Water vapor corrosion behaviors of high-entropy pyrosilicates

Highlights

• The water vapor corrosion resistance of two high-entropy pyrosilicates were systematically evaluated for the first time.

• The nucleation and growth of the corrosion product monosilicate began on the inner surface of the pyrosilicate grains.

• The corrosion mechanism was analyzed from the perspectives of grain size, bulk hydrophilicity and binding energy.

Abstract

In this study, the water vapor corrosion resistance of two types of high-entropy pyrosilicates ((Yb_0.2Y_0.2Lu_0.2Ho_0.2Er_0.2)₂Si₂O₇ ((5RE_1/5)₂Si₂O₇) and (Yb_0.25Lu_0.25Ho_0.25Er_0.25)₂Si₂O₇ ((4RE_1/4)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, (4RE_1/4)₂Si₂O₇ generated many nanoscale monosilicate grains during corrosion. The corrosion resistance of Lu₂Si₂O₇ was clearly better than those of the others, and (4RE_1/4)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.