Aluminum Foil (2021)
5 hours ago
- #aluminum-foil
- #material-science
- #DIY-fabrication
- Kitchen aluminum foil is remarkably thin (10 μm) with a high aspect ratio, making it suitable for forming metamaterials and having properties like being impermeable to oxygen and water when thick enough (25 μm or more).
- It is highly reflective, conductive, corrosion-resistant, non-toxic, lightweight, and cheap (under 50¢/m²). Robert Lang's 'tissue foil' laminates tissue paper with foil for origami.
- Aluminum foil is made from alloys like 1100 and 1200, with room-temperature yield strengths of 30–170 MPa, remaining ductile down to absolute zero and melting at almost 650°C, suitable for cryogenic and high-temperature applications.
- When oxidized, it forms amorphous sapphire, which can be used as an insulator or abrasive, and aluminum foil can be used in fuel cells due to its high energy density.
- It is cost-effective for solar concentrators (50¢/kWp), though vulnerable to deflections; stiffening methods like corrugated structures with boric acid or borax glue are suggested.
- Work-hardening allows foil to be used as tooling for manipulating other foil, demonstrated by creating cones that can pierce foil or apples and forming ribs for incremental forming and stamping.
- Experiments include making expanded sheet metal with slits, folding origami cranes, and testing alternatives like aluminum cans (thicker and more hazardous).
- A hypothetical matter compiler could use foil's high aspect ratio to create billions of 'parts' per roll, but challenges include electrical limitations and the need for other materials like coatings for functionality.
- Other potential processes include electrolytic machining, electric discharge machining, and anodization, which could expand its applications in metal cutting and optical systems.