Australia's work in the development of methods to deal with radioactive waste has led to an unusual spin-off - the expertise and equipment that is assisting new local enterprises in the production of artificial body parts. The same capabilities have the potential to be applied to the production of other materials where quality is critical, such as the turbines in aircraft.
The key to one such enterprise is Hot Isostatic Pressing (HIP), a process that was brought to the Australian Nuclear Science and Technology Organisation (ANSTO) at Lucas Heights for the development of a new way of immobilising radioactive waste. ANSTO maintains the only facilities in Australia for the process.
When metals and other materials are shaped using casting, the material inside usually contains some porosity and a number of irregular flaws. Hot Isostatic Pressing involves the simultaneous application of heat and high pressure in all directions on the heated material to remove the flaws and produce a fully dense material. This results in improved strength, flexibility and fatigue life of the material.
A commercial company, Australian Surgical Design and Manufacture (ASDM), which is based in Miranda in Sydneys south, is utilising this technology to develop improved artificial knees, with a view to taking the multi-million dollar international market by storm. Declan Brazil of ASDM says they will produce around 1,500 artificial knees this year using a cobalt chrome molybdenum alloy. The group expects to increase production to around 35,000 over the next few years.
By utilising the HIP technique, as well as ANSTO's certified labs for metallographic work and mechanical testing, ASDM was able to pass the US
Federal Drug Administration fatigue standards, allowing the company access to the multi-million dollar market.
Sam Moricca of ANSTO Materials says that in the future there may be opportunities to work with ASDM to produce other bio-implants using ceramics. The Hot Isostatic Pressing facilities at ANSTO allow the heating of materials, such as metals, to temperatures high enough to make them soft without melting.
This can be controlled to any temperature up to 2000 degrees Celsius. An inert gas such as argon is pumped in at high pressure so that it has a consistency somewhat like water. The combination of heat and pressure is controlled at optimum levels to heal voids and other inconsistencies that normally occur during casting.
As well as helping to develop new and improved materials for prosthetic devices, ANSTO staff also routinely help medical organisations by sterilising artificial body parts such as hips, using ANSTOs irradiation facilities.