Rare earth fluoride spray powder and rare earth fluoride-sprayed article

Abstract

A powder comprising rare earth element fluoride particles having an aspect ratio of up to 2, an average particle size of 10-100 m, a bulk density of 0.8-1.5 g/cm 3 , and a carbon content of 0.1-0.5 wt % is amenable to atmospheric plasma spraying. An article obtained by spraying the rare earth fluoride spray powder to a substrate undergoes few partial color changes and performs well even when used in a halogen gas plasma.

1 . A rare earth element fluoride spray powder comprising rare earth element fluoride particles having an aspect ratio of up to 2, an average particle size of 10 to 100 m, a bulk density of 0.8 to 1.5 g/cm 3 , and a carbon content of 0.1 to 0.5% by weight. 
     
     
         2 . The spray powder of  claim 1  wherein the total content of water and hydroxyl group is up to 10,000 ppm. 
     
     
         3 . The spray powder of  claim 1  wherein the rare earth element is one or more elements selected from the group consisting of Y and 3A Group elements from La to Lu. 
     
     
         4 . The spray powder of  claim 3  wherein the rare earth element is selected from the group consisting of Y, Ce and Yb. 
     
     
         5 . A rare earth element fluoride sprayed article comprising a substrate and a sprayed coating which is deposited on the substrate by plasma spraying the spray powder of  claim 1 , the sprayed coating having a carbon content of up to 0.1% by weight and an oxygen content of 0.3 to 0.8% by weight. 
     
     
         6 . The sprayed article of  claim 5  wherein the sprayed coating has a L*a*b* color space chromaticity with a L* value of 65 to 85, an a* value of −3.0 to +3.0, and a b* value of 0.0 to +8.0.