Improvement of high temperature oxidation resistance of γTiAl alloys by slurry coatings

摘要

This research document aims to deepen the understanding of slurry coatings asan effective barrier against the oxidation of promising Titanium-aluminide intermetallicalloys. For that purpose, the research is carried out with a Titanium-Aluminum alloy substrate {(Ti 45Al 2Nb 2Mn + 0.8%vol TiB2){ which wasmanufactured by means of two different techniques: Hot Isostatic Pressing (HIP)and Centrifugal Casting (CC).Additionally, two different slurry coatings have been applied and analyzed inorder to understand the effects they produce. One of them was based on Aluminumpowders and the other on a mixture of Aluminum-Boron powders. Bothcarry polyethylene glycol (PEG) as a binder.A total of twenty four samples were used, from which twelve were manufacturedby hot isostatic pressing and the remaining twelve by centrifugal casting.Each group of twelve pieces was divided in three subgroups, each made up offour samples. The first subgroup was subjected to oxidation without having anycoating, the second was coated by the aluminum slurry and the third by thealuminum-boron slurry.The samples were oxidized in static air for 300 hours at 800ºC (1073 K) inan interrupted oxidation test.Finally, the characterization of the samples was performed by means of massgain,X-Ray diffraction and Scanning Electron Microscope (SEM) analyses.