Key Takeaways & Executive Findings
- •• • Au-catalysed C3T achieved near-zero wear and a stable COF of ~0.3 under a 20 N load, demonstrating superior tribological performance for high-load sliding contacts. • • Ag-catalysed C3T delivered antibacterial efficacies of 99.878% against E. coli and 99.999% against S. aureus within 3–6 h of contact, via passive Ag-ion release, addressing infection risks in biomedical and marine applications. • • Both treatments increased bulk tensile strength by ~50%, from 872±39 to 1,280±40 MPa, enhancing structural integrity without compromising surface functionality. • • The IBTSF strategy integrates bulk heat treatment with surface functionalisation in a single step, offering a scalable and efficient route for multifunctionalising metastable β-titanium alloys.
Abstract
The growing demand for high-performance and long-service components in challenging applications has driven the development of high-strength metastable β-titanium alloys with multifunctional surfaces. This study introduces a novel surface engineering strategy, integrated bulk heat treatment with surface functionalisation (IBTSF), which combines bulk aging treatment with catalytic ceramic conversion treatment (C3T) incorporating Ag or Au. This approach simultaneously imparts surface multifunctionalities—high hardness, desirable tribological properties, and high antibacterial efficacy—while enhancing bulk mechanical properties. Using the metastable β-titanium alloy Ti–15V–3Al–3Cr–3Sn (Ti–15–3) as a representative, C3T was catalysed with either Au or Ag. Under a 20 N load, Au-catalysed C3T achieved near-zero wear and a low, stable coefficient of friction (COF) of ~0.3, attributed to the formation of a lubricating tribo-film. In contrast, Ag-catalysed C3T maintained stable tribological performance up to 10 N while delivering high antibacterial efficacies of 99.878% and 99.999% against E. coli and S. aureus within 3–6 h of contact, respectively, through passive Ag-ion release. Both treatments enhanced bulk tensile strength by approximately 50%, from 872±39 to 1,280±40 MPa. This combination of exceptional wear resistance, potent antibacterial activity, and improved mechanical strength offers a promising pathway to surface multifunctionalising metastable alloys for long-service, high-reliability applications.
1. Introduction
High-performance materials used in marine and biomedical environments face simultaneous mechanical wear and biological threats, such as microbiologically influenced corrosion (MIC) and infection from wear debris. Traditional titanium alloys, despite their excellent strength-to-weight ratio and corrosion resistance, suffer from poor tribological performance, limiting their service life. Existing surface engineering approaches, such as laser cladding with CrMoNbW–Cu coatings, improve hardness and wear resistance but often introduce high interfacial stress concentrations and lack integrated antibacterial functionality, failing to meet the multifunctional demands of modern applications.
The integrated bulk heat treatment with surface functionalisation (IBTSF) strategy addresses this bottleneck by combining bulk aging treatment with catalytic ceramic conversion treatment (C3T) using Ag or Au. This single-step process simultaneously enhances surface hardness, wear resistance, and antibacterial efficacy while improving bulk mechanical strength. By applying this to metastable Ti–15–3 alloy, the study demonstrates a near-zero wear under 20 N load with Au catalysis and high antibacterial activity with Ag catalysis, alongside a 50% increase in tensile strength. This approach offers a promising solution for long-service, high-reliability components in resource-intensive environments.
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Tong Pan, Xuan Huang, Behnam Dashtbozorg, Siyu Sun, Yepeng Yang, Ke Ren, Artemis Stamboulis, Xiaoying Li, Kan Ma, Hanshan Dong (2026). Novel surface engineering design enabled surface multifunctionalisation of metastable Ti–15–3 β-titanium alloy. SinoTechIntel Verified Research. https://doi.org/10.26599/FRICT.2026.9441262
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Frequently Asked Questions
What is the maximum load capacity for Ag-catalysed C3T before tribological performance degrades?
Ag-catalysed C3T maintained stable tribological performance up to a load of 10 N; beyond this, performance may degrade, as indicated by the study's load-dependent testing.
How does the Au-catalysed C3T achieve near-zero wear under a 20 N load?
Au-catalysed C3T forms a lubricating tribo-film during sliding, which reduces friction and wear, resulting in a low, stable COF of ~0.3 and near-zero wear under 20 N.
What are the antibacterial mechanisms and efficacy of Ag-catalysed C3T?
Ag-catalysed C3T releases Ag ions passively, which are toxic to bacteria. It achieved 99.878% and 99.999% reduction of E. coli and S. aureus, respectively, within 3–6 hours of contact.
Does the IBTSF treatment compromise bulk mechanical properties?
No, the IBTSF treatment enhances bulk tensile strength by approximately 50%, from 872±39 to 1,280±40 MPa, while simultaneously improving surface properties.
What is the scalability potential of the IBTSF process for industrial applications?
The IBTSF process integrates bulk heat treatment and surface functionalisation in a single step, potentially reducing processing time and cost, making it scalable for industrial adoption.
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