| Compared with traditional electrodeposition technology,scanning electrodeposition technology has the technological characteristics of high-speed jet impact and reciprocating cycle scanning during the processing process,which can accelerate the material transfer,improve the liquid phase mass transfer effect,and finally achieve the goal of improving the deposition efficiency of the coating.Meanwhile,by increasing the limiting current density,promote the nucleation speed,can promote more uniform coating of dense tissue structures,so that the surface having more excellent surface morphology and coating properties,which is widely attention.Sandblasting pretreatment technology is the most commonly used method for pretreatment of metal material substrates in the industrial field.Its process is simple,efficient,and low-cost.It uses compressed air to form a high-speed jet beam to spray sand particles on the surface of the substrate at high speed to cause plastic deformation,so as to improve the mechanical properties and increase the deposition rate of the coating on the surface of the substrate during the scanning electrodeposition process.At present,most researches on electrodeposited composite coatings focus on the surface characterization and performance testing of the coating,such as the influence of microscopic morphology,grain structure,and element distribution on the corrosion resistance.The research on the cross-section is limited to the thickness and cross-sectional shape of the coating.However,there are few studies on the interaction between the coating morphology,element distribution,adhesion resistance and corrosion resistance.Based on the sandblasting pretreatment device and the scanning electrodeposition device,this paper carries out the process experiment of preparing the Ni-P-SiC composite coating by the scanning electrodeposition of the sandblasting pretreatment on the surface of 45 steel.In this paper,the morphology and element scanning characterization of the surface and cross-section of the coating are carried out to describe that the element penetration region of the cross-section is formed by the interpenetration of elements in the coating and the substrate.The influence mechanism of sandblasting time and particle concentration on element penetration is studied,and carry out the adhesion test and corrosion resistance test of the coating to explore the mapping relationship between element penetration and coating performance.The main research contents are as follows:（1）The sandblasting pretreatment scanning electrodeposition system and the formulation of the process test plan was designed,designed and built the sandblasting pretreatment system device and the scanning electrodeposition system device,and determined the appropriate process test parameters.The preparation process of the scanning electrodeposition Ni-P-SiC composite coating on the surface of 45 steel by sandblasting and the performance characterization process of the coating performance are proposed,including the preparation of test materials,the composition and function of the coating composition,and the preparation process of the coating;（2）An experimental study on the preparation of Ni-P-SiC composite coatings by scanning electrodeposition on the surface of 45 steel by sandblasting pretreatment.Carried out basic experimental research on preparation of composite coatings on the surface of 45steel by sandblasting.The results showed that the pretreatment of the substrate by sandblasting and the addition of SiC nanoparticles improved the surface and cross-sectional quality,increased the thickness of the coating,and expanded the range of element penetration region.A test study of sandblasting time on the surface of 45 steel prepared by sandblasting pretreatment was carried out.The results showed that as the sandblasting time increased to30s,the surface roughness of the substrate and the coating gradually increased,the surface and cross-section quality improved,and the thickness of the coating the element penetration region gradually increased,and the element penetration effect between the substrate and the coating is enhanced.When the sandblasting time continues to increase,the surface roughness of the substrate and the coating gradually decreased and tended to be stable,and the quality of the surface and cross-section decreased,inhibited the growth of the coating and weakened the effect of element penetration.The experimental study of particle concentration on the preparation of composite coatings on the surface of 45 steel pretreated by sandblasting showed that as the concentration of SiC nanoparticles gradually increased to 3g/L,the surface and cross-section quality of the coating improved,the thickness of the coating and the element penetration region increased,and improved the interpenetration of elements.When the particle concentration continues to increase,the quality of the coating surface and cross-section decreased,the thickness of the coating and the element penetration region decreased,reduced the interpenetration ability of elements.Research on the element penetration mechanism of composite coating prepared by sandblasting pretreatment on the surface of 45steel was carried out,and the influence mechanism of sandblasting time and particle concentration on element penetration was summarized;（3）The adhesion performance of Ni-P-SiC composite coating prepared by scanning electrodeposition on the surface of 45 steel with sandblasting pretreatment was studied,and the adhesion test and the scratch microscopic morphology test were designed.A preliminary study on the adhesion performance of Ni-P-SiC composite coatings prepared by scanning electrodeposition on the surface of 45 steel by sandblasting pretreatment.The results showed that both the sandblasting pretreatment and the addition of SiC nanoparticles can improve the adhesion of the coating to the substrate and increase the coating adhesion.A study on the adhesion performance of the composite coating prepared by the sandblasting time on the surface of the sandblasted pretreated 45 steel was carried out.The results showed that as the sandblasting time increases,the element penetration region first increased and then decreased,so that the scratch surface microcracks first decreased and then increased.The coating adhesion presented a trend of first increased and then decreased,and the coating adhesion performance reached the best when sandblasting for 30s.The study of particle concentration on the adhesion performance of composite coatings prepared on the surface of sandblasted pretreated 45 steel showed that with the gradual increase of SiC nanoparticle concentration,the element penetration region first increased and then decreased,making the surface quality of scratches improved first and then decreased.The coating adhesion presents a tendency to increase first and then decrease,and the coating adhesion performance reached the best when the concentration was 3g/L.Based on the influence of element penetration,the adhesion mechanism of sandblasting time and particle concentration on the composite coating was analyzed;（4）The corrosion resistance of Ni-P-SiC composite coating prepared by scanning electrodeposition on the surface of 45 steel by sandblasting pretreatment was studied,the electrochemical corrosion test was designed,and the microscopic morphology inspection test after corrosion was designed.A preliminary study on the adhesion performance of the Ni-P-SiC composite coating prepared by scanning electrodeposition on the surface of 45 steel by sandblasting pretreatment.The results showed that both the sandblasting pretreatment and the addition of SiC nanoparticles can improve the corrosion resistance of the coating and effectively protect the substrate from corrosion.The corrosion resistance of composite coating prepared by sandblasting time on the surface of sandblasting pretreatment 45 steel was carried out.The results showed that with the increase of sandblasting time,the corrosion resistance of composite coating gradually increased and then gradually decreased.The best sandblasting time was when the time was 30s,the Ni-P-SiC composite coating prepared by scanning electrodeposition had the largest self-corrosion potential,the smallest self-corrosion current density,the lowest corrosion rate,the largest impedance arc radius of the coating,and the largest corresponding equivalent resistance value R2,and the corrosion resistance was up to optimal.The corrosion resistance of composite coatings prepared by particle concentration on the surface of 45 steel prepared by sandblasting pretreatment was carried out.The results showed that with the increase of SiC nanoparticle concentration,the corrosion resistance of composite coatings gradually increased and then gradually decreased.The optimum particle concentration was when the concentration of SiC nanoparticles was 3g/L,The Ni-P-SiC composite coating prepared by scanning electrodeposition had the largest self-corrosion potential,the smallest self-corrosion current density,and the smallest corrosion rate.At the same time,the impedance arc radius of the composite coating was the largest,the corresponding equivalent impedance value was the largest,and the corrosion resistance was up to optimal.The corrosion mechanism of the composite coating was analyzed based on the sandblasting time and particle concentration based on the element penetration region;... |
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