Interlayer design for the graphite-like carbon film with high load-bearing capacity under sliding-friction condition in water

• Interlayer design affects the microstructure of GLC film slightly. • Nano-interlocked microstructure is formed in composition gradient Cr/C interlayer. • Hard CrC phase is formed inside the composition gradient Cr/C interlayer. • GLC with composition gradient Cr/C interlayer exhibits high adhesion strength . • GLC on composition gradient Cr/C layer shows high load-bearing capacity in water. GLC films with single Ti interlayer, single Cr interlayer, thickness gradient Cr/C interlayer and composition gradient Cr/C interlayer were fabricated by magnetron sputtering technique. The microstructures, mechanical properties and tribological performance under sliding friction in distilled water and seawater of the as-deposited GLC films were investigated. Results showed that the adhesion strength and the load-bearing capacity under sliding-friction condition in water of GLC film could be improved effectively by interlayer design. GLC film with composition gradient Cr/C interlayer exhibited highest adhesion strength and load-bearing capacity under sliding-friction conditions in water, which was closely related to nano-interlocked microstructure and hard carbide phase formations inside the interlayer. The adhesion strength in scratch test and the critical bearing load under sliding-friction in water of the GLC film with composition gradient Cr/C interlayer exceeded 50 N and 2.73 GPa, respectively.