Corrosion behavior of yttrium oxyfluoride ceramics in HCl, HNO 3 and HF solutions at room temperature

Abstract Dense bulk of Y 2 O 3 , YOF, Y 5 O 4 F 7 and Y 5 O 4 F 7 + YF 3 ceramics samples were immersed in HCl, HNO 3 , and HF solutions at room temperature. Scanning electron microscopy revealed that HCl and HNO 3 severely damaged Y 2 O 3 while these acid solutions attacked grain boundaries of YOF, Y 5 O 4 F 7 and Y 5 O 4 F 7 + YF 3 ceramics. Energy-dispersive X-ray spectroscopy analysis resulted that Y 5 O 4 F 7 + YF 3 ceramics immersed in HCl and HNO 3 were partially corroded in its YF 3 region. Y 5 O 4 F 7 showed better durability than YOF and Y 5 O 4 F 7 + YF 3 in viewpoint of weight losses and microstructure change. Weight change after dilute HF immersion was negligible and almost the same among the samples. Slight reaction at grain boundaries were observed in Y 2 O 3 , YOF, Y 5 O 4 F 7 and Y 5 O 4 F 7 + YF 3 after dilute HF immersion. Y–O–F ceramics samples are as durable as conventional Y 2 O 3 against HF.