Study On Electro-thermal And Electromagnetic Shielding Performance Of Carbon Conductive Coatings

Carbon-based conductive coating has been widely applied in the field of electro-thermal and electromagnetic shielding for its excellent performance. This paper analyzes the factors affecting the electro-thermal performance and electromagnetic shielding properties of aqueous carbon-based conductive coating, Optimized a carbon-based conductive coating with good electro-thermal performance and a carbon-based conductive coating with excellent electromagnetic shielding performance.Experiments show that, under the same conditions, in the coatings with waterborne acrylic resin as binder, the mass ratio of waterborne acrylic resin and conductive fillers should be maintained at 5:5,. The amount of water should choose between 23% to 27%. The volume resistivity of the coating is 0.76Ω·cm when the mass ratio of waterborne acrylic resin and conductive fillers is 5:5 and water content in the coating is 27%. Proper curing temperature is 50℃ under the experimental conditions. The carbon-based coating with graphite/carbon blacks/calcined coke as filler have better performance than using a single carbon-based materials as filler. Based on analysis and comparison, the optimum quality proportion of electro-thermal coating is waterborne acrylic resin:graphite:fillers= 5:4:1.The experiment selected water-based acrylic resin, graphite:calcined coke/carbon black= 5:4:1 (mass ratio, of which the calcined coke/carbon black is 1/3) as the best ratio, The mass fraction of water in the coating is 23%, curing temperature about 50℃, the thickness of coating is about 0.2mm, The electro-thermal coating prepared under such conditions have best electro-thermal performance. Surface heating temperature can reach 106℃ when the testing condition is keeping heating 5min at 40V voltage, and coating adhesion, hardness, high and low temperature test results meet the using requirement.The experiments concluded that, under the same condition, electromagnetic shielding performance of coatings enhanced with the increasing of silver powder content. Experimental selected conductive coating with mass ratio of waterborne acrylic resins:silver:graphite is 5: 3:2;Under the condition of the thickness of the coating is 0.2±0.02mm, waterborne acrylic resin:silver powder:graphite:water:carbon blacks is 5: 3:2:3:0.8 (mass ratio), electromagnetic shielding performance is up to 41 dB. With the same conditions and the mass ratio of water-based acrylic resin:silver:graphite=5:1:4., shielding performance of coating gradually strengthened along with the increase of the thickness of the coating. The shielding performance is best when the coating thickness is 0.4 mm. shielding performance can up to 28 dB under the conditions presented above.The experiment concluded that, with the condition of mass ratio of water-based acrylic resin:silver powder:graphite:water:carbon blacks= 5:3:2:3:0.8 (mass ratio), curing temperature of the coating is 50℃, coating thickness is 0.4±0.02mm, the electromagnetic shielding performance can reach 44 dB at the frequency range of 8.2 GHZ to 12.4GHZ, has a significant electromagnetic shielding performance. Coating adhesion, hardness, high and low temperature test results meet the use requirement.