Effect of Y2O3 addition on the microstructure and properties of NiCoCrAlYTa coatings prepared by electrospark deposition: From a perspective of thermal physical properties

Abstract

Oxide dispersion strengthened (ODS) NiCoCrAlYTa coatings with different Y2O3 additions (0, 3, 5 and 10 wt%, respectively) were prepared by electrospark deposition (ESD), and the effect of Y2O3 addition on the thermal physical properties of the electrodes was investigated. The relationship between the thermal physical properties and the microstructure and properties of the coatings was studied in detail. The results show that, with the increase of Y2O3 addition, the thermal diffusivity and the thermal conductivity were decreased at first and then increased when 10 wt% Y2O3 was added, which influenced the deposition process and the deposition efficiency. Most of the Y2O3 particles were transformed into Y-Al-O oxides, which were mainly consisted of Y4Al2O9 and amorphous Y-Al-O oxides. The amorphous Y-Al-O oxides core was surrounded by a shell enriched in Ti, Ta, Cr, which could be identified as mixed oxides at the region adjacent to the core, and (Ta, Ti, Cr) intermetallic compound at the exterior zone of the shell. Y-Al-O oxides consumed the Al atoms and thus decreased the amount of β-NiAl, resulting in the variation of the microhardness, wear resistance and oxidation behavior.