| Corrosion of metals is very common in life.It has brought a lot of security risks to industrial production,transportation,construction and so on.Therefore,metal protection has always been a subject of continuous research in the field of materials.Since the photo-electrochemical anticorrosion properties of Ti02on metal surface have been found,this photocathode protection technology has attracted much attention.The principle of photocathode protection lies in the fact that when nano-TiO2 is exposed to UV irradiation,the electron-hole pairs are generated.Thephotogenerated electrons transfer to metal substrate,thus making its potential a negative shift.Because of Ti02 functions as a non-sacrificial anode,this method has a long anticorrosive effect and low cost.Therefore,it has a broad prospect for the protection of metal materials.First of all,Ti02 loaded graphene(RGO)composite particles with visible light response were prepared through sol-immobilization process and heat treatment.The structure and photoelectrical properties of the samples were thoroughly investigated by XRD,TEM,FT-IR,UV-Vis DRS and photoelectrochemical test.Results showed that the composite particles had a red shift and the band gap decreased from 3.18 eV to 2.65 eV compared to pure Ti02.What is more,Nano-Ti02 was attached onto the surface of RGO and there was a chemical bond of Ti-O-C between TiO2 and RGO.Photoelectrochemical test indicated that photocurrent of RGO/TiO2 composite particles reached the maximum value when the content of RGO was 5.0%.Besides,the smaller size of graphite and the greater intensity of light,the bigger value of photocurrent.Furthermore,a crosslinked styrene-acrylate emulsion was synthesized by means of emulsion copolymerization using St,BA,EHA and AA as main monomers,DAAM and ADH as crosslinking system,SR-10 as emulsifier and PPS as initiator.It was found that the emulsion and its film showed the best performance when the content of SR-10 was 2.0%,the content of PPS was 0.5%and the DAAM monomers amount was 1.0%respectively.Finally,the waterborne anticorrosive coating was prepared by using RGO/Ti02 composite particles as functional pigments,styrene-acrylate emulsion as film forming material and a small amount of auxiliary agent.Then the corrosion resistance of prepared coating was investigated by means of coating thickness,adhesion,hardness,NaCl solution resitance and Tafel polarization curve.Results showed that the thickness of the coating was uniform and no rust phenomenon appeared after immersion for 400 h in 3%NaCl solution.The Tafel polarization curve showed that in the absence of light the coating could form a physical barrier effect to corrosive media.While in the presence of light the potential of metal had a negative shift to the cathode protection area,indicating a photocathode protection to the metal matrix.It was showed that the modified acrylate coating using RGO/TiO2 composite particles can provide a excellent protection for Q235 substrate. |
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