ICMCTF2015 Session B6-1: Coating Design and Architectures

Thursday, April 23, 2015 1:30 PM in Room Royal Palm 1-3

Thursday Afternoon

Start	Invited?	Item
1:30 PM	Invited	B6-1-1 Advanced Coating Designs for Hybrid Deposition Processes Günter Bräuer, Jochen Brand, Andreas Dietz, Martin Keunecke, Peter Klages, Michael Thomas, Michael Vergöhl, Wolfgang Viöl (Fraunhofer Institute for Surface Engineering and Thin Films IST, Germany) Current megatrends like climate change, shortage of resources, demographic change and globalization cause various challenges in fields like renewable energies, efficient production, health care or intelligent mobility concepts. In this context, also surface engineering plays an important role, and thin film architectures with increasing complexity often combining various functions like hardness, specific optical properties or hydrophilic/hydrophobic behavior are required. Today we have the choice to select amongst various process families to modify surfaces or to coat them. The most important are electroplating, evaporation, low pressure plasma deposition, diffusion treatment or wet-chemical methods. Besides these, Atomic Layer Deposition (ALD) and atmospheric pressure plasma discharges have gained an increasing importance during the last decade. Hybrid techniques using a combination of different processes are often necessary in order to meet high requirements on the performance of the modified surface. Many examples of industrial products demonstrate the successful combination of sputtering and electroplating. Satellite components operating under extreme conditions in space are initially coated by a thin sputtered Cu film, a subsequent thick silver layer for effective reflection of solar radiation is deposited by electroplating. Hardness, biocompatibility and variable colour can be combined if a sputtered thin niobium film is oxidized by anodic oxidation. The “teamwork” of surface treatment by dielectric barrier discharge and deposition sequences allows even more complex coating designs. In a so-called plasma printing process a local surface modification (generation of functional groups) is achieved by structured discharges. Subsequent local metallization is the basis for flexible circuit boards or various kinds of sensors. A well established example for the use of hybrid processes in the optical coating industry is the anti-reflective film stack on plastic lenses for ophthalmics. First a several micron thick transparent scratch resistant film is applied, deposited by PECVD or a wet-chemical process, then followed by an electron beam evaporated interference coating of anorganic materials. High performance optical filters nowadays call for more sophisticated deposition processes. Magnetron sputtering of ultrathin pure metal films and oxidation in a separate oxygen plasma has shown to be a route to meet highest demands on precision even for several hundreds of individual layers. But also the combination of sputtering, ALD and PECVD may be a promising approach for the future of optical coatings.
2:10 PM		B6-1-3 Structure and Mechanical Properties of TiAlN/ZrN Multilayer Coatings by Combining Experimental Investigation and First-principles Calculations Yuxiang Xu (Central South University, China); Keke Chang (RWTH Aachen University, Germany); Li Chen, Fei Pei (Central South University and Zhuzhou Cemented Carbide Cutting Tools Co., LTD, China); Yong Du (Central South University, China) Improvement of the mechanical and thermal properties of Ti-Al-N coatings can be obtained by multilayer architecture. Here, TiAlN/ZrN multilayer coatings, which have similar modulation period of ~6 nm and varied thickness ratios (λ) of ZrN versus TiAlN sublayers from 1:4 to 4:1, were synthetized using cathode arc evaporation. With the increase of λ value, a change from incoherent to coherent growth between TiAlN and ZrN sublayers is observed. Such a change leads to a modification of their mechanical properties. Especially, the TiAlN/ZrN coating with λ value of 4:1, which shows columnar structure with coherent growth, behaves the maximum hardness value of ~33.3 GPa. In order to better understand this structural change, the total energy and separation work of (200) crystal plane for TiAlN/ZrN are obtained by means of first-principles calculation. Increasing λ leads to a drop in the total energy as well as an elevated separation work, which is beneficial to the thermodynamic stability of coherent TiAlN/ZrN system. This calculation is in good agreement with the experimental results. The financial support from National Natural Science Foundation of China (Grant nos. 51371201 and 51371199) is highly acknowledged. Li Chen thanks the support from the teacher research foundation (Grant No. 2013JSJJ005) and YuYing plan of Central South University of China.
2:30 PM		B6-1-4 Effect of Duplex Treatment and Film Architecture on the Mechanical Properties of ZrN-TiN Multilayer Coatings Jolanta Klemberg-Sapieha (Ecole Polytechnique, Canada); Avi Raveh (Rotem Industries, Israel) Controlled microstructure may enhance the physical and mechanical properties of a singlelayer coating, while the architecture of nanolaminate coatings may significantly enhance the tribological performance while reducing residual stress. In this study, we design and fabricate different combinations of ZrN and TiN coatings on nitrided Ti-6Al-4V alloy, and we investigate their structure and mechanical properties. Single-layer ZrN and TiN, and doublelayer and multilayer ZrN-TiN coating systems with various modulation periods wereprepared by pulse-dc magnetron sputtering. The Zr and Ti targets were pulsed in asynchronized mode, both at 300 kHz and 1.1 μs reverse time. A total thickness of approximately 1 μm for each coating was obtained by adjusting deposition time. In the caseof the nanolaminate coatings, the number of sublayers was selected to be in the range of 100 to 1000 for an individual layer thickness of 1 to 10 nm (bilayer period λ of 2 to 20 nm). It was found that the nanolaminates with smaller λ improve hardness, fracture toughness, adhesion and wear. For example, the hardness of the multilayers was 32 Gpa which was significantly higher than 21 Gpa of TiN or 18 Gpa of ZrN single-layer coatings. In addition, a smaller λ led to lower compressive stress σ and friction coefficient μ. The value of σ decreased from 600 Mpa for TiN or 100 Mpa for ZrN coatings toward 20 Mpa for the multilayer ZrN-TiN coatings. Also, μ ~0.5 of the single-layer coatings decreased to 0.15 for the multilayer. With respect to tailoring the substrate-coating interface, the nitrided layer was found to be formed by a solid solution of nitrogen in titanium α-(Ti,N) leading to an improved adhesion confirmed by an increase of the scratch test critical load by one order of magnitude compared to samples with no nitriding.
2:50 PM		B6-1-5 Thermo-mechanically Optimized Multilayer Thin Films Matthias Bartosik, Melanie Todt, Helmut Riedl, Christian Koller (Vienna University of Technology, Austria); Richard Rachbauer (Oerlikon Balzers Coating AG, Liechtenstein); Helmut Böhm, Paul Mayrhofer (Vienna University of Technology, Austria) In this contribution, nitride-based multilayer thin films relevant for machining industry (e.g. Cr-Al-N) are analysed regarding their mechanical and thermal properties. In particular, the influence of chemical composition and layer thicknesses on the film structure, hardness, and residual stresses as well as the thermal properties are investigated. The latter will be studied by combining experimental thermal conductivity measurements and continuum mechanics modeling. It will be shown, how directional-dependent thermal transport properties of the coating can be tailored by optimizing the coating architecture, while at the same time sustaining high mechanical performance.
3:10 PM	Invited	B6-1-6 Customized Coating Design for Cutting Tool Applications Mirjam Arndt (Oerlikon Balzers, Oerlikon Surface Solutions AG, Liechtenstein) Regarding coatings for cutting tools, the coating supplier and tool manufacturer are confronted with different challenges. On the one hand, broadband coatings can increase efficiency of the tool manufacturing considerably, on the other hand sophisticated operations like machining of difficult to cut materials need highly specialized coating designs in order to enable efficient high performance cutting. The development of hard coatings for tooling applications requires therefore the understanding of the correlation between the physical coating properties and the application demands. The selection of the suitable combination of deposition process conditions is then essential in order to adjust the coating growth resulting in the desired property combination. This work focuses on the discussion of the influence of properties like coating microstructure, composition, and architecture on the wear behaviour and performance of hard coatings in diverse cutting tool applications like drilling and solid carbide milling of different materials.