Water vapor corrosion behaviors of high-entropy pyrosilicates

In this study, the water vapor corrosion resistance of two types of high-entropy pyrosilicates ((Yb0.2Y0.2Lu0.2Ho0.2Er0.2)2Si2O7 ((5RE1/5)2Si2O7) and (Yb0.25Lu0.25Ho0.25Er0.25)2Si2O7 ((4RE1/4)2Si2O7)) and two single-component pyrosilicates (Yb2Si2O7 and Lu2Si2O7) were evaluated at 1350 °C for 50–100 h, and the initial corrosion behaviors of these pyrosilicates were studied. The results showed that the final corrosion products of the four types of pyrosilicates were all X2-type monosilicates, exhibiting similar corrosion phenomena. However, (4RE1/4)2Si2O7 generated many nanoscale monosilicate grains during corrosion. The corrosion resistance of Lu2Si2O7 was clearly better than those of the others, and (4RE1/4)2Si2O7 exhibited the worst corrosion resistance. The corrosion mechanism of the pyrosilicate blocks was analyzed from the perspectives of grain size, bulk hydrophobicity, and binding energy. This study potentially provides a theoretical basis for the preparation of high-entropy pyrosilicates with different atomic ratios according to the different properties of the various rare earth elements.