22 October 2020

Researchers develop an energy efficient technique for densification of biocompatible glass powder.

Researchers from the Department of Materials Science and Engineering have applied a new low temperature (<250°C) processing technique to bioactive glasses which could be used to repair human tissues in a safe, sustainable way.

The process of cold sintering to densify glass
Schematic illustrating the different stages of the cold sintering process (Reproduced under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. (https://doi.org/10.1595/205651320X15814150061554)

Recent developments by researchers within the Department of Materials Science and Engineering to the technique known as cold sintering, have demonstrated the ability to densify glass powders at temperatures significantly lower than those used in traditional processing methods. Safety and energy efficiency features of this process are proving to be attractive to the healthcare industry in particular.

The process has been used to produce glass components with a density of 95% from powders by applying pressure and heat up to 250°C in the presence of simple solvents such as water.

Although the technique is still in its infancy, the potential for its application in a huge number of sectors has been recognised by chemical giant Johnson Matthey, sponsors of the research, who have already applied for a patent for the process.

The idea for the process development came from an understanding of the cold sintering of ceramics. In addition to densifying (the process of forming a dense final product from powder by the application of heat and pressure) a range of specialist glasses, cold sintering is of particular interest for bioactive glasses such as Bioglass®, which are biocompatible and widely used in the medical and healthcare sectors.

The advantages of using this process to densify Bioglass® are manifold:

  • The low temperatures mean that glasses can be co-densified with polymers to achieve better mechanical properties, without compromising their bio-active properties.
  • We envisage the potential for drugs to be embedded in the Bioglass® before densification to create a slow release delivery system.
  • Cold sintered glasses can be used to coat surfaces and stick together a wide range of materials, including other glasses, ceramics, composites and metals.
  • The scope to create a wide range of composites with high polymer to high glass volume fractions, impossible with other techniques and facilitating a wider range of bio-applications

Already known for their ability to promote bone growth, bioactive glasses can be used to create scaffold structures which, when placed in the body, can contribute to the rapid repair of damaged tissue. Indeed, one of the next areas for investigation is how the technique can be applied to 3D printing of bespoke parts with more complex shapes.

Materials Science and Engineering PhD student, Jess Andrews, who progressed from her undergraduate degree at the University of Sheffield, is leading the research under the supervision of Professor Ian Reaney said: “Cold sintering is still a relatively new technique, but we are beginning to see it's huge potential - it has already been utilised in a really broad range of applications from electroceramics to bioactive glasses. I think it will be exciting to see what larger scale changes can come from these initial developments in the lab.”

Jonathan Booth, Research Manager at Johnson Matthey Technology Centre, said: “We are very excited about the enabling potential of this technology which will hopefully allow us to explore new functional glass, polymer composites hitherto impossible to manufacture.”

Looking to the future, the researchers are seeking interest from potential end-users of the process to allow them to investigate possible applications, as well as further funding to expand the scope of the research.