Valeriia Reveko Physical Sciences ︱ strong alkaline environments. Therefore SPECIAL ASPECTS OF certain elements, like aluminium or ELECTRODEPOSITION ON ZINC copper, are added to obtain zinc alloys with superior properties. Although, DIE CASTINGS adding those dissimilar elements opens Zinc die casting part in cross section: difference Setting new horizons in structure between the surface and the bulk. the way to corrosion, a process of metal deterioration. In this way, electroplating coatings are a necessity in order to in electroplating change surface properties: reduce metal cations from a solution with the help of electric current, and hence form a protective metallic coating. Furthermore, of zinc die castings and disregarding the long usage of electroplating as the surface treatment for it, zinc die casting persistently generates Our supply of zinc, a metal ith over 7 billion people on Collini Holding AG, the leading group several challenges for plating, especially abundant in our planet’s crust, the planet – theoretically of companies in coating metals and when it comes to decorative use (Reveko could run out by 2100 unless we Wfrom today – there will be an plastics in Europe, has been investigating and Møller, 2018). Consequently, there are begin to change the way we use inevitable increase in the demand on the and developing surface solutions to a variety of challenges associated with zinc it. Collini Holding AG creates a world’s natural resources. Natural gas, render zinc alloys more sustainable and die casting that has recently become the step change in uncovering and oil, and coal are some of the key natural efficient. Founded as a grinding shop primary research of the Austrian surface addressing the core causes of resources that are in danger of being over 120 years ago, Collini is now an treatment company Collini Holding AG in common faults of plating on diminished. Yet, there are additional industrial surface treatment company, zinc die cast by investigating resources provided to us by our planet creating surfaces for fittings, electrical this material and the ways of that although their existence is an integral and automotive industry, machine, plant By 2100, it is anticipated the supply it surface finishing in a more part of our daily lives, they will eventually and building construction, and also for of most metals will run out. sustainable way. vanish; that is unless we begin to change medicine and various consumer goods. the way we use them. The company has thirteen production sites conjunction with the Technical University and Møller (2018), one of the most in Austria, Germany, Italy, Russia, Mexico of Denmark (DTU). Their work has resulted common issues with zinc coating over zinc Zinc and its alloys are essential to and Switzerland that specialise in a wide in the completion of a series of studies by die-cast components involves a distinct morphology. Hence, and as suggested manufacturing processes because of range of surface technologies including Collini scientist Valeriia Reveko. blue discolouration – blue areas on the by Collini team, a viable and attractive their respective properties such as electroplating, hot-dip galvanizing, surface of the electroplated zinc coatings. solution can be a double-layered zinc castability and performance while also anodizing and organic coating. ZINC PLATING COLOUR CHANGE In this study, Reveko and co-workers coating in which the inner layer is offering significant energy and cost Valeriia Reveko, a PhD candidate in the suggest that aluminium from the mildly acid zinc and the outer layer savings. However, this metallic element ZINC DIE CASTING Department of Mechanical Engineering, substrates will gradually diffuse through is alkaline zinc. is a profound example of a vanishing From toy cars that children play with to DTU, has published several peer-reviewed the coating and will propel the natural resource because its supply the metal parts used in actual cars, there research studies that highlight the distinct manifestation of these blue areas as a INACCURATE ANALYSIS from our planet’s crust is predicted to is a huge variety of consumer parts made challenges that are associated with the result of oxidation under the influence of OF CHROMIUM-PASSIVATED last only until 2100. This is exactly why using the die casting process. In fact, die electroplating of zinc die-casted parts. ambient moisture and potential ZINC SURFACES casting is a manufacturing process that has More specifically, Reveko has conducted contaminants. Furthermore, and perhaps In principle, trivalent chromium conversion been around for more than 180 years and thorough morphological and more importantly, the environment within coating is a very efficient way to anticipate was initially invented in order to develop compositional tests and analyses to verify which zinc plating occurs – from alkaline or corrosion of zinc coating while meeting portable typewriters. Essentially, this the performance and safety of zinc acidic solution– directly influences the rate environmental and safety requirements. process involves heating metal alloys until galvanic coatings on zinc die-cast items to of aluminium diffusion: alkaline zinc However, some recent research studies they become molten and consequently improve the plating quality. For instance, demonstrates higher rates of diffusion reported the presence of hexavalent pressed between steel moulds until they and as noted in Reveko, Lampert, Winther compared to acidic zinc due to its chromium in the surface passivation layers. cool down and solidify in the required shape. One of the most popular alloys to Electron Image 1 AI K Series Electron Image 1 AI K Series use in the die casting process is zinc alloys because they are easier to cast and solidify at a lower temperature in comparison to alternatives such as aluminium, therefore, the die casting process is cheaper and more efficient.

Zinc is a hard, ductile, self-lubricating material that has high thermal conductivity and dimensional stability. However, unalloyed zinc is brittle, is weaker and it is Scanning electron microscope images with Energy-dispersive X-ray spectroscopy analysis showing Al presence in zinc plated, zinc die-casted component susceptible to corrosion in acidic and/or before (left) and after (right) blue discolouration.

www.researchoutreach.org www.researchoutreach.org The Registration, Evaluation, Authorisation ZINC PRESSURE DIE CASTING and Restriction of Chemicals (REACH) has Conventional Hot Chamber Machine banned hexavalent Cr coatings because Behind the Research they are carcinogenic. In addition, 4% of people in Europe and 5% in America are allergic to chromium, and hexavalent Cr is Valeriia Reveko much more likely to cause a skin reaction such as dermatitis than the trivalent one. E: [email protected] T: +43 664 6105 729 www.linkedin.com/in/valeriia-reveko-10047a118/ W: collini.eu In general, colourimetric 1,5-diphenylcarbazide (DPC)-based spot test is one of the principal methods Research Objectives References used to identify hexavalent chromium on various metallic and leather surfaces. PhD candidate Valeriia Reveko from the Austrian Valeriia Reveko and Per Møller (2018). ‘Special Aspects However, and as noted in Reveko, electroplating company Collini, has completed a series of Electrodeposition on Zinc Die Castings’. NASF Surface Lampert, Din, Thyssen and Møller (2018), of studies looking into how to make the usage of zinc Technology White Papers, 82 (8), pp. 1-9, Article Post: DPC testing on trivalent chromium Zinc die casting machine. more sustainable. 3/19/2018.

Valeriia Reveko, Felix Lampert, Grethe Winther and Per SUSTAINABLE SOLUTIONS Detail Møller (2018).’Change of The Decorative Properties Of Zinc- Research in Collini intends to reveal This research would be remiss if it did Plated Zinc Die Castings Over Time’. International Journal of and address the causes of common not consider the present-day ecological Collini GmbH, Metalcasting, pp. 1-7, https://doi.org/10.1007/s40962-018- sustainability challenges. Coated metal Schweizer Str. 59, 0237-0. plating faults and support sustainable alloys consist of parts with multiple coating 6845 Hohenems use of materials. layers of different metals that are tricky to Austria Valeriia Reveko, Felix Lampert, Rameez Ud Din, Jacob P. recycle. This is because separating metals Thyssen, Per Møller (2018) ‘False-positive result when a diphenylcarbazide spot test is used on trivalent chromium- passivated zinc surfaces can actually on the surface because of atmospheric such as chromium and nickel – metals Bio passivated zinc surfaces.’ Contact Dermatitis, Volume 78: Issue be misleading. X-ray photoelectron corrosion can be the reason for these false- that are traditionally used to coat zinc Valeriia Reveko is a Product- and Process Development 5, pp. 315-320, doi:10.1111/cod.12955. spectroscopy (XPS) measurements positive results. The importance of this metal alloys – is a process with increased engineer in Collini GmbH, Austria. She holds an MSc degree performed in this research study did study is not limited to the impeccable level energy demands. Therefore, researchers in technical electrochemistry from Kiev Polytechnic Institute not verify the presence of hexavalent of quality control needed in the European have shifted their focus on coating zinc and is conducting a PhD project in materials science and chromium previously identified on such metal industry, but also because these alloys with zinc coatings because this surface technology at the Technical University of Denmark surfaces by DPC. The study suggests that false-positive results can unavoidably result process reduces the overall number of (DTU). unintended oxidation of the DPC indicator in the prescription of erroneous treatment metals used, thus rendering the recycling Personal Response in reaction with the substances present to patients with contact dermatitis. process easier. This is exactly why Collini Funding has turned its attention towards improved The research was funded by Collini GmbH, Hohenems. Why do you think it’s important to find ways ZINC RESPONSIBLE USAGE CYCLE approaches of the surface treatment of to recycle zinc? zinc die-cast parts. The usage of recycled Collaborators It is my position that in today’s world, we cannot zinc is an energetically favouring process • Professor Per Møller, Technical University of Denmark (DTU). continue to use natural resources in such an exploiting because its energy requirements are less manner as we currently do at the moment. Our planet has than 10% compared to the production given us a great deal, and the least we can do in return is SUSTAINABLE to use these resources wisely. Zinc, copper, nickel, steel, INCREASED of primary zinc. Essentially, the research SERICE LIFE aluminium, plastic – before putting those materials to the presented in this article is directly market, we must carefully consider the whole product connected to the increasing industrial lifecycle, aiming for sustainable solutions; and the surface need for recyclable zinc components. treatment industry can be a conductor who make a real impact on this.

CONSU BLE PT SI ION CONCLUSIONS ON SP E ‘Applied surface intelligence’ is the motto at Collini, R This research conducted by Collini intends SUSTAINABLE and we all work together with the aim of using materials IMPROED to identify and evaluate the core causes of

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SUSTAINABLE evaluate the hidden challenges of zinc- PRODUCTION plated and zinc die-casted components, and trivalent chromium-passivated zinc surfaces. DECREASED CO ENIRONMENTAL IMPACTS COSTS REDUCTION

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