Analyses of the influence of diamond-like-carbon (DLC) coatings on the fatigue behavior of Ti6Al4V and its corresponding crack initiation mechanisms

• Applicant: Professorin Dr.-Ing. Martina Zimmermann
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins ; Coating and Surface Technology
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 566407620

In the project, a material-physical understanding of the influence of a hard coating, primarily designed as wear-resistant, on the fatigue behavior of a component compared to the uncoated state at room temperature and an application-relevant temperature of 300 °C is being developed. This is exemplified by the material composite Ti6Al4V base material with DLC coating. The ta-C variant is chosen as the coating system, as this is the hardest and most wear-resistant coating variant for particularly demanding tribolog-ical applications and ta-C can be deposited almost defect-free in a wide range of varying coating properties of hardness, modulus of elasticity and topography. The aim is to investigate what kind of precursors of fatigue crack initiation occur or are suppressed in this material composite with a transition from amorphous (ta-C) to crystalline (Ti6Al4V) structure and what effect they have on the fatigue strength. The planned fatigue tests will be supplemented by two new methodological approaches to clarify the development of damage. On the one hand, cyclical indentation for the preliminary estimation of coating fatigue is to be systematically investigated and evaluated according to the respective damage phenomena. On the other hand, the use of surface wave spectroscopy serves as indirect detection of fatigue crack initiation in the hard-to-access layer-substrate composite. After completion of the project, the dominant influencing variables of the layer-substrate composite on its fatigue behavior and a possible temperature influence have been clarified.

• DFG Programme: Research Grants