| WANG Gui-yun,CHEN Li.Effect of Al Content on the Mechanical Properties, Thermal Stability, Oxidation Resistance and Corrosion Resistance of Cr1–xAlxN Coatings[J],51(2):39-47, 65 |
| Effect of Al Content on the Mechanical Properties, Thermal Stability, Oxidation Resistance and Corrosion Resistance of Cr1–xAlxN Coatings |
| Received:October 31, 2021 Revised:January 04, 2022 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.02.004 |
| KeyWord:CrAlN coatings structure hardness, thermal stability, oxidation resistance,corrosion resistance |
| Author | Institution |
| WANG Gui-yun |
State Key laboratory of Powder Metallurgy, Central South University, Changsha , China |
| CHEN Li |
State Key laboratory of Powder Metallurgy, Central South University, Changsha , China;Zhuzhou Cemented Carbide Cutting Tools Company Limited, Zhuzhou , China |
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| Abstract: |
| This paper is to investigate the effect of Al content on the structure and properties of Cr1–xAlxN coatings. Cr1–xAlxN coatings with different Al content were prepared in the cathodic arc evaporation equipment using Cr, Cr0.70Al0.30, Cr0.50Al0.50, Cr0.40Al0.60 and Cr0.30Al0.70 targets, respectively. The composition, structure, mechanical properties, thermal stability, oxidation resistance and corrosion resistance of the Cr1–xAlxN coatings were studied with the aid of energy dispersive X-ray spectroscopy (EDX), X-ray diffractometer (XRD), nanoindentation, scanning electron microscopy (SEM) and electrochemical workstations. All five Cr1-xAlxN coatings have a single-phase face-centered cubic structure, and their hardness increases with increasing Al content, from (16.9±0.8) GPa for CrN to (25.1±0.7) GPa for Cr0.75Al0.25N, (27.0±1.1) GPa for Cr0.56Al0.44N, (28.5±1.5) GPa for Cr0.46Al0.54N and (30.4±0.8) GPa for Cr0.36Al0.64N. After annealing at 1000 ℃, the diffraction peaks of hexagonal h-Cr2N began to appear in all coatings, and the intensity of the diffraction peaks decreased with the increase of Al content; the Cr0.75Al0.25N, Cr0.56Al0.44N and Cr0.46Al0.54N coatings can be detected in the hexagonal wurtxite w-AlN phase after annealing at 1100 ℃, while the high Al content Cr0.36Al0.64N coating can be detected in the w-AlN phase after annealing at 1000 ℃. After being oxidized at 1000 ℃ for 15 h, the CrN coating has been completely oxidized, and the oxide layer thicknesses of the Cr0.75Al0.25N, Cr0.56Al0.44N, Cr0.46Al0.54N and Cr0.36Al0.64N coatings were 0.4, 0.3, 0.3 and 0.2 μm, respectively. After being oxidized at 1100 ℃ for 15 h, the CrN, Cr0.75Al0.25N and Cr0.56Al0.44N coatings were completely oxidized, while the oxide layer thicknesses of Cr0.46Al0.54N and Cr0.36Al0.64N coatings were only 2.5 and 1.4 μm. The polarization resistances of CrN, Cr0.75Al0.25N, Cr0.56Al0.44N, Cr0.46Al0.54N and Cr0.36Al0.64N coatings measured in 3.5wt.% NaCl solution were 567.69, 5.34, 71.80, 160.10 and 92.56 kΩ.cm2. Respectively, the hardness and oxidation resistance of the coating increase with the increase of Al content; the addition of Al promotes the formation of w-AlN in the coating while inhibiting the decomposition of Cr-N bond; CrN coating has the best corrosion resistance, while in the Al-containing coating, the corrosion resistance of the coating first increased and then decreased with the increase of Al content. |
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