Properties of plasma sprayed La2Zr2O7 coating fabricated from powder synthesized by a single-step solution combustion method

In recent years, rare earth zirconates with the general formula Ln2Zr2O7 have been investigated as futuristic thermal barrier coatings (TBCs). In the present study, the use of solution combustion process for the preparation of plasma sprayable grade La2Zr2O7 powder is reported. The powder was prepared by using urea as fuel in a single-step without using spray drying process. The powder was characterized for phase, morphology, flowability and particle size analysis by using powder X-ray diffractometry, field emission scanning electron microscopy (FESEM), a Hall flow meter and a particle size analyzer respectively. The powder was plasma sprayed and the phase purity of the plasma sprayed coating was analyzed by X-ray diffractometry. A Rietveld analysis of the coating was performed in order to understand the shift in the peak positions of the coating. The analysis revealed the coating to be a mixture of La2Zr2O7, La2O3 doped ZrO2 and ZrO2. The coating surface and cross-section were analyzed by FESEM. The density of the free-form of the coating was determined and the thermal conductivity of the coating was measured at 900 °C. The coating exhibited a conductivity value of 1.08 W m− 1 K− 1.

► Synthesis of plasma sprayable La2Zr2O7 powder without agglomeration step
► Rietveld analysis of the plasma sprayed La2Zr2O7 coating
► Plasma sprayed coating showed the presence of zirconia along with La2Zr2O7.
► La2Zr2O7 coating exhibited a thermal conductivity value of 1.08 Wm− 1 K− 1 at 900 °C.