Surface modification

The novel ‘material microsurgery’ technique developed by Professor Veena Sahajwalla and her team can extract valuable materials and elements from complex waste items and reform them into strengthening layers for steel and other applications.

The technique is outlined in a new scientific paper published by the esteemed American Chemical Society Omega Journal. The SMaRT Centre created the phrase ‘mircorecycling science’ to describe its novel approach to researching innovative approaches and technologies to reform various waste streams into value-added materials and products.

Material microsurgery uses the foundational selective thermal transformation techniques developed in the microrecycling science by the SMaRT Centre to extract from electronic waste valuable core elements that can be used in a novel way as a high-performance hybrid layer to improve performance of the surface of steel. This means that regular steel can be enhanced to have a ‘super surface’ via the modification.

This method could be a suitable alternative to conventional surface coatings and reduce the burden on raw material feedstocks. In the material microsurgery study, glass and plastic from spent computer monitors and copper from waste printed circuit boards were used to produce a hybrid thin film layer on a steel substrate to provide a protective layer over the base material at the microscale to alter the overall performance of the material.

This high-performance advanced material is a hybrid layer chemically bonded in situ on steel to produce a super surface with enhanced mechanical properties compared to the uncoated steel. “We use the term ‘material microsurgery’ because we were inspired by the processes medical surgeons use in microsurgery where they apply targeted and selective solutions to problems,” Professor Sahajwalla said. “Existing waste and recycling technology doesn’t do this for our traditional waste treatments. We need to step up to do the things that were thought unimaginable for waste management so it can be cutting edge.”

After developing novel surface modification technology for improving the wear and corrosion resistance of high carbon steel, Hub researchers worked with industry partner MolyCop and initiated a pilot scale plant trial at MolyCop's Newcastle steelworks site. This pilot scale trial helped to understand limitations of implementing the process in industrial scale settings.

After number of rounds of modification, the process was optimised and the production of grinding media using the novel modified surface commenced, using onsite waste at MolyCop. Lab analysis of samples found that this new process improved the abrasion resistance of these steels by 30% and corrosion resistance by 50%. These samples then were subjected to an industrial scale ball-mill to identify the grinding media performance. Not only was new science and technology developed for this grinding media application, but the process to implemented this novel process in industrial setting and produce these new grinding media products was commenced.