Generation and Preconditioning of Aluminium Matrix Composite Friction Surfaces of Braking Discs

• Applicants: Professor Dr.-Ing. Thomas Lampke; Professor Dr.-Ing. Andreas Schubert
• Subject Area: Coating and Surface Technology ; Metal-Cutting and Abrasive Manufacturing Engineering
• Term: from 2020 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 414236319

• Final Report Year: 2024

Final Report Abstract

Particle-reinforced aluminium matrix composites (AMCs) are promising materials to be used in moving components subjected to tribological load. Suchlike parts are represented by friction rings of brake discs. This is due to the ideal combination of lightweight material and high wear resistance, that can be gained from targeted AMC material designs. From a tribological point of view, particle-reinforced AMCs comprise a comparatively soft aluminium-based matrix with low thermal load-bearing capacity and a hard, temperature-resistant phase of ceramic particles. The use of AMCs in safety-relevant brake systems requires a defined and steady-state friction behaviour, which can be achieved through the controlled formation of a tribological friction layer (tribofilm). The friction layer’s properties and formation speed can be influenced by the AMC’s surface geometry. The aim of the research project was to improve the formation of nearly wear-free tribofilms on AMC samples reinforced by a volume proportion of 35% silicon carbide particles. In order to simulate the tribological conditions in automotive brake systems, specifically finish-machined AMC samples were tested in a pin/disc tribometer setup against conventional brake pad material under dry sliding conditions. The surfaces were generated by previous face turning with different CVD diamond tipped indexable inserts, feeds, superimposed ultrasonic vibrations or additional plasma-electrolytic treatment. The influence of the respective surface microstructurewas investigated at different test pressures, speeds and glide paths. The investigation focussed on the tribofilm build-up phase, i.e. the stage at which the protective tribolayer begins to form. Surface analyses show that a kinematic microstructure with high roughness values and distinct edges, resulting from the finishing process, leads to a faster and more homogeneous tribological film build-up.

Publications

• Influence of the kinematic roughness resulting from facing of AMC specimens on preconditioning of friction surfaces. CIRP CSI, 08. ‒ 10.06.2022, Lyon (Frankreich)
  Eiselt, P.; Hirsch, S. J.; Nestler, A.; Grund, T.; Schubert, A. & Lampke, T.
  
• Influence of the kinematic roughness resulting from facing of AMC specimens on preconditioning of friction surfaces. Procedia CIRP, 108, 1-6.
  Eiselt, Patrick; Hirsch, Sarah J.; Nestler, Andreas; Grund, Thomas; Schubert, Andreas & Lampke, Thomas
  
• Preconditioning of aluminium matrix composites for brake disc applications. 23. Symposium Verbundwerkstoffe und Werkstoffverbunde, 20. ‒ 22.07.2022, Leoben (Österreich)
  Hirsch, S. J.; Bergelt, T.; Schwöbel S. D.; Eiselt, P.; Grund, T.; Lampke, T. & Schubert, A.
  
• Erzeugung und Vorkonditionierung von Reibflächen an Bremsscheiben aus Aluminiummatrix-Verbundwerkstoffen (Erkenntnistransfer-Projekt). Gemeinschaftsausschuss Kombinierte Oberflächentechnik, 21.03.2023, Dresden
  Hirsch, S. J.
  
• Investigation of the Tribological Behaviour of Various AMC Surfaces against Brake Lining Material. Materials, 16(3), 1001.
  Hirsch, Sarah Johanna; Eiselt, Patrick; Ozdemir, Ismail; Grund, Thomas; Nestler, Andreas; Lampke, Thomas & Schubert, Andreas
  
• Surface conditioning effects on the tribological behavior of AlSi7Mg/SiCp composites for brake disk application. FEMS Euromat, 03. ‒ 07.09.2023, Frankfurt am Main
  Ozdemir, I.; Hirsch, S. J.; Eiselt P.; Grund, T.; Nestler, A.; Lampke, T. & Schubert, A.