Stowe, Eric
(2021)
Passivation of the HAYNES® 214® Nickel-base Superalloy via Pulsed Laser Deposition of Alumina and Chromia Nanocoatings for Degradation Resistance at Elevated Temperatures.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
HAYNES® 214® is a nickel-base superalloy that forms a protective alpha alumina (α-Al2O3) scale at temperatures above 950°C, which is necessary for oxidation and corrosion protection. At temperatures lower than 950°C, the formation of a protective α-Al2O3 layer is very difficult due to the significantly slower diffusion of aluminum from within the bulk alloy compared to the faster inward diffusion of oxygen. Due to this, internal precipitates of α-Al2O3 are routinely observed within the subsurface region of the alloy and these precipitates can negatively impact the alloy’s mechanical strength and other material properties.
This thesis investigates the role of using pulsed laser deposited Al2O3 and chromia (Cr2O3) nanocoatings as a means to apply a passivation layer on the surface of the HAYNES® 214® alloy in an effort to provide oxidation and corrosion resistance at a temperature as low as 800°C. Through the use of various material characterization techniques, the use of a Cr2O3 nanocoating about 150 nanometers in thickness is capable of promoting and sustaining the formation of a protective α-Al2O3 scale for durations of at least 100 hours of exposure to air. The Cr2O3-coated alloy also provides superior protection under thermal cycling and hot corrosion conditions. The Al2O3-coated alloy provided intermediate results compared to the uncoated alloy in all isothermal oxidation tests performed; however, when exposed to hot corrosion conditions, the Al2O3-coated alloy performed similarly to the uncoated alloy. The Al2O3-coated alloy did appear to provide some benefit under thermal cycling conditions.
Share
| Citation/Export: |
|
| Social Networking: |
|
Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
3 September 2021 |
| Date Type: |
Publication |
| Defense Date: |
16 July 2021 |
| Approval Date: |
3 September 2021 |
| Submission Date: |
21 July 2021 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
205 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Materials Science and Engineering |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
HAYNES 214, Oxidation, Hot Corrosion, Nickel-base Superalloys, Al2O3, Cr2O3, Coatings |
| Date Deposited: |
03 Sep 2021 17:36 |
| Last Modified: |
03 Sep 2021 17:36 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/41465 |
Metrics
Monthly Views for the past 3 years
Plum Analytics
Actions (login required)
 |
View Item |
![[feed]](/images/feed-icon-32x32.png){kind=icon}