Electromagnetic properties of plasma sprayed thermal barrier coatings in terahertz range

Dielectric properties of yttria partially stabilized zirconia thermal barrier coatings with various pore density were investigated by terahertz time domain spectroscopy in the continuous frequency range of 0.3 ~ 1.3 THz. The real part of the refractive index was 4.2 ~ 4.8 and the value increases as the porosity decreases. It indicates the potential application of terahertz spectroscopy to inspect the microstructure of plasma sprayed coatings nondestructively.