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 sea-water 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. (C) 2014 Elsevier B.V. All rights reserved.