Effects of PVD DLC Coating on 7075-T6 Alloy Fatigue Strength

7075-T6 aluminium alloy is under investigation in the last decades because of its sensitivity to corrosion and its poor surface behaviour. The alloy is widely used in many mechanical, aeronautical and structural engineering appliances because of its high strength-toweight-ratio. Notwithstanding its strength and light weight advantages, its applications in corrosive environments, with fatigue applied loads, is still under research. The mechanical and chemical driving forces have still to be accurately evaluated and the role of each one identified. Results of tests on rotating bending fatigue (R = -1) 7075-T6 uncoated and PVD DLC coated specimens are reported in this paper under various stress levels and number of cycles to failure. Fracture surfaces were observed via SEM characterization in order to assess the role of the chemical aggressive environment, the residual stress field and the applied load.