Iron
Element 26 · chemical symbol: Fe
These Vrulum profiles mention Iron by name. Read each profile for its specific context; a mention alone does not establish composition, performance or use of the pure element.
For periodic-table data and other properties, consult the Royal Society of Chemistry periodic table.
Related technology profiles
Industrial steelmaking
Industrial steelmaking turns molten iron into steel by removing carbon and other impurities. The main methods date from the Bessemer process of 1856 and the open-hearth furnace, and today's routes are the basic oxygen furnace and the electric arc furnace.
Iron-air batteries
Iron-air batteries are a long-duration storage design that uses iron, oxygen from the air and a water-based electrolyte, aimed at delivering power for days rather than hours. In a 2025 California Energy Commission report, kilowatt-scale prototype modules discharged for more than 100 hours under controlled tests, but round-trip efficiency is not public and no multi-day commercial plant has yet been shown to operate.
Lithium-ion batteries
Lithium-ion batteries store and release electricity by moving lithium ions between two electrodes, and they power electric cars. Their cost and energy density keep changing, but fire risk, dependence on nickel-containing chemistries and recycling that is still developing remains an open limit.
Nitrogen-fixing cereals
Nitrogen-fixing cereals would take nitrogen from the air through engineered plants or root-associated microbes, reducing the need for synthetic fertiliser. Some commercial microbial products are sold for maize, but their field results vary, and engineering cereals to fix nitrogen themselves has so far only reached early laboratory steps.
Organ and tissue cryopreservation
Vitrification cools tissue into a glass-like solid without ice, using high concentrations of cryoprotectants, and nanowarming heats it back evenly with magnetic nanoparticles. Vitrified eggs and embryos are used in fertility clinics, and vitrified rat kidneys have worked after transplant, but the sources reviewed here report no human-sized organ banked and transplanted this way.
Precision machine tools and interchangeable parts
Precision machine tools cut metal to set sizes, and standard gauges and threads let separately made parts fit together. Late eighteenth and early nineteenth century work on boring cylinders, screw threads and interchangeable parts made steam engines, and later cars, practical to build in quantity.
Rolling bearings
Rolling bearings put balls or rollers between a moving part and its support, so the parts roll over each other instead of sliding, which reduces friction. The basic ideas were in place by 1800, but precision manufacture and mass production were still needed to confirm their value. Later work on precision ball grinding and Henry Timken's 1898 tapered roller design made rolling bearings practical for wheels and shafts.
Structural batteries
A structural battery stores electrical energy while also carrying mechanical loads, for example in a composite panel whose carbon fibres act as electrodes. Laboratory cells have reported energy densities from about 30 to 187 Wh/kg, depending on design, electrolyte and mass basis, and high stiffness, but no complete vehicle or aircraft powered by a load-bearing battery structure has been demonstrated in the sources reviewed.
The electric motor
An electric motor turns electrical energy into rotary motion using magnetic force, a principle Michael Faraday demonstrated at the Royal Institution in 1821. From Thomas Davenport's battery-powered motor of 1837 and Nikola Tesla's alternating-current patents of 1888, it now powers electric vehicles and starter motors in the form of permanent-magnet and induction designs.
Vehicle brakes
Vehicle brakes have moved from wooden blocks and band brakes to hydraulic, disc and electronically controlled systems over more than a century. Peer-reviewed studies link electronic stability control, which Bosch says reached the market in 1995, to fewer loss-of-control crashes, but the size of the effect is uncertain.