Preparation and Properties of High Emissivity Coatings on the Surface of High Thermal Conductivity Cabon/carbon Composites

The infrared emissivity of high thermal conductivity carbon/carbon (HTC-C/C) composite surface is low, resulting in poor radiative heat dissipation ability. In order to further improve its thermal control ability, it is necessary to coat its surface with high emissivity coating. Carbon nanotube (CNTs)/carbon black (CB) composite coating with high infrared radiation and thermal shock resistance was prepared on the surface of HTC-C/C composite material by compressed air spraying method. After a certain amount of pyrogenic carbon (PyC) was deposited, the coating obtained stronger interface bonding performance while maintaining high infrared emissivity. The effects of thermal shock and high temperature heat treatment on the microstructure and properties of high emissivity coatings were investigated. The results showed that When the mass ratio of CNTs to CB reached the optimal ratio, the emissivity of the prepared coating reached more than 0.94, and no cracking and spalling occurred after 60 thermal shock resistance tests at 300℃↔−196℃, indicating good thermal stability. After heat treatment, the microstructure order of the nano-carbon materials in the coating changes, resulting in wavelength dependence of the coating emissivity. However, due to the synergistic effect of each band, the emissivity of the whole test band (1-22 μm) fluctuates little.