Tribological behavior of TiN-coated titanium fiber reinforced 5056-aluminum matrix composites

The present study investigates the tribological behavior of high-performance TiN-coated titanium fiber-reinforced 5056-Aluminum matrix composites (Ti_f@TiN/5056 Al) produced through pressure infiltration method. Before producing the composites, physical vapor deposition (PVD) technique was employed to develop a uniform, dense TiN coating on titanium fibers. Findings demonstrate that the TiN coating effectively suppresses Ti-Al interfacial reactions, preventing formation of brittle TiAl₃ phase enhancing the bending strength of the composite by 13% (to 542.8 ± 15.5 MPa). The Ti_f@TiN/5056 Al composite showed a wear rate of 3.33 × 10⁻³ mg/(N·m) and coefficient of friction (COF) of 0.290 representing 17.8% and 13.4% improvement in tribological behavior, respectively, compared to the uncoated counterparts (wear rate: 4.05 × 10⁻³ mg/(N·m), COF: 0.335). These improvements primarily originate from the TiN coating's exceptional mechanical properties (elastic modulus: 406.4 ± 1.5 GPa, hardness: 19.3 ± 1.5 GPa), which substantially enhance the load-transfer capacity between titanium fibers and matrix. During wear processes, the coating acts as a protective barrier preventing direct fiber exposure at friction interfaces, as well as a performance modifier by facilitating the formation of a stable mechanically mixed layer (MML). This transition shifts the dominant wear mechanism from severe adhesive wear to mild abrasive wear while effectively inhibiting material transfer phenomena.