Process, Microstructure, and Properties of Continuous Thermal Jet-PVD Zinc Coatings on Steel Strips

ZHAO Xingyuan; ZHANG Ziyue; LIU Xin; LIU Qiuyuan; ZHANG Qifu

doi:10.16490/j.cnki.issn.1001-3660.2026.10.008

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Surface Technology ›› 2026, Vol. 55 ›› Issue (10) : 92-106. DOI: 10.16490/j.cnki.issn.1001-3660.2026.10.008

Corrosion and Protection

Process, Microstructure, and Properties of Continuous Thermal Jet-PVD Zinc Coatings on Steel Strips

ZHAO Xingyuan¹, ZHANG Ziyue^1,2, LIU Xin¹, LIU Qiuyuan¹, ZHANG Qifu^1,*

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Abstract

To address the critical limitations of traditional continuous galvanizing technologies, specifically high energy consumption, poor wettability on advanced high-strength steels, and environmental risks like hydrogen embrittlement, this study proposes and systematically investigates a Continuous Thermal Jet-PVD process. While conventional batch physical vapor deposition (PVD) offers an eco-friendly alternative, it has historically suffered from low deposition efficiency unsuitable for industrial-scale production. To overcome this bottleneck, this work establishes a comprehensive theoretical model coupling Hertz-Knudsen evaporation kinetics with choked-flow fluid dynamics. This coupled model quantitatively describes the complex mass transfer mechanism, tracing the zinc vapor journey from the evaporation source, through a vapor distribution box (VDB) where pressure stabilizes, to a supersonic Laval nozzle. The model accounts for critical fluid dynamic factors, including the choking flow threshold (pressure ratio < 0.53) and the acceleration of vapor to supersonic speeds (M_a > 1) at the nozzle exit, which provides the high kinetic energy necessary for dense film growth.
The theoretical framework is rigorously validated against experimental data obtained from a custom-built continuous thermal jet-PVD system applied to SPCC cold-rolled steel strips at substrate temperature of 160 ℃. The results demonstrate a linear correlation between deposition thickness and crucible temperature within the process window of 913 K to 943 K. The calculated theoretical thickness (9.49-15.42 µm) show a consistent alignment with measured values (9.22-13.2 µm), with minor deviations attributed to viscous dissipation and non-ideal Rayleigh flow effects within the transport piping. Most significantly, the continuous thermal jet-PVD process achieves an ultra-high deposition rate of 1.32×10⁴ nm/s, representing a massive 2,600-fold increase compared to the 5 nm/s rate typical of non-continuous vacuum evaporation.
Microstructural characterization via SEM and XRD reveals that the high-energy jet deposition fundamentally alters the coating's growth mode. Unlike the porous, granular structure with random orientation observed in vacuum evaporation, the thermal jet-PVD coatings exhibit a highly dense, fiber-like morphology. Image binarization analysis quantifies this improvement, showing a dramatic reduction in cross-sectional porosity from 13.7% to 2.6%. Crystallographic analysis identifies a distinct texture evolution: the high deposition rate suppresses atomic surface diffusion, preventing the formation of thermodynamically stable (002) and (100) planes. Instead, a metastable (102) preferred orientation is induced. This is quantitatively confirmed by the Scherrer equation, which shows the (100) crystallite size shrinking from 60 nm to 30.1 nm, while the (102) crystallite size increases to 74.5 nm. Density Functional Theory (DFT) calculations further support this, linking the texture evolution to the minimization of total free energy via a balance between surface and elastic energies under these specific kinetic constraints.
These microstructural modifications translate into superior macroscopic performance. Scratch tests demonstrate a 42% increase in adhesion strength, with the critical load (L_c3) rising from 24,316 mN to 34,618 mN. The failure mechanism shifts from brittle peeling to ductile deformation, attributed to the activation of pyramidal <c+a> slip systems in the (102)-oriented grains, which accommodate local stress more effectively than the basal plane orientation of evaporated coatings. Furthermore, the electrochemical corrosion current density decreases from 66.4 μA/cm² to 27.8 μA/cm², and the neutral salt spray (NSS) tests show that the time to red rust appearance extends from 48 hours to 72 hours.
This enhanced corrosion resistance is directly attributed to the elimination of through-thickness pores and the dense stacking of grains, which effectively block the infiltration of corrosive media. In conclusion, the continuous thermal jet-PVD process not only meets industrial efficiency demands but also yields coatings with superior structural integrity and corrosion resistance.

Key words

continuous galvanizing / physical vapor deposition / thermal jetting / deposition mechanism / pure zinc coating / microstructure / corrosion resistance / adhesion

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ZHAO Xingyuan, ZHANG Ziyue, LIU Xin, LIU Qiuyuan, ZHANG Qifu. Process, Microstructure, and Properties of Continuous Thermal Jet-PVD Zinc Coatings on Steel Strips[J]. Surface Technology. 2026, 55(10): 92-106

References

[1] DAN A, BIJALWAN P K, PATHAK A S, et al.A Review on Physical Vapor Deposition-Based Metallic Coatings on Steel as an Alternative to Conventional Galvanized Coatings[J]. Journal of Coatings Technology and Research, 2022, 19(2): 403-438.
[2] ZHAO X Y, ZHANG Z Y, LIU X, et al.Enhanced Corrosion Protection of Steel Strip through Advanced Zn-Mg Alloy Coatings Manufactured by Continuous Physical Vapor Deposition: A Review[J]. Materials Chemistry and Physics, 2024, 328: 129884.
[3] LAUREYS A, DEPOVER T, VERBEKEN K.Effect of Environmental and Internal Hydrogen on the Hydrogen Assisted Cracking Behavior of TRIP-Assisted Steel[J]. Materials Science and Engineering: A, 2019, 739: 437-444.
[4] WANG M Q, AKIYAMA E, TSUZAKI K.Effect of Hydrogen on the Fracture Behavior of High Strength Steel during Slow Strain Rate Test[J]. Corrosion Science, 2007, 49(11): 4081-4097.
[5] TIAN H L, LIU P F, SUN H J, et al.Efficient One-Step Removal and Immobilization of Recalcitrant Cr(Ⅲ) and Cr(VI) Fractions in Real Electroplating Wastewater Using Electrolysis with O₂ Aeration[J]. Journal of Water Process Engineering, 2024, 65: 105783.
[6] BELLHOUSE E M, MCDERMID J R.Selective Oxidation and Reactive Wetting during Galvanizing of a CMnAl TRIP-Assisted Steel[J]. Metallurgical and Materials Transactions A, 2011, 42(9): 2753-2768.
[7] LEE H J, KIM M S.Behavior of the Surface Precipitation of Manganese Oxides during Hot-Dip Galvanizing[J]. Journal of the Korean Institute of Surface Engineering, 2015, 48(1): 27-32.
[8] CHALEIX D, JACQUESON E, PESCI C, et al.Jet Vapour Deposition: a Technical Economic Alternative to Electro-galvanizing for Zn Coatings of Future Steels[C]. Leoben: Austrian Society for Metallurgy and Materials, 2021.
[9] BARSHILIA H C, ANANTH A, KHAN J, et al.Ar + H₂ Plasma Etching for Improved Adhesion of PVD Coatings on Steel Substrates[J]. Vacuum, 2012, 86(8): 1165-1173.
[10] NAVINŠEK B, PANJAN P, MILOŠEV I. Industrial Applications of CrN (PVD) Coatings, Deposited at High and Low Temperatures[J]. Surface and Coatings Technology, 1997, 97(1/2/3): 182-191.
[11] GUZMAN L, WOLF G K, DAVIES G M.PVD-IBAD Zinc Coating Development for Automotive Application[J]. Surface and Coatings Technology, 2003, 174: 665-670.
[12] NAVINŠEK B, PANJAN P, MILOŠEV I. PVD Coatings as an Environmentally Clean Alternative to Electroplating and Electroless Processes[J]. Surface and Coatings Technology, 1999, 116: 476-487.
[13] MATTOX D M.Handbook of physical vapor deposition (PVD) processing[M]. Westwood, N.J.: Noyes Publications, 1998.
[14] BOYER M, GOISET L, CSAY A.Jet Vapor Deposition: The Choice for Zn Coatings of Future Steels for Automotive[C]//3rd Automotive Steel International Conference. AIST, 2025: 140-153.
[15] VESPER J E, OBIJI C S, WESTERWAAL R, et al.Modeling of a Continuous Physical Vapor Deposition Process: Mass Transfer Limitations by Evaporation Rate and Sonic Choking[J]. Applied Thermal Engineering, 2021, 195: 117099.
[16] PESCI C, DIEZ L, CHALEIX D, et al.Jet Vapor Deposition: Coatings Steels of the Future[C]. Tokyo: Iron and Steel Institute of Japan, 2017.
[17] 罗晔. 韩国WPM项目智能涂层钢板材料研究进展[J]. 工程研究——跨学科视野中的工程, 2018, 10(1): 49-55.
LUO Y.Research Progress of Smart Coating Steel Plate in South Korea's WPM Project[J]. Journal of Engineering Studies, 2018, 10(1): 49-55.
[18] KOLL T, ULLRICH K, FADERL J, et al.Properties and Potential Applications of Novel ZNMG Alloy Coatings on Steel Sheet[J]. Revue de Métallurgie, 2004, 101(7/8): 543-550.
[19] YOUNG J K, WOO S J, KYUNG-HOON N, et al.Manufacture and Characteristics of Zn & Zn-Mg Coated Steel Sheets by PVD Process[C]. Seoul: Corrosion Science Society of Korea, 2023.
[20] 邱肖盼. 真空蒸发制备锌镁合金镀层的沉积工艺与机理研究[D]. 北京: 钢铁研究总院, 2021.
QIU X P.Study on Process and Mechanism of Zn-Mg Coatings Deposited by Vacuum Evaporation[D]. Beijing: Central Iron and Steel Research Institute, 2021.
[21] ZIJP J P, SCHADE VAN WESTRUM J A F M. Physical Vapour Deposition for Metal Strip Coating[C]// Proc. 5th Int. Conf. Zinc and Zinc Alloy Coated Steel Sheet (Galvatech 2001). Duesseldorf: Verlag Stahleisen, 2001: 131-136.
[22] MARDER A R, GOODWIN F E.History of Zinc-Coated Steel[M]//The Metallurgy of Zinc Coated Steels. Amsterdam: Elsevier, 2023: 1-14.
[23] BAYAZITOGLU Y, BROTZEN F R, ZHANG Y.Metal Vapor Condensation in a Converging Nozzle[J]. Nanostructured Materials, 1996, 7(7): 789-803.
[24] PINTO G, SILVA F J G, PORTEIRO J, et al. A Critical Review on the Numerical Simulation Related to Physical Vapour Deposition[J]. Procedia Manufacturing, 2018, 17: 860-869.
[25] LIN E J, LI J, XING C Y, et al.Dynamic Behavior Investigation of Zinc Vapor in the Vacuum Spray Galvanizing Process Based on the Direct Simulation Monte Carlo Method[J]. Applied Thermal Engineering, 2025, 266: 125719.
[26] LEE S H, KIM S M, LEE S Y.Controlling Void Contents in the Zn Interlayer for Improving Adhesion Strength of ZNMG/Zn Bilayer Coatings on TRIP Steel[J]. ISIJ International, 2023, 63(10): 1769-1773.
[27] SUURMEIJER B, MULDER T, VERHOEVEN J.Vacuum Science and Technology[M]. Eindhoven: High Tech Institute, 2016.
[28] SAFARIAN J, ENGH T A.Vacuum Evaporation of Pure Metals[J]. Metallurgical and Materials Transactions A, 2013, 44(2): 747-753.
[29] LIJO V, KIM H D, SETOGUCHI T.Effects of Choking on Flow and Heat Transfer in Micro-Channels[J]. International Journal of Heat and Mass Transfer, 2012, 55(4): 701-709.
[30] FALKOVICH S V.On the Theory of the Laval Nozzle[J]. Prikladnaya Matematika i Mekhanika, 1946, 10(4): 503-512.
[31] LIU Y, ZHANG J, WEI J P, et al.Optimum Structure of a Laval Nozzle for an Abrasive Air Jet Based on Nozzle Pressure Ratio[J]. Powder Technology, 2020, 364: 343-362.
[32] SANJARI E.A New Simple Method for Accurate Calculation of Saturated Vapor Pressure[J]. Thermochimica Acta, 2013, 560: 12-16.
[33] THOMSON G W.The Antoine Equation for Vapor- Pressure Data[J]. Chemical Reviews, 1946, 38(1): 1-39.
[34] ROSE M, BARTHA J W, ENDLER I.Temperature Dependence of the Sticking Coefficient in Atomic Layer Deposition[J]. Applied Surface Science, 2010, 256(12): 3778-3782.
[35] MALI C, RAI A K, SHRIVASTAVA N, et al.Numerical Analysis of Uneven Coating near Steel Strip Edges in Continuous Hot-Dip Galvanizing[J]. Ironmaking & Steelmaking, 2023, 50(9): 1181-1194.
[36] QIU X P, LIU X, JIANG S M, et al.Growth Mechanism for Zinc Coatings Deposited by Vacuum Thermal Evaporation[J]. Journal of Iron and Steel Research International, 2021, 28(8): 1047-1053.
[37] JO H J, KWAK Y J, TAKAI M, et al.Blackening Phenomenon and Corrosion Resistance of Zn-Mg Alloy Coated Steel by Steam Treatment[J]. Applied Surface Science, 2024, 672: 160838.
[38] ZHENG J X, ARCHER L A. Controlling Electrochemical Growth of Metallic Zinc Electrodes: Toward Affordable Rechargeable Energy Storage Systems[J]. Science Advances, 2021, 7(2): eabe0219.
[39] THORNTON J A.Influence of Apparatus Geometry and Deposition Conditions on the Structure and Topography of Thick Sputtered Coatings[J]. Journal of Vacuum Science and Technology, 1974, 11(4): 666-670.
[40] DAWSON K J, KEARNS K L, YU L, et al.Physical Vapor Deposition as a Route to Hidden Amorphous States[J]. Proceedings of the National Academy of Sciences of the United States of America, 2009, 106(36): 15165-15170.
[41] SILVA FILHO J F, LINS V F C. Crystallographic Texture and Morphology of an Electrodeposited Zinc Layer[J]. Surface and Coatings Technology, 2006, 200(9): 2892-2899.
[42] SONNWEBER-RIBIC P.Strain Energy Effects on Texture Evolution in Thin Films: Biaxial Vs. Uniaxial Stress State[J]. AIP Conference Proceedings, 2006, 817(1): 192-197.
[43] MA Y, CHANG Y C, YIN J Z.Evaluation of Lattice Strain in ZnO Thin Films Based on Williamson-Hall Analysis[J]. Journal of Optoelectronics and Advanced Materials, 2019, 21(11-12): 702-709.
[44] ZHANG J M, ZHANG Y, XU K W, et al.Young's Modulus Surface and Poisson's Ratio Curve for Orthorhombic Crystals[J]. Journal of Chemical Crystallography, 2008, 38(10): 733-741.
[45] HAYASHI H, NAKAGAWA T.Recent Trends in Sheet Metals and Their Formability in Manufacturing Automotive Panels[J]. Journal of Materials Processing Technology, 1994, 46(3/4): 455-487.
[46] YE M, DELPLANCKE J L, BERTON G, et al.Characterization and Adhesion Strength Study of Zn Coatings Electrodeposited on Steel Substrates[J]. Surface and Coatings Technology, 1998, 105(1/2): 184-188.
[47] LEE S H, KIM H K, SONG M K, et al.Studies on the Microstructure-Controlled Zn Interlayer for Improving the Adhesion Strength of the Zn/Zn-Mg Double Layer Coating[J]. Korean Journal of Metals and Materials, 2019, 57(11): 695-700.
[48] ZHOU M, GUO S, LI J L, et al.Surface-Preferred Crystal Plane for a Stable and Reversible Zinc Anode[J]. Advanced Materials, 2021, 33(21): 2100187.
[49] SONG G M, SLOOF W G.Characterization of the Failure Behavior of Zinc Coating on Dual Phase Steel under Tensile Deformation[J]. Materials Science and Engineering: A, 2011, 528(21): 6432-6437.
[50] AHMADI M, SALGıN B, KOOI B J, et al. Outstanding Cracking Resistance in Mg-Alloyed Zinc Coatings Achieved via Crystallographic Texture Control[J]. Scripta Materialia, 2022, 210: 114453.
[51] WANG Y X, WONG B C, CHAN T M, et al.Towards Strength-Ductility Synergy in Cold Spray for Manufacturing and Repair Application: A Review[J]. Processes, 2024, 12(10): 2216.
[52] TANG Q, ICHIKAWA Y, HASSANI M.Microparticle Impact-Induced Bond Strength in Metals Peaks with Velocity[J]. Proceedings of the National Academy of Sciences of the United States of America, 2025, 122(14): e2424355122.
[53] MARDER A R.The Metallurgy of Zinc-Coated Steel[J]. Progress in Materials Science, 2000, 45(3): 191-271.