In-flight particle states and coating properties of air plasma sprayed ytterbium disilicates

Optimization of spraying process and stoichiometric stage of plasma‐sprayed Yb2Si2O7 environmental barrier coating

“…However, the internal pores of the Yb 2 Si 2 O 7 coating with a spray distance of 90 mm are larger than those of the coating with a spray distance of 100 mm. This is due to the short spraying distance, which leads to overheating and serious ablation of spraying powder and drastic contraction of droplets 27,28 . According to the reported literature, 28 the smaller the spraying distance, the shorter the heating time of spraying powder in the plasma flame flow.…”

“…This is due to the short spraying distance, which leads to overheating and serious ablation of spraying powder and drastic contraction of droplets. 27,28 According to the reported literature, 28 the smaller the spraying distance, the shorter the heating time of spraying powder in the plasma flame flow. When the spraying distance becomes large, the flying speed of spray particles in the plasma flame flow will be reduced and the melting effect will be worse, which will affect the quality of the coating.…”

Significantly improved corrosion resistance of high‐entropy rare‐earth silicate multiphase ceramics against molten CMAS

“…Moreover, the formation of apatite crystal phase in the (4RE 0.25 ) 2 SiO 5 sample also suggests that the (4RE 0.25 ) 2 SiO 5 more easily dissolved into the molten CMAS compared to the (4RE 0.25 ) 2 Si 2 O 7 . The reactions of RE 2 SiO 5 and RE 2 Si 2 O 7 with CMAS are shown in Equations () and (), respectively 28,29 $$$$\begin{equation}4{\rm{RE}}_2{\rm{SiO}}_5 + {\rm{ }}2{\rm{CaO }} + 2{\rm{SiO}}_2 = {\rm{ Ca}}_2{\rm{RE}}_8{\left( {{\rm{SiO}}_4} \right)}_6{{\rm{O}}}_2\end{equation}$$$$ $$$$\begin{equation}4{\rm{RE}}_2{\rm{Si}}_2{{\rm{O}}}_7 + {\rm{ }}2{\rm{CaO }} = {\rm{ Ca}}_2{\rm{RE}}_8{\left( {{\rm{SiO}}_4} \right)}_6{{\rm{O}}}_2 + {\rm{ }}2{\rm{SiO}}_2\end{equation}$$$$…”

Microstructure and mechanical properties of Yb₂Si₂O₇/ZrO₂ ceramic coatings exposed to CMAS corrosion at 1450 °C

“…13)- 15) In addition, the coefficient of thermal expansion of Yb 2 Si 2 O 7 varies from 3.6-to 4.5 © 10 ¹6 K ¹1 , which matches well with that of SiC-based ceramic substrates (4.3-5.4 © 10 ¹6 K ¹1 ). 16), 17) However, with the increase in the service temperature of aviation hot components, a higher working temperature can lead to serious corrosion damage of the EBC in the engine environment. Among them, hightemperature corrosion caused by CMAS deposits is one of the key problems in current research on EBCs, and it is also a fundamental challenge to achieve the target working temperature.…”