| The corrosion of metal materials is widespread in production and life.it will not only cause economic loss,also threaten people’s life.Therefore,it is very important to slow down and control the corrosion of metals.One of the most cost-effective methods is to use anti-corrosion coating technology.However,the coating may be damaged during use,such as cracks,scratches,and coating defects,thereby losing the protective function of the coating on the substrate material.Therefore,the preparation of anticorrosive coatings with excellent performance and self-healing function has important engineering application value.In this paper,ethyl cellulose(EC)is used as the film-forming substance,and the ethyl cellulose composite coating(EC-C),EC-C/Fe3O4,and EC-C/Ni with thermoplasticity are prepared by melt blending.Self-healing of coating damage was achieved by induction heating.The specific research work is as follows:EC-C,EC-C/Fe3O4,EC-C/Ni composite coating materials were prepared.In the experiment,ethyl cellulose was used as the film-forming substance,mineral oil and castor oil were used as the solvent,titanium dioxide used as fillers,and a little auxiliary agent was added to prepare the EC-C composite coating with thermoplastic function by melt blending.Based on the preparation of EC-C composite coating,nano-Fe3O4 was used as the magnetic filler,and EC-C/Fe3O4 magnetic composite coating was successfully prepared by studying the amount of nano-Fe3O4 added.Based on the preparation of EC-C composite coatings,Ni powder was used as the magnetic filler,and EC-C/Ni magnetic composite coatings was successfully prepared by studying the amount of Ni powder added.Characterization of EC-C,EC-C/Fe3O4,EC-C/Ni composite coating materials.In the experiment,scanning electron microscope(SEM),X-ray energy spectroscopy(EDS).Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),thermogravimetric analyzer(TGA),differential scanning calorimeter(DSC),universal tensile testing machine,hardness tester,neutral salt spray test chamber,chemical immersion,electrochemical workstation,highfrequency induction heater and other instruments were used to characterize EC-C,EC-C/Fe3O4,EC-C/Ni composite coating.The results show that the EC-C composite coating prepared by the experiment has a soft texture,a hardness of 60 HA,a tensile strength of 0.35 MPa,and no defects such as pore cracks on the surface.The EC-C composite coating starts to decompose at 200℃ and completely decomposes at 550℃.After 120 days of immersion,the resistance value is 3.47×109 Ω/cm2.After 1000 hours of neutral salt spray,the coating has no obvious change.In 3.5%NaCl and 5%HCl solution,after 28 days of immersion,the surface morphology remained unchanged,and the mass gain rate was small.The EC-C/Fe3O4 composite coating prepared by the experiment has increased the hardness and tensile strength with the increase of the nano-Fe3O4 content,and the dispersion has decreased.The mass gain rate in the soaking of acid-base salt solution shows a downward trend with the increase of the nano-Fe3O4 content.Electrochemical impedance analysis shows that the impedance value of the EC-C/Fe3O4 composite coating increases first and then decreases with the increase of nano-Fe3O4 content,and the impedance value reaches a maximum of 4.39×109 Ω/cm2 when the nano-Fe3O4 content is 15 wt%.The analysis of magnetocaloric effect shows that the magnetocaloric effect of ECC/Fe3O4 composite coating increased with the increase of nano-Fe3O4 content.The EC-C/Ni composite coating prepared by the experiment has increased hardness and tensile strength with the increase of Ni powder content,and the dispersion has decreased.The mass gain rate in acidbase salt solution immersion showed a downward trend with the increase of the Ni powder content.The electrochemical impedance analysis shows that the impedance value of the ECC/Ni composite coating increases with increasing Ni powder content.When the Ni content reaches 25 wt%,the impedance value is 4.74×109Ω/cm2.The analysis of magnetocaloric effect shows that the magnetocaloric effect of EC-C/Ni composite coating increased with the increase of Ni content.Induction self-healing and research of EC-C,EC-C/Fe3O4,EC-C/Ni composite coating.Induction heating self-healing of the damaged EC-C,EC-C/Fe3O4,EC-C/Ni composite coating using a high-frequency induction heater.The effects of induction heating power,time and distance on self-healing were studied through orthogonal experiments.At the same time,the performance of composite coating before and after induction self-healing under the optimal healing process conditions was studied.The analysis shows that the damaged EC-C composite coating can effectively self-healing by induction heating on the magnetic substrate with the process parameters of 3 kW heating power,self-healing time 50 s and self-healing distance 20 mm.After the EC-C/Fe3O4 magnetic composite coating with Fe3O4 content of 10 wt%was damaged,induction self-healing was carried out under the process conditions of induction heating power of 3.5 kW,self-healing time of 65 s,and self-healing distance of 4 mm.The damaged EC-C/Fe3O4 magnetic composite coating could be effectively healed.After the ECC/Ni magnetic composite coating containing 10 wt%Ni was damaged,induction self-healing was carried out under the process conditions of induction heating power of 3.5 kW,self-healing time of 95 s,and self-healing distance of 4 mm.It also has a good healing effect on the damaged EC-C/Ni magnetic composite coating.Analysis of the morphology,structure,corrosion resistance and magnetic properties of EC-C,EC-C/Fe3O4,EC-C/Ni composite coating before and after self-healing.The research shows that the composite coating after induction selfhealing has a complete morphology and structure,no new crystal structure appeared,the impedance value was basically the same as the complete coating,and the magnetic properties were enhanced.The composite coating after induction self-healing has good performance and also has excellent anti-corrosion properties. |
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