Nov 2021
Proving performance could boost battery manufacturers’ confidence in reused materials
Lithium-ion batteries made with recycled materials can outlast newer counterparts
Oct 2020
Using traditional welding methods, rocket engine nozzles and combustion chambers are some of the most difficult parts to fabricate, requiring up to a year to produce a single part. Now, however, the U.S. National Aeronautics and Space Administration (NASA) is using additive manufacturing technology, also known as 3D printing, to additively build those parts, layer upon layer. This technology differs completely from traditional manufacturing methods that manufacture destructively by taking away material until a final geometry is realized. 3D printing has allowed NASA to produce rocket engine nozzles with integrated cooling channels in 30 days by way of an additive process called blown powder directed energy deposition (BP-DED). See also: Nozzle; Rocket propulsion; 3D printing
3D printing of large and complex rocket engine parts
Jan 2015
Biodegradable metals, also known as bioresorbable or bioabsorbable metals, are compatible with human tissues and degrade to nontoxic by-products. The most promising candidates for use as orthopedic and cardiovascular implants are alloys of magnesium, which biodegrade in 6–15 months, and alloys of iron, which biodegrade in 12–36 months. Both types of alloy degrade by corrosion—the oxidation and dissolution of the metals. See also: Alloy; Corrosion; Iron; Iron alloys; Magnesium; Magnesium alloys
Biodegradable metal implants
Jan 2014
The rare-earth elements, or rare earths—the group of 17 chemical elements with atomic numbers 21, 39, and 57 through 71—are not truly rare in terms of their chemical abundance in the Earth’s crust. However, they are typically found in low concentrations in ore and mineral deposits, and the current supply of them is somewhat limited. Notwithstanding their scarcity, demand for them is great because of their applications in what are now largely throw-away technologies: cell phones, tablets, laptops, televisions, hybrid and electric vehicles, wind turbines, and solar cells. See also: Periodic table; Rare-earth elements; Rare-earth minerals
Rare-earth elements: recycling or replacement
Jul 2018
Researchers from Pohang University of Science and Technology, Republic of Korea, reported in the journal Nature Communications an alloy design concept that could broaden the use of magnesium (Mg) alloys in engineering applications requiring lightweight materials. Magnesium alloys are the lightest structural alloys. Their use in automotive and aerospace applications for weight reduction could provide improved fuel economy, for example. A commonly used Mg alloy is AZ31, which has low density and good mechanical properties. However, AZ31 parts either must be cast or machined, because reshaping the alloy without adding or removing material—known as forming—requires high-temperature (260°C) processing. In contrast, steel and aluminum (Al) forming is possible at room temperature. See also: Airplane; Alloy; Aluminum alloys; Automobile; Density; Machinability of metals; Magnesium; Magnesium alloys; Mechanical properties of metal; Metal forming; Steel
Strong and easy-to-form magnesium alloys
Jan 2016
Internal combustion engines are very inefficient at converting chemical energy to mechanical energy. Among the energy losses are friction and heat losses. In October 2016, researchers from the Georgia Institute of Technology, Atlanta, United States, and Technion–Israel Institute of Technology, Haifa, Israel demonstrated a process for reducing the energy losses due to friction by chemically and mechanically modifying the surfaces of metal parts. This process could potentially be used for friction reduction in automotive engines. See also: Energy conversion; Engine; Friction; Internal combustion engine; Tribology
Surface treatment for improved lubricity of metal surfaces