AbstractEnglish Translation
Titanium alloys, particularly TC4 (Ti–6Al–4V), suffer from poor tribological performance and susceptibility to pitting corrosion, limiting their application in marine and biomedical fields. Layered double hydroxide (LDH) coatings offer potential protection but are hindered by the dense oxide layer on titanium alloys. In this study, a ZnAl LDH coating was fabricated on TC4 via in situ growth, followed by molybdate anion intercalation through ion exchange. A biomimetic slippery liquid-infused porous surface (SLIPS) was then created by UV-grafting polydimethylsiloxane (PDMS) onto the nanoporous LDH structure. The resulting surface exhibited excellent hydrophobicity, corrosion resistance, and wear resistance. Electrochemical tests (Tafel polarization and electrochemical impedance spectroscopy) demonstrated superior corrosion protection, with a low corrosion current density of 2.34×10−7 A/cm2. The infused silicone oil and ZnAl LDH nanosheets synergistically improved wear performance compared to bare TC4. This work provides insights into controllable in situ fabrication of LDH coatings and offers a novel strategy for broadening TC4 alloy applications in metal protection.
Executive Findings & Technical Breakthroughs
- •• • The ZnAl LDH coating with molybdate intercalation and PDMS infusion achieved a corrosion current density of 2.34×10−7 A/cm2, indicating a significant reduction in corrosion rate compared to bare TC4, which is critical for long-term durability in marine environments. • • The nanoporous LDH structure provides a physical confinement effect that limits PDMS lubricant loss, enhancing wear resistance; this is essential for moving components in orthopedic implants and marine machinery where lubricant depletion leads to failure. • • UV-grafted PDMS chains chemically bond to hydroxyl groups on LDH, reducing lubricant depletion and ensuring sustained hydrophobicity and corrosion protection over extended operational periods. • • The synergistic effect of LDH nanosheets and infused silicone oil improves wear performance, addressing the adhesive wear issue of TC4 alloys, which is a bottleneck for their use in high-friction applications.
Abstract
Titanium alloys, particularly TC4 (Ti–6Al–4V), suffer from poor tribological performance and susceptibility to pitting corrosion, limiting their application in marine and biomedical fields. Layered double hydroxide (LDH) coatings offer potential protection but are hindered by the dense oxide layer on titanium alloys. In this study, a ZnAl LDH coating was fabricated on TC4 via in situ growth, followed by molybdate anion intercalation through ion exchange. A biomimetic slippery liquid-infused porous surface (SLIPS) was then created by UV-grafting polydimethylsiloxane (PDMS) onto the nanoporous LDH structure. The resulting surface exhibited excellent hydrophobicity, corrosion resistance, and wear resistance. Electrochemical tests (Tafel polarization and electrochemical impedance spectroscopy) demonstrated superior corrosion protection, with a low corrosion current density of 2.34×10−7 A/cm2. The infused silicone oil and ZnAl LDH nanosheets synergistically improved wear performance compared to bare TC4. This work provides insights into controllable in situ fabrication of LDH coatings and offers a novel strategy for broadening TC4 alloy applications in metal protection.
1. Introduction
TC4 alloys are widely used in marine and biomedical applications due to their light weight, high strength, and weldability, yet their poor tribological performance and susceptibility to localized corrosion, especially under prolonged exposure to corrosive environments, have hindered broader adoption. The native oxide film on titanium alloys is thin, has poor wear resistance, and is vulnerable to fluoride ions, leading to compromised corrosion resistance. Furthermore, friction-induced wear can exacerbate surface corrosion, releasing harmful Al and V ions in biomedical contexts. Conventional surface modification strategies have struggled to simultaneously address wear and corrosion, particularly on titanium alloys where the dense oxide layer impedes the growth of protective coatings like layered double hydroxides (LDHs).
This study introduces a novel approach by first fabricating a ZnAl LDH coating on TC4 via in situ growth, overcoming the oxide layer barrier, then intercalating molybdate anions to enhance corrosion inhibition. A slippery liquid-infused porous surface (SLIPS) is constructed by UV-grafting PDMS onto the nanoporous LDH, creating a chemically anchored lubricant layer that resists depletion. This dual-action surface provides both corrosion resistance and wear protection, addressing the critical bottleneck of simultaneous degradation mechanisms. The reported corrosion current density of 2.34×10−7 A/cm2 and improved wear performance demonstrate a viable strategy for extending TC4 alloy service life in demanding applications.
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Xionggang Chen, Deke Li, Tianqi Wei, Zhiwei Chen, Haidong Wang, Danyan Zhan, Jinxia Huang, Zhiguang Guo (2026). Slippery Liquid-Infused Porous Surface with Layered Double Hydroxides for Enhanced Corrosion and Wear Resistance of TC4 Alloys. SinoTechIntel Verified Research. https://doi.org/10.26599/FRICT.2025.9441191
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, corporate R&D benchmarking, and educational evaluation under international fair use principles.
Copyright Ownership: Source copyright remains with original Chinese academic publishers and authors. SinoTechIntel claims editorial rights over its original English translations and structural index enhancements.
Frequently Asked Questions
What is the long-term stability of the SLIPS under cyclic mechanical loading or abrasive wear conditions?
The study demonstrates that the nanoporous LDH structure provides a physical confinement effect and chemical grafting of PDMS reduces lubricant depletion, but long-term cyclic wear data are not provided. The corrosion current density of 2.34×10−7 A/cm2 indicates excellent initial corrosion resistance, but further testing under dynamic mechanical stress is required to assess durability.
How does the cost of this LDH-based SLIPS fabrication compare to conventional protective coatings for titanium alloys?
The in situ growth and ion exchange processes are relatively straightforward and use common chemicals (ZnAl LDH precursors, molybdate, PDMS), potentially offering cost advantages over vacuum-based or plasma-sprayed coatings. However, a detailed cost analysis is not provided, and scale-up feasibility remains to be evaluated.
What is the adhesion strength of the LDH coating to the TC4 substrate, and how does it withstand thermal cycling or high-temperature exposure?
The paper does not report adhesion strength or thermal stability data. The in situ growth method suggests strong interfacial bonding, but quantitative measurements (e.g., scratch test, pull-off test) are necessary to confirm reliability under thermal and mechanical stresses.
Can the molybdate intercalation be optimized to further reduce corrosion current density below 2.34×10−7 A/cm2, and what is the mechanism?
Molybdate acts as a corrosion inhibitor by forming insoluble compounds at anodic sites. The current density achieved is already low, but optimization of ion exchange time and concentration could potentially enhance protection. The mechanism involves release of molybdate upon damage, but further electrochemical studies are needed to quantify the self-healing effect.
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