Transforming e-waste into a strong, protective coating for metal

Date:
July 29, 2020
Source:
American Chemical Society
Summary:
A typical recycling process converts large quantities of items
made of a single material into more of the same. However, this
approach isn't feasible for old electronic devices, or ''e-waste,''
because they contain small amounts of many different materials that
cannot be readily separated. Now researchers report a selective,
small-scale microrecycling strategy, which they use to convert old
printed circuit boards and monitor components into a new type of
strong metal coating.



FULL STORY ==========================================================================
A typical recycling process converts large quantities of items made
of a single material into more of the same. However, this approach
isn't feasible for old electronic devices, or "e-waste," because they
contain small amounts of many different materials that cannot be readily separated. Now, in ACS Omega, researchers report a selective, small-scale microrecycling strategy, which they use to convert old printed circuit
boards and monitor components into a new type of strong metal coating.


==========================================================================
In spite of the difficulty, there's plenty of reason to recycle e-waste:
It contains many potentially valuable substances that can be used
to modify the performance of other materials or to manufacture new,
valuable materials.

Previous research has shown that carefully calibrated high
temperature-based processing can selectively break and reform chemical
bonds in waste to form new, environmentally friendly materials. In this
way, researchers have already turned a mix of glass and plastic into
valuable, silica-containing ceramics.

They've also used this process to recover copper, which is widely used in electronics and elsewhere, from circuit boards. Based on the properties of copper and silica compounds, Veena Sahajwalla and Rumana Hossain suspected that, after extracting them from e-waste, they could combine them to
create a durable new hybrid material ideal for protecting metal surfaces.

To do so, the researchers first heated glass and plastic powder from old computer monitors to 2,732 F, generating silicon carbide nanowires. They
then combined the nanowires with ground-up circuit boards, put the mix
on a steel substrate then heated it up again. This time the thermal transformation temperature selected was 1,832 F, melting the copper to
form a silicon-carbide enriched hybrid layer atop the steel. Microscope
images revealed that, when struck with a nanoscale indenter, the
hybrid layer remained firmly affixed to the steel, without cracking
or chipping. It also increased the steel's hardness by 125%. The team
refers to this targeted, selective microrecycling process as "material microsurgery," and say that it has the potential to transform e-waste into advanced new surface coatings without the use of expensive raw materials.


========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Rumana Hossain, Veena Sahajwalla. Material Microsurgery: Selective
Synthesis of Materials via High-Temperature Chemistry for
Microrecycling of Electronic Waste. ACS Omega, 2020; 5 (28):
17062 DOI: 10.1021/ acsomega.0c00485 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200729124407.htm

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