Corrosion resistance and electrochemical behavior of Fe₃Al intermetallic matrix composites reinforced by TiC : Résistance à la corrosion et comportement électrochimique des composites matriciels intermétalliques Fe₃Al renforcés par TiC

Authors: Ahledel, Najmeh
Advisor: Darvishi Alamdari, HoushangHermawan, Hendra
Other Title(s): Résistance à la corrosion et comportement électrochimique des composites matriciels intermétalliques Fe₃Al renforcés par TiC
Abstract: The corrosion behavior of two Fe₃Al intermetallic matrix composite coatings (Fe₃Al/TiC and Fe₃AlCr/TiC) that prepared by high velocity oxy fuel (HVOF) technique was studied in 3.5 wt.% NaCl solution and compared with non-reinforced Fe₃Al. Furthermore, chromium as an alloying element used in the feedstock of HVOF to evaluate the effect of chromium on corrosion behaviour of the coating. Four electrochemical techniques, open circuit potential potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) were employed to examine corrosion behavior in detail. Post-corrosion analysis was done using Scanning Electron Microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS) to reveal the surface morphology and chemistry of the corroded samples. Results from the open circuit potential test revealed that an oxide layer formed on the coating which could be due to oxidation during the HVOF coating process. The Potentiodynamic polarization graphs revealed that adding TiC particles to Fe₃Al matrix improved the corrosion performance of Fe₃Al so that the Fe₃Al/TiC coatings exhibit slightly six times more corrosion rate. The EIS results indicated a more compact corrosion layer formed on the Cr-added coating resulting into the highest coating resistance. This is supported by the SEM/EDS and XPS analyses which revealed that a mixed oxide and hydroxide formed a passive layer. The Cr in the composite coating took the role in providing a more protective passive layer by blocking the entry sites of Clions. The pitting resistance of the Fe₃Al-Cr/TiC coating in 0.25 M H₂SO₄ solution was, however, lower compared to that of the two other coatings. It is concluded that the addition of TiC particles to Fe₃Al matrix, which primarily done for improving wear resistance, improves the corrosion resistance of the coating in saline solution. The addition of Cr into the Fe₃Al/TiC composite coating further improves its corrosion resistance, but the pitting resistance is not improved when tested in acid solution.
Document Type: Mémoire de maîtrise
Issue Date: 2018
Open Access Date: 22 November 2018
Grantor: Université Laval
Collection:Thèses et mémoires

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