| With the rapid development of the marine industry,marine materials have been confronted with various kinds of problems such as biofouling,corrosion and cavitation erosion which have been widely concerned by researchers both at home and abroad.Surface technology is the key to solving the mentioned above problems.To date,numerous methods including spark plasma sintering,laser cladding technology,plasma transferred arc welding and thermal spraying technology etc.have been used for anticorrosion,anti-biofouling and cavitation erosion resistance applications in marine environment.As an important part of surface engineering technology,thermal spraying technology such as high velocity oxygen fuel sprayed coatings have favorable properties such as lower porosity,higher adhesion and higher hardness and attracted much attention for potential marine applications.Corrosion are commonly occurred in chloride ions-rich marine environment by destruction of the passivation film of the marine metal structures and then going into the metal lattice,thereby changing the surface properties of the material.As another key concern for the marine environment,biofouling is a complex phenomenon involving polysaccharides and/or proteins and more than 4000 species of marine organisms,leading to material failure eventually.In addition,cavitation is a surface degradation process in which vapor bubbles in a low-pressure liquid form and collapse,usually explosively,at surfaces and within the liquid causing severe surface erosion and material removal or vibrations of the devices in which the liquid is enclosed.Cavitation erosion commonly causes damage in hydrodynamic systems,shortening their service life,reducing their operating efficiency,and increasing cost.What’s more,biofouling can cause electrochemical corrosion resulting in a synergistic effect with the cavitation damage.However,the interaction between the biofouling-corrosion and corrosion-cavitation erosion in the marine environment remains unclear.Thus,ongoing efforts are still needed to elucidate the interaction between the biofouling-corrosion and corrosion-cavitation erosion of coatings used for marine applications.In this study,typical thermal sprayed Fe-based amorphous/nanocrystalline coating,WC-10Co4 Cr coating,Co-based coating,WC-10Co4Cr/Co-based composite coating and aluminum coating were prepared by HVOF spraying and arc spraying respectively.Fe-based amorphous/nanocrystalline coatings were used to investigate the influence of corrosion on biofouling due to their excellent corrosion resistance,wear resistance,high strength,and low material processing cost.The arc sprayed aluminum coatings were selected to investigated the influence of biofouling on corrosion behavior.The Fe-based amorphous/nanocrystalline coating,WC-10Co4 Cr coating,Co-based coating and WC-10Co4Cr/Co-based composite coatings were used to comparatively investigate the influence of corrosion on cavitation erosion behavior.The WC-10Co4 Cr coatings after sealing were prepared to explore the effect of cavitation erosion on corrosion behavior.The aim of this study is to preliminary explore the interaction between the biofouling-corrosion and corrosion-cavitation erosion of thermal sprayed coatings in seawater environment.Herein,the as-sprayed Fe-based amorphous/nanocrystalline coating and post crystallization treated coatings were deposited by HVOF to investigate the influence of corrosion on the biofouling behavior.The results show that the as-sprayed coatings displayed excellent corrosion resistance and reduced the adhesions of Phaeodactylum tricornutum,while the coating after heating treatment exhibited poor corrosion resistance,but significantly inhibits the attachment of the Phaeodactylum tricornutum.In addition,arc sprayed aluminum coatings were employed to study the influence of biofouling on corrosion behavior.Results show that surface roughness of the coatings plays a key role in determining the adhesion of chlorella on the coating surface and the homogeneous biofilm enhanced the corrosion resistance of the coating in the early stage.Several HVOF sprayed coatings were fabricated to investigate the effect of corrosion on cavitation erosion behavior tested in deionized water and artificial seawater,respectively.316 L stainless steel substrates were used as controls.Results show that the effect of marine corrosion on cavitation erosion was most significant on the stainless steels,WC-10Co4 Cr coatings,and Co-based coatings,but negligible on the WC-10Co4Cr/Co-based composite coatings and the Fe-based amorphous/nanocrystalline coatings.The WC-10Co4Cr coatings appear to be a promising cavitation erosion resistance material for marine applications.The assprayed WC-10Co4Cr coating and WC-10Co4Cr coating after sealing by epoxy resin,as well as 316 L stainless steel were prepared to investigate of the influence of cavitation erosion on corrosion behavior.And the open circuit potential test and impedance spectrum test were carried out.Results show that cavitation inhibited the early stage of corrosion of the coatings. |
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