High temperature water vapour corrosion of rare earth disilicates (Y,Yb,Lu)2Si2O7 in the presence of Al(OH)3 impurities

Recent progress on synthesis, multi-scale structure, and properties of Y–Si–O oxides

“…172 In a similar way to silica, the water vapour corrosion of rare-earth silicates also results in the formation of volatile silicon hydroxide as: Re 2 Si 2 O 7 z 2H 2 ORRe 2 SiO 5 zSi(OH) 4 (g). 172 Courcot et al 173 3 than Y 2 SiO 5 , less YAG was detected at the end of the corrosion test and resulted in a weight loss. It was also reported that the preparation methods have an influence on the corrosion resistance.…”

First-principles investigation on the corrosion resistance of rare earth disilicates in water vapor

“…As can be seen from Fig. 2 14,15 However, the calculation suggests that the substitution of Lu results in the decrease in the water corrosion resistance of Y 2 Si 2 O 7 , which conflicts with the experimental results. 15 The possible reason could be aluminum contamination.…”

“…11,12 In order to improve the operation temperatures of EBC systems, rare earth silicates, RE 2 Si 2 O 7 (RE = rare earth element, including Y, Sc, Yb and Lu), have been developed to meet these requirements because of their low recession rates, low CTE mismatch with matrix, and their high chemical compatibility. 2,[13][14][15][16][17] Although rare earth silicates are promising EBC materials for high temperature applications, the available experimental data on wet corrosion behaviors of these materials are scarce, sometimes contradictory. 2,[13][14][15][16][17][18][19] Possible reasons for the contradictory could be the contamination effects, 14 the variation in the precision of test facility, and the difficulties in test condition control.…”

“…2,[13][14][15][16][17] Although rare earth silicates are promising EBC materials for high temperature applications, the available experimental data on wet corrosion behaviors of these materials are scarce, sometimes contradictory. 2,[13][14][15][16][17][18][19] Possible reasons for the contradictory could be the contamination effects, 14 the variation in the precision of test facility, and the difficulties in test condition control. Overall, predicting the hydro corrosion resistance of these materials beyond trial and error has been a challenge for the researchers in this field.…”

Addressing Rare-Earth Element Criticality: An Example from the Aviation Industry

“…While the monosilicates exhibit lower silica activity and hence are more stable in high-temperature water vapor, the disilicates have a better CTE match to SiC. 11 Of the disilicates, Y 2 Si 2 O 7 possesses perhaps the best balance of properties and affordability; however, it exhibits up to five polymorphs up to its melting point, including a Type C C2/m (b) to Type D P2 1 /c (c) monoclinic phase transition between 1300°C and 1350°C. 10,12 This phase transformation has been seen to be accompanied by exaggerated grain growth and subsequent microcracking after thermal cycling (because of the highly anisotropic thermal expansion).…”