Effects of loads on high-temperature wear properties of HVOF sprayed CoCrAlYTa-10%Al2O3 and Cr3C2-NiCr coatings

Abstract

In this paper, the CoCrAlYTa-10%Al2O3 and Cr3C2-NiCr coatings were prepared by High-velocity oxygen-fuel (HVOF) spraying. The high-temperature wear test was carried out by ball-on-disk high temperature tribometer. The results showed that the CoCrAlYTa-10%Al2O3 coating exhibited lower micro-hardness and higher high-temperature wear resistance as compared with the Cr3C2-NiCr coating. At the end of the wear test, the friction coefficients of the coatings flattened out gradually, which illustrated that the coatings had not failed. With increasing of the loads, the wear rate of the CoCrAlYTa-10%Al2O3 coating first decreased and then increased as loads higher than 9 N. A similar trend was also observed in the Cr3C2-NiCr coating, while the difference was that the wear rate started to rise after the loads more than 6 N. As the loads were lower than 9 N, the wear mechanism of the CoCrAlYTa-10%Al2O3 coating was primarily abrasive wear, there were tribofilms formation on the worn track. Severe plastic deformation and micro-ploughing were appeared on the worn track surface under the load of 12 N. The wear mechanism was mainly abrasive wear, followed by adhesive wear. At 3 N, the worn surface of the Cr3C2-NiCr coating exhibited comparatively rough and some spalled pits. As increasing of the loads, spalled pits and grooves appeared on the surface of the worn track, the wear mechanism of Cr3C2-NiCr coating was mainly abrasive wear, followed by adhesive wear.