Publication details

Synthesis and oxidation behavior of Ti0.35Al0.65By (y=1.7-2.4) coatings

Authors

KASHANI Amir Hossein Navidi MRAZ Stanislav HOLZAPFEL Damian M HANS Marcus LOFLER Lukas ONDRAČKA Pavel PRIMETZHOFER Daniel SCHNEIDER Jochen M

Year of publication 2022
Type Article in Periodical
Magazine / Source SURFACE & COATINGS TECHNOLOGY
Citation
Doi http://dx.doi.org/10.1016/j.surfcoat.2022.128190
Keywords Coatings; Hightemperatureoxidation; TiAlN; TiAlB2
Description The effect of B concentration on phase formation and oxidation resistance of (Ti0.35Al0.65)By coatings with y = 1.7, 2.0, 2.4 was investigated. Elemental B targets in radio frequency mode and a compound Ti0.4Al0.6 target in direct current mode were sputtered. The B concentration was varied systematically by adjusting the applied power to the respective magnetrons, while keeping the power supplied to the magnetron with the Ti0.4Al0.6 target constant. Measured lattice parameters and elastic properties are consistent with ab initio predictions. The oxidation resistance at 700 degrees C in air for up to 8 h was compared to a cathodic arc evaporated (Ti0.37Al0.63)0.49N0.51 coating with an Al/Ti ratio of 1.69 +/- 0.20 which is very similar to 1.84 +/- 0.40 for the boride coatings. Scanning transmission electron microscopy imaging revealed oxide scale thicknesses of 39 +/- 7 and 101 +/- 25 nm for (Ti0.35Al0.65)B2.0 and (Ti0.37Al0.63)0.49N0.51 after 8 h, respectively. Hence, the close to stoichiometric diboride outperforms the nitride coating. This behavior can be understood based on composition and structure analysis of the oxide scales: While the protective layer on the diboride is primarily composed of Al and O, the porous oxide layer on the nitride coating contains Ti, Al and O.

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