Novel surface engineering design enabled surface multifunctionalisation of metastable Ti–15–3 β-titanium alloy
Authors: Tong Pan, Xuan Huang, Behnam Dashtbozorg, Siyu Sun, Yepeng Yang, Ke Ren, Artemis Stamboulis, Xiaoying Li, Kan Ma, Hanshan Dong
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.