Presentation Title

Aluminization of Ni-base Superalloys by Slurry and Pack Cementation Processes

Faculty Mentor

Dr. Vilupanur Ravi, Chemical and Materials Engineering, Cal Poly Pomona

Start Date

17-11-2018 2:00 PM

End Date

17-11-2018 2:15 PM

Location

C301

Session

Oral 3

Type of Presentation

Oral Talk

Subject Area

engineering_computer_science

Abstract

Ni-base superalloys are used in gas turbine applications because of their desirable mechanical strength and oxidation resistance at temperatures up to 1000°C. To increase the efficiency of gas turbines, higher operating temperatures are needed. Protective coatings can increase the longevity of the substrates in high temperature and corrosive environments. Both halide activated pack cementation (HAPC) and and halide activated slurry cementation (HASC) are in situ chemical vapor deposition processes activated by halide salts. The chemical reactions deposit the desired element (aluminum in this case) on the surface of metallic alloys. The coating element subsequently diffuses into the substrate. Under oxidizing conditions, the surface modified alloy forms a passive oxide layer that protects it from high temperature corrosion. In this study, aluminide coatings were produced by HAPC and HASC on Ni-base superalloys (UNS N07208, UNS N06230, and UNS N07718). Alloy coupons were coated in an inert environment at 950°C for 4 hours. The characteristics of the coatings produced, i.e., thickness, microhardness, microstructure and elemental distribution, were studied using a broad range of techniques - X-ray diffraction (XRD), macrophotography, optical and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS).

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Nov 17th, 2:00 PM Nov 17th, 2:15 PM

Aluminization of Ni-base Superalloys by Slurry and Pack Cementation Processes

C301

Ni-base superalloys are used in gas turbine applications because of their desirable mechanical strength and oxidation resistance at temperatures up to 1000°C. To increase the efficiency of gas turbines, higher operating temperatures are needed. Protective coatings can increase the longevity of the substrates in high temperature and corrosive environments. Both halide activated pack cementation (HAPC) and and halide activated slurry cementation (HASC) are in situ chemical vapor deposition processes activated by halide salts. The chemical reactions deposit the desired element (aluminum in this case) on the surface of metallic alloys. The coating element subsequently diffuses into the substrate. Under oxidizing conditions, the surface modified alloy forms a passive oxide layer that protects it from high temperature corrosion. In this study, aluminide coatings were produced by HAPC and HASC on Ni-base superalloys (UNS N07208, UNS N06230, and UNS N07718). Alloy coupons were coated in an inert environment at 950°C for 4 hours. The characteristics of the coatings produced, i.e., thickness, microhardness, microstructure and elemental distribution, were studied using a broad range of techniques - X-ray diffraction (XRD), macrophotography, optical and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS).