| WANG Bei-chuan,CHEN Li.Effect of Al Content on Microstructure and Properties of TiAlN Coatings[J],51(2):29-38 |
| Effect of Al Content on Microstructure and Properties of TiAlN Coatings |
| Received:November 29, 2021 Revised:January 14, 2022 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2022.02.003 |
| KeyWord:TiAlN hardness thermal stability oxidation resistance corrosion resistance |
| Author | Institution |
| WANG Bei-chuan |
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 Co., Ltd., Zhuzhou , China |
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| Abstract: |
| To investigate the effect of Al content on structure as well as mechanical properties, thermal stability, oxidation resistance and corrosion resistance of TiAlN coating completely, we deposited 4 Ti1‒xAlxN coatings by cathodic arc evaporation on Ti, Ti50Al50, Ti40Al60 and Ti33Al67 targets. The composition, structure, mechanical properties, thermal stability, oxidation resistance and corrosion resistance of Ti1‒xAlxN coatings were studied in detail by energy-dispersive X-ray spectrometer (EDX), X-ray diffraction, scanning electron microscopy (SEM) with, nanoindentation, thermal gravimetric analyzer (TGA) and electrochemical workstation. All Ti1‒xAlxN coatings exhibit a face-centered cubic (fcc-) structure. With the increase of Al content, the hardness values of Ti1‒xAlxN continue to increase from ~26.4 GPa of TiN to ~32.7 GPa of Ti0.38Al0.62N. We detected the wurtzite (w-) AlN phase in Ti0.55Al0.45N and Ti0.44Al0.56N after annealing at 1100 ℃, however, in Ti0.38Al0.62N decrease to 1000 ℃. During the annealing process, the Ti0.55Al0.45N and Ti0.44Al0.56N show the highest hardness of ~32.8 GPa and ~33.3 GPa after annealing at 900 ℃ respectively, and Ti0.38Al0.62N exhibits the highest hardness of ~36.2 GPa at 800 ℃. After oxidation at 800 ℃ for 20 h, the TiN coating has been completely oxidized, while the oxide layer thicknesses of Ti0.55Al0.45N, Ti0.44Al0.56N and Ti0.38Al0.62N coatings were ~3.5 μm, ~0.6 μm and ~0.6 μm, respectively. In addition, the oxidation activation energies of Ti0.55Al0.45N, Ti0.44Al0.56N and Ti0.38Al0.62N in parabolic oxidation stage are 530.9 kJ/mol, 370 kJ/mol and 375.9 kJ/mol, severally. The last, the polarization resistance of TiN, Ti0.55Al0.45N, Ti0.44Al0.56N and Ti0.38Al0.62N is 4.59× 104Ω·cm2, 1.97×103 Ω·cm2, 3.71×103 Ω·cm2 and 4.42×104 Ω·cm2, respectively. In summary, within x<0.62, the coating maintains a single-phase cubic structure. With the increase of Al content, the lattice constant and grain size are reduced, the hardness values of Ti1‒xAlxN continue is increased, and thermal decomposition is promoted. Ti0.44Al0.56N coatings have the best oxidation resistance. In addition, the introduction of Al reduces the corrosion resistance of the TiN coating, but the corrosion resistance of Al-containing coatings increases with increasing Al content. |
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