Ablation behavior and mechanisms of high-entropy rare earth titanates (Y0.2Gd0.2Ho0.2Er0.2Yb0.2)2Ti2O7 coating deposited by plasma spraying technology

Abstract

High-entropy rare earth titanates (Y0.2Gd0.2Ho0.2Er0.2Yb0.2)2Ti2O7 (YHT) have great application potential in the thermal protection coating field. In this work, the YHT coating was successfully prepared by atmospheric plasma spraying. The influence of different spraying powers and coating ablation behavior by plasma flame on the phase composition and microstructure morphology of the coating surface, cross-section and fracture surface were investigated using X-ray diffraction, scanning electron microscopy and atomic force microscope. Results show that the YHT powder has a sufficiently melted state before impacting the metal substrate and the coating can be effectively deposited through optimizing the plasma spraying power. And the YHT coatings undergo slight sintering, leading to the formation and growth of a spherical structure at 1200 °C, while the grain preferential growth, mechanical failure and water-like structure occurred due to strong thermal shock at 1400 °C. In addition, when the coating surface temperatures are 1200 °C and 1400 °C, the corresponding heat insulation temperatures are 590 °C and 620 °C, respectively, indicating that YHT coating has good thermal insulation ability. This study provides a powerful theoretical basis and technical support for the application of high-entropy rare earth titanates YHT as a thermal protection material for high temperature devices.