Production and characterization of Nd and Dy doped lanthanum zirconate-based thermal barrier coatings

In this study, thermal barrier coatings in (La-0.7(Nd, Dy)(0.3))(2)Zr2O7 compound were produced by the plasma spray method as a single and double layer with YSZ. Microstructure, X-ray diffraction analysis, thermal conductivity measurements in the temperature range of 25-805 degrees C, tensile adhesion strengths, and thermal cycle tests at 1250-1300 degrees C of the coatings were performed. It was observed that the thermal conductivity values of single-layer and double-layer coatings were lower than in the undoped lanthanum zirconate coating, and that thermal conductivity value increased with increasing temperature. According to thermal-cycle test results, the single-layer Dy, Nd doped lanthanum zirconate-based coating was damaged at 163 and 300 cycles respectively. There was no damage after 400 cycles in the double-layer coatings. The adhesion-strength values of single-layer coatings were lower than those of double-layer coatings. Such results imply that LDZ and LNZ ceramics can be top-layer materials on YSZ for a double-layer TBC system.