Material Characterization and Thickness Measurement of Iron Particle Reinforced Polyurethane Multi-layer Coating for Aircraft Stealth Applications Using THz-Time Domain Spectroscopy

Particle reinforced polymer matrix composites (PMCs) are widely used in the military aviation industry as a stealth coating for incident radar attenuation. These coatings made up of many layers different materials with varying thicknesses. In this study, we terahertz (THz) spectral range by means time-domain spectroscopy (TDS) to examine thickness iron particle polyurethane absorbing paint (FE-PU-RAP) composite non-destructively. For accurate estimation individual layer multi-layer coatings, precise knowledge material properties is prerequisite. Hence, standalone samples have been initially employed extract properties, such refractive index and absorption coefficient. Then, time-of-flight measurement principle has carried out using reflected THz pulses. Further, since pulses from multi-layered sample overlapping nature due optically thin thickness, sparse deconvolution technique utilized extracting each time instant. The scattering particles also provides challenge identification interface signals. This was addressed optimizing regularization parameter algorithm. With technique, accomplished, otherwise difficult