Application Of Tin-based Materials In Photocathodic Protection Of Marine Engineering

The ocean is an environment with many corrosive factors and complicated conditions.Stainless steel,as a metal material with good corrosion resistance,still suffers from pitting under the combined influence of seawater corrosion and microbial attack.At the same time,there are gap corrosion and stress corrosion cracking.When the stainless steel is damaged by corrosion,it will not only affect the mechanical properties such as strength and hardness,but also reduce its reliability.Therefore,it is of practical significance to explore a green and effective corrosion protection method to extend the life of components and ensure safe production.In view of the defects of TiO₂ in photocathodic protection,this paper modified TiO₂with other semiconductors to enhance the photocathodic protection effect of 304 stainless steel.In this paper,SnS/TiO₂ and SnS₂/TiO₂ were prepared by anodic oxidation and successive ion layer absorption and reaction technique?SILAR?.SnSe/TiO₂ was prepared by hydrothermal method.The samples were characterized by scanning electron microscopy?SEM?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?and UV-VIS diffuse reflectance spectrum?DRS?.The open circuit potential?OCP?,photocurrent density curve and electrochemical impedance spectroscopy?EIS?were used to test the performance of the samples.In this paper,characterization experiments have confirmed that SnS/TiO₂,SnS₂/TiO₂and SnSe/TiO₂ nanocomposites have been successfully prepared.With the increase of the concentration of raw materials,more SnS nanoparticles were adsorbed on the surface of TiO₂.With the increase of deposition times,SnS₂ agglomeration gradually became obvious.The results of diffuse reflection experiment also show that SnS/TiO₂,SnS₂/TiO₂ and SnSe/TiO₂nanocomposites have better visible light absorption performance than pure TiO₂.Electrochemical experiments show that SnS/TiO₂ as a photoanode coupled with 304 stainless steel can reduce the potential of stainless steel to-630^-710 mV,and can store electrons to protect them in the dark state.The optimal load SnS₂/TiO₂?6C?can produce optical current about 30?A/cm²,which is about five times higher than TiO₂.SnSe/TiO₂ samples also showed better photocathodic protection effect on 304 stainless steel than TiO₂.And SnSe/TiO₂ exhibited good stability after long-time OCP test.