Advanced Structured Materials

Additive manufacturing offers unique opportunities to produce complex components which are impossible or very difficult to realise using conventional manufacturing processes. The potential of additive manufacturing of aluminium alloys is already recognised in prototyping, but still holds potential in regards to the optimisation of the materials used and, above all, mass production. Due to the large growth in different areas of application, the structural mechanical properties are becoming increasingly important. The specification of anisotropies, preferred directions and weak points in the microstructure vary with the considered material, and completely opposite behaviour patterns are not uncommon. Thus, it is becoming increasingly important to gain precise knowledge about the mechanical properties of additively manufactured components. One aim of my research is to provide an overview of the mechanical properties of additively produced AlSi10Mg alloy. In particular, the influence of various heat treatments and the orientation of the components in the built environment are examined. AlSi10Mg represents the most frequently used alloy for selective laser melting followed by AlSi12. Both alloys are not optimized for additive manufacturing, as they were developed and optimized for casting. Therefore, another goal of my research is to develop an alloy, which is optimized for additive manufacturing. The AlSi alloy is develop without allying elements as they are contained in currently used aluminium alloys optimized for casting processes. Subsequently, the additive manufacturing process with integrated heat treatment is developed and optimised by using the novel AlSi alloy.

Main researcher: Enes Sert (M.Eng.)

The aim of the project is to develop a biodegradable, antimicrobial polymer powder based on recycled leftover powder PA12 from the selective laser sintering process. Afterwards the powder should be reused again for the production of components by the selective laser sintering process. The polymer powder suitable for this purpose should not only have antiviral properties, but also thermostability, colour fastness and UV compatibility. So far, only PLA-based powders with nano-copper additives are available on the market and are much more expensive than conventional plastic powders. Since PLA is only degradable in industrial composting plants and has a large CO₂ footprint, an alternative base (PA12) is to be found here. Currently available plastic granulate with the desired properties costs over 90 €/kg and thus almost three times as much as conventional PLA powder. In order to realise the project, a recycling circuit is to be developed in which the thermally aged base polymer PA12 is reprocessed and then mixed with suitable additives such as titanium oxide (TiO₂). By using the new materials, both ecological and economic progress can be achieved, since expensive, non-biodegradable materials are not used.

Besides the integration of various additives like TiO₂ to achieve the desired properties another part of this project is to develop a proper recycling technology for the leftover powder from the selective laser sintering process. Up to now, a complete reuse of the unsintered powder is not possible as the material is affected by a thermal degradation during the laser sintering process.

Forscher: Philippe du Maire (M.Eng.)