Microstructure and Wear-Corrosion Properties of TiAlN/VN Multilayer Films on Titanium Alloy Connecting Rods
TiAlN/VN multilayer films with modulation periods (Λ) of 186, 280, and other values were deposited on TC4 titanium alloy connecting rods via microwave-enhanced magnetron sputtering to address the inadequate tribological and corrosion performance of monolithic TiAlN and VN coatings. X-ray diffraction confirmed coherent epitaxial growth of a face-centered cubic structure across all multilayers. As Λ decreased from 280 to 186 nm, hardness increased to a maximum of 25.46 ± 0.69 GPa and residual compressive stress decreased to 0.88 GPa, attributed to increased interface density and alternating stress fields that inhibit dislocation motion and relieve internal strain. The multilayer with Λ = 280 nm exhibited the highest H/E and H³/E² ratios, yielding superior fracture toughness, film-substrate adhesion, a stable friction coefficient of 0.5, and optimal wear resistance. Electrochemical testing revealed that the Λ = 186 nm multilayer, with its higher interface count and lower porosity, effectively blocked micro-pores and micro-cracks, increasing the self-corrosion potential and reducing corrosion current density relative to the TC4 substrate. These results demonstrate that TiAlN/VN multilayers provide a dual-function barrier against wear and corrosion, extending the service life of titanium alloy connecting rods in harsh environments and offering a theoretical basis for broadening titanium alloy applications.