Due to the pandemic, the ZVO Surface Days took place this time with a reduced audience and without supporting programs.
Climate neutrality
Climate neutrality - this topic was also on the agenda in the first block of the ZVO Surface Days. Jan Mehlberg, MVV Enamic GmbH, presented the move towards a decarbonized future. In recent years, climate change has led to a social rethink to stop the rise in the global average temperature. By recording the individual consumption structures in the company, drawing up a carbon footprint and defining their own climate protection targets, from which the measures are determined and ultimately implemented, companies can achieve climate neutrality step by step. The company's upstream and downstream activities are also included in the assessment of climate targets, with logistics playing a special role. The speaker suggested that the carbon footprint should be product-related.
Lars Baumgürtel, ZINQ Technologie GmbH, also spoke in favor of a product passport. Economic growth should be defined by quality and not quantity. The design of a product should also be adapted to the requirements of recycling. For example, he is critical of the material used for the rotor blades of wind turbines, which cannot be recycled. Circular business models must be geared towards decarbonization, waste-free and emission-free production.
Michael Zöllinger, Dr.-Ing. Max Schlötter GmbH & Co. KG, reported on the energy efficiency of electroplating systems. The main energy consumers, such as rectifiers, heating and cooling for the process solutions and room air, electrical drives, compressed air, dryers and lighting, should be as energy-efficient as possible. As an example, he cited the optimum matching of the anode surface and the anode material to the electrolyte. The lower the anodic current density, the lower the bath voltage required, resulting in higher efficiency. Therefore, the overall system, electrolyte composition and anode material must always be considered in order to both deposit layers of perfect quality and work in an energy-efficient manner.
Digitalization in electroplating technology
This lecture block began with a presentation by Peter Schwanzer, Fraunhofer IPA. In a small electroplating machine with a bath volume of 50 to 60 liters, 6 active stations including rinsing, trolley and peripheral equipment, data is collected for process optimization, such as the electrolyte composition for predictive electrolyte maintenance. The learning electroplating system can also be used to inform and train employees. In addition, new application products can be tested and validated in learning electroplating. The speaker emphasized that, in addition to the research project "Intelligent, augmented reality-supported production processes in electroplating technology (SmARtPlaS)", the learning electroplating system was also designed as a demonstrator and is open to new ideas and approaches.
Christine Maier, Dr.-Ing. Max Schlötter GmbH & Co. KG, presented digital solutions for electroplating technology. As an inspiration for her own solutions, she recommended finding out about digital solutions in other industries and adapting them. As examples, she cited woodworking with tool management, furniture configuration, cutting optimization and the steel industry, which enables registered customers to intervene in production planning and thus increase delivery reliability. Approaches can be derived from this for electroplating technology. Individual processes can be optimized through targeted online data collection. For example, service can be supported, orders planned or machines and processes monitored.
Key figures are becoming increasingly important and form a basis for innovations to support planning, control and monitoring tasks in the company, says Michael Hellmuth, Softec AG. Complex relationships can be represented with key figures and related to customers and delivery times. Printed delivery bills have many disadvantages, in particular that they take much longer to process. Apps on employees' smartphones can be used to quickly transfer important information such as incoming goods, machine occupancy or planned orders. With RFID-tagged goods, movement profiles are created and the processing status is visible at all times. This makes it easier to plan and react spontaneously to unplanned orders. Relevant information and photos are stored for quality assurance purposes.
Cathodic corrosion protection
Andreas Tolz, NOF Metal Coatings Europe S. A., gave a progress report on water-based zinc flake technology in series application on car chassis components. The zinc flake coating (layer thickness: only 5 to 15 µm) offers excellent corrosion protection. It is possible to coat cavities without using solutions containing chromate or heavy metals. The electroless coating also prevents hydrogen embrittlement. The zinc and aluminum flakes are bound in a sol-gel binder matrix. An additional topcoat can be used. The process begins with alkaline degreasing and shot blasting, then the zinc flake coating is applied using the rack dip-spin process and then baked and cured at approx. 300 °Celsius. The zinc flake coating and baking process steps must be carried out twice to ensure long-term corrosion protection.
Sebastian Hahn, Atotech Deutschland GmbH, presented resource-saving passivation solutions. Chromium(III)-valent passivation layers are applied to zinc or zinc alloy layers for corrosion protection. The service life of the passivation is shortened by the iron and zinc ions introduced. The foreign metals can be removed by ion exchangers. By using an inhibitor, the pH value is adjusted to 2.5 and iron dissolution is significantly inhibited. The inhibitor has no influence on the passivation process and consistently good corrosion properties are maintained. Longer passivation lifetimes help to reduce the use of chemicals and thus save resources in production.
Zinc-chromium alloy coatings offer better corrosion protection than simple zinc coatings.
Andreas Bán, VDEh-Betriebsforschungsinstitut, reported on kinetic investigations into zinc-chromium deposition under direct and pulsed current conditions. The electrolyte composition, the current density and the speed of a cylinder electrode were changed and tests were carried out under direct and pulsed current conditions. The kinetic inhibition of zinc deposition during zinc-chromium alloy deposition can be adjusted using organic additives. A desired chromium content in the zinc-chromium layer is also possible in principle by adjusting the relative current density. Due to the dependence of the chromium content on the relative current density, a flexible production method with different throughput speeds and current densities is difficult. For a flexible production method, either the flow speed in the cell must be regulated or the current density must be modulated in order to keep the relative current density constant.
New requirements for electroplating and surface technology
Annika Bauer and David Zapf, Hansgrohe SE, presented a process for recovering palladium from rinsing water. Tin-palladium complexes are used to activate plastic surfaces so that they can be electroplated. The palladium contained in the rinsing water can be present in both particulate and ionic form. Elimination is therefore carried out by means of filtration and ion exchange. The filtration tests show a pH dependency. First the palladium is removed by pre-filtration with a cartridge filter (1 µm), then the pH value is raised, tin agglomerates are removed via a pleated filter (0.5 µm) and in the final step the palladium is adsorbed on amine-doped ionic surfaces. Rising palladium costs make the multi-stage process economical.
Peter Böttcher, SurTec Deutschland GmbH, gave an overview of the current status of REACH-compliant substitution of chromium(VI) in electroplating and presented decorative chromium(III) coatings. Chromium(III) coatings are used in series production for decorative purposes while retaining characteristic properties such as color and corrosion resistance and meet the increasing OEM requirements. The chromium(III) electrolytes can be integrated into existing lines and the coating costs are stable, although maintenance costs must be taken into account. Work is underway on a new generation of chromium(III) electrolytes to reduce coating times to less than 5 minutes, use fewer complexing agents, eliminate boric acid and work without cooling. Chromium(VI)-free pickling agents for plastic electroplating will not be available on the market for another 5 to 6 years.
Joachim Becker, Conventya GmbH, presented a sustainability analysis using the example of an alkaline zinc-nickel electrolyte. In a conventional zinc-nickel electrolyte that works with steel anodes, the organic additives are oxidized. Heat is released and cyanides and sodium carbonate are formed. Only 50 to 60 % of the applied current is used for metal deposition. These disadvantages no longer occur when using the PERFORMA3S anode. The anode is made of stainless steel and coated with a ceramic membrane, which prevents oxidation of the organic additives. The energy-intensive cooling of the electrolyte and anolyte can be reduced when using the 3S membrane system, as low voltages are constantly applied. With the PERFORMA3S anode, up to 75% of the total energy requirement and the resultingCO2 emissions can be saved compared to conventional zinc-nickel electrolytes.
Electroless nickel-phosphorus coatings are widely used due to their high resistance to wear and corrosion. The phosphorus content determines the respective application. Lars Lehmann from Chemnitz University of Technology investigated whether hard chrome coatings can be replaced by electroless nickel coatings. He compared industrially deposited hard chrome coatings with electroless nickel coatings also deposited in practice in terms of wear resistance, abrasion, adhesion and plastic deformation as criteria for guideline values for the application. The documentation is intended to help users to use the optimum electroless nickel electrolyte for them if they need to substitute hard chrome for electroless nickel.
Energy and material efficiency, resource and environmental protection in electroplating and surface technology
High-quality surfaces are required in the automotive industry, and various coating technologies are available. The respective application should not only be based on the required quality or design, but also take resource efficiency and recycling into account, as Felix Heinzler, BIA Kunststoff- und Galvanotechnik GmbH & Co KG, emphasized. Using the example of a plastic trim frame in the center console, he compared painting with electroplating. Because the waste was lower with electroplating, the energy consumption andCO2 emissions are lower, although the painted plastic parts only represent just under 55% of the value. A higher reject rate is therefore currently worthwhile. The speaker advocates the recycling of all coated components. To this end, metals and plastics must be separated and the ABS polymer mixtures processed so that ABS recyclate components can also be processed in future.
Diffusion dialysis has been used for many years to recover valuable materials from etching media. Rainer Klein, Spiraltec GmbH, reported on membrane spiral wound modules that can be used to recover free acids and dissolved metals from acidic process solutions. The metal ions are retained on the anion exchange membranes so that the acid can be reused in the diffusate. Further application examples are the recovery of hydrochloric acid in hot-dip galvanizing, sulphuric acid in anodizing or the recovery of chromic acid. Thanks to the compact design of the spiral wound modules, the system can be implemented in existing production plants to save space.
Operators of wastewater treatment plants know that micro-organisms can grow if the sedimentation tank or sludge collector is left standing for too long. Organic substances in the wastewater serve as food. Reactions between the decomposition products cause heavy metals that have already been precipitated to dissolve again and the metal limit values are exceeded. Alois Kinateder, GusChem G. & S. Philipp Chemical Products, gave tips on how to avoid these problems. He suggests disposing of fats and oils externally, using bentonite mixtures instead of polymer flocculants, aerating with oxygen to avoid anaerobic areas and reducing COD and AOX with precipitants and flocculants containing activated carbon. During shutdowns, the tanks should be emptied and limescale incrustations removed regularly. By adding biocides to the batch treatment, previously cleaned tanks can be protected against microbial infestation for longer. The treated wastewater is then easy to filter and dry filter cakes are obtained.
Marc Longerich, SurTec Deutschland GmbH, and Marco Rösch, SurTec International GmbH, spoke about sustainability in surface technology. Sustainability serves the economic use of limited resources so that they are never exhausted. Individual processes on their own often play only a minor role in the global life cycle of products, raw materials and water. Recycling measures are usually only used when they bring economic benefits. However, a longer service life makes ecological sense. Using the example of hot degreasers, which can be used much longer than conventional ones because builders and surfactants can be added separately and the oils and greases can be removed, the speakers showed that sustainability is also good for the best cleaning results.
