Recycling electronics waste is challenging because it contains a variety of materials that are difficult to separate. Instead of separating all materials and reusing them in pure form on a large scale, microrecycling approaches use heat-induced reactions between the different materials in complex waste to create new, useful materials. By tuning the heating times and temperatures, selective transformations can be achieved.

Rumana Hossain and Veena Sahajwalla, University of New South Wales, Sydney, Australia, have developed a microrecycling strategy for converting old printed circuit boards (PCBs) and computer monitor components into a new, strong coating for steel. The team used the glass and plastic from the monitors and entire PCBs and pulverized all three. The glass and plastic powders were mixed and heated at 1500 °C for 30 min in an oxygen-free atmosphere to create silicon carbide (SiC), which formed nanowires. Then, the PCB powder was added and the resulting waste mixture was placed on a steel substrate. Another heating step (1000 °C for 15 min) created an SiC-reinforced copper layer on the steel.

The hybrid layer adheres well to the steel and could protect its surface from wear and corrosion. The surface hardness increased by ca. 125 % compared to the base steel. According to the researchers, further development of this approach could allow the transformation of growing electronics waste stockpiles into value-added surface coatings.

• Material Microsurgery: Selective Synthesis of Materials via High-Temperature Chemistry for Microrecycling of Electronic Waste,
  Rumana Hossain, Veena Sahajwalla,
  ACS Omega 2020.
  https://doi.org/10.1021/acsomega.0c00485