The traditional V2021 event on plasma and vacuum technology for surface finishing took place from October 12 - 14, 2021 at the International Congress Center Dresden with 370 participants. Organized by the European Research Association for Thin Films (EFDS), energy, bio and medicine, optics as well as tools and components played a role in workshops.
The energy transition through thin films
The energy transition continues to progress both in Germany and worldwide. Many issues are still unresolved. Modern energy systems play a decisive role in shaping our future in an ecologically sustainable way - in the use of renewable energies, in energy conversion and storage and in the reduction of heat loss. Thin layers and layer systems play a key role in determining performance and price. This requires an optimal material design of the layer systems combined with perfectly adapted process technology. Different strategies and technologies are in competition and must assert themselves on the market in order to make the required increases in efficiency and cost savings a reality.
Siemens Energy built the world's largest PEM (proton exchange membrane) electrolysis cell for hydrogen production in 2018. The plant is powered by electricity from renewable sources such as wind or solar. In 24 modules, 335 kilograms of green hydrogen can be produced per hour with a maximum power consumption of 17.5 MW. However, this hydrogen is still very expensive, as Yashar Musayev, Siemens Energy Global GmbH & Co KG, reported.
Various coatings of bipolar plates for PEM fuel cells used in passenger cars were presented by Gerrit Jan van der Kolk, Ionbond AG Netherlands. The target value for the service life of fuel cells in cars is 10,000 hours. Various dopings on titanium plates were examined. Doping with gold and platinum provided good corrosion protection. The carbon layers were also the most stable in terms of mechanical stability.
Fabian Bergenthun, Zentrum für Brennstoffzellen Technik GmbH, also discussed various coatings for metallic fuel cells. Metallic bipolar plates are thinner than graphite polar plates and have good mechanical properties. However, coatings are necessary to prevent corrosion.
Barriers on the cathode particles enable a longer service life for Li-ion batteries. OLEDs and solar cells are also protected with barriers to prevent the lateral penetration of water vapor through permeation and to protect the components from corrosion. (Spatial) ALDs are ideal for barriers, as Hannes Klumbies, FHR Anlagentechnik GmbH, summarized. Atomic Layer Deposition (ALD) is used for surface conformal deposition without shading at 80 to 100 degrees Celsius, whereby coatings with Al2O3, TiO2, ZnO or SiO2 are possible. Spatial ALD enables high productivity, but is cost-intensive.
The acceptance of electric cars depends on the range and fast-charging capability of the batteries. With 5 minutes charging, 80 % of the capacity should be reached. When using graphite anodes containing Si, the lithium is well distributed on the anode, but there is already a loss of capacity of up to 40% in the first cycle of discharging or charging. The vacuum coating process of lithium prevents the loss of capacity, as Daniel Stock, Applied Materials WEB Coating GmbH, reported.
Although perovskite silicon tandem solar cells have the best efficiency of 29.5%, they cannot yet be manufactured industrially. Daniel Amkreutz, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, emphasized that this will only be possible in around 5 to 6 years. Triple solar cells with even higher efficiency have already been developed.
Vacuum-processed organic photovoltaics enable environmentally friendly electricity production. Karsten Walzer, Heliatek GmbH, described the process sequence and many example applications. Organic solar film can be applied to smooth facades and curved surfaces, such as the towers of wind turbines, because they are flexible, ultra-thin and lightweight. They can also be easily retrofitted.
The energy required to cool buildings has risen steadily in recent years, one reason being the huge window façades. Energy can be saved with effective solar shading on windows. Electrochromic glass as an energy-saving technology for the building envelope was presented by Alexander Kraft of ChromoGenics AB (Sweden). An electrochromic film is applied between the window panes. The film is colored by means of electronic control. Until now, all windows had to be wired individually, which is time-consuming and expensive, but soon there will be dynamic glass without cables.
Jolanta Szelwicka, Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, presented VO2-based thermochromic coatings on ultra-thin glass for smart energy saving in buildings with a high proportion of windows and glass façades. The thermochromic layers are applied to thin glass in a roll-to-roll process. The optical properties of the thermochromic layers change due to the temperature.
Materials in contact with hydrogen
This year, the focus was on "Hydrogen as a key element for the energy transition" and was addressed by Christian Elsässer, Fraunhofer Institute for Mechanics of Materials IWM, as a keynote speech. "Green" hydrogen is produced by electrolysis. The production, distribution and use of hydrogen place high demands on materials. This is because molecular or atomic hydrogen can penetrate the materials and lead to mechanical or chemical changes, which in turn can result in the failure of components. The lecture presented experimental methods for measuring and testing the mechanical behavior of materials in contact with hydrogen. The speaker also discussed theoretical models and computer simulations of material physics and material mechanics.
Thin layers and surfaces for tools and components
Industrial exhibition with a view of the Elbe. 68 companies, 5 research institutes and 2 associations presented themselves hereFunctionalsurfaces determine the usage properties, service life and functionality of components in many areas of product development, i.e. the performance and thus the value for the user. The use of technologies from the field of industrial surface technology makes it possible to refine surfaces to such an extent that significant added value is created.
The application of tetrahedral amorphous carbon coatings (ta-C material) to motorcycle chains reduces the coefficient of friction from approx. 0.7 to approx. 0.1 on the chain rollers (to the chain sprocket and wheel) and sleeves (to the inside of the rollers), thus reducing wear to such an extent that the motorcycle chains no longer need to be re-tensioned, as Franz-Josef Wetzel, BMW Group Motorrad, said.
The temperature resistance of diamond-like carbon layers can be increased by variable doping with silicon. Julia Wöckel, Robert Bosch Manufacturing Solutions GmbH, explained the topic using the example of injector components coated with carbon-containing wear protection layers, the so-called "diamond-like carbon" layers (DLC or a-C:H). An a-C:H:Si coating was developed that meets the requirement of higher thermal resistance with the same wear protection. Resistance to oils has not yet been tested.
Ricardo Brugnara, Schaeffler Technologies AG & Co. KG, presented studies on optimizing the tribological efficiency of rolling bearing components with modified ta-C coatings. Different doping elements were examined in the lubricated tribocontact. In addition to analyzing the mechanical and topological properties, the various doped ta-C coating systems were compared with a non-doped ta-C coating. It was shown that the doping element has a significant influence on the roughness.
With HiPIMS (high-energy pulse magnetron sputtering), an innovative leap forward has been achieved. The dense, fine-grained structure of HiPIMS coatings (12 µm) exhibits not only toughness but also hardness and wear resistance, as Christoph Schiffers, CemeCon AG, pointed out. The coatings can be precisely adapted to the geometry of the tool via the pulse parameters. For example, super-hard TiAlSiN coatings were produced on micro-tools with the highest Si content for medical technology.
Daniel Barnholt, voestalpine eifeler Vacotec GmbH, presented an innovative wear protection for machining, gear cutting and forming. High-alloy materials, heat- or corrosion-resistant materials place high demands on machining and forming. AlCrN-based PVD coatings (physical vapor deposition) are very suitable for tools as they have excellent oxidation resistance, abrasion resistance and sliding wear resistance. For better adhesion, the coating is applied in a gas mixture of argon and nitrogen, whereby not only AlCrN but also AlTiN is used.
Tim Krülle, TU Dresden, discussed PVD coating concepts for the challenges of tomorrow. PVD hard coatings have been protecting tools from wear and tear for many decades and play a key role in determining their performance characteristics. High coating hardness and temperature resistance are crucial in this respect. Suitable process parameters can be used to influence coating growth and the production of sharp edges is now possible. The chemical composition (e.g. AlCrSiN/TiN) is also adapted.
Artificial intelligence
Digitalization has made rapid progress in the last year. Klaus Böbel, Robert Bosch Manufacturing Solutions GmbH, presented fully networked manufacturing - smart production for surface processes. Networking offers great opportunities in surface technology in terms of quality optimization and increased productivity. It is necessary to consider the entire production chain. Intelligent production facilities make production "smart". With the correlation of data from production, starting points for optimization are already available today. For example, relevant environmental factors such as temperature, humidity, particle load or the inspection status of the coating system can be evaluated and the connection to the quality achieved can be established. Productivity can be increased through intelligent production planning, which takes into account incoming goods, delivery planning, personnel utilization, processing times and online tracking. The use of artificial intelligence requires high quality data.
The symposium and industry exhibition brought together employees from research institutes, suppliers of high-performance metals and materials, manufacturers of systems for industrial vacuum coating and component manufacturers. Current trends and the latest results were presented. In a workshop, practical demonstrations were given on systems at von Ardenne GmbH in Dresden. The opportunity to meet and exchange ideas in person at a face-to-face event ensured an intensive exchange of experiences and was very much welcomed by the participants.
