Effect of CeO2 on crack sensitivity and tribological properties of Ni60A coatings prepared by laser cladding

Abstract

All the time, the wear resistance of TC4 titanium alloy restricts its application in friction parts. In order to solve this problem, in this work, CeO2/Ni60A composite coatings (0, 1, 2, 3, 4 wt.% CeO2) were prepared on TC4 titanium alloy by laser cladding technology. The detection and characterization of the coatings were mainly carried out by X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy-dispersive spectrometer, Vickers hardness test, and wear test. The results showed that appropriate proportion of CeO2 powder could effectively reduce the crack sensitivity of Ni60A coating on TC4 substrate. While the amount of CeO2 powder was 3wt.%, there were no obvious cracks, pores, and other defects in the coating. Coatings mainly consisted of Ti2Ni, TiC, TiB2, Ce2O3, and the substrate α–Ti. CeO2 has negligible influence on the composition of the phase, but it significantly increased the absorption rate of the powder to light, promoted the fluidity of the molten pool. Among five coatings, the average hardness of the 3Ce coating was the highest and the highest hardness value could reach 1163.7 HV0.3, which was 3.58 times higher than TC4 substrate, the friction coefficient was 0.307, and the wear rate was 1.11 × 10−5 mm3/N m, which reflected extremely high wear resistance performance. Adding an appropriate amount of CeO2 improved the microstructure of the coating, and realized the fine crystal strengthening of the coating.