Yttrium fluoride sprayed coating, spray material therefor, and corrosion resistant coating including sprayed coating

Abstract

An yttrium fluoride sprayed coating having a thickness of 10-500 μm, an oxygen concentration of 1-6 wt %, and a hardness of 350-470 HV is deposited on a substrate surface. The yttrium fluoride sprayed coating exhibits excellent corrosion resistance in a halogen-base gas atmosphere or halogen-base gas plasma atmosphere, functions to protect the substrate from damage by acid penetration during acid cleaning, and minimizes particle generation from a reaction product and due to spall-off from the coating.

1 . An yttrium fluoride sprayed coating deposited on a substrate surface, having a thickness of 10 to 500 μm, an oxygen concentration of 1 to 6% by weight, and a hardness of at least 350 HV. 
     
     
         2 . The sprayed coating of  claim 1 , having a crack amount of up to 5% based on the surface area of the coating. 
     
     
         3 . The sprayed coating of  claim 1 , having a porosity of up to 5% based on the surface area of the coating. 
     
     
         4 . The sprayed coating of  claim 1 , having an yttrium fluoride crystal structure composed of YF 3  and at least one compound selected from the group consisting of Y 5 O 4 F 7 , YOF and Y 2 O 3 . 
     
     
         5 . The sprayed coating of  claim 1 , having a carbon content of up to 0.01% by weight. 
     
     
         6 . An yttrium fluoride spray material for forming the yttrium fluoride sprayed coating of  claim 1 , in the form of a granulated powder consisting essentially of 9 to 27% by weight of Y 5 O 4 F 7  and the balance of YF 3 . 
     
     
         7 . An yttrium fluoride spray material for forming the yttrium fluoride sprayed coating of  claim 1 , which is a powder mixture consisting essentially of 95 to 85% by weight of a granulated powder of yttrium fluoride and 5 to 15% by weight of a granulated powder of yttrium oxide. 
     
     
         8 . A corrosion resistant coating having a multilayer structure comprising a lower layer in the form of a rare earth oxide sprayed coating having a thickness of 10 to 500 μm and a porosity of up to 5% and an outermost surface layer in the form of the yttrium fluoride sprayed coating of  claim 1 . 
     
     
         9 . The coating of  claim 8  wherein the rare earth element of the rare earth oxide sprayed coating is at least one element selected from the group consisting of Y, Sc, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.