Synthesis and characterization of single-phase X2-Lu₂SiO₅ nanostructured feedstocks for advanced plasma-sprayed environmental barrier coatings

The objective of this work is to synthesize the single-phase X2-Lu₂SiO₅ nanostructured feedstocks for plasma-sprayed environmental barrier coatings (EBCs). Generally speaking, high-performance feedstocks are a prerequisite for obtaining high-performance coatings. The single-phase X2-Lu₂SiO₅ nanostructured feedstocks were fabricated by a nanopowder reconstitution method for the first time. The morphology and phase structure of X2-Lu₂SiO₅ nanostructured feedstocks were examined. The physical properties of X2-Lu₂SiO₅ feedstocks were evaluated. In addition, the thermal conductivity of nanostructured X2-Lu₂SiO₅ coatings was measured. Results show that the single-phase X2-Lu₂SiO₅ nanostructured feedstocks are successfully synthesized when the mole ratio of Lu₂O₃ and SiO₂ nanopowder is 1:1.1 and the agglomerated powders are sintered at 1300 °C for 2 h. The nanocrystalline size of the X2-Lu₂SiO₅ feedstocks ranges from 40 to 70 nm. Moreover, the d₁₀, d₅₀ and d₉₀ of X2-Lu₂SiO₅ feedstocks are 24.69 μm, 37.78 μm and 54.75 μm, respectively. The apparent density and tap density of X2-Lu₂SiO₅ feedstocks are 1.76 g/cm³ and 2.09 g/cm³, respectively. The thermal conductivity of as-deposited Lu₂SiO₅ coating is 0.78–1.20 W m⁻¹ K⁻¹ (30–1200 °C). Overall, the single-phase X2-Lu₂SiO₅ nanostructured feedstocks are the most promising feedstocks for advanced EBCs system in the future.