Effect of Cr2O3 addition on mechanical and tribological properties of atmospheric plasma-sprayed NiAl-Bi2O3 composite coatings.

Existing atmospheric plasma sprayed NiAl-20 wt% Bi 2 O 3 composite coating displays the poor mechanical properties, thus this paper investigated the influence of adding different fractions of Cr 2 O 3 on microstructural alteration and tribological behavior of NiAl-20 wt% Bi 2 O 3 coating at RT, 400 °C and 800 °C. Desirable lubrication of NiAl-Bi 2 O 3 -Cr 2 O 3 coating primarily resulted from Bi 2 O 3 by its virtues of soft, low shear stress, and diffusion with temperature stimulus. Instead, Cr 2 O 3 addition improved the wear resistance significantly, which was attributed to the increase of hardness and plastic deformation resistance, especially when 15 wt% Cr 2 O 3 was adopted. The relationship between the Cr 2 O 3 addition and relevant composition migration and mechanical transition on the worn surface at varying temperatures was further researched in this work. • NiAl-Bi 2 O 3 coatings with different amount of Cr 2 O 3 were prepared by the APS process. • Proper amount of Cr 2 O 3 enhanced the mechanical capability and wear resistance. • The consolidation of Cr 2 O 3 on tribo-layer supported the lubricity of Bi 2 O 3 and NiO. • Grain refinement and evolution of Bi 2 O 3 , Cr 2 O 3 and NiO governed the resulting wear. [ABSTRACT FROM AUTHOR]