Flow chemistry shapes future of high-performance ceramics
Understanding the fundamental flow characteristics of suspensions of high-temperature ceramics has been a crucial part of developing new boron-carbide body armour now being used to protect Australian soldiers during active deployment.
The armour demonstrates how molecular-level manipulation of chemistry can be used to tailor ceramics for specific high-performance end-use requirements
Professor George Franks has led the University of Melbourne team working as part of a larger collaboration to develop the new ceramic armour technology. He says the strength of boron carbide has long been recognised.
When CSIRO developed a process to form the ceramic into curved shapes, researchers from the University of Melbourne’s Department of Chemical and Biomolecular Engineering helped to refine the boron carbide formula to ensure the ceramic would retain its strength in the new curved forms.
The ceramic is created from a boron carbide powder, which is mixed with water and other ingredients to the consistency of modelling clay. This is then pressed into the desired shape. But ceramics are brittle and any flaw, such as an air pocket or crack, reduces the strength of the material, Professor Franks says.
“The fundamental science in this work is understanding how to control the plasticity of the ceramic compound when liquid is added. What chemical properties will help to control the flow of the material when it is shaped so that we can preserve the qualities we need?”
In the case of body amour, a high-strength and lightweight combination is required. The new armour is tough enough to stop an armour-piercing bullet, but up to 20 per cent lighter than previous armour. For a single breastplate, this could reduce the weight a soldier carries by 600 grams, providing better protection while improving their mobility and endurance.
It can be produced with near-net shaping, offering the potential to tailor armour for specific body shapes, including for frontline female combatants. Professor Franks says other armour pieces being developed include front helmet plates and protection for the upper arms.
The boron-carbide ceramic research was part of a Defence Materials Technology Centre project. Other partners included CSIRO, the Swinburne University of Technology, the Victorian Centre for Advanced Materials Manufacturing and Australian Defence Apparel, which manufactured the armour.
Professor Franks says by understanding ceramic suspension flow properties it is also possible to tailor high-performance characteristics to meet other needs, such as in the mineral-refining or aerospace industries, where the focus might be on greater corrosion or heat resistance.