Chen, Lingpeng
(2018)
Compositional and structural effects on the high-temperature oxidation and hot corrosion behavior of MCrAlY coating alloys at 900℃.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Hot corrosion is a highly accelerated surface degradation process, which has been found in gas turbine engines, accompanied by impurities and occurred at high temperature. To increase the hot corrosion resistance of components, a coating is often used to isolate the gas phase and deposited salt from the base alloy. In practice, MCrAlY (M=Co, Ni or Co+Ni)-based coatings are often used. The hot-corrosion resistance of MCrAlY-based coatings relies on the formation of a continuous Al2O3 scale in the corrosive environment. Thus, an understanding of the compositional and microstructural factors affecting the high-temperature corrosion behavior of MCrAlY-based coatings is needed.
The main aim of this study was to assess the influences of overall composition, phase volume fraction and phase composition of MCrAlY-based alloys on oxidation process and hot corrosion resistance. By heat-treating at different temperatures, a given alloy could same alloy composition but different phase volume fractions and phase compositions. Comparing the performance of different variations of the same alloys under oxidation and hot corrosion conditions, the influence of phase volume fraction and phase composition could be investigated. The results showed that aluminum content in the alloys is the key factor determining oxidation behavior. Higher aluminum content resulted in a thicker oxide scale. In addition, the steady-state oxidation rate was determined by the total aluminum content in the alloy. For hot corrosion, higher Cr content could promote the rapid establishment of a continuous Al2O3 layer. Higher Al content is beneficial to the formation of thicker aluminum oxide layer, while phase volume fraction and phase composition do not have obvious influence on hot-corrosion resistance.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
11 June 2018 |
| Date Type: |
Publication |
| Defense Date: |
6 April 2018 |
| Approval Date: |
11 June 2018 |
| Submission Date: |
28 March 2018 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
106 |
| 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: |
Hot corrosion; Oxidation; MCrAlY; Aluminium oxide |
| Date Deposited: |
11 Jun 2018 19:40 |
| Last Modified: |
11 Jun 2018 19:40 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/33974 |
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