An environmentally friendly laser cleaning method to remove oceanic micro-biofoulings from AH36 steel substrate and corrosion protection

Abstract

An environmentally friendly nanosecond ultraviolet (UV) laser is employed in laser cleaning micro biofouling from the Fe substrate surface. The morphologies and chemical compositions of the UV laser cleaned surface are examined by field emission scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS), digital ultra-depth-of-field microscope and optical profiler (OP). The results indicate that a laser fluence of 5.30 J/cm2 demonstrates outstanding cleaning effectiveness and a corresponding surface roughness of 4.031 μm. Notably, the initial cleaning threshold and completely clean threshold are 2.75 J/cm2 and 5.30 J/cm2 respectively. The anti-corrosion properties are characterized by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) respectively. In this regard, the UV laser cleaned micro biofouling surface at laser fluence of 5.30 J/cm2 also enhanced the anti-corrosion properties significantly. A novel thermodynamic model of UV laser cleaning of micro biofouling is developed firstly, which illuminates the relationships between the temperature and laser fluence. This investigation not only provides significant insights into the theoretical model and mechanism of UV laser cleaned micro biofouling surface, but also provides a guide for practical oceanic industrial applications.