New division for Australia's materials industry

Materials World magazine
1 Nov 2007
T-Mag process

Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) has launched a Materials Science and Engineering (CMSE) division to help the country’s manufacturing industry become globally competitive.

‘The division combines most of CSIRO’s materials chemistry, materials physics and materials engineering,’ says Dr Calum Drummond, Chief of the CMSE.

‘Australian manufacturing is dominated by SMEs. We have a particular emphasis on assisting [their] development.’

The AUS$83 million facility will focus on light metals, nanotechnology, and manufactured devices for applications in security, automotive, minerals exploration and the medical sector. It follows in the footsteps of other CSIRO materials innovations, including a lightweight concrete called HySSIL, and T-Mag, a magnesium casting technique.

Created by CSIRO’s former Manufacturing and Materials Technology division, HySSIL is a pre-fabricated concrete panel technology. It is claimed to be almost half the weight of regular concrete but just as strong, offering major energy savings. The product will be commercially available from December, having passed the Australian building code approval process.

The concrete is made from a precise mixture of Portland cement, fly ash, sand, plasticiser and an activator compound. The activator produces a chemical aeration reaction, similar to a foaming mechanism. During casting, the cement swells to nearly twice its size as bubbles form inside. ‘We don’t use aggregate in our mix. We’ve replaced the stones with air bubbles, so it rises like a cake mix,’ says Gary Bertuch, Managing Director of HySSIL Pty Ltd, a CSIRO spin-off company.

This cellular structure creates a material that is light yet strong, adds Bertuch. ‘Normal concrete is around 2,400kg/m3. Our product ranges in density from about 1,000 to 1,500kg/m3. And we have similar compressive strength [between eight and 25MPa].’

Whether this product will have an impact on the building industry remains to be seen, says one UK concrete industry expert. ‘The HySSIL technology is not a radical departure from technologies that are already available in the area of lightweight pre-cast concrete panels. The performance data look good but are not particularly surprising for a factory-made product, where all of the variables are controlled.’

He adds, ‘Its main claimed advantage seems to be low manufacturing costs compared to other competitive lightweight concrete [it uses fewer processes than autoclaved aerated concrete, for example]. We will have to wait and see how it does.’

Moving on to magnesium casting, the metal yield from traditional automotive magnesium casting can be quite low, down to 50%, according to the CSIRO. ‘In sand and high pressure die casting, the runners, overflows and risers [have to be] large to get the metal from the source to the casting. The [excess] metal is not part of the casting and needs to be recycled, which results in a low yield,’ says Sam Tartaglia, Business Development Manager for CSIRO’s Light Metals Flagship, now part of the CMSE.

The Flagship is developing an alternative process called T-Mag (see image above), which uses gravity, rather than high pressure or a vacuum, to fill a mould. The magnesium die flows up from the bottom of the mould, minimising the turbulence that causes gas entrapment in the casting. This results in nearly defect-free castings and reduces excess metal – it only requires 3.7kg of metal for a 3.5kg casting, says Tartaglia.

The finished magnesium alloy engine block is two-thirds the weight of an aluminium alloy version, and the process is around 15% faster than aluminium casting due to the lower specific heat of magnesium.

‘We see the CSIRO work as synergistic with the work at Brunel [University] on melt conditioning of magnesium,’ says Geoff Scamans of Innoval Technology Ltd, Banbury, UK. ‘It is possible to feed a conditioned melt into the T-Mag casting process to obtain additional benefits in terms of the range of castable alloys, the use of non-refined scrap and the provision of finer, more uniform as-cast microstructures.’


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