| The electrothermal coating is a kind of functional coating which can convert electric energy into heat energy.It has a wide range of applications in civil,commercial,agricultural and industrial heating fields.However,the traditional electrothermal coating has some shortcomings such as low heating temperature,poor heat resistance and adhesion,and easy falling off of the coating,which limits its practical application.Therefore,it is necessary to develop a new type of electrothermal coating with good safety,high efficiency and stability.This thesis studied the effects of the addition amounts of conductive fillers,binder,water and thickener on the coatings' characteristics of electrothermal performance,adhesion,aging resistance,storage stability and microstructure.A self-control temperature performance and influencing factors were preliminarily discussed,and the carbon-based electrothermal coating was prepared with better performance and good self-control temperature at a safe voltage of 24 V.The experimental results show that the temperature of ternary composite conductive filler is higher than those of binary composite and single conductive filler with water-based acrylic emulsion as a binder.When investigating the influence of conductive filler addition at the safe voltage of 24 V,the fixed amount of water,thickener and binder added were 50wt%,0.6wt% and 10wt%,respectively.When the addition amounts of graphene and carbon fiber were 15wt% and 6wt%,respectively.It is found that when the adding amount of carbon black is 25wt%,the highest surface temperature of the coating is 90.7?,and the lowest volume resistivity is 2.956 ?·cm.When the addition amount of carbon black and graphene were both 15wt%,it is concluded that the appropriate addition amount is 6wt%,then the temperature of the coating surface is 83.3?,and the volume resistivity is 3.612 ?·cm.When the addition of carbon fiber does not exceed 6wt%,the shelling-out performance of the electric heating coating is better.When the adding amount of carbon black and carbon fiber were 15wt% and 6wt%,respectively.It is concluded that the surface temperature of the coating is the highest at 92.6? and the volume resistivity is the lowest of 2.914?·cm when the amount of addition amount is 25wt%.The suitable addition amount of the binder is 11wt%,then the surface temperature of the coating reaches the highest of 87.9?,and the volume resistivity reaches the lowest of 3.274 ?·cm.At the voltage of 36 V,the maximum temperature of the coating reaches 136.6°C,and there is no crack on the surface after 24 h power-on,and the adhesion level reaches 0 grade.The suitable addition amount of water is 50wt%,then the temperature of the coating reaches the highest of 83.3?,the volume resistivity is the lowest of 3.612 ?·cm,the adhesion grade of the coating reaches 0 grade,and the storage stability is also good.The appropriate amount of thickener added is 0.8wt%,the surface temperature of the coating reaches 86.4?,the volume resistivity is 3.302 ?·cm,and the storage stability is also excellent.Choose better formula for performance testing,where the addition amount of binder?water and thickener are 11wt%?50wt% and 0.8wt%,respectively.Based on the addition of the binder,when the adding amount of carbon fiber is 6wt%,and the adding amount of carbon black and graphene are both 25wt%,the electrothermal performance of the coating is then the best.At the voltage of 24 V,the stable heating temperature of the coating is 108.1?,and the volume resistivity is 2.154 ?·cm.At the voltage of 36 V,the maximum stable heating temperature of the coating is194.8?.After 24 hours of continuous electrification,the surface of the coating is intact.It can realize self-control temperature,at the same time,the adhesion reaches 0grade,and the aging resistance is excellent. |
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