Enhanced high-temperature wear resistance of CoNiCrAlY coatings: Strengthening mechanisms of ZrB2 and Al2O3 reinforcements at 1000 °C

To avoid the wear failure of hot parts at 1000 °C, a ZrB 2 -reinforced CoNiCrAlY coating was prepared using step-fashion mechanical alloying and high-velocity oxygen-fuel (HVOF) spraying. With CoNiCrAlY and CoNiCrAlY-Al 2 O 3 coatings as controls, the microstructure, mechanical properties, and tribological performance at 1000 °C of the CoNiCrAlY-ZrB 2 coatings with different ZrB 2 contents (10–25 wt%) were investigated. Compared with the CoNiCrAlY coating, the incorporation of either Al 2 O 3 or ZrB 2 can improve the hardness, elastic modulus, and wear resistance of the coatings. However, the pinning effect of Al 2 O 3 disrupts the oxide film integrity, leading to a debris accumulation on the CoNiCrAlY-10wt%Al 2 O 3 coating with a wear rate of 68.61×10 −14 m 3 (N m) −1 . In contrast, ZrB 2 promotes the formation of a protective oxide film composed of ZrO 2 , (Co,Ni)Cr 2 O 4 , Cr 2 O 3 , and Al 2 O 3 , resulting in a lower wear rate of 8.95×10 −14 m 3 (N m) −1 for CoNiCrAlY-10wt%ZrB 2 coating. As the ZrB 2 content increases, the mechanical properties and wear resistance further improve. The CoNiCrAlY-20wt%ZrB 2 coating exhibits minimized COF (0.40) and wear rate (2.34×10 −14 m 3 (N m) −1 ), demonstrating promising potential as a protective coating of hot parts. • Al 2 O 3 - and ZrB 2 - reinforced CoNiCrAlY powders were prepared by step-fashion mechanical alloying. • Tribological performance at 1000 ℃ of the HVOF sprayed composite coatings was tested. • The effect of Al 2 O 3 and ZrB 2 on tribological behavior compared to CoNiCrAlY was discussed. • ZrB 2 promotes the formation of a protective oxide film, enhancing the wear resistance.