New Scientist
Researchers in Austria have developed a method to recycle car scrap aluminium into a strong new alloy, tackling the looming waste crisis from electric vehicles. By melting mixed alloys together and heat-treating them, the brittle product becomes strong enough for car chassis—cutting waste and emissions from virgin aluminium production.
No more cars on the scrap heap?
Author: Madeleine Cuff
A NEW way to recycle the metal from scrap cars could eliminate millions of tonnes of waste each year and cut the carbon emissions from producing virgin aluminium.
For decades, much of the scrap aluminium in cars has been recycled into a low-grade cast alloy for use as engine blocks in new combustion engines. But as the car industry transitions to building only electric vehicles, there is nowhere for this low-grade scrap metal to go.
Without a solution, the world risks creating mountains of unusable scrap and emitting millions of tonnes of additional carbon dioxide by producing more virgin aluminium for vehicle manufacturing, warns Stefan Pogatscher at the University of Leoben in Austria.
Together with his colleagues, Pogatscher has developed a new process to recycle the metal from scrap cars – which in Europe alone amounts to 7 million to 9 million tonnes per year – into a new high-grade aluminium alloy that can be used to make a variety of car components.
The solution lies in retaining a wide range of alloy materials from scrap cars to make the new product, he explains.
The new material could be used to make a wide range of car parts, including chassis and frames
Normally, when cars go to scrap, the materials are sorted, with plastics, fabrics, steels and aluminium all dealt with separately. Next, the aluminium alloys – of which there can be up to 40 in a single car – are separated as much as possible for different recycling streams. What can’t be separated is then melted and cast into engine blocks for combustion engines.
The new recycling method developed by Pogatscher’s team involves melting down all of the scrap aluminium from an old car in one go, thereby including a much wider range of alloys and impurities than standard.
This produces a slab of very brittle material that is “more like a ceramic than like a metal”, says Pogatscher. But the team found that reheating this material to about 500°C, for a 24-hour period, helps to change the structure of the metal to make it stronger and more mouldable (Research Square, doi.org/p4nq).
The team claims the new material rivals typical automotive alloys with its “impressive” strength and could be used to make a wide range of car parts, including chassis and frames. It can be made using common industrial processes and therefore could be immediately scalable, says Pogatscher. He admits that it will be challenging to get the “conservative” manufacturing sector to adopt the new alloy at scale, but the research team is already in talks with industry partners about developing the process.
Geoffrey Scamans at Brunel University of London says although the idea is “very interesting”, more work is needed to prove that the new alloy can pass the stringent tests necessary to allow its use in car body parts.
He also warns it may prove challenging to produce a consistent high-grade alloy, given that vehicles are scrapped “at random and not as individual vehicle types”. “It’s difficult to see how the individual alloy compositions could be collected in a practical way,” he says.
Credits: TCA, LLC.