Study On Corrosion Prevention And Thermal Conductivity Of Carbon Steel Heat Exchanger Coatings For Oil And Gas Treatment

The working conditions of the heat exchanger are harsh in the corrosive environment,and the poor corrosion resistance of carbon steel leads to low reliability,which seriously affects the safety and stability of service.Compared to corrosion resistant metal materials and electrochemical corrosion protection,coatings have higher economy and safety.Adding fillers with good thermal conductivity and corrosion resistance to the coating can effectively improve the thermal conductivity and corrosion resistance of the coating,ensuring the functional and reliability requirements of the heat exchanger.Therefore,this article chooses to add carbon fibers and aluminum oxide with different particle sizes and contents to the coating to improve the thermal conductivity and corrosion resistance of the coating,and silane modify carbon fibers and aluminum oxide to improve their interfacial solubility with the resin.The functional groups and components of carbon fibers and alumina were characterized by Fourier Transform Infrared Spectrometer（FTIR）,X-ray diffractometer phase detection（XRD）,and X-ray photoelectron spectroscopy（XPS）.Secondly,through electrochemical testing methods such as Open Circuit Potential Method（OCP）,Electrochemical Impedance Spectroscopy（EIS）,The Tafel curve（Tafel）,the corrosion resistance of carbon fiber and aluminum oxide coatings with different sizes and contents was studied.The results showed that the corrosion resistance of epoxy phenolic resin coatings without carbon fiber addition was better than that of epoxy phenolic resin coatings with carbon fiber addition;Add 1μm the corrosion resistance of alumina coating is better than that of adding 20 nm alumina coating.Wherein at 25 wt%of the addition amount,1μm the low frequency mode value of the alumina coating|Z|_0.01Hzis two orders of magnitude greater than the addition of 20 nm alumina coating;Add 1μm the corrosion resistance of the coating with alumina is the best when the addition amount is 10 wt%;The coating added with 20nm alumina has the best corrosion resistance when the addition amount is 5 wt%.Description of coating microstructure characterization,for the addition of 1μm aluminum oxide coating,when 10 wt%aluminum oxide is added,the coating does not show obvious defects;When 25 wt%alumina is added,the defects on the coating cross section increase and larger pits appear.Finally,using a thermal conductivity meter and an infrared thermal imaging camera,the effects of the addition of aluminum oxide with different sizes and contents on the thermal conductivity of the coating were investigated.For Add 1μm the thermal conductivity and thermal diffusion coefficient of the alumina coating increase with the increase of the amount of alumina added;With the addition of 20nm alumina,the thermal conductivity and thermal diffusion coefficient of the coating first increase and then decrease with the increase of the amount of alumina added.At 1μm when 25 wt%alumina is added to the coating,the thermal conductivity of the coating reaches 1.7478 W/m·K.Using molecular dynamics software,an epoxy phenolic resin model and a filling model of epoxy phenolic resin matrix composites doped with Al₂O₃ particles were established.The reason for the increase in thermal conductivity of epoxy phenolic resin added with alumina was explained through the model.The microscopic morphology characterization results show that adding 1μm the coating of alumina has formed a overlap between alumina and carbon fibers when the addition amount of alumina is 10 wt%.Comprehensive analysis of the impact of adding carbon fibers and different sizes and contents of aluminum oxide on the corrosion resistance and thermal conductivity of the coating:Although the addition of carbon fibers helps to improve the thermal conductivity of the coating,it also causes a decrease in the corrosion resistance of the coating,which cannot meet the requirements for both corrosion resistance and thermal conductivity of the heat exchanger coating.On the basis of adding 15 wt%carbon fiber,adding 25 wt%particle size of 1μm the low frequency mode value of the alumina coating is increased by one order of magnitude compared to the low frequency mode value without the addition of the alumina coating,and the thermal conductivity is increased to1.7478 W/m·K.It is worth noting that based on the addition amount of 15 wt%carbon fiber,adding an aluminum oxide coating with a particle size of 20 nm only improves the anti-corrosion and thermal conductivity of the coating when the addition amount is only5 wt%,compared to the non added aluminum oxide coating.When the addition amount exceeds 5 wt%,the anti-corrosion and thermal conductivity of the coating decreases.This indicates that compared to alumina with a particle size of 20 nm,1μm alumina with a particle size of is more suitable for the preparation of high thermal conductivity anti-corrosion coatings using carbon fiber alumina filler systems.