Preparation,Heat Dissipation And Corrosion Resistance Of Graphene Composite Coating On Copper Surface

The high integration of high-power electronic components requires smaller and smaller devices,which leads to local overheating,which brings challenges to traditional high thermal conductivity copper radiators.At the same time,copper radiators are required to have good corrosion resistance and high-temperature oxidation resistance in a marine corrosive environment or special high-temperature environment.In order to improve the comprehensive properties of radiation heat dissipation and corrosion resistance,a graphene or graphene-containing composite coating with high thermal conductivity and emissivity is proposed.Firstly,high-quality graphene oxide(EGO)was prepared by electrochemical exfoliation method with simple operation,high efficiency,and environmental protection.Then,three system coatings were constructed:reductive graphene oxide(rEGO),reductive graphene oxide/sodium carboxymethyl cellulose(rEGO/CMC),reductive graphene oxide/Alumina/aluminium phosphate(rEGO/Al2O3/AlPO4).The effects of coating structure on infrared radiation,heat dissipation,and temperature drop and corrosion resistance were studied.The results show that the surface of EGO sheets prepared by electrochemical exfoliation method has obvious wrinkles and irregular shape.Raman spectroscopy showed that the ID/IG value was 0.84.XPS showed that the atomic ratio of C/O was1.17.Infrared spectroscopy showed that EGO contained a large number of epoxy and hydroxyl groups on the surface of the lamellae and a small amount of carbonyl and carboxyl groups on the edge of the lamellae.All the results showed that EGO sheets contained more defects and had higher oxidation degree.Reduced graphene oxide coatings(rEGO),reduced graphene oxide/sodium carboxymethyl cellulose coatings(rEGO/CMC)and reduced graphene oxide/alumina/aluminum phosphate coatings(rEGO/Al2O3/AlPO4)were constructed and optimized by electrochemical exfoliation of graphene oxide(EGO).The optimum preparation parameters are as follows.The optimum process of rEGO coatings was deposition voltage 10V,deposition time 2-11min,electrolyte concentration 0.4-1.6mg/ml.The optimum technological ratio of rEGO/CMC coatings were rEGO:CMC=4:1,4:2,4:3,4:3,respectively.The optimum composition ratio of rEGO/Al2O3/AlPO4 coatings was Al2O3 30wt%-40wt%and rEGO 0.04wt%-0.16wt%.The bonding strength between coating and copper matrix is in the order of rEGO/Al2O3/AlPO4>rEGO/CMC>rEGO.High emissivity coating on the copper surface can significantly improve the efficiency of radiation heat dissipation.The rEGO?rEGO/CMC and rEGO/Al2O3/AlPO4 coatings had high infrared emissivity in the range of 3-20 um,which were 0.80,0.77 and 0.78,respectively.Because of copper surface coating with high emissivity,the radiation cooling temperature drop and cooling efficiency can be enhanced and the radiation cooling effect was rEGO>rEGO/Al2O3/AlPO4>rEGO/CMC.Coatings can improve corrosion resistance to varying degrees.The impedance modulus and corrosion resistance of rEGO coatings increased with the increase of coating thickness and the corrosion resistance of rEGO coatings was as high as3.27×10~4?·cm~2.The corrosion resistance of rEGO/CMC coatings decreased when the content of CMC in the coatings was excessive.When rEGO:CMC=4:1,the corrosion resistance can reach 6.45×10~4?·cm~2.For rEGO/Al2O3/AlPO4 coatings,when the content of rEGO was 0.16wt%,it dispersed uniformly in the coatings,and formed a diffusion barrier layer of corrosive medium,which prevented the penetration of corrosive medium,and significantly improved the corrosion resistance of the coatings,the corrosion resistance can reach 6.39×10~4?·cm~2.The corrosion resistance of coatings from strong to weak was rEGO>rEGO/CMC>rEGO/Al2O3/AlPO4.