Unraveling the corrosion behavior and mechanism of DLC film on the inner surface of N80 lengthy pipeline in CO2-H2S-Cl- environment

A diamond like carbon (DLC) film was successfully prepared on the inner surface of N80 pipeline to slow down the pitting corrosion and cracking of N80 lengthy pipeline in oil and gas exploitation. Electrochemical measurements, scanning electron microscopy and X-ray photoelectron spectroscopy were applied to characterize the corrosion behavior and mechanism of DLC film on the inner surface of N80 pipeline in CO2-H2S-Cl- environment. The DLC film after corrosion still maintains excellent compactness. Sulfides and oxides of iron effectively obstructed the infiltration path within the DLC film and improved the compactness. Notably, there is a correlation between the surface morphology of DLC film and substrate after corrosion. The corrosion environment affects the morphology of the substrate after corrosion, and then changes the morphology of the DLC film after corrosion.