2

Figure 11. Sample LG87 (special treatment by Howmet). (A.) 2 hours at 1080°C. (B.) 16 hours at 1080°C. (C.) 16 hours at 1093°C. (D) 16 hours at 1121°C. All exposures done in dry air
Figure 12. Grit Blast sample LI3 exposed at 1100°C for 2 hours in (A) Ar-H and (B) dry air environments.

Figure 13. Sample LG96, media finished for 40 minutes, was exposed for 2 hours at 1100°C in (A) Ar-H and (B) dry air. Sample LG92, 120 minute media finish, was exposed for 2 hours at 1100°C in (C) Ar-H and (D) dry air.

Note (B) was also taken at 1600x

Figure 13. Sample LG96, media finished for 40 minutes, was exposed for 2 hours at 1100°C in (A) Ar-H and (B) dry air. Sample LG92, 120 minute media finish, was exposed for 2 hours at 1100°C in (C) Ar-H and (D) dry air.

Note (B) was also taken at 1600x

Task IB: Media Finishing and Surface Roughness Reduction

In the previous reporting period media finishing trials were carried out on as-coated Pt-Al disk specimens by a media finishing company approved for work on turbine airfoils. Laser surface profilometry was used to quantitatively determine the surface geometry on as-coated samples and the changes that occurred after 20, 40 60 and 120 minutes of media finishing. Data was obtained for changes in (a)ridge height, (b) peak to valley distances, and average roughness. I was concluded that 40 and 120 minutes would be used in the experiments as the two conditions for the experimental program. In the current period trial shot peening was done on the MCrAlY samples and it was found that such surfaces are not suitable as is for EB-PVD coating. Note that the range in height is from 14-27^. Optical profilometry images and roughness measruments on these samples are given in the figure and table below:

Sample #

KOH cleaned

Shot Peened

Pv (m)

Rms(m)

Ra(m)

0 0

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