Film of yttria-alumina complex oxide, a method of producing the same, a sprayed film, a corrosion resistant member, and a member effective for reducing particle generation
The invention provides a film of an yttria-alumina complex oxide having a high peel strength with respect to a substrate. A mixed powder of powdery materials of yttria and alumina is sprayed on a substrate to form a sprayed film made of an yttria-alumina complex oxide. Preferably, the powdery material of yttria has a 50 percent mean particle diameter of not smaller than 0.1 μm and not larger than 100 μm, and the powdery material of alumina has a 50 percent mean particle diameter of not smaller than 0.1 μm and not larger than 100 μm. Preferably, the yttria-alumina complex oxide contains at least a garnet phase, and may further contain a perovskite phase.
1. A member effective for reducing particle generation and comprising a substrate and a surface layer on said substrate, wherein said surface layer comprises a yttria-alumina complex oxide having an α value in a range of 50 to 700 calculated according to the following formula, wherein α=(a specific surface area measured by Krypton adsorption method (cm 2 /g))×(a thickness of said surface layer (cm))×(a bulk density of said surface layer (g/cm 3 )); and
wherein said surface layer has an open porosity of at least 11 volume percent.
2. The member of claim 1 , wherein the open porosity of said surface layer is not higher than 30 volume percent.
3. The member of claim 1 , wherein a ratio of the open porosity to a closed porosity (open porosity/closed porosity) of said surface layer is not higher than 10.
4. The member of claim 1 , wherein a pore diameter of main open pores of said surface layer is in a range of 0.05 to 50 μm.
5. The member of claim 1 , wherein said surface layer has a thickness of at least 50 μm.
6. The member of claim 1 , wherein said surface layer further comprises a material selected from the group consisting of an oxide containing a rare earth element, an oxide containing an alkaline earth element, a carbide, a nitride, a fluoride, a chloride, an alloy, a solid solution thereof and a mixture thereof.
7. The member of claim 1 , wherein when said member is exposed to a corrosive substance, a material constituting said substrate has an etching rate against said corrosive substance that is larger than that of a material constituting said surface layer.
8. The member of claim 7 , wherein said corrosive substance is a halogen gas or a plasma of a halogen gas.
9. The member of claim 1 , wherein said substrate is made of a material selected from the group consisting of alumina, spinel, yttria, zirconia and the complex oxide thereof.
10. The member of claim 1 , wherein said surface layer is a film formed by spraying a mixed powder of powdery materials of yttria and alumina an said substrate.
11. The member of claim 10 , wherein 50 percent mean particle diameter of said powdery material of yttria is in a range of 0.1 μm to 100 μm.
12. The member of claim 10 , wherein said a 50 percent mean particle diameter of said powdery material of alumina is in a range of 0.1 μm to 100 μm.
13. The member of claim 10 , wherein said film is thermally treated.
14. The member of claim 10 , wherein said yttria-alumina complex oxide includes at least garnet phase.
15. The member of claim 14 , wherein said yttria-alumina complex oxide comprises garnet and perovskite phases, and wherein a YAL(420)/YAG(420) ratio is in a range of 0.05 to 1.5, provided that said YAL(420)/YAG(420) ratio is the ratio of a peak strength YAL(420) of the (420) plane of said perovskite phase to a peak strength YAG(420) of the (420) plane of said garnet phase, said peak strengths being measured by X-ray diffraction method.