Titel ta-C coatings for automotive applications
Autor Christian Scholz1*, Juergen Becker1, Neir Beganovic2, Astrid Gies2, Johann Karner2, Joerg Vetter3
Infos zum Autor

1) Dr. Juergen Becker, Dr. Christian Scholz, Oerlikon Balzers Coating Germany GmbH, Am Ockenheimer Graben 41, 55411 Bingen, Germany

2) Neir Beganovic, Dr. Astrid Gies, Dr. Johann Karner, Oerlikon Surface Solutions AG, Iramali 18, 9496 Balzers, Liechtenstein

3) Dr. Joerg Vetter, Oerlikon Balzers Coating Germany GmbH, Am Boettcherberg 30- 38, 51427 Bergisch Gladbach, Germany

*) Corresponding author: christian.scholz@oerlikon.com, Tel.: +49 (0)6721 793 387

Inhalt Diamond Like Carbon (DLC) coatings and in particular the hydrogenated a-C:H coatings are widely used where friction and wear reduction is required. However, a-C:H coatings have a limited thermal stability and start to graphitize at temperatures higher than about 300°C. Depending on the contact pressure, graphitization might even occur at much lower temperatures. In addition, the tribological performance of a-C:H coatings can be negatively influenced by different lubricants and additives.
To overcome the drawbacks of a-C:H coatings hydrogen-free DLC coatings like ta-C and a-C are currently investigated as a possible solution. ta-C shows a significant higher coating hardness than a-C:H coatings and due to the lack of hydrogen a different surface chemistry which results in a different behavior under lubricants. ta-C is usually deposited by high-energy deposition processes like arc evaporation; the arc evaporation is possible with or without filtering. Inherent to these processes is the generation of coating defects like droplets. A suitable post-treatment is mandatory to reduce the roughness to an acceptable level. High roughness in combination with a high coating hardness would lead to significant counter body wear.
In this work, the thermal stability of ta-C coatings and their compatibility with different lubricants additives was investigated. The results of ta-C were compared to the results of a C:H and MoN.
Datum 2018