25 SQ: Recycling

What is the definition of recycling?

• Using a material again after it has served its original purpose

• Downcycling: recycling but the recycled item has lower quality

What are the main materials composing an aircraft?

• Composites (50%), Aluminum (20%), Titanium (15%), Steel (10%), others (5%)

Name 2 reasons why the recycling of aircraft aluminium is more complex than recycling aluminium form the automotive and car industry

• Anti-corrosion coating needed for aerospace applications, whcih is toxic as fuck to remove and dispose

• High concentrations of alloying components not present in automotive or food industry

Why is a “Smart disassembly and dismantling“ of an aircraft needed for recycling aluminum?

• To facilitate scrap sorting and scrap refining of the aluminum

• To achieve an efficient and effective aluminum recycling and minimize contamination

• To be able to get high-value alloys out of the Al scraps

How does an ideal aircraft life cycle look like?

• Design → Manufacturing → Operation and Maintenance → (End of Life) → Decomissioning → Disassembly → Demantling → Recycling → Manufacturing → …

What are the advantages and drawbacks of the mechanical recycling of CFRP components?

• + Recovery of fibers and matrix

• + No use of harmful substances

• - Significant degradation of mechanical properties

• - Unstructured, coarse and heterogeneous fiber architecture

• - Limited use possibilities

Name 2 methods to recover carbon fibers from used CFRP parts

• Pyrolysis

• Solvolysis

What are the advantages and drawbacks of oxidation during the pyrolisis process?

• + Good retention of mechanical properties

• + No use of hazardous solvents

• - Possible deposition of char on the fiber surface

• - Polluting exhaust gas

Why can recylced CF not always be used in high-performance applications?

• The recycling processes of CFRP usually degradate the fibers to a certain degree, which prevents that high FVR, sufficient fiber length and coherent fiber alignment is achieved