Inoxidizability of NiCoCrAlY Coatings Deposited on Ti Alloys by Magnetron Sput-tering

摘要

An unbalanced magnetron sputtering technology was used to deposit NiCoCrAlY coatings on TC4 alloy under different sputtering process. The coatings' microstructure and phase composition before and after the oxidation were analyzed by SEM.EDS and XRD. An increase trend of surface roughness was observed along with the sputtering time, there was a small amount of a diameter of about l0μm of the dome-shaped protrusions on coating surfaces which affected by the preferential deposition. The coating was mainly composed of AlNi3, Al0.9 Ni4.22 phase and others existed as amorphous form. After oxidation,a transition layer was formed by the diffusion of Ti and Ni at the interface. The amorphous structure showed a crystalline character gradually after oxidation at 800°C/17h with a peak of strong γ-NiAl、γ-Ni and weak Cr、α-Al2O3. The coating could enhance the TC4 alloys oxidation resistance with about 0. 0052mg/cm2. h weight gain rate at 800°C/17h and about 0. 03mg/cm2. h at 900°C/17h.