Key Takeaways & Executive Findings
- •• • 10 wt.% Fe-based amorphous powder addition raises coating hardness to 1200 HV0.2, a 1.3× increase over NiCrMo baseline, directly enhancing resistance to abrasive wear in marine hydraulic components. • • Passive current density decreases from 1 mA to 100 μA (an order of magnitude) at 10 wt.% amorphous content, significantly reducing corrosion rates in seawater exposure. • • Under wear-corrosion coupling, the 10 wt.% coating maintains optimal passive film stability, with electrochemical response closest to an ideal capacitor, minimizing material loss in tribocorrosion conditions. • • Excessive amorphous content (20 wt.%) degrades hardness to 723 HV0.2 due to increased FCC phase and coarsened Mo-rich precipitates, establishing a clear upper threshold for industrial formulation.
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Abstract
Marine engineering components demand simultaneous wear and corrosion resistance, yet conventional NiCrMo high-entropy alloy (HEA) coatings produced by laser cladding exhibit insufficient hardness and passive film stability under tribocorrosion. This study introduces Fe-based amorphous powder (Fe77Si9B14) at 0, 10, and 20 wt.% into NiCrMo HEA coatings via laser cladding. Microstructural analysis reveals a transition from FCC/σ eutectic to FCC+σ with nanoscale Mo-rich precipitates. At 10 wt.% amorphous addition, hardness peaks at 1200 HV0.2 (1.3× the NiCrMo baseline), and the passive current density drops from 1 mA to 100 μA, an order-of-magnitude improvement. Dry sliding wear tests show a stable friction coefficient and a shift from severe spalling to smooth ploughing. Under wear-corrosion coupling, the 10 wt.% coating exhibits optimal passive film stability, with electrochemical response closest to an ideal capacitor. Excessive amorphous content (20 wt.%) increases FCC phase fraction and coarsens Mo-rich precipitates, reducing hardness to 723 HV0.2. The synergistic effect of σ-phase refinement and amorphous-derived nanostructure delivers superior wear and corrosion resistance, offering a viable route for extending the service life of marine components.
1. Introduction
Marine engineering equipment operates under simultaneous mechanical wear and electrochemical corrosion, a synergistic degradation that accelerates material failure and shortens component service life. Existing NiCrMo high-entropy alloy coatings, while offering moderate corrosion resistance, suffer from insufficient hardness and passive film breakdown under tribocorrosion, leading to premature replacement and high maintenance costs. Laser cladding provides a rapid solidification route to refine microstructures, but residual stresses and cracking often limit coating integrity.
This study addresses the bottleneck by incorporating Fe-based amorphous powder (Fe77Si9B14) as a modifier to NiCrMo HEA coatings. The amorphous phase acts as a binder, reducing cracking and promoting compatibility with the steel substrate. By systematically varying amorphous content (0, 10, 20 wt.%), the work establishes a quantitative link between microstructure, hardness, and corrosion-wear performance, identifying 10 wt.% as the optimal formulation for marine applications.
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MA Heng, LIU Minglei, WANG Zhongxue, LI Zhenwei, ZHANG Qingpu, ZHU Yuming, HE Kang, CUI Hongzhi (2026). Microstructure and Wear and Corrosion Resistance of NiCrMo High-Entropy Alloy Coatings Modified with Fe-Based Amorphous Powders via Laser Cladding. Surface Technology (表面技术). https://doi.org/10.16490/j.cnki.issn.1001-3660.2026.10.010
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Frequently Asked Questions
What is the dominant failure mechanism under wear-corrosion coupling for the NiCrMo HEA coating without amorphous modification?
The baseline NiCrMo coating exhibits severe spalling and unstable passive film, with a passive current density of 1 mA and friction coefficient fluctuations. The wear scar morphology shows extensive surface剥落 (spalling), indicating that mechanical wear disrupts the passive film, accelerating localized corrosion.
How does the 10 wt.% Fe-based amorphous addition improve passive film stability compared to the 20 wt.% addition?
At 10 wt.%, the coating achieves a passive current density of 100 μA and an electrochemical response closest to an ideal capacitor, indicating a compact and stable passive film. In contrast, 20 wt.% addition increases FCC phase fraction and coarsens Mo-rich precipitates, leading to a less protective film and hardness reduction to 723 HV0.2.
What is the quantitative hardness improvement and its industrial implication for marine components?
The 10 wt.% coating reaches 1200 HV0.2, a 1.3× increase over the NiCrMo baseline. This translates to improved resistance to abrasive wear in high-load marine applications such as pump impellers and hydraulic rods, potentially extending service intervals by reducing material loss.
Does the addition of Fe-based amorphous powder compromise the corrosion resistance of the NiCrMo HEA coating?
No. At 10 wt.% addition, the passive current density decreases by an order of magnitude (from 1 mA to 100 μA), and the coating exhibits the best corrosion resistance. The amorphous phase promotes a more uniform and protective passive film, enhancing overall corrosion performance.
What are the scalability and cost considerations for implementing this coating in industrial marine applications?
Laser cladding is already an industrial process, and Fe-based amorphous powder (Fe77Si9B14) is commercially available. The optimal 10 wt.% addition minimizes powder cost while maximizing performance, avoiding the degradation seen at 20 wt.%. The process requires precise powder mixing and vacuum drying, but offers a viable route for large-scale production of wear-corrosion resistant coatings.
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