Al
2O
3 and ZrO
2 ceramics thin coating test was performed on the surface of high strength Ni based super alloy by ion plating technique to prevent fission product (FP) plate-out contamination from helium gas turbine, and these ceramics coated specimens were tested to examine its contamination protection behavior and cyclic heat shock resistance.
The following conclusions were derived;
(1) Less than 4 μm thickness of Al
2O
3 and ZrO
2 ceramic coating layer were formed on the surface of super alloy by ion plating technique and highly densified and homogeneous Al
2O
3 ceramic coating layer were obtained with surface roughness under ±10 nm.
(2) There was no breakaway and dropout in Al
2O
3 coating layers under 100 cyclic heat shock test between 1173-288 K. However, crack in Al
2O
3 ceramic coating layer was found over 100 cycles.
(3) It was found that there was no plate-out of vaporized Ag onto the Al
2O
3 ceramic coated specimen on the same heat transfer fluid conditions of gas turbine system, whereas Ag plate-out was found in the cracked Al
2O
3 and ZrO
2 coated specimens damaged by long cyclic heat shock test.
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