UNSW Sydney scientists have developed a new process for turning mineral rich e-waste into a strong, protective coating for metals.
According to a paper published in ACS Omega, a team led by UNSW Sydney Professor Veena Sahajwalla and postdoc Rumana Hossain have reported a new selective, small-scale microrecycling strategy which they say could help convert old printed circuit boards and monitor components into a new type of strong metal coating.
A typical recycling process converts large quantities of items made of a single material into more of the same.
This approach isn’t however feasible for old electronic devices (e-waste) because they contain small amounts of many different materials that cannot be readily separated.
In spite of such difficulties, there is still plenty of reasons to recycle e-waste.
For instance, 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.
Taking a cue from this, the UNSW team turned a mix of glass and plastic into valuable, silica-containing ceramics.
They also used this process to recover copper, which is widely used in electronics and elsewhere, from circuit boards.
In order to create their new coating, Sahajwalla and Hossain 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 and 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 reveal 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 UNSW team has referred to this targeted, selective micro-recycling process as ‘material microsurgery.’
They opine that their microsurgical process could help transform e-waste into advanced new surface coatings without needing expensive raw material.
Image and content: Adapted from ACS Omega/American Chemical Society
