| In order to avoid the problems of the metal oil tank caused by corrosion and static electricity, such as oil spills, equipment damage, and even major accidents and other issues. The use of anti-corrosion conductive coating is very necessanry. Currently, anticorrosive conductive coating which uses epoxy resin, polyaniline and polyurethane as film forming material, metallic particles, graphite or carbon black as conductive particles, this coating temperature is below 10O0?. It can make polyaniline, polyurethane and epoxy resin reduce the corrosion resistance of the coating by chemical broken bond when using temperature is over 100?, so that corrosion perforrmance fails. The added conductive particles generally add a large amount,and the conductivity is poor to make coating peel off. For this reality, we prepared composite coating with good electrical conductivity and corrosion resistance by brushing method, which used high temperature performance good phenolic resin as film foming material, multi-walled carbon material as conductive medium. The paper studied the contents of carbon nanotubes and the thickness of composite coatings on conductivity, corrosion resistance, thermal stability,microstructure and mechanical properties of composite coatings by four-probe tester,polarization curves,TG, SEM and tensile testing machine.(1) The volume resistivity of the composite coating first decreased and then increased with the increase of multiwall carbon nanotube content. The resistivity of the composite coatings reached 2180?-m when the content of multiwall carbon nanotube was 0.Sw%, fully meeting the anti-static requirements of oil refining tank. The surface resistivity of the composite coating has become stable because of the formalion of conductive network structure after curing 5 days,(2) The results by the corrosion weightlessness in H2SO4 solution and polarization curve test of the composite coating showed that the corrsion resistance of the composite coating was deteriorated with the increase of temperature, the content of carbon nanotube and H2SO4 concentration. The coating has the best corrosion resistance when the temperature was 25?, the content of carbon nanotube was 0.5wt%, the H2SO4 solution concentration was 1% and the thickness of the surface layer was 100 microns. The surface resistivity of the coating increased continuously, and increased slowly until stable after 20 days with the increase of the immersion time in the H2SO4 solution.(3) The surface roughening of the underlying epoxy conductive coating improved the bonding strength between the epoxy substrate and the surface phenolic conductive coating. The bond strength between the bottom layer and the surface layer first increased and then decreased with the increase of the curing time. The bonding strength of the coating was the best when the curing time of the bottom layer was 12h, the thickness of the surface layer was 100 microns and the content of the added multiwall carbon nanotube ranges from 0.5wt% to 2wt%. Carbon nanotubes can improve the hardness and the wear resistance of the coating. The composite coating has good thermal stability before 350?.(4) Aging the same time, 2wt% of the composite coating has better corrosion resistance than the pure phenolic resin coating. And with the increase of aging time, corrosion resistance decreased.(5) Comprehensive consideration: when multiwall carbon nanotubecontent was 2wt% and the surface layer thickness was 100?m, the composite coating performance was the best, which met the requirements of the use of oil refining tanks. |
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