LAUSR

Abstract Indium tin oxide (ITO) and titanium dioxide (TiO2) are both widely used as pigments for thermal barrier coatings. Instead of being assumed to be the overall spherical particles, the ITO and TiO2 pigment particles in the coatings were modeled as clusters with connected structures to simulate the morphology of the fractal aggregates that are shown in the transmission electron microscope (TEM) images. The ball-necking factor η was applied to quantify the connectors by utilizing the particle superposition model. A approach, which combined the Monte Carlo method and discrete dipole approximation (DDA), was applied to evaluate the reflective and absorptive performances of the functional coatings that were pigmented with the ITO and TiO2 fractal clusters. This approach considered the effects of the pigments with fractal aggregate structures on the scattering properties, including the phase functions and asymmetry factor. These parameters reflected the dependence of the scattering intensity on scattering angles and the radiative transfer directions of the beams in the coatings and had a subsequent influence on the coatings’ absorptivity. Based on the Monte Carlo-DDA method, the impacts of the cluster material, ambient media, coating thicknesses and volume fraction of the pigment clusters on the coatings absorption rates were discussed.