| Title |
Study on Wear Resistance and High Temperature Stability of Cr-Al-N/Al2O3 Hard Coating Deposited by Magnetron Sputtering |
| Authors |
이범무(Beom-Mu Lee) ; 김왕렬(Wang Ryeol Kim) ; 박인욱(In-Wook Park) ; 허성보(Sung-Bo Heo) ; 이욱진(Wook-jin Lee) |
| DOI |
https://doi.org/10.3365/KJMM.2026.64.9.780 |
| ISSN |
1738-8228(ISSN), 2288-8241(eISSN) |
| Keywords |
Wear resistance; Hard coating; Hardness; Oxidation resistance |
| Abstract |
Cr-Al-N/Al2O3 composite coatings were deposited via magnetron sputtering to improve the wear resistance and high-temperature stability of conventional Cr-Al-N hard coatings. The Cr-Al-N layer was deposited using reactive DC magnetron sputtering, followed by the deposition of an Al2O3 top layer by RF magnetron sputtering at temperatures ranging from 400 to 700 °C. The effects of the Al2O3 deposition temperature on the microstructure, mechanical properties, tribological behavior, adhesion, and oxidation resistance of the coatings were systematically investigated. X-ray diffraction analysis confirmed that all coatings maintained a cubic-structured c-(Cr, Al)N phase with a preferred (200) orientation, while the crystallinity of the Al2O3 layer gradually increased with increasing deposition temperature. In particular, γ-Al2O3 diffraction peaks were observed above 500 °C, indicating enhanced crystallization of the oxide layer. Mechanical properties, including hardness, elastic modulus, H/E, and H3/E2, were strongly dependent on the Al2O3 deposition temperature, with the coating deposited at 700 °C exhibiting the highest hardness of approximately 28 GPa along with improved resistance to plastic deformation. Rockwell adhesion tests revealed severe cracking and delamination at 400 °C, whereas coatings deposited at 500-700 °C showed stable adhesion with minimal interfacial failure. Tribological tests demonstrated that the coatings deposited at higher temperatures exhibited lower friction coefficients and improved wear resistance, owing to the formation of stable Al-O-based tribolayers and enhanced interfacial bonding between the nitride and oxide layers. Furthermore, high-temperature oxidation tests performed at 900-1,100 °C revealed that the Al2O3 top layer effectively suppressed oxygen diffusion and reduced the formation of porous oxide scales compared to the monolithic Cr-Al-N coating. These results indicate that the deposition temperature of the Al2O3 layer plays a critical role in determining the structural stability, tribological performance, and oxidation resistance of Cr-Al-N/Al2O3 composite coatings, with the 700 °C condition demonstrating the optimal overall performance. |