In-situ construction of plasma-pretreated CNT networks endow the LPDS dual-layer coating with advanced thermal management and anti-static properties

Abstract

Carbon nanotubes (CNTs) for temperature regulation have been proven to be promising for passive radiative heat dissipation. However, it remains a considerable challenge to assemble a CNTs layer in situ while simultaneously achieving horizontal electrical conductivity, vertical electrical insulation, and radiative heat dissipation. Herein, plasma pretreatment was employed to functionalize CNTs in an aqueous solution, thus improving their dispersion capability. Subsequently, a liquid-plasma-assisted particle deposition and sintering (LPDS) technology was proposed to prepare a dual-layer coating with an Al2O3-P2O5-SiO2-In2O3 glass system embedded with crystalline indium tin oxide (ITO) as the porous bottom layer and ITO-CNTs as the top layer on the aluminum alloy surface. The results show that plasma pretreatment significantly increases the deposition amount of ITO nanoparticles and functionalized CNTs on the coating surface, resulting in the transition from a single-layer composite coating to a dual-layer coating. The surface micro-/nano hierarchical structure favors strong absorptance/emittance, exhibiting a high infrared emittance of 0.94 (3-20 μm) and high solar absorptance of 0.92 (0.2-2.5 μm). Meanwhile, the surface balance temperature of the dual-layer coating is about 392 K, which is 146 K lower than that of aluminum alloy. Furthermore, the top conductive ITO-CNTs layer contributes to the low surface resistivity of 3.46×102 Ω, while the glass phase of the bottom layer ensures vertical electrical insulation with a volume resistance of 4.20×107 Ω. The process provides a new path for preparing thermal control coatings with anti-static function.