Preparation And Properties Of Carbon-based Thermal Conductivity Coatings

The carbon-based thermal conductive coating is a material compounded of high performance resins filled with carbons.Carbon nanotube（CNT）is a preferred thermal material because of its advantage of light weight,high thermal conductivity with excellent mechanical properties and electrical conductivity.However,CNTs are composed of the hexatomic rings,with little active groups and poor solvent compatibility,meanwhile CNTs are easy to forming aggregates which have a bad influence on thermal conductivity due to their high aspect ratio,and twining by catalyst impurities.CNTs should be purified and modified in order to improve the dispersion of CNTs in water-based fluorocarbon resins（DF-S06）and solvent-based resins（JF-2X）.Carbon-based thermal conductive coatings are prepared by blending these two kinds of resins filled with modified CNTs and purified CNTs respectively.CNTs were modified by liquid-phase oxidation and surfactant-coating for purification and the improvement of surface activity.The effect of acidification time on dispersion of CNTs was studied in this paper.The modified CNTs were characterized by FT-IR,Raman,UV-VIS,sedimentation texts and SEM.The result showed that the infrared characteristic peaks of carboxyl groups appeared at the acidication time of 90 minutes.The ratio of Raman D peak and G peak intensity were minimum that I_D:I_G was 1.47.And the UV absorption was the maximum.There was no settlement in 45 days.The above reflected that the dispersion of CNTs modified at the acidification time of 90 minutes were improved.The CNTs/water-based fluorocarbon resin composites with the CNTs content of0.2wt%,0.4wt%,0.6wt%,0.8wt%,1.0wt%and 1.2wt%were prepared by high speed ball mill blending.The basic mechanical properties of coatings,thermal conductivity,electrical conductivity and corrosion resistance of coatings were tested in this paper.The result showed that the viscosity of coatings increased continuously with the increase of CNTs mass fraction.The maximum of viscosity was 15 seconds when CNTs content went to 1.2wt%.The adhesion,impact resistance,hardness,settlements and the CNTs dispersion in the matrix were improved at this mixture ratio.The composite coating films had a good comprehensive properties that the thermal conductivity and electrical conductivity respectively reached up to 0.328W/m·K and0.211s/m.The CNTs/solvent-based fluorocarbon resin composites with the CNTs content of 2wt%,4wt%,6wt%and 8wt%were prepared by high speed ball mill blending.The basic mechanical properties,thermal conductivity,electrical conductivity and corrosion resistance of coatings were studied in this paper.The result showed that the viscosity of coatings decreased continuously with the increase of CNTs mass fraction and the minimum of viscosity was 23 seconds.The impact resistance,adhesion hardness and CNTs dispersion in the matrix were improved relatively,when CNTs mass fraction was 6wt%.The thermal conductive composite coating films had optimum performances with good corrosion resistance that the thermal conductivity was 0.528W/m·K and the electrical conductivity was 0.528s/m which were respectively improved by 214%and 228%than pure resins.In conclusion,two kinds of carbon-based thermal conductive coatings were prepared by blending fluorocarbon resins with modified CNTs.The modified CNTs dispersed in the resin matrix uniformly.The basic mechanical properties and corrosion resistance of these composite coatings were in good condition.The thermal conductivity and electrical conductivity were improved obviously.