| Popis: |
In order to improve the surface erosion resistance of titanium alloy substrate and study the effect of Cr based multilayer film on the fatigue mechanical properties of titanium alloy substrate, three kinds of Cr-CrN-Cr-CrAlN multilayer film with different thickness(3.99,6.85,9.62 μm) were deposited on the surface of TC4 titanium alloy by vacuum cathodic arc deposition technology. The axial tensile performance and axial high low cycle fatigue performance of TC4 titanium alloy substrate and the film specimens at room temperature were studied and compared mainly through tensile tests and axial loading fatigue tests. Results showed that the thicknesses of Cr-CrN-Cr-CrAlN multilayer film prepared on the surface of TC4 titanium alloy were approximately 3.99, 6.85 and 9.62 μm, respectively. Moreover, the corresponding hardnesses were 2 455, 3 024 and 3 578 HV, and the adhesion forces of film-substrate were 12.4, 15.2 and 20.1 N, respectively. After coated with multiple layers, the tensile yield strength, tensile strength and elastic modulus of TC4 titanium alloy were improved, while the elongation at break was reduced. The multilayer film with 6.85 μm decreased the axial high cycle fatigue limit of TC4 titanium alloy by 4.15%, and the film had little effect on the high cycle fatigue performance. Besides, the effect of film on the low cycle fatigue performance was significant, with a decrease of approximately 21.04% in fatigue strength corresponding to a lifespan of 50 000 cycles. |
