Terahertz dielectric properties of plasma-sprayed thermal-barrier coatings

► The transmittance and dielectric properties of TBCs were evaluated by THz-TDS. ► The real part of the dielectric constant has strong correlation with the porosity. ► The prediction agrees with the experiment results assuming oblate ellipsoidal pores. ► THz-TDS can be effective tool for the evaluation of coating microstructure.