Investigation of the influence of the manufacturing conditions and the design on the tribo-mechanical properties and residual stresses of PVD multilayer systems

• Applicant: Professor Dr.-Ing. Wolfgang Tillmann
• Subject Area: Coating and Surface Technology
• Term: from 2010 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 191961127

The residual stresses present in the PVD coatings multilayer systems have high influence in their final tribo-mechanical behaviour. In previous experiments where different multilayer systems of Ti/TiAlN where deposited by means of DCMS, has been proved that the concentration of high compressive residual stresses promote the generation of cracks and spallation of the coatings. Additionally, was evidenced that compressive residual stresses increased with increasing thickness of the metallic interlayers deposited by means of DCMS, and thus, affecting tribological and mechanical properties of the compounds multilayer/substrate. It is assumed that this behavior is due to the microstructural differences of the Ti-interlayers.On this basis, the microstructure of Ti/TiAlN multilayer coatings should be varied selectively by means of HiPIMS technology. The comparison of these coating with the above mentioned, allow demonstrating the influence of different microstructures and growing mechanisms on the residual stresses of PVD multilayer coatings. For this purpose, Ti/TiAlN HiPIMS coating designs are evalu-ated by XRD and their residual stresses depth profiles generated through cross- sectional X-ray nanobeam diffraction analysis. Moreover, due to the high residual stresses and poor tribo-mechanical response of the Ti/TiAlN coatings deposited by means of DCMS, a new combination of materials are proposed for these section of the project, TiAlN/TiAlCN. The combination of two materials which exhibit great corrosion resistant and high thermal stability together with improved tribo-mechanical behavior, because of the incorporation of carbon. Besides, and in terms of thermal residual stresses, the similarity between the new two materials, both are ceramics, has a great effect in their thermal expansion coefficients, which are also similar. Thus, thermal induced residual stresses in the system are re-duced notably.Finally and to draw conclusions about the coating architecture and combinations of materials in multilayer systems, tribo-mechanical experiments as nanoindentation, ball-on-disk experiments, scratch tests and impact tests are conducted and compared between them and the results from previous experiments.

• DFG Programme: Research Grants
• International Connection: Colombia, Taiwan
• Cooperation Partners: Professor Gilberto Bejarano, Ph.D.; Professor Dr. Yin-Yu Chang, Ph.D.
• Co-Investigator: Dr.-Ing. Ursula Selvadurai