Abstract
RE2SiO5 with low thermal conductivity, compatible thermal expansion coefficients and excellent high-temperature reliability in harsh environments are excellent candidates as advanced environmental/thermal barrier coating materials for high-efficiency gas turbine engines. A series of rare earth silicates (HoxY1-x)2SiO5 are designed and their properties are comprehensively investigated in this paper. Through doping Ho into Y2SiO5, the thermal conductivity of Y2SiO5 is significantly decreased and the thermal expansion coefficient is also optimized closer to Si-based ceramics. High-temperature elastic stiffness and bending strength are increased with the enhancing of Ho content. Most important, doping Ho element provides (HoxY1-x)2SiO5 with tunable luminescence characteristic. (HoxY1-x)2SiO5 exhibit green, to yellow-green, then to orange-red luminescence color with increased Ho concentration. The results show that they can be used as damage self-monitoring environmental/thermal barrier coating materials for Si-based ceramics.
Highlights
Gas turbine engines have benefited from decades of development of nickel-based superalloys, operating temperatures are reaching limits posed by the melting temperatures of these materials[1]
Further increase in operating temperature, thermal barrier coating (TBC) is essential to allow a steep temperature gradient across it to lower the temperature of the matrix ceramics that for increasing the lifetime and efficiency of gas turbine engines[2]
It is urgent to lower the thermal conductivity and thermal expansion coefficients and improve the high-temperature mechanical properties of Y2SiO5 to realize its application as ETBC for Si-based ceramics
Summary
Both room temperature and high temperature bending strengths of Ho2SiO5 are higher than that of Y2SiO5. They decrease with the increase of temperature and gradually approach steady at high temperature. Thermal expansion coefficients of Y2SiO5 and Ho2SiO5 are close and they are Figure 5. Macroscopic thermal expansion coefficients of solid solutions have smaller magnitude compared with two end members, Y2SiO5 and Ho2SiO5. All, (HoxY1-x)2SiO5 solid solutions with tunable luminescence color, low thermal conductivity, and matchable thermal expansion coefficients are novel damage self-monitoring ETBC candidates
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
