Evading the strength and toughness trade-off dilemma in Lu₂Si₂O₇ environmental barrier coatings via micro-nano reinforcement

Lu₂Si₂O₇ nanostructured environmental barrier coating was prepared using as–synthetic Lu₂Si₂O₇ feedstock via atmospheric plasma spraying. The structure and mechanical performances of Lu₂Si₂O₇ coatings were characterized in detail. Results indicate that nanostructured Lu₂Si₂O₇ coating exhibits a bi-modal microstructure, lamella structure and unmelted particles. The phase components of nanostructured Lu₂Si₂O₇ coatings consist of β-Lu₂Si₂O₇ and a small number of X2-Lu₂SiO₅. Furthermore, the nanohardness and elastic modulus of Lu₂Si₂O₇ coatings have the characterization of bi-modal properties via Weibull analysis, i.e., the large Weibull modulus and the small Weibull modulus represent molten lamella structure and unmelted particles, respectively. Meanwhile, the fracture toughness of nanostructured Lu₂Si₂O₇ coatings is superior to conventional Lu₂Si₂O₇ coatings, and the adhesion strength of Lu₂Si₂O₇ coatings is about 22.6 MPa by pull-extend test. Results of research are helpful for the design and preparation of advanced thermal spray coating.