Advanced Corrosion Protection of Additive Manufactured Light Metals by Creating Ceramic SurfaceThrough CERANOD® Plasma Electrolytical Oxidation Process

Lightweight structures produced by additive manufacturing (AM) technology such as the selective laser melting (SLM) process enable the fabrication of 3D structures with a high degree of freedom. A printed component can be tailored to have specific properties and render possible applications for industries such as the aerospace and automotive industries. Here, AlSi10Mg is one of the alloys that is currently used for SLM processes. Although the research with the aim improving the strength of AM aluminum alloy components is rapidly progressing, corrosion protection is scarcely addressed in this field. Plasma electrolytic oxidation (PEO) is an advanced electrolytical process for surface treatment of light metals such as aluminum, magnesium, and titanium. This process produces an oxide ceramic-like layer, which is extremely hard but also ductile, and significantly improves the corrosion and wear behavior. The aim of this study is to understand the corrosion behavior of 3D-printed AlSi10Mg alloy and to improve its corrosion resistance. For this reason, the properties of CERANOD®—PEO coating on an AlSi10Mg alloy produced by SLM were investigated on different AM surfaces, i.e., as-built, polished and stress relieved specimens. The corrosion performance of these surfaces was analyzed using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and long-term immersion tests. Moreover, the microstructure and morphology of the resulting coatings were characterized by SEM/EDS, taking into account the corrosive attacks. The results exhibited a high amount of localized corrosion in the case of the uncoated specimens, while the PEO process conducted on the aluminum AM surfaces led to enclosed homogeneous coatings by protecting the material’s pores, which are typically observed in AM process. Thereby, high corrosion protection could be achieved using PEO surfaces, suggesting that this technology is a promising candidate for unleashing the full potential of 3D light metal printing.

Environmental and Economic Effects of Fuel Savings in Driving Phase Resulting from Substitution of Light Metals in European Passenger Car Production

The European Union (EU), which realizes one-quarter of the automobile production in the world, has made legal regulations to minimize fuel consumption and CO2 emissions in the automotive sector, to prevent global warming and climate change. Life cycle analysis for passenger cars revealed that 90% of this effect is caused by the driving phase of the vehicles. One of the practices used in the automotive industry to minimize the impact of these factors is to reduce the vehicle mass as much as possible. Aluminum (Al) and magnesium (Mg) are increasingly preferred lightweight materials, since the weight is a critical design element for automobile production. This study aims to evaluate the environmental and economic impacts of fuel consumption, fuel expense, and CO2 emission resulting from the driving cycle by creating a mathematical model of the weight savings achieved with Al and Mg substitution in the passenger car fleet produced in the EU. The results show that the average weight reduction per vehicle achieved by substituting light metals in passenger car production in the EU over the past 20 years has reached approximately 11.2% and that the positive effect on fuel consumption and CO2 emissions in the driving cycle will contribute to environmentally and economically sustainable road transport.

Innovative Surface Technologies to Create Protective Functional Coatings on Light Metal Alloys

Weight reduction in automotive and aerospace components can improve energy efficiency, reduce emissions, and increase performance. The adoption of light metals such as aluminium, magnesium and titanium alloys, is essential to these performance improvements; however, these alloys require protective surface coatings to prevent corrosion and resulting mechanical failures during service life. Traditional protective coatings for light-weight materials can be costly in terms of energy, raw materials, and environmental sustainability. New durable coating approaches are required to allow light-weight materials to be fully exploited in high performance applications. Novel Cirrus HybridTM coatings, a recent innovation in surface finishing, can protect a wide range of light metal alloy components using a sustainable, non-toxic process. Cirrus HybridTM coating technology deposits a thin-film, inorganic coating that bonds tightly to the light-metal alloy substrate. The process is energy efficient, does not rely on hazardous chemicals, and is up to 5 times thinner than traditional coatings for light metals. A Cirrus HybridTM coating provides excellent anti-corrosion, scratch, and wear properties, along with superior tribological, electrical, and optical performance. This paper updates the art of these innovative new coating technologies for reducing weight in industrial components without compromising functionality or performance.

Adapted tool design for the cold forging of gears from non-ferrous and light metals

Due to growing competitive pressure within the manufacturing sector, there have been increasing attempts to establish resource saving production methods in gear manufacturing within recent years. Cold forging offers the potential—in addition to a high material and energy efficiency—to produce gears with an excellent surface quality, increased hardness as well as a load adapted fiber orientation. With regard to the wide range of applications there is a broad demand for gear materials, ranging from high-strength steels to non-ferrous and light metals. The flow behavior of the material has a significant influence on the cold forging process. Therefore, no consistent process result is achieved when forming different materials. Challenges exist due to deficient die filling and poor resulting geometrical accuracy. In this contribution, material-specific challenges during the full forward extrusion of gears from non-ferrous and light metals have been identified and suitable tool-sided measures were derived. A validated numerical process model was used to determine the underlying mechanisms of action and to verify the derived measures. A reduced yield stress leads to inflow formation, insufficient die filling, and low achievable strain hardening, as well as gearing accuracy. The tool-sided measures achieved a significant increase of resulting die filling and gearing accuracy as well as the mechanical properties. That provides the basis for the production of ready-to-use gears from various metal materials.