Effects of Complexing Agent Types and Concentrations on Vanadium-cerium Conversion Coatings for Magnesium Alloys

TANG Yexi; QIAN Shanhua; LIU Sen; LI Yuanxiang; ZHANG Jia; CHEN Juan; GAO He; BIAN Da

doi:10.16490/j.cnki.issn.1001-3660.2025.20.018

PDF(15482 KB)

Surface Technology ›› 2025, Vol. 54 ›› Issue (20) : 238-251. DOI: 10.16490/j.cnki.issn.1001-3660.2025.20.018

Surface Functionalization

Effects of Complexing Agent Types and Concentrations on Vanadium-cerium Conversion Coatings for Magnesium Alloys

TANG Yexi¹, QIAN Shanhua^1,2,*, LIU Sen¹, LI Yuanxiang³, ZHANG Jia³, CHEN Juan³, GAO He³, BIAN Da¹

Author information +

History +

Abstract

Magnesium alloys have become an important material in the engineering field due to its high recyclability, lightweight property, excellent electromagnetic shielding property and superior electrical/thermal conductivity. However, the inherent difficulties of magnesium alloys (such as high chemical activity and poor corrosion resistance) have limited their broader applications in the engineering industries. Common surface treatments can improve the corrosion resistance of magnesium alloys, but they often reduce the electrical conductivity of the magnesium alloys or bring about high complexity. In 3C Digital and other industries, there is an urgent need for surface technologies that enhance corrosion resistance and electrical conductivity to simplify protection processes and expand engineering applications. In this study, a novel complex system was designed by combining stearic acid (SA), sodium dodecylbenzene sulfonate (SDBS) or sodium tetraborate (Borax) with the complexing agent EDTA-2Na to prepare conversion coatings of different components under the conditions of neutral pH and room temperature. Microstructure was characterized by scanning electron microscopy with an energy dispersive spectrometer and white light interferometry. The electrochemical tests (Tafel polarization and electrochemical impedance spectroscopy) were performed in 3.5% NaCl solution. Electrical conductivity of conversion coatings was performed by four-probe tester. Adhesion strength was assessed by the cross-cut test (GB/T 9286—2021). In addition, the composition of the conversion coating (exhibiting both superior corrosion resistance and electrical conductivity) was investigated by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and the skin cell toxicity of its corresponding conversion solution was evaluated. A novel surface treatment strategy was developed for post-machined magnesium alloy components, enabling the hands to come into direct contact with the parts or the conversion solution. The results indicated that SA showed a negligible improvement in corrosion resistance compared to the baseline, among the three additives with varying concentrations. With the addition of SDBS, the coatings exhibited limited protective efficiency (78.5% maximum), and Borax demonstrated optimal performance. At 6 g/L Borax, the corrosion potential of the coating sodium tetraborate was -1.282 V, while the corrosion current density was 2.326 × 10^-5 A/cm² (one order of magnitude lower than that of the bare substrate). The protection efficiency was 86.1% when the Borax concentration was 6 g/L. Borax also enhanced conductivity by 20.8% compared to the blank sample. The coating including 6 g/L Borax displayed a dense structure (1.25 µm thickness, 1.181 µm roughness), exhibiting the strong adhesion to the substrate. The surface elemental composition of the conversion coating included Mg, Al, O, V, and Ce, with Mg(OH)₂ and V₂O₅ being the major components. Borax was found to accelerate the dissolution of the α-phase of the magnesium alloy and inhibit phosphate deposition on the β-phase. This process formed conductive contact spots (CCS) under neutral and room temperature conditions. The conversion solution was relatively safe (with human immortalized keratinocytes viability over 80%) for human skin within a certain concentration range (0.05 μg/mL-50 g/L). The conversion coating produced by the conversion solution with 6 g/L Borax has better comprehensive performance. The results will provide valuable insights into surface protection strategies and the engineering applications of magnesium alloy in electronic components.

Key words

magnesium alloy / chemical conversion coating / corrosion resistance / electrical conductivity / skin cell toxicity / vanadium salt

Cite this article

EndNote

Ris (Procite)

Bibtex

Download Citations

TANG Yexi, QIAN Shanhua, LIU Sen, LI Yuanxiang, ZHANG Jia, CHEN Juan, GAO He, BIAN Da. Effects of Complexing Agent Types and Concentrations on Vanadium-cerium Conversion Coatings for Magnesium Alloys[J]. Surface Technology. 2025, 54(20): 238-251 https://doi.org/10.16490/j.cnki.issn.1001-3660.2025.20.018

References

[1] FRANCIS A, YANG Y, BOCCACCINI A R.A New Strategy for Developing Chitosan Conversion Coating on Magnesium Substrates for Orthopedic Implants[J]. Applied Surface Science, 2019, 466: 854-862.
[2] BADISHA V, SHAIK S, DUMPALA R, et al.Developing Mg-Zn Surface Alloy by Friction Surface Allosying: In Vitro Degradation Studies in Simulated Body Fluids[J]. International Journal of Minerals, Metallurgy and Materials, 2020, 27(7): 962-969.
[3] SONG J F, SHE J, CHEN D L, et al.Latest Research Advances on Magnesium and Magnesium Alloys Worldwide[J]. Journal of Magnesium and Alloys, 2020, 8(1): 1-41.
[4] ALIAS J, ALANG N A, AHMAD A H, et al.Emerging Progress of Chemical-Based Coating for the Corrosion Protection of Magnesium Alloys: A Review[J]. Journal of Adhesion Science and Technology, 2024, 38(8): 1125-1160.
[5] NAZARI H, BARATI DARBAND G, AREFINIA R.A Review on Electroless Ni-P Nanocomposite Coatings: Effect of Hard, Soft, and Synergistic Nanoparticles[J]. Journal of Materials Science, 2023, 58(10): 4292-4358.
[6] ABDELGAWAD M, USMAN C A, SHUNMUGASAMY V C, et al.Corrosion Behavior of Mg-Zn-Zr-RE Alloys under Physiological Environment - Impact on Mechanical Integrity and Biocompatibility[J]. Journal of Magnesium and Alloys, 2022, 10(6): 1542-1572.
[7] 朱金成, 李宏战, 李争显, 等. 镁合金表面耐蚀导电防护技术研究进展[J]. 材料保护, 2022, 55(10): 180-187.
ZHU J C, LI H Z, LI Z X, et al.Research Progress of Corrosion-Resistant and Conductive Protection Technology on the Surface of Magnesium Alloys[J]. Materials Protection, 2022, 55(10): 180-187.
[8] WANG D, MA C, LIU J Y, et al.Corrosion Resistance and Anti-Soiling Performance of Micro-Arc Oxidation/Graphene Oxide/Stearic Acid Superhydrophobic Composite Coating on Magnesium Alloys[J]. International Journal of Minerals, Metallurgy and Materials, 2023, 30(6): 1128-1139.
[9] HATTAB M, BEN HASSEN S, SPRIANO S, et al.Ce-Doped MgO Films on AZ31 Alloy Substrate for Biomedical Applications: Preparation, Characterization and Testing[J]. Biomedical Materials, 2024, 19(2): 025013.
[10] 张博, 蔡辉, 张阳, 等. 铝基板表面微弧氧化膜厚度对其导电导热性的影响[J]. 表面技术, 2017, 46(5): 23-27.
ZHANG B, CAI H, ZHANG Y, et al.Effect of Oxide Film Thickness on Electrical and Thermal Conductivity of Micro-Arc Oxidize Aluminium Substrates[J]. Surface Technology, 2017, 46(5): 23-27.
[11] 付明, 金梦辉. 镁合金微弧氧化-溶胶凝胶导电膜的制备及其性能研究[J]. 材料保护, 2021, 54(5): 108-111.
FU M, JIN M H.Preparation and Properties of Microarc Oxidation/Sol-Gel Conductive Coatings on Magnesium Alloy[J]. Materials Protection, 2021, 54(5): 108-111.
[12] JENA G, CHELLAPPANDIAN R, NEELAKANTAN L, et al.Development of Potentiostatically Deposited Cerium Conversion Coating for Mg Alloys[J]. Materials and Corrosion, 2024, 75(10): 1313-1330.
[13] LIU D, LI Y, DING Y, et al.The Preparation, Characterization and Formation Mechanism of a Calcium Phosphate Conversion Coating on Magnesium Alloy AZ91D[J]. Materials, 2018, 11(6): 908.
[14] WANG R Z, ZHAO C, PENG Z J, et al.Corrosion and Wear Resistant Polyp-Xylene Composite Coating on AZ31 Magnesium Alloy Prepared by Micro-Arc Oxidation and Vapor Deposition[J]. Progress in Organic Coatings, 2024, 186: 108016.
[15] CHEN X W, XIE W L, TANG S, et al.Study on the Structure and Corrosion Resistance of MoS₂/MgO Micro-Arc Oxidation Composite Ceramic Coating on the Surface of ZK60 Magnesium Alloy[J]. Anti-Corrosion Methods and Materials, 2024, 71(2): 213-222.
[16] HSIEH C Y, HUANG S Y, CHU Y R, et al.Role of Second Phases in the Corrosion Resistance and Cerium Conversion Coating Treatment of As-Extruded Mg-8Al-4Ca Magnesium Alloy[J]. Journal of Materials Research and Technology, 2023, 22: 2343-2359.
[17] PRASUTIYO Y J, MANAF A, HAFIZAH M E.Synthesis of Polyaniline by Chemical Oxidative Polymerization and Characteristic of Conductivity and Reflection for Various Strong Acid Dopants[J]. Journal of Physics: Conference Series, 2020, 1442(1): 012003.
[18] 夏先朝, 聂敬敬, 孙京丽, 等. 基于磷酸盐化学转化的超疏水抗菌涂层的制备与性能研究[J]. 表面技术, 2025, 54(6): 115-124.
XIA X C, NIE J J, SUN J L, et al.Preparation and Properties of Superhydrophobic and Antibacterial Coating Based on Phosphate Chemical Conversion[J]. Surface Technology, 2025, 54(6): 115-124.
[19] 刘坤, 邹忠利, 马琳梦, 等. 成膜时间对AZ31B镁合金镨盐转化膜形貌和耐蚀性的影响[J]. 表面技术, 2023, 52(3): 255-265.
LIU K, ZOU Z L, MA L M, et al.Effect of Film Formation Time on the Morphology and Corrosion Resistance of Praseodymium Salt Conversion Film of AZ31B Magnesium Alloy[J]. Surface Technology, 2023, 52(3): 255-265.
[20] ANTLER M.Electrical Effects of Fretting Connector Contact Materials: A Review[J]. Wear, 1985, 106(1/2/3): 5-33.
[21] ZHANG T, LI Y, WANG F H.Roles of β Phase in the Corrosion Process of AZ91D Magnesium Alloy[J]. Corrosion Science, 2006, 48(5): 1249-1264.
[22] UBEDA C, GARCES G, ADEVA P, et al.The Role of the Beta-Mg₁₇Al12 Phase on the Anomalous Hydrogen Evolution and Anodic Dissolution of AZ Magnesium Alloys[J]. Corrosion Science, 2020, 165: 108384.
[23] AKBARZADEH F Z, RAJABI M, JAMAATI R, et al.Effect of Β-Mg₁₇Al12 Phase on the Surface Interactions and Morphology of Hydroxyapatite Coating Deposited on AZ91 Alloy[J]. Surfaces and Interfaces, 2024, 51: 104589.
[24] DUAN G Q, YANG L X, LIAO S J, et al.Designing for the Chemical Conversion Coating with High Corrosion Resistance and Low Electrical Contact Resistance on AZ91D Magnesium Alloy[J]. Corrosion Science, 2018, 135: 197-206.
[25] ZHANG S D, XU Y H, LIU L K, et al.Preparation of Conductive and Corrosion Resistant Phosphate Conversion Coating on AZ91D Magnesium Alloy[J]. Coatings, 2023, 13(10): 1706.
[26] HUNG S M, LIN H, CHEN H W, et al.Corrosion Resistance and Electrical Contact Resistance of a Thin Permanganate Conversion Coating on Dual-Phase LZ91 Mg-Li Alloy[J]. Journal of Materials Research and Technology, 2021, 11: 1953-1968.
[27] ADIJANTO L, BALAJI PADMANABHAN V, KÜNGAS R, et al. Transition Metal-Doped Rare Earth Vanadates: A Regenerable Catalytic Material for SOFC Anodes[J]. Journal of Materials Chemistry, 2012, 22(22): 11396-11402.
[28] MANSOUR E, EL-EGILI K, EL-DAMRAWI G.Mechanism of Hopping Conduction in New CeO₂-B₂O₃ Semiconducting Glasses[J]. Physica B: Condensed Matter, 2007, 389(2): 355-361.
[29] FIEDLER T, WHITE N, DAHARI M, et al.On the Electrical and Thermal Contact Resistance of Metal Foam[J]. International Journal of Heat and Mass Transfer, 2014, 72: 565-571.
[30] WANG D J, ZHOU C, ZHU D C.Nanosized CeO₂ Particles Obtained by Mechanical Solid-State Reaction Combined with Sol-Gel Method[J]. Transactions of the Indian Institute of Metals, 2017, 70(10): 2667-2672.
[31] BÚS C, JANOVÁK L, DEÁK Á, et al. Complexation of Magnesium Ions in Sodium Dodecyl Benzenesulfonate- Flopaam AN125SH Mixtures Using Sodium Citrate[J]. Polyhedron, 2025, 267: 117339.
[32] 王丽, 顾威, 郭荣, 等. 环保型无机缓蚀剂对AZ91D镁合金的缓蚀效果[J]. 电镀与精饰, 2020, 42(4): 18-22.
WANG L, GU W, GUO R, et al.Inhibition Effect of Environmental Protection Inorganic Corrosion Inhibitor on AZ91D Magnesium Alloy[J]. Plating & Finishing, 2020, 42(4): 18-22.
[33] 邵文婷, 蒋百灵, 房爱存. 镁合金微弧氧化体系中四硼酸钠的作用机理研究[J]. 稀有金属材料与工程, 2016, 45(4): 918-922.
SHAO W T, JIANG B L, FANG A C.Effects of Sodium Tetraborate in the Electrolyte Systems on Micro-Arc Oxidation of Magnesium Alloy[J]. Rare Metal Materials and Engineering, 2016, 45(4): 918-922.
[34] YANG J X, WANG X D, CAI Y R, et al.Corrosion Resistance and Electrical Conductivity of V/Ce Conversion Coating on Magnesium Alloy AZ31B[J]. International Journal of Minerals, Metallurgy and Materials, 2023, 30(4): 653-659.
[35] 国家市场监督管理总局, 国家标准化管理委员会. 色漆和清漆划格试验: GB/T 9286—2021[S]. 北京: 中国标准出版社, 2021., Standardization Administration of the People’s Republic of China. Paints and Varnishes— Cross-Cut Test: GB/T 9286—2021[S]. Beijing: Standards Press of China, 2021.
[36] WU G Z, HUANG Y, LI J, et al.Chronic Level of Exposures to Low-Dosed MoS₂ Nanomaterials Exhibits More Toxic Effects in HaCaT Keratinocytes[J]. Ecotoxicology and Environmental Safety, 2022, 242: 113848.
[37] HAN N R, PARK H J, KO S G, et al.The Protective Effect of a Functional Food Consisting of Astragalus Membranaceus, Trichosanthes Kirilowii, and Angelica gigas or Its Active Component Formononetin Against Inflammatory Skin Disorders through Suppression of TSLP via MDM2/HIF1α Signaling Pathways[J]. Foods, 2023, 12(2): 276.
[38] ZHANG W T, CHEN Y Q, CHEN M Y, et al.Strengthened Corrosion Control of Poly(lactic acid) (PLA) and Poly(ε-caprolactone) (PCL) Polymer-Coated Magnesium by Imbedded Hydrophobic Stearic Acid (SA) Thin Layer[J]. Corrosion Science, 2016, 112: 327-337.
[39] 董丽惠, 王华, 李琳. AZ31B镁合金钒/硅烷复合转化膜的制备与表征[J]. 表面技术, 2024, 53(4): 34-45.
DONG L H, WANG H, LI L.Preparation and Characterization of Vanadium/Silane Composite Conversion Coating on AZ31B Magnesium Alloy[J]. Surface Technology, 2024, 53(4): 34-45.
[40] HSU C H, MANSFELD F.Technical Note: Concerning the Conversion of the Constant Phase Element Parameter Y into a Capacitance[J]. Corrosion, 2001, 57(9): 747-748.
[41] KOGUT L, KOMVOPOULOS K.Electrical Contact Resistance Theory for Conductive Rough Surfaces Separated by a Thin Insulating Film[J]. Journal of Applied Physics, 2004, 95(2): 576-585.
[42] UREÑA-BEGARA F, CRUNTEANU A, RASKIN J P. Raman and XPS Characterization of Vanadium Oxide Thin Films with Temperature[J]. Applied Surface Science, 2017, 403: 717-727.
[43] ZHENG J Q, ZHANG Y F, HU T, et al.New Strategy for the Morphology-Controlled Synthesis of V₂O₅ Microcrystals with Enhanced Capacitance as Battery-Type Supercapacitor Electrodes[J]. Crystal Growth & Design, 2018, 18(9): 5365-5376.
[44] LI H Y, WEI C, PENG Z W, et al.Novel 3D V₂O₅ Nanocorals with Continuous Size-Gradient Mesopore Channels for High Performance Supercapacitors[J]. Materials Letters, 2018, 220: 12-15.
[45] LIU Y X, LIU Z, XU A Y, et al.Understanding Pitting Corrosion Behavior of AZ91 Alloy and Its MAO Coating in 3.5% NaCl Solution by Cyclic Potentiodynamic Polarization[J]. Journal of Magnesium and Alloys, 2022, 10(5): 1368-1380.
[46] YANG K H, GER M D, HWU W H, et al.Study of Vanadium-Based Chemical Conversion Coating on the Corrosion Resistance of Magnesium Alloy[J]. Materials Chemistry and Physics, 2007, 101(2/3): 480-485.
[47] SÁNCHEZ-AMAYA J M, BLANCO G, GARCIA- GARCIA F J, et al. XPS and AES Analyses of Cerium Conversion Coatings Generated on AA5083 by Thermal Activation[J]. Surface and Coatings Technology, 2012, 213: 105-116.
[48] ROSHAN S, SARABI A A.Improved Performance of Ti-Based Conversion Coating in the Presence of Ce/Co Ions: Surface Characterization, Electrochemical and Adhesion Study[J]. Surface and Coatings Technology, 2021, 410: 126931.
[49] YU X W, CAO C N, YAO Z M, et al.Study of Double Layer Rare Earth Metal Conversion Coating on Aluminum Alloy LY12[J]. Corrosion Science, 2001, 43(7): 1283-1294.

Funding

National Natural Science Foundation of China (52375184); Technology Autonomous Research Program of Jiangsu Provincial Key Laboratory of Advanced Food Manufacturing Equipment (FMZ202204); "Qinglan Engineering" Foundation for Colleges and Universities in Jiangsu Province