| YANG Zhu-fang,HE Guang-yu,LUO Si-hai.Erosion Damage Characteristics and Mechanism of TiN/Ti Multilayer Coatings of Different Heat Treatment[J],51(10):49-57 |
| Erosion Damage Characteristics and Mechanism of TiN/Ti Multilayer Coatings of Different Heat Treatment |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.10.006 |
| KeyWord:sand erosion TiN/Ti multilayer coatings temperature heat treatment damage mechanism |
| Author | Institution |
| YANG Zhu-fang |
1. Science and Technology on Plasma Dynamics Laboratory, Air Force Engineering University, Xi'an , China |
| HE Guang-yu |
1. Science and Technology on Plasma Dynamics Laboratory, Air Force Engineering University, Xi'an , China |
| LUO Si-hai |
1. Science and Technology on Plasma Dynamics Laboratory, Air Force Engineering University, Xi'an , China |
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| Abstract: |
| Sand erosion causes serious damage to the compressor blades of military helicopter engine, which has become one of the factors restricting helicopters to carry out combat/rescue missions in sand environment. Alternating soft and hard multilayer ceramic coating can properly balance strength and toughness, which is an ideal material to improve the service performance of aero-engine compressor blade under sand erosion condition. The work aims to solve the problem that the erosion failure mechanism of TiN/Ti multilayer coatings at high temperature is still unclear, and investigate the erosion damage mechanism of TiN/Ti multilayer coatings with different heat treatment. In this study, TC4 titanium alloy with a size of 50 mm×20 mm×3 mm was selected as the matrix, and then polished with metallographic sandpaper until the surface roughness reached Ra<0.20 μm. The TiN/Ti multilayer coatings were prepared on the surface of TC4 substrate by magnetic filter cathode vacuum arc deposition technology. The specimens were heated in a heat treatment furnace under different conditions (300 ℃/40 min, air-cooled; 400 ℃/40 min, air-cooled; 300 ℃/40 min, air-cooled + 300 ℃/40 min, air-cooled) to simulate its performance change under the high temperature. The adhesion strength of the coatings was tested by scratch tester (WS-2005) with the load of 80 N, loading rate of 80 N/s, and scratch length of 5 mm. The microhardness was tested by microhardness tester (SCTMC) with the load of 300 g and loading time of 15 s. Moreover, the surface morphology and cross-section morphology of the coatings were observed by scanning electron microscope (Zeiss EVO-10), and the elements distribution on the surface of the sample was tested by energy dispersive spectrometer (Bruker Xflash 6130). Afterwards, the erosion performance tests were carried out at a speed of 130 m/s and an angle of 45° on the erosion test platform to obtain the erosion resistance evolution law of the coatings under different temperature. The results indicated that after short time heat treatment at low temperature (≤400 ℃), the multilayer coating structure was intact and the main phases of the coating remained unchanged, showing TiN (111), TiN (200), TiN (220) and TiN (311) textures. No oxidation phenomenon occured in the top TiN layer and the adhesion strength of the coatings before and after heat treatment remained roughly the same, which were 64.1, 64.4, 64.4, 65.6 N, respectively. After heat treatment, the microhardness of the coatings decreased slightly, changing from 2 764.1HV to 2 748.9HV, 2 493.2HV and 2 255.2HV, respectively. The variation of erosion resistance of TiN/Ti multilayer coatings was not significant. The erosion rate changed from 0.117 mg/min to 0.100 mg/min, 0.156 mg/min and 0.120 mg/min, respectively. In conclusion, the effect of short time heat treatment at low temperature (≤400 ℃) on erosion damage mechanism of TiN/Ti multilayer coating is insignificant. Under the action of sand erosion, transverse cracks and longitudinal cracks form inside the coating, and the cracks develop continuously and new cracks are initiated with the further development of erosion. Then the cracks cross and form ring cracks, which leads to coating spalling and loss of protection to matrix. The erosion damage mechanism is brittle peeling failure mechanism caused by ring crack. |
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