Zircon and alumina precursor hybrid suspension on high-velocity plasma spray – coating morphology and compositional analysis

Abstract

© 2025 Elsevier B.V.This study explores the synthesis and comprehensive characterization of thick coatings developed using alumina (liquid phase) and zirconium silicate (solid phase) hybrid precursors. The coatings were deposited onto graphite substrates using a supersonic plasma spray process, allowing for the simultaneous deposition of liquid and solid phases, and forming Al₂O₃, SiO₂, ZrO₂, and ZrSiO₄. Advanced characterization techniques, including SEM, EDS, XRD, Raman spectroscopy, FTIR, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), were employed to investigate the microstructure, phase composition, and thermal stability of the coatings. The TGA/DSC results revealed critical thermal events, including the crystallization of spinel and α-Al₂O₃ phases, mullite formation, and ZrSiO₄ recrystallization, suggesting the hybrid precursor's effectiveness in generating thermally stable phases. Post-thermal testing at 1400 °C showed increased tetragonal ZrO₂ content and the formation of amorphous and aluminosilicate phases, convenient to enhanced coating densification, self-healing properties, and thermal resistance. These findings highlight the potential of hybrid precursor-based coatings for high-temperature applications, pointing toward the development of a robust solution for advanced thermal and environmental barrier systems in the aerospace and industrial sectors.

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