| It is difficult for the traditional absorbing coating to meet the requirements of marine service environment with high temperature,humidity and salt spray.According to the requirements of application characteristics of absorbing coating in the corrosion-prone environment,a three-layer composite coating composed of superhydrophobic,absorbing and anticorrosive coatings was prepared in this study.The influencing law and mechanism of formula composition and process conditions on the properties of superhydrophobic and anticorrosive coatings were studied respectively.And the effects of different factors on the absorbing performance of composite coating were explored.The main research contents are as follows:(1)Superhydrophobic surface coating was prepared by adding waterborne fluorocarbon resin(film-forming material),polytetrafluoroethylene,graphene and additives.Its wettability,hydrophobic mechanism,influencing factors and other properties were investigated.Test results show that the superhydrophobicity of coating using PTFE and graphene at a high temperature of 180? is optimal;the static water contact angle is 153°,and the rolling angle is 8°.After 40 times' mechanical wear and 4 h's water impact test,the static water contact angle is stable at about 120° and 110° respectively.The superhydrophobicity of the coating is attributed to a large number of C-F bonds and nano-pulled structures on its surface.Among them,the increase of surface C-F bonds and nanostructures is caused by the addition of PTFE and graphene after high temperature treatment.When the epoxy resin was added,the superhydrophobicity of the coating was weakened,but its mechanical wear resistance was improved.Other properties of superhydrophobic coating were tested finally.It is shown that the adhesion of the coating is 5 B,and its hardness is 4 H.After one month's outdoor exposure and 24 h's high temperature aging,the coating is intact.The coating began to be damaged after 24 h's neutral salt spray,3 d's strong acid and 24 h's strong base treatments.It also has excellent properties of self-cleaning,bending and impact resistance.(2)Anticorrosive bottom coating was developed using waterborne epoxy resin as film forming material,and adopting zinc powder,microcrystalline graphite,zinc trimeric sulfate and aluminum trimeric sulfate as fillers.The effects of different fillers on the corrosion resistance of the coating were explored.It is found that the effect of zinc powder on anti-corrosive performance of the coating is the most significant,followed by microcrystalline graphite,aluminum tripolyphosphate,and zinc tripolyphosphate.The ability of the coating to resist neutral salt spray and strong acid is the best when the content of zinc powder is 15%.Its corrosion inhibition efficiency in electrochemical test is 99.998%.When the content of microcrystalline graphite is 20%,the corrosion inhibition efficiency of the coating is 99.440%.At this point,the hardness of the coating is only 2 H,while its adhesion is 4 B.When the content of aluminum tripolyphosphate is 20%,the corrosion inhibition efficiency of the coating is 97.185%.At that time,the hardness of the coating is 5 H,but its adhesion is only 1 B.When the content of Zinc tripolyphosphate is 25%,the corrosion resistance of the coating is optimal.The corrosion inhibition efficiency of the coating is 94.424%.At the same time,the hardness of the coating is 4 H,and its adhesion is 4 B.In addition,the effects of different proportions of microcrystalline graphite and aluminum tripolyphosphate on the properties of the coating was investigated.It is revealed that the ratio of aluminum tripolyphosphate to microcrystalline graphite is 6:12 and 12:6,the coating has the strongest abilities to resist salt spray and strong acid respectively.(3)The effects of different iron powders and carbon blacks on the absorbing effect of the coating using waterborne epoxy resin as binder were investigated.Among them,the coating prepared by phosphorus coated carbonyl iron powder has the best absorbing effect.Broadbands with reflectivity below-10 dB is 2-4 GHz and 10-18 GHz.After the superhydrophobic coating was added to the absorbing coating,the ability of the coating to absorb the band with a frequency of 1-2 GHz was enhanced.After salt spray treatment,its abilities to absorb the bands with frequencies of 2-6 GHz and 6-18 GHz were improved and reduced respectively.At the same time,it is observed that the damage to the coating prepared by phosphorus coated carbonyl iron powder is the lowest after 480 h's salt spray treatment.The effects of different proportions of iron powders on the absorbing properties of the coating was analyzed in the end.It is found that the absorbing effect of the coating is best when the proportion of iron powder increases gradually from the surface to the bottom. |
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