Control of scale effects in the localized anodic oxidation of aluminium based materials – lokO

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Anodic oxide layers are widely established for the wear and corrosion protection of aluminum products as well as for decoration purposes of their components. These resilient layers are manufactured electrochemically. So far, the whole anodizing process has either been realized on a large scale or locally, in which case extensive masking was required, in an electrolytic immersion bath. Regarding complex components or assemblies of several materials such as metal and plastic, anodizing should not be performed for the modification of the surface properties (e.g. wear, friction, and hardness) of all subareas, since it might induce undesired damaging effects. The resulting damage of the plastic can only be excluded if the dimensions of the areas which are to be anodized are flexibly variable. Due to the lack of resource- and energy-efficient processes, the generation of local oxide layers was not yet possible on components. Furthermore, it is well-known that multi-phase aluminum-based substrate materials entail process-related challenges and require customized anodizing strategies. The manufacture of local anodic oxide layers is feasible due to the application of the electrolytic free jet. Electrochemical machining using the electrolytic free jet represents a technology for the localization of electrochemical processes, which has thus far been used for electrochemical material removal, the so-called Jet-ECM.The overall goal of the second project period is the investigation and experimental realization of homogeneous, geometrically sharp-contoured surface structures with high resistance against tribological load for a wide range of technical aluminum alloys. By increasing the localization of jet-based anodizing, locally porous, anodic oxide layers are to be produced. A layer thickness of the local oxide spots of at least 5 µm shall be realized to exceed the dimensions of finely divided, sub-microscaled and microscaled, metallographic constituents. In addition, the homogeneous oxide formation on inhomogeneous wrought alloys shall be realized through simulation-assisted control of the transformation behavior of the structural constituents.