Investigation of ZrO2-toughened Yb2SiO5 environmental barrier coating on Nb alloy under water-vapor corrosion at 1500 °C.

To protect niobium alloy against water-vapor corrosion at high temperatures, an innovative ZrO 2 -modified Yb 2 SiO 5 environmental barrier coating was prepared via supersonic atmosphere plasma spraying. The service life of the modified coating (50 h) is 10 times higher than the pristine due to the higher fracture toughness (2.07 MPa∙m1/2) to inhibit cracking during frequent thermal cycles. With exposure prolonging, the in-situ formation of (Zr,Yb)O 2 solid solution would weaken the fracture toughness of the coating by hindering the phase transformation of ZrO 2 from cubic to monoclinic, while improving the corrosion resistance of the coating by enhancing atomic bonding strength. • The water vapor corrosion behavior of the coatings was tested up to 1500 °C. • Higher fracture toughness of the ZrO 2 -modified Yb 2 SiO 5 coating (2.07 MPa∙m1/2) enabled the longer service life (50 h). • Disorder-to-order structural changes appeared in the (Zr,Yb) 2 solid solution caused by the rearrangement of Zr and Yb atoms. • The (Zr,Yb) 2 solid solution weakened the fracture toughness by inhibiting cubic-to-monoclinic phase transformation. • Improvement of the Zr-O and Yb-O atomic bonding strength leads to better corrosion resistance. [ABSTRACT FROM AUTHOR]