Influence of HPPMS pulse parameters on the stoichiometry and the formation of reaction layers on nitride hard coatings for cutting applications

• Applicant: Professorin Dr.-Ing. Kirsten Bobzin
• Subject Area: Coating and Surface Technology ; Metal-Cutting and Abrasive Manufacturing Engineering
• Term: from 2016 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 321041164

• Final Report Year: 2024

Final Report Abstract

The forming of high-strength steel sheets for automotive body production places high demands on service life of the forming tools. Powder metallurgically (PM) produced high-speed steels, due to their homogeneous microstructure, high hardness and high toughness, are well-suited for production of such forming tools. The hard machining of these forming tools requires cutting tools with exceptional wear resistance. Finely distributed carbides in high-speed steels may cause high abrasive wear on both rake and the flank face of the cutting tool. Furthermore, due to the oxidation and high temperatures during the cutting process, high thermal resistance of the cutting tools is required. Here, nanocomposite (nc) TiAlCrSiN and TiAlCrSiON coatings, produced by pulsed high-power plasmas in physical vapour deposition (PVD), offer a promising solution to increase the service life of cutting tools. Hence, the main goal of the research project was to gain understanding on the influence of process parameters on coating properties and stoichiometry of the reaction layers as well as the effect of the chemical composition of nanocomposite coatings on tool damage behaviour during milling of PM HS6-5-3C. It was shown that the chemical composition of the reaction layer can be controlled by the targeted addition of oxygen during the coating process. Furthermore, the coatings fulfil their function as a diffusion barrier between the steel and the coated cemented carbide. The phase stability, oxidation resistance, elastic-plastic properties and application behaviour of the coatings were analysed in correlation with the process parameters and a suitable process window for depositing wear-resistant TiAlCrSiN and TiAlCrSiON nanocomposites was identified. Moreover, the influence of oxygen incorporation on the friction and damage behaviour of the coated tools during milling of PM HS6-5-3C was studied. It was found that the TiAlCrSiON top layer may reduce friction between the coated carbide tool and the steel workpiece, thereby increasing the tool life. Increasing the aluminium content of the coatings also exhibited promising potential for improving the wear resistance of the coated tools. The findings regarding the influence of oxygen incorporation in top layer on the friction and application behaviour of the coated tools were also transferrable to Al-rich coatings. Thus, the research project represents an important step towards the qualification of TiAlCrSiN and TiAlCrSiON nanocomposite coatings for cutting of PM high-speed steels.

Publications

• Nanocomposite (Ti,Al,Cr,Si)N HPPMS coatings for high performance cutting tools. Surface and Coatings Technology, 378, 124857.
  Bobzin, K.; Brögelmann, T.; Kruppe, N.C. & Carlet, M.
  
• HPPMS TiAlCrSiN - Influence of substrate bias and pulse frequency on cutting performance. Surface and Coatings Technology, 397, 126056.
  Bobzin, K.; Brögelmann, T.; Kruppe, N.C. & Carlet, M.
  
• Wear behavior and thermal stability of HPPMS (Al,Ti,Cr,Si)ON, (Al,Ti,Cr,Si)N and (Ti,Al,Cr,Si)N coatings for cutting tools. Surface and Coatings Technology, 385, 125370.
  Bobzin, K.; Brögelmann, T.; Kruppe, N.C. & Carlet, M.
  
• HPPMS tool coatings: Chip formation and friction. Vakuum in Forschung und Praxis, 33(4), 26-33.
  Bobzin, K.; Brögelmann, T.; Kruppe, N.C.; Carlet, M.; Hoffmann, D.C.; Breidenstein, B.; Krödel, A. & Beblein, S.
  
• Influence of residual stresses in hard tool coatings on the cutting performance. Journal of Manufacturing Processes, 69, 340-350.
  Bobzin, K.; Brögelmann, T.; Maier, H.J.; Heidenblut, T.; Kahra, C. & Carlet, M.
  
• Qualification of PVD Coatings for Machining Using a Planing Test Setup. Lecture Notes in Production Engineering, 301-309. Springer International Publishing.
  Carlet, M.; Hoffmann, D. C.; Kruppe, N. C.; Brögelmann, T.; Bobzin, K.; Beblein, S.; Krödel, A. & Breidenstein, B.
  
• Tribological behavior of TiAlCrSiN coated cutting tools. Vakuum in Forschung und Praxis, 36(3), 18-22.
  Bobzin, Kirsten; Kalscheuer, Christian & Tayyab, Muhammad