EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The results presented in this study were developed within the transnational “SYMPA” project, funded by the German “Bundesministerium für Bildung und Forschung” and the Austrian “Bundesministerium für Klimaschutz, Umwelt, Energie, Mobilität, Innovation und Technologie”. SYMPA aims to develop sustainable materials, processes and post-treatment methods for the use of stereolithography (SLA) systems. One aspect is the improvement of scratch resistance and wear reduction of SLA components by atmospheric pressure plasma deposition (APPD), enabling long-term use in the field of automotive applications.
High performance acrylic photopolymers, newly developed by the associated partner Henkel AG & Co, were reinforced by carbon and glass fibres and composites additively manufactured within an adapted digital light processing (DLP) printing process (Rapid Shape GmbH, cirp GmbH, Institute of Aircraft Design). Coatings of molybdenum disulfide ($\mathrm{MoS_2}$) – graphite with a thickness between 0.5 and 50 µm were deposited on the composites by APPD (JOANNEUM RESEARCH, INOCON Technologie GmbH) and characterized amongst others by stylus profilometry, linear pin-on-disc wear test, and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX).
Well-adhering coatings could be deposited on the surfaces of the printed composites. The coatings reduced the coefficient of friction (COF) of ~$\mathrm{0.8}$ for uncoated samples down to about ~$\mathrm{0.2}$, which is significantly lower than reported values for graphite modified cotton fibre polyester composites (~$\mathrm{0.4}$ – $\mathrm{0.8}$). In addition, dependency of wear rate with APPD current was observed, the specific wear rates range between $\mathrm{7 – 9\cdot10^{-12} m^3/Nm}$ for coated carbon fibre composites and $\mathrm{3.2 – 3.4\cdot10^{-12} m^3/Nm}$ for glass fibre composites, which is higher than reported values for e.g. glass fibre reinforced polyoxymethylene ($\mathrm{5 – 6\cdot10^{-15} m^3/Nm}$). This suggests that coatings help to improve friction and wear of composites but also the strong influence of the applied material systems.