Effect of powder grain size and titania content on mechanical and tribological properties of plasma sprayed Al 2 O 3 -TiO 2 ceramic coatings

Abstract

In this work, three ceramic composite coatings Al 2 O 3 -3TiO 2 C, Al 2 O 3 -13TiO 2 C, and Al 2 O 3 -13TiO 2 N were plasma sprayed on steel substrates. They were deposited with two conventional powders differing the volume fraction of TiO 2 and nanostructured powder. The mechanical and tribological properties of the coatings were investigated and compared. The increase in TiO 2 content from 3 wt.% to 13 wt.% in the conventional feedstock improved the mechanical properties and abrasion resistance of coatings. However, the size of the used powder grains had a much stronger influence on the properties of deposited coatings than the content of the titania phase. The Al 2 O 3 -13TiO 2 coating obtained from nanostructured powder revealed significantly better properties than that plasma sprayed using conventional powder, i.e. 22% higher microhardness, 19% lower friction coefficient, and over twice as good abrasive wear resistance. In turn, the Al 2 O 3 -13TiO 2 conventional coating showed an increase in microhardness and abrasive wear resistance, 36% and 43%, respectively, and 6% higher coefficient of friction compared to the Al 2 O 3 -3TiO 2 conventional coating.