ICMCTF2016 Session G5: Application-Driven Cooperations between Industry and Basic Research Institutions

Further progress in surface engineering is strongly stimulated by a simultaneous action of two forces: a) the “pulling force” represented by the economic, technological and societal needs including sustainable development; and b) the “pushing force” related to the curiosity-driven nanotechnology combining new design concepts of materials and devices, fabrication processes and innovative characterization tools, where the only limitation appears to be our imagination.

This presentation will describe different aspects of cooperation between our university laboratory that has developed a close collaboration with industry, while bringing together a consortium of OEM (original equipment manufacturer) partners representing different sectors. Using the setting of university-industry partnership programs in Canada, we will discuss tangible benefits for both industry and academia when developing a research program in which multiple outcomes are at stake, namely the marketable product or technology, new knowledge, and training of highly qualified personnel. We will provide specific examples of the synergies between research activities on the development of novel nanostructured coating systems related to different multibillion-dollar sectors including optics, aerospace and outer space, manufacturing, and energy generation, distribution and saving.

Within the last decade Al-Cr based oxides have attracted large interest in academic research as well as industrial coating development due to phase formation of chemically inert and wear resistant α-(Al,Cr)₂O₃ at deposition temperatures < 600°C. We present our recent findings regarding the effect of Ti incorporation in Al-Cr-Ti-O on the structure and mechanical properties. (Al_0.67Cr_0.33-xTi_x)₂O_3-z coatings (0 ≤ x < 0.18) were synthesized with a combinatorial approach by reactive cathodic arc deposition in an Oerlikon Balzers Ingenia P3e™ deposition system. Chemical composition analysis by Time-of-flight elastic recoil detection suggests the substitution of Cr by Ti, while the Al concentration remains constant. The homogeneous distribution of Al, Cr, Ti and O was examined by 3D atom probe tomography. Crystal structure investigations were carried out by X-ray diffraction and experimental evidence for α-Al₂O₃ phase formation is given in case of x < 0.05. Mechanical properties were measured by nanoindentation of polished coatings, deposited onto cemented carbide substrates. Coatings with x < 0.15 exhibit elastic modulus and hardness values of 297 ± 21 GPa and 21 ± 2 GPa, respectively, while a reduction to 236 ± 19 GPa and 13 ± 2 GPa is obtained for 0.15 < x < 0.18. The present study on the relationship between chemical composition, crystal structure and mechanical properties of Al-Cr-Ti-O contributes to the design of protective Al-Cr based oxide coatings.

Aluminum die casting is one of the most important production processes in the die casting industry. Damage mechanisms, such as abrasive and adhesive wear, corrosion due to metallic melt as well as heat-shock cracks by thermo-cyclical load, have significant influence on tool life and product quality. Aluminum die casting cores are exposed to a thermo-cyclical load, high pressures and a high flow velocity of the melt. Multilayer coatings like CrN/AlN/Al₂O₃ based on transition metal nitrides such as CrN and AlN and oxide toplayers such as Al₂O₃ deposited via physical vapor deposition (PVD), offer high potential to be used as protective coatings due to their high hardness and chemical inertness. The present work deals with the investigation of a CrN/AlN/Al₂O₃ coating deposited by using pulsed cathodic arc evaporation and two industrially used hard coatings on AISI H11 (1.2343) hot work steel after application in tribological rotating immersion tests and furthermore in industrial scale aluminum die casting machines. Therefore, the uncoated die casting cores were pretreated by a plasma nitriding and pressure blasting process in order achieve a specific stress state at the surface. These cores were coated with CrN/AlN/Al₂O₃ and two industrially used hard coatings. In order to investigate the temperature stability of the Al₂O₃ toplayer, the coating was annealed at T_F = 680 °C for t_F = 2 h and analyzed by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). For the purpose of analyzing the corrosion resistance of the coatings against aluminum die casting melt A333.1 (EN AC-46000), tribological rotating immersion tests at T_I = 680 °C for t_I1 = 2 h and t_I2 = 6 h were conducted. The tested samples were then analyzed by means of SEM and energy dispersive X-ray spectroscopy (EDS). In order to investigate the behavior of the three different coatings under realistic conditions, coated cores were tested in an industrial scale aluminum die casting machine. After 5,884 shots the coated cores were analyzed nondestructively by means of large chamber SEM and micrographs of the cores by means of SEM and EDS. It has been demonstrated that the pretreatment process led to an excellent resistance to heat-shock cracks in the die casting cores. Analyses of the thermal stability by means of TEM showed that the Al₂O₃ toplayer of the CrN/AlN/Al₂O₃ coating was deposited in an amorphous state and transformed into partially crystalline γ-Al₂O₃. Nevertheless, the results of the core analyses after 5,884 die casting shots indicate a good performance of CrN/AlN/Al₂O₃, also in comparison to industrially used coatings.

Today’s cutting applications pose extreme requirements on the mechanical, chemical and thermal stability of coated cutting tools, which are often fulfilled by applying hard coatings to cemented carbide cutting inserts. Despite the tremendous progress achieved during the past decades, there is still a serious lack of the required basic coating information needed for knowledge-based development. Furthermore, also a detailed insight in coating degradation and failure mechanisms occurring during application is often missing. Breakthroughs in development and design of novel coating materials thus require intensive contributions from basic research, enabling access to sophisticated methods and facilities to provide the necessary information about coating microstructure and properties, and industry, defining needs and requirements and providing access to applications. Within this presentation, an example for a successful industry/university collaboration is given. There, advanced characterization techniques like site-specific preparation of coating cross-sections by focused ion beam milling, electron backscatter diffraction and synchrotron X-ray nanodiffraction enable to obtain the necessary depth-resolved information on coating microstructure and mechanical properties. With the feedback from application tests, the established fundamental understanding of microstructure/property/performance relations provides the basis for a knowledge-based design of advanced coating materials.