Exploration on intrinsic corrosion resistance of β-Lu2Si2O7 against calcium–magnesium–aluminosilicate (CMAS) at 1500 °C via grain boundary engineering

• Single crystal β-Lu 2 Si 2 O 7 was successfully grown via the optical floating zone (OFZ) directional solidification method. • Single crystal β-Lu 2 Si 2 O 7 exhibits exceptional intrinsic resistance against CMAS at 1500 °C. • The grain boundary reduction of β-Lu 2 Si 2 O 7 plays a key role in the restriction of CMAS infiltration. • Grain boundary engineering is an effective strategy for improving CMAS resistance of E/TBC materials. The exploration of environmental barrier coatings (EBCs) with reliable resistance against molten calcium–magnesium–aluminosilicate (CMAS) poses a fundamental obstacle to progress in gas turbine technology. However, rare-earth silicates, which are most commonly recognized as highly desirable choices for EBCs, are susceptible to CMAS infiltration along grain boundaries at high temperatures. Premature failure, stemming from grain boundary degradation at elevated temperature, could lead to inaccurate information concerning the mechanisms of CMAS corrosion. In this study, single crystal β-Lu 2 Si 2 O 7 was prepared using the optical floating zone (OFZ) directional solidification method and exposed to CMAS corrosion at 1500 °C for 50 h. The results demonstrate that single crystal β-Lu 2 Si 2 O 7 possesses exceptional intrinsic resistance against CMAS corrosion, as evidenced by a maximum recession depth of approximately 103 μm, in comparison to polycrystalline β-Lu 2 Si 2 O 7 . This study proves the exceptional intrinsic corrosion resistance against CMAS of single-crystal β-Lu 2 Si 2 O 7 and validates previous hypotheses regarding grain boundary engineering for enhancing CMAS corrosion resistance. Furthermore, it further illuminates new avenues including material design for intrinsic CMAS corrosion resistance and the application of grain boundary engineering in environmental and thermal barrier coatings.