Radiation Characteristics Of Fiber-doped Particle Type TiO₂/SiO₂ Composites Based On FDTD Method

The rapid development of aerospace,high temperature manufacturing and other fields has put forward higher requirements for the performance of thermal protection system materials.The application of high-performance composite materials with better performance can improve the reliability of the system.Silica and titanium dioxide fiber materials have become hot spots of thermal insulation composites due to their excellent refraction and reflectance.In addition,with the development of nanotechnology,nanoscale composite materials are more widely used.In this paper,nano-titanium dioxide and nano-silicon dioxide composite materials are selected.Through the analysis of the radiation characteristics of the materials,a better combination of materials is determined,which provides a theoretical basis for the subsequent optimization of material structure.In this paper,the finite-difference time-domain method is adopted.Firstly,aiming at the thermal insulation performance of SiO₂ nanofiber-doped TiO₂ nanoparticle composite and TiO₂ nanofiber-doped SiO₂ nanoparticle composite,different particle volume ratios,different particle size ranges and different fiber diameter ranges are established.The corresponding two-dimensional and three-dimensional random distribution of fiber doped particle type TiO₂/SiO₂ composite structure model.Secondly,for the thermal insulation performance of fiber doped particle type TiO₂/SiO₂ composite and core-shell type TiO₂/SiO₂ composite,The structure models of fiber doped particle type TiO₂/SiO₂composites and core-shell type TiO₂/SiO₂composites with two-dimensional and three-dimensional random distribution under the same volume proportion of the same particles were established.Finally,aiming at the performance of fiber doped particle type TiO₂/SiO₂ composites under the resin matrix,Two dimensional and three dimensional randomly distributed polystyrene（PS）and polyimide（PI）based fiber doped particle TiO₂/SiO₂ composite models were established,and the radiation characteristics of the models were calculated.The results show that the composition structure,particle volume ratio,particle size,fiber diameter and matrix of fiber-doped particle type TiO₂/SiO₂composites all affect the radiation properties of the materials,and there is a large deviation between two-dimensional random distribution structure and three-dimensional random distribution structure composite in scattering cross section,absorption cross section,transmittance and reflectance.There is also an obvious difference in the radiation properties between SiO₂ fiber doped TiO₂ particles and TiO₂ fiber doped SiO₂ particles.In-depth analysis of radiation characteristics of fiber doped particle type TiO₂/SiO₂ composites can provide theoretical basis for improving the structure of TiO₂/SiO₂ composites,so that it can be better applied in thermal protection.