WOOD-BASED COMPOSITES AS SATELLITE STRUCTURES: MANUFACTURING AND APPLICATION OF COATINGS AGAINST ATOMIC OXYGEN EROSION

Kurzfassung

Wood-based composites offer an alternative to metals for satellite structures that is both eco-friendly and available in Europe. DLR Stuttgart previously reported their feasibility for CubeSats, yet the behaviour of bio-based materials in space remains largely unknown. This work addresses that gap by manufacturing a plywood panel from acetylated radiata pine and testing coatings against atomic oxygen (ATOX) erosion. A preceding Micro-VCM test on beech and balsa wood showed TML of 5-6 % but RML << 1 %, indicating moisture as the main driver. Acetylated radiata pine was therefore selected: acetylation reduces moisture content (TML of about 2 %) and pine offers superior specific mechanical properties. Preliminary shear tests (ISO 6237) compared a two-component epoxy and a film adhesive on different wood species. The epoxy yielded higher shear strength and better wood suitability and was chosen. Veneers were bonded in a 0°/90° lay-up and cured under controlled pressure and temperature in a universal testing machine fitted with an oven. Small samples were milled from the panel. After surface cleaning and plasma activation (removing organic contaminants, enhancing surface energy and adhesion), Al2O3- and SiO2-based thin films were deposited via magnetron sputtering PVD under optimised vacuum and gas-flow conditions to achieve dense, uniform, adherent coatings. These steps represent the first promising path toward a space-suitable plywood panel that reduces the environmental footprint of the space industry. A follow-up campaign is planned to test ATOX effects on the wood directly.