Effect of Co Contents on Microstructure and Cavitation Erosion Resistance of NiTiAlCrCoxN Films

Abstract

In order to investigate the effect of Co contents on the structure and cavitation erosion property, NiTiAlCrCoxN films were prepared by the magnetron sputtering system. The X-ray diffractometer (XRD), the scanning electron microscope (SEM) and the energy dispersive spectrometer (EDS) were used to characterize the structure and morphology of the films. The nanoindenter and the scratch tester were used to analyze the mechanical properties of the films. Cavitation erosion experiments were carried out by the ultrasonic vibration cavitation machine. The results show that NiTiAlCrCoxN films with different Co contents have a simple face-centered cubic (FCC) structure and show a preferred orientation on the (200) crystal plane. The diffraction angle on the (200) crystal plane decreases and the interplanar spacing increases with the increase in Co content in NiTiAlCrCoxN films. NiTiAlCrCoxN films exhibit a typical columnar crystalline structure. With the increase in Co content, the nanohardness of the films increases and the elastic modulus of the films decreases, while the mass loss of cavitation erosion monotonously increases except for the film with a 1.2 Co molar ratio. The NiTiAlCrCo1.4N film has a minimum hardness of 13.264 GPa, a maximum elastic modulus of 253.22 GPa and a minimum mass loss of 0.72 mg in the cavitation erosion experiment. The NiTiAlCrCo1.4N film exhibits the best cavitation corrosion resistance because the addition of the Co element enhances the solid solution strengthening effect and the NiTiAlCrCox1.4N film with the biggest elastic modulus has better elasticity to reduce the micro jet impact.