀层厚度逐渐增加,镀层和基体界面处Fe2Al5Zn0.8合金相层逐渐减薄并演变为分散块状分布于镀层中。随着Mg、Al含量的增加,镀层的自腐蚀电位逐渐正移,腐蚀电流密度呈下降趋势,极化阻抗逐渐增大,镀层的全浸腐蚀速率逐渐降低。通过中性盐雾腐蚀对比,锌铝镁镀层的耐蚀性优于纯锌镀层;与纯锌镀层相比,Zn-2Al-2Mg镀层的白色腐蚀产物没有发现ZnO,出现了含Mg2CO3的化合物,Zn5(OH)8Cl2H2O衍射峰增多。结论 因此,锌浴中添加Al（0.5 %~2%,质量分数）、Mg（0.5 %~2%,质量分数）时,批量镀可以获得Zn/MgZn2二元共晶相、Zn/Al/MgZn2三元共晶相特征明显的锌铝镁镀层,且镀层的耐蚀性随着Al、Mg的添加量增多而逐渐提高。
Abstract
Hot-dip galvanized aluminum-magnesium coatings have experienced rapid development over the past few decades and are now widely used in various industries. Current researches on hot-dip galvanized aluminum-magnesium mainly focus on continuous galvanizing, with limited research on batch galvanizing. Batch galvanizing processes in production often suffer from issues such as poor coating adhesion, numerous defects, and difficulties in controlling aluminum and magnesium content. Therefore, the work aims to employ a batch galvanizing process through a self-developed ammonium-free flux and flux treatment process to investigate the effect of Al and Mg element content in the zinc bath on the microstructure and properties of batch hot-dip galvanized aluminum-magnesium coatings. Zinc-aluminum-magnesium alloy coatings with different aluminum and magnesium contents were prepared with an intermittent plating method. The microstructure and chemical composition of the coatings were systematically characterized through scanning electron microscopy (SEM) combined with energy-dispersive spectroscopy (EDS). The corrosion resistance of the coatings was comprehensively evaluated through electrochemical polarization curve testing, neutral salt spray (NSS) corrosion testing, and full immersion corrosion experiments. X-ray diffraction (XRD) was used to analyze the corrosion products of the coatings. After aluminum and magnesium were added to the zinc bath, the coatings consisted of a zinc-rich phase, a Zn/Al/MgZn2 ternary eutectic phase, a Zn/MgZn2 binary eutectic phase, and a Fe2Al5Zn0.8 alloy phase. The distribution of aluminum in the coatings was obvious, located at the interface between the coating and the substrate, exhibiting a band-like overlapping feature with iron, indicating the presence of a Fe-Al alloy phase. Magnesium did not show aggregation, was widely distributed, and mainly existed in the dendrite structure, while zinc was significantly enriched in the free solidified layer. As the magnesium content increased, the Zn/Al/MgZn2 ternary eutectic phase and Zn/MgZn2 binary eutectic phase in the coatings increased. With the increase of aluminum content, the Fe2Al5Zn0.8 phase layer at the coating-substrate interface thickened, and a blocky structure similar to the Fe2Al5Zn0.8 phase formed in the coatings. This process involved iron atoms in the substrate, breaking through the inhibition of the Fe2Al5Zn0.8 alloy phase layer and diffusing outward, leading to the gradual thinning of the Fe2Al5Zn0.8 alloy phase layer at the coating-substrate interface and its evolution into a dispersed blocky distribution within the coatings. Simultaneously, the coating thickness gradually increased. As the magnesium and aluminum content increased, the self-corrosion potential of the coatings gradually shifted positively, the corrosion current density showed a decreasing trend, the polarization resistance gradually increased, and the full immersion corrosion rate of the coatings gradually decreased. Neutral salt spray corrosion results showed that the corrosion resistance of zinc-aluminum-magnesium coatings was significantly better than that of pure zinc coatings. Corrosion product analysis showed that, compared to pure zinc coatings, the white corrosion products of the Zn-2Al-2Mg coatings did not contain ZnO but included compounds containing Mg2CO3, and the diffraction peak of Zn5(OH)8Cl2H2O increased. Therefore, by adding aluminum (0.5wt.%-2wt.%) and magnesium (0.5wt.%-2wt.%) to the zinc bath, batch plating can achieve zinc-aluminum-magnesium coatings with distinct characteristics of Zn/MgZn2 binary eutectic and Zn/Al/MgZn2 ternary eutectic phases. The corrosion products also show significant differences from those of pure zinc coatings, and the corrosion resistance of the coatings is gradually improved with the increasing amounts of aluminum and magnesium.
关键词
批量热浸镀锌 /
锌铝镁镀层 /
Al、Mg元素含量 /
锌浴 /
微观组织 /
耐蚀性能
Key words
batch hot-dip galvanizing /
zinc-aluminum-magnesium coating /
Al and Mg element content /
zinc bath /
microstructure /
corrosion resistance
{{custom_sec.title}}
{{custom_sec.title}}
{{custom_sec.content}}
参考文献
[1] YU Z, HU J M, MENG H M.A Review of Recent Developments in Coating Systems for Hot-Dip Galvanized Steel[J]. Frontiers in Materials, 2020, 7: 74.
[2] 刘旭亮, 刘云, 孙震, 等. 锌铝镁镀层钢板耐腐蚀性能研究[J]. 环境技术, 2022, 40(3): 104-108.
LIU X L, LIU Y, SUN Z, et al.Investigations on Anti-Corrosion Properties of Zn-Al-Mg Coated Steel Plates[J]. Environmental Technology, 2022, 40(3): 104-108.
[3] 邹建国, 卢琳. 锌铝镁镀层中合金相与耐蚀性关系的研究进展[J]. 中国有色金属学报, 2022, 32(7): 1934-1944.
ZOU J G, LU L.Research Progress on Relationship between Alloy Phase and Corrosion Resistance in Zn-Al-Mg Coating[J]. The Chinese Journal of Nonferrous Metals, 2022, 32(7): 1934-1944.
[4] 孔纲, 王丽平, 车淳山. 热浸镀Zn-Al-Mg合金镀层的研究与应用[J]. 材料保护, 2014, (4): 45-47.
KONG G, WANG L P, CHE C S.Current Research Status and Application Prospect of Hot-Dipped Zn-Al-Mg Alloy Coating[J]. Materials Protection, 2014, 47(4): 45-47.
[5] 崔桂彬, 鞠新华, 严春莲, 等. 热浸镀低合金高强钢Zn-Al-Mg镀层的组织结构表征[J]. 钢铁, 2023, 58(1): 153-160.
CUI G B, JU X H, YAN C L, et al.Microstructure Characterization of Hot-Dip Zn-Al-Mg Coating of Low Alloy High Strength Steel[J]. Iron & Steel, 2023, 58(1): 153-160.
[6] 周谊军, 代云红, 蒋光锐. 近20年全球锌铝镁镀层钢板技术专利分析[J]. 钢铁, 2016, 51(11): 7-13.
ZHOU Y J, DAI Y H, JIANG G R.Analysis of Global Patents Technology on Zn-Al-Mg Coated Steel Sheets in Recent 20 Years[J]. Iron & Steel, 2016, 51(11): 7-13.
[7] 杜昕, 张满仓, 段生朝, 等. 高耐蚀锌铝镁镀层研究现状[J]. 工程科学学报, 2019, 41(7): 847-856.
DU X, ZHANG M C, DUAN S C, et al.Research Status of High Corrosion-Resistant Zn-Al-Mg Coating[J]. Chinese Journal of Engineering, 2019, 41(7): 847-856.
[8] 孙霖, 钱婷婷, 李超. Mg含量对于高铝锌铝镁镀层组织及耐蚀性的影响[J]. 焊管, 2023, 46(6): 21-25.
SUN L, QIAN T T, LI C.Effect of Magnesium Content on the Microstructure and Corrosion Resistance of High Aluminum Zinc-Aluminum-Magnesium Coating[J]. Welded Pipe and Tube, 2023, 46(6): 21-25.
[9] GAO B, LIU C, HU C L, et al.Effect of Mg and RE on the Surface Properties of Hot Dipped Zn-23Al-0.3Si Coatings[J]. Science of Advanced Materials, 2019, 11(4): 580-587.
[10] YAO C Z, LV H B, ZHU T P, et al.Effect of Mg Content on Microstructure and Corrosion Behavior of Hot Dipped Zn-Al-Mg Coatings[J]. Journal of Alloys and Compounds, 2016, 670: 239-248.
[11] DUTTA M, HALDER A K, SINGH S B.Morphology and Properties of Hot Dip Zn-Mg and Zn-Mg-Al Alloy Coatings on Steel Sheet[J]. Surface and Coatings Technology, 2010, 205(7): 2578-2584.
[12] SCHOULLER G P, ALLELY C, VOLOVITCH P.Zn-Al-Mg: An Innovative Metallic Coating that Offers Protection in the Harshest Environments(95)[C]//International Conference on Zinc and Zinc Alloy Coated Steel Sheet, 2011.
[13] 康永林. 国内外汽车板的现状需求和发展趋势[J].中国冶金,2003,(6):21-26.
KANG Y L. Present Situation, Demand and Development Trend of Automobile Plates at Home and Abroad[J]. China Metallurgy, 2003, (6): 21-26.
[14] 王胜民, 何明奕, 赵晓军, 等. 无铵盐助镀条件下热浸镀锌层组织的分析[J]. 昆明理工大学学报(自然科学版), 2011, 36(6): 26-29.
WANG S M, HE M Y, ZHAO X J, et al.Microstructure of Hot-Dipped Zn Coating in Fluxing without Ammonium[J]. Journal of Kunming University of Science and Technology (Natural Science Edition), 2011, 36(6): 26-29.
[15] 王胜民, 赵晓军, 党建伟, 等. 批量热浸镀锌工艺机理的研究现状[J]. 表面技术, 2016, (5): 19-25.
WANG S M, ZHAO X J, DANG J W, et al.Research Status of the Process Mechanism of Batch Hot-Dip Galvanizing[J]. Surface Technology, 2016, 45(5): 19-25.
[16] 马坤, 刘亚, 涂浩, 等. 镁含量和硅对铁-锌铝镁合金固- 液扩散偶中Fe-Al反应层的影响[J]. 材料导报, 2017, 31(6): 61-65.
MA K, LIU Y, TU H, et al.Effect of Mg Content and Si on Fe-Al Reaction Layer in Solid-Liquid Diffusion Couples of Fe/Zn-Al-Mg Alloys[J]. Materials Reports, 2017, 31(6): 61-65.
[17] 贺志荣, 刘继拓, 解亚丹, 等. Al和Si对热浸Zn-Al-Mg合金镀层组织和耐腐蚀性的影响[J]. 中国有色金属学报, 2015, 25(5): 1250-1255.
HE Z R, LIU J T, XIE Y D, et al.Effect of Al and Si on Microstructure and Corrosion Resistance of Hot Dipping Zn-Al-Mg Alloy Coatings[J]. The Chinese Journal of Nonferrous Metals, 2015, 25(5): 1250-1255.
[18] XIE Y Y, DU A, ZHAO X, et al.Effect of Mg on Fe-Al Interface Structure of Hot-Dip Galvanized Zn-Al-Mg Alloy Coatings[J]. Surface and Coatings Technology, 2018, 337: 313-320.
[19] 李远鹏, 杨伟芳, 江社明, 等. Zn-Mg合金镀液中Al含量对批量热浸镀镀层结构的影响[J]. 材料保护, 2018, 51(8): 6-9.
LI Y P, YANG W F, JIANG S M, et al.Effect of Al on Microstructure of Generally Batch Hot-Dip Galvanized Zn-Mg Alloy Coatings[J]. Materials Protection, 2018, 51(8): 6-9.
[20] 史学星, 张莉霞, 严春莲, 等. Zn-Al-Mg镀层在3.5%NaCl溶液中的腐蚀产物分析[J]. 物理测试, 2024, 42(2): 12-18.
SHI X X, ZHANG L X, YAN C L, et al.Analysis of Corrosion Products of Zinc-Aluminum-Magnesium Coating in 3.5%NaCl Solution[J]. Physics Examination and Testing, 2024, 42(2): 12-18.
[21] 黎敏, 董妮妮, 商婷, 等. 锌铝镁镀层和纯锌镀层在典型大气环境中初期腐蚀行为研究[J]. 表面技术, 2024, 53(2): 120-129.
LI M, DONG N N, SHANG T, et al.Study on Initial Corrosion Behavior of Zn-Al-Mg Coating and Pure Zinc Coating in Typical Atmospheric Environment[J]. Surface Technology, 2024, 53(2): 120-129.
[22] WINT N, COOZE N, SEARLE J R, et al.The Effect of Microstructural Refinement on the Localized Corrosion of Model Zn-Al-Mg Alloy Coatings on Steel[J]. Journal of the Electrochemical Society, 2019, 166(11): C3147-C3158.
[23] TOKUDA S, MUTO I, SUGAWARA Y, et al.Micro-Electrochemical Investigation on the Role of Mg in Sacrificial Corrosion Protection of 55mass%Al-Zn-Mg Coated Steel[J]. Corrosion Science, 2017, 129: 126-135.
[24] LEE J W, PARK B R, OH S Y, et al.Mechanistic Study on the Cut-Edge Corrosion Behaviors of Zn-Al-Mg Alloy Coated Steel Sheets in Chloride Containing Environments[J]. Corrosion Science, 2019, 160: 108170.
[25] RAI P K, ROUT D, SATISH KUMAR D, et al.Effect of Magnesium on Corrosion Behavior of Hot-Dip Zn-Al-Mg Coating[J]. Journal of Materials Engineering and Performance, 2021, 30(6): 4138-4147.
PDF(19173 KB)
渝公网安备 50010702501715号 渝ICP备15012534号-3
