Enhanced tribological behavior of VAlN hard ceramic coating with intermittent amorphous carbon layer

• Published in: Ceramics international 2023-05, Vol.49 (10), p.15091-15100
• Main Authors: Zhang, Yupeng, Wang, Zhenyu, Guo, Peng, Wang, Aiying, Ke, Peiling
• Format: Article
• Language: English
• Subjects: a-C film; Friction coefficient; Lubricating phase; Transfer film; VAlN hard coating
• ISSN: 0272-8842
• DOI: 10.1016/j.ceramint.2023.01.092

Long-term lubricate coatings over a wide temperature range are prerequisite and still facing open challenge for aero-engines and sliding components in harsh conditions. In this work, DC magnetron sputtered VAlN hard ceramic coating was modified by the subsequently post-annealing treatment with graphite powder, where the intermittent amorphous carbon (a-C) top-layer was achieved under temperature of 800 °C and high vacuum. The tribological behavior of modified VAlN coatings was investigated and the results showed that displayed the high hardness of 34.4 GPa and the excellent self-adaptive lubrication from room temperature to 600 °C. Especially, due to the benefits of lamellar sliding interface between a-C top-layer and the a-C transfer film (30 nm–68 nm), the modified coating behaved the lowest friction coefficient of 0.11 at 300 °C. However, increasing the temperature to 600 °C led to the increased and stabilized friction coefficient at 0.36–0.41, which could be attributed to the formation of V2O5 lubricating phase. Further insight into the tribological behavior of the modified VAlN coating by a-C top-layer was discussed in terms of the microstructure evolution during friction test.