Preparation And Application Of Epoxy Resin-based Electrothermal Anti-icing/de-icing Superhydrophobic Coating

In recent years,wind power energy as an emerging green energy with safe,clean, uninterrupted form of power generation is increasingly concerned by the state and society.However,wind turbine blades and units are often located in coastal areas or high-altitude mountainous areas,where large temperature differences between day and night can easily lead to icing on the surface of wind turbine blades and units,thus affecting the output of wind power energy and causing serious economic losses,so how to solve the icing problem on the surface of wind turbine blades and units has become a bottleneck hindering the rapid development of wind power energy.This thesis proposes a solution to coat the surface of glass fibre wind turbine blades with an epoxy resin-based electrothermal anti-icing/de-icing superhydrophobic coating,achieving the aim of anti-icing/de-icing through a synergistic mechanism of electrothermal de-icing and superhydrophobic de-icing.The sandwich structure of the electrothermal coating with a heat generating layer in the middle and heat transfer layer on both sides was firstly prepared using epoxy resin（EP）as the substrate,silver-coated copper powder（Ag-Cu）as the heat generating filler and multi-walled carbon nanotubes（MWCNTs）as the heat transfer filler in this paper.The epoxy resin gives excellent shear strengths of 16.24 MPa and 8 MPa to the heat-generating and heat-transfer layers respectively,and the EP/Ag-Cu heat-generating and EP/MWCNTs heat-transfer layers have excellent thermal conductivity of 2.24 W/（m·K）and 1.32 W/（m·K）respectively.of uniform heat transfer and wide coverage.In addition,the EP/Ag-Cu heat layer exhibits excellent electrical conductivity,with a maximum conductivity of 4517 S/cm,and its conductivity is stable in acid,alkali and salt solutions.The heating layer maintains a maximum surface temperature of around 65.7°C during eight cycles of heating and cooling,with stable Joule heating performance.The data show that the thermal decomposition temperature and glass transition temperature of the EP/Ag-Cu/MWCNTs electrothermal coating are both much higher than the maximum temperature that can be generated on its surface,with excellent thermal stability and heat resistance.In order to protect the bottom electrothermal coating for a longer service life and to improve the overall hydrophobicity of the coating,a superhydrophobic coating was proposed by using cetyltrimethoxysilane（HDTMS）modified Si O₂,kaolin（kaolin）and EP to build a layered micro-nano structure.By testing the contact angle and rolling angle of the EP/HDTMS@Si O₂/kaolin coating and analysing the surface morphology,it was found that the surface of the coating had an obvious layered micro-nano structure,while the contact angle of the coating reached 156.3°and the rolling angle was 3°,showing excellent superhydrophobic properties.Due to the presence of epoxy resin,the coating has good mechanical properties with a shear strength of 2.8 MPa.In addition,the EP/HDTMS@Si O₂/kaolin coating was found to have good wear resistance,acid and alkali resistance,salt spray resistance and excellent self-cleaning properties.Finally,the static and dynamic anti-icing/de-icing properties of the prepared epoxy resin- based electrothermal anti-icing/de-icing superhydrophobic coatings were investigated.It was found that the presence of the layered micro-nano structure makes the surface of the coating hemispherical when the water droplets are completely frozen.The hemispherical shape can trap a large amount of air layer at the solid-liquid interface,which prevents the water droplets from completely wetting the coating surface,reduces the contact area and adhesion,and improves the anti-icing/de-icing capability of the coating.At various temperatures（-5°C,-10°C and-15°C）,the static icing time of water droplets on the surface of the anti-icing/de-icing coating was much longer than that of water droplets on the surface of the exposed glass fibre wind turbine blade,while the coating significantly reduced ice adhesion,with a low surface ice adhesion force of 0.01 MPa,indicating that the coating has a strong static anti-icing capability.Complete de-icing was found to take only 78 s at a constant electrical power（0.2 W）and remained excellent and stable after 20 cycles of dynamic de-icing tests.In a special dynamic de-icing test at an angle of 60°,the ice layer on the surface was completely frozen and fell off in just 41 s,which meets with the requirements for wind turbine blade de-icing applications.The epoxy resin-based electrothermal anti-icing/de-icing superhydrophobic coating prepared in this work is suitable for anti-icing/de-icing work on glass fibre materials in addition to other metal and inorganic fibres such as carbon fibres,ceramic fibres and asbestos,and also has some applicability in the field of textile materials.This will give more options for anti-icing/de-icing of outdoor substrates made from textile-based materials.