Effect of Cr doping on the mechanical, tribological, and corrosion properties of ta-C films

Tetrahedral amorphous carbon (ta-C) films are promising protective materials, but their practical applications in harsh environments (high temperature, high mechanical load, and marine corrosion-wear conditions) are limited by high residual stress, poor adhesion, and insufficient stability. This study systematically investigates the effects of Cr doping (0–41.1 at. %) on the microstructure, mechanical, tribological, and corrosion properties of ta-C films prepared via a hybrid filtered cathodic vacuum arc and pulsed DC magnetron sputtering system. The core novelty lies in revealing Cr's dual regulatory mechanism: Cr doping promotes film graphitization (reducing residual stress) while inducing the formation of CrC hard nanophases (recovering mechanical properties), achieving synchronous stress reduction and performance enhancement. Specifically, low Cr content forms solid solutions in the carbon network, while excess Cr precipitates as face-centered cubic CrC; bond conversion from sp3 to sp2 accompanies graphitization, with hardness initially decreasing then increasing due to nanocomposite structure formation. The optimized Cr doping (9.6 at. %) realizes synergistic improvements in room-temperature/high-temperature (400 °C) dry tribological properties, simulated seawater tribological performance, and corrosion resistance (higher corrosion potential and lower corrosion current density). This work provides a new design strategy for balancing ta-C films’ comprehensive properties, offering experimental/theoretical support for their applications in marine engineering (ship propellers and seawater valves), high-temperature mechanical components (engine piston rings and aviation bearings), and other harsh-environment fields.