Study On Preparation And Performance Of Heat Conductive Self-cleaning Anticorrosive Coating For Heat Exchanger

Heat exchanger is the key equipment in industrial and mining,electric power,chemical,aerospace and other industries,but its corrosion is very serious.Heat exchanger corrosion will not only reduce the service life of heat exchangers and affect normal production,but also cause an annual economic loss of about$300 billion.Therefore,the anti-corrosion of heat exchanger is very important.Traditional anticorrosion technologies include the addition of chemicals,cathodic protection of sacrificial anodes,the use of corrosion-resistant metal materials and so on.The anticorrosive coating technology is to spray the coating on the surface of the heat exchanger,which can effectively isolate the contact between the metal material and the corrosive liquids and particles in the environmental medium,and prevent the formation of chemical reaction and erosion corrosion on the surface of the metal material.reduce the corrosion of the heat exchanger and protect the equipment.Anticorrosive coating has been widely used in the anticorrosion of heat exchangers.At present,commercial anticorrosive coatings include acrylic acid,modified silicone,epoxy furan,epoxy phenolic resin,epoxy amino and fluorocarbon coatings and so on.However,there are also some defects in the preparation and performance of these anticorrosive coatings,such as large amount of solvent and volatile,high curing temperature and time-consuming,low hardness,easy to be contaminated,low erosion resistance,high preparation cost and so on.Therefore,there is an urgent need to develop an anti-corrosion coating with self-cleaning,corrosion resistance,good thermal conductivity,low cost and easy to be used in the field.In this paper,thermally conductive composite coatings were prepared by blending thermally conductive fillers of different particle sizes,types and loadings with epoxy resins by blending,and the surface of the composite coating was hydrophobically modified by low surface energy fluoride.The effects of filler particle size,type and loading on the surface roughness,thermal conductivity,hydrophobicity and erosion resistance of epoxy resin composite coatings are discussed.The main findings are as follows:（1）By blending,under the same load,the Epoxy/Al₂O₃ thermally conductive composite material prepared by different particle size alumina（Al₂O₃）thermally conductive filler and epoxy resin（Epoxy）is coated and sprayed on the aluminum sheet,and the The surface of the composite coating is prepared for hydrophobic modification.The effect of the particle size of Al₂O₃ particles on the thermal conductivity of the composite coating was studied.The results showed that the thermal conductivity of the composite coating prepared by filling 30 nm,1～3μm,and 20μm Al₂O₃ was similar,and the thermal distribution of the composite coating filled with 30 nm Al₂O₃ was uniform.,Has the best thermal conductivity,2.52 W/m·k,and the 74μm composite coating has the worst thermal conductivity,1.6 W/m·k.（2）The dispersion behavior of fillers has an important effect on improving the thermal conductivity of polymer composites.Al₂O₃ particles with different particle sizes show different dispersion behaviors in epoxy resin.As the particle size increases,the aggregates become more obvious.When the particle size is greater than 20μm,micropapillae are formed.The smaller the filler particle size,the more uniform the dispersion,and the more continuous the conductive path formed.（3）Epoxy/graphite composite coating was prepared by adding graphite to Epoxy by blending.The thermal conductivity of the composite coating increased with the increase of graphite loading.Under 70 wt%loading,Epoxy/graphite The thermal conductivity of graphite is greater than that of Epoxy/Al₂O₃,which are 2.85 W/m·k and 2.52 W/m·k,respectively.In order to increase the wear resistance of the composite coating,1.5 wt%of lanthanum oxide（La₂O₃）was added to the Epoxy/graphite composite coating by blending and grafting.The results show that the Epoxy/graphite@La₂O₃ composite coating is resistant to erosion The performance is the best.When the filler loading is 65 wt%,the weight loss rates of Epoxy/graphite,Epoxy/graphite/La₂O₃,and Epoxy/graphite@La₂O₃are 0.1195 mg/g,0.0558 mg/g,and 0.0398 mg/g,respectively.The addition of La₂O₃ not only improves the wear resistance and crack resistance of the composite coating,but also changes the structure of the composite coating,making the composite coating more compact and changing the hydrophilic properties of the composite coating.