Bonding strength and thermal conductivity of novel nanostructured Lu₂Si₂O₇/Lu₂SiO₅ environmental barrier coating

As is known to all, environmental barrier coating requires high bonding strength and low thermal conductivity to extend the service life of ceramic matrix composite (CMC) components. In this work, a novel nanostructured Lu₂Si₂O₇/Lu₂SiO₅ environmental barrier coating was deposited successfully using as-synthetized Lu₂Si₂O₇ feedstocks and Lu₂SiO₅ feedstocks. Meanwhile, the microstructure, bonding strength and thermal conductivity of Lu₂Si₂O₇/Lu₂SiO₅ coating were analysed systematically. Results indicate that the nanostructured Lu₂Si₂O₇/Lu₂SiO₅ environmental barrier coating processes a bi-model microstructure. The Lu₂Si₂O₇/Lu₂SiO₅ coating is relatively dense and the Lu₂Si₂O₇ layer and Lu₂SiO₅ layer achieve the mechanical interlocking. The bonding strength of Lu₂Si₂O₇/Lu₂SiO₅ coating is 14.9 MPa. In addition, the thermal conductivity of Lu₂Si₂O₇/Lu₂SiO₅ coating is 0.59 W·m⁻¹·K⁻¹–1.24 W·m⁻¹·K⁻¹ from 25 °C to 1200 °C, which is visibly lower than that of Lu₂SiO₅ coating.