Enhanced corrosion resistance of graphite-like carbon coatings via dense ta-C interlayer encapsulating

Taking the combination of atomic bond density, in this work, the tetrahedral amorphous carbon (ta-C) layer with high sp3 bond were especially introduced into the sp2-riched graphite-like carbon (GLC) coatings, using a hybrid filtering cathodic arc and magnetron sputtering deposition technique. The focus was elaborated on the electrochemical behavior of coatings against the stimulated chloride solutions for marine applications. Results showed that inserting dense ta-C layer significantly encapsulated the intrinsic pore defects within GLC growth, thereafter enhancing the corrosion resistance remarkably. In particular, the coating porosity was reduced from 10.84 % for pristine GLC system to 3.19 % for GLC with ta-C sealing layer, accompanying with a reduction in corrosion current to 7.8 × 10−9 A/cm2 and an increment in protective efficiency to maximum value of 95.49 %. The small angle X-ray scattering (SAXS) analysis evidenced qualitatively that the coating porosity was suppressed greatly, which were well consisted with the enhanced corrosion resistance of GLC coating with ta-C sealing layer. Furthermore, the balance between pores sealing and interfacial matching could be tailored by controlling the thickness ratio of ta-C and GLC layers, enabling the achievement of both the compact structure and the superior corrosion resistance. These observations offer a new promising strategy to develop the protective coatings for harsh marine environment that required both excellent capability against corrosion and friction with long lifetime.