Reduction of residual stresses in CVD diamond layers on steel parts through creation of hierarchically structured surface topographies by applying cutting processes

• Applicants: Professor Dr.-Ing. Stefan Rosiwal; Professor Dr.-Ing. Andreas Schubert
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering ; Coating and Surface Technology
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 407169265

• Final Report Year: 2024

Final Report Abstract

CVD diamond coating of steel components enables various improvements of the performance of technical systems, such as the reduction of friction and wear on tribomechanically highly stressed contact surfaces or the reduction of the adhesion tendency of functional surfaces in thermomechanical applications. Due to the different coefficients of thermal expansion of the two materials, which results in strong residual compressive stresses in the diamond layer as an effect of cooling from the coating to room temperature, the coating of steel with diamond has so far only been possible to a very limited extent, as thicker layers in particular tend to flake off. However, in combination with the TiNB intermediate layer, an interface was generated and has enabled a closed and homogeneous, adhesive CVD diamond layer with a thickness of up to 40 µm on X46Cr13. Within the project it could be determined that a substrate surface defined by ultrasonic vibration superimposed face milling has a significant influence on the distribution of the layer-inherent residual stresses. This was achieved by the help of FE analyses carried out on the cooling characteristics of the diamond layer-steel substrate composite and residual stress measurements using Raman spectroscopy in the deposited CVD diamond layers on steel. The relatively good adhesive strength of the diamond layers is also attributed to the reduction in residual cooling stresses due to the large increase in volume of this material during austenite-bainite transformation. Based on these results, the properties of CVD diamond-coated samples with a higher heat capacity and from a "less favorable" (higher bainite starting temperature) transforming steel (X40CrMoV5-1) with the resulting higher residual cooling stresses were investigated. This extended both the basic understanding of the adhesion mechanisms and the potential application possibilities. Due to its special vibration properties, it is used, for example, as a sonotrode material in the ultrasonic welding of aluminum components. This was the basis for the final application example, whereby "micro-macrostructured" and diamond-coated sonotrode tips were compared with uncoated steel tips. Aluminium sheet samples of the alloy EN AW-6082 were selected as the components to be joined. The material is characterized, among other things, by a very good weldability. The results showed a (subjectively perceived) significantly lower tendency to adhere to the CVD diamond-coated sonotrode compared to the uncoated sonotrode, thus confirming the approach of the research project.

Link to the final report

https://doi.org/10.60687/2025-0023

Publications

• Design of Deterministic Microstructures as Substrate Pre-Treatment for CVD Diamond Coating. Surfaces, 2(3), 497-519.
  Börner, Richard; Penzel, Michael; Junge, Thomas & Schubert, Andreas
  
• Reduction of thermally induced residual stresses in HF-CVD diamond coatings on steel by microstructured substrate surfaces. Vortrag und Posterbeitrag auf der International Conference on Diamond and Carbon Materials, Sevilla (Spanien)
  Göltz, M., Börner, R., Kupfer, T., Helmreich, T., Schubert, A. & Rosiwal, S. M.
  
• Simulation of cooling induced residual stress distribution in diamond layers on steel. Proceedings of the European COMSOL Conference, Cambridge (Vereinigtes Königreich)
  Penzel, M., Börner, B., Müller, F., Zinecker, M. & Schubert, A.
  
• Geometrische Oberflächencharakterisierung von durch spanende Verfahren hergestellten Mikrostrukturen. Gröger, S. (Hrsg.), Weißgerber, M. (Hrsg.): Sächsisches Geometriesymposium 2020, Chemnitz. Universitätsverlag Chemnitz, S. 143-153. ISBN: 978-3-96100-109-5
  Funke, R., Börner, R. & Schubert, A.
  
• Surface Microstructuring of Steel Components for CVD Diamond Coating by Ultrasonic Vibration Superimposed Face Milling using Tailored Tools. Procedia CIRP, 87, 234-239.
  Börner, Richard; Göltz, Maximilian; Helmreich, Thomas; Schubert, Andreas & Rosiwal, Stefan
  
• Fundamental Investigations in Tool Wear and Characteristics of Surface Microstructure for Ultrasonic Vibration Superimposed Machining of Heat-Treated X46Cr13 Steel Using Different Cutting Materials. Journal of Manufacturing and Materials Processing, 5(2), 27.
  Börner, Richard; Landgraf, Pierre; Kimme, Simon; Titsch, Christian; Lampke, Thomas & Schubert, Andreas
  
• Crystalline diamond coatings on steel. Vortrag auf der 32nd International Conference on Diamond and Carbon Materials, Lissabon (Portugal)
  Helmreich, T., Göltz, M. & Rosiwal, S.
  
• Spatial distribution of thermally induced residual stresses in HF-CVD diamond coatings on microstructured steel surfaces. Diamond and Related Materials, 136, 109931.
  Göltz, Maximilian; Helmreich, Thomas; Börner, Richard; Kupfer, Tobias; Schubert, Andreas & Rosiwal, Stefan
  
• Finite Element Analysis of Plastic Deformation in Ultrasonic Vibration Superimposed Face Milling of Steel X46Cr13. Micromachines, 15(6), 730.
  Börner, Richard; Steinert, Philipp; Bandaru, Nithin Kumar & Schubert, Andreas
  
• Influence of the width of cut in ultrasonic vibration superimposed face milling of X46Cr13 and X40CrMoV5-1 on the surface microstructure and CVD diamond coating adhesion. Procedia CIRP, 123, 215-220.
  Börner, Richard; Helmreich, Thomas; Schubert, Andreas & Rosiwal, Stefan