Concentrated solar power is one of the
technologies that urgently needs alloys with superior ability to
withstand high temperature corrosion. The image shows a solar power
plant in Spain, named PS20.
Many current and future technologies require alloys that can withstand
high temperatures without corroding. Now, researchers at Chalmers
University of Technology, Sweden, have hailed a major breakthrough in
understanding how alloys behave at high temperatures, pointing the way
to significant improvements in many technologies. The results are
published in the highly ranked journal Nature Materials.
Developing alloys that can withstand high temperatures
without corroding is a key challenge for many fields, such as renewable
and sustainable energy technologies like concentrated solar power and
solid oxide fuel cells, as well as aviation, materials processing and
petrochemistry.
At high temperatures, alloys can react violently with
their environment, quickly causing the materials to fail by corrosion.
To protect against this, all high temperature alloys are designed to
form a protective oxide scale, usually consisting of aluminium oxide or
chromium oxide. This oxide scale plays a decisive role in preventing the
metals from corroding. Therefore, research on high temperature
corrosion is very focused on these oxide scales – how they are formed,
how they perform at high heat, and how they sometimes fail.
The article in Nature Materials answers two classical
issues in the area. One applies to the very small additives of so-called
‘reactive elements’ – often yttrium and zirconium – found in all
high-temperature alloys. The second issue is about the role of water
vapour.
Potential consequences of the research breakthrough
High temperature alloys are used in a variety of areas, and are
essential to many technologies which underpin our civilisation. They are
crucial for both new and traditional renewable energy technologies,
such as "green" electricity from biomass, biomass gasification,
bio-energy with carbon capture and storage (BECCS), concentrated solar
energy, and solid oxide fuel cells. They are also crucial in many other
important technology areas such as jet engines, petrochemistry and
materials processing.
All these industries and technologies are entirely dependent on
materials that can withstand high temperatures – 600 ° C and beyond –
without failing due to corrosion. There is a constant demand for
materials with improved heat resistance, both for developing new high
temperature technologies, and for enhancing the process efficiency of
existing ones.
For example, if the turbine blades in an aircraft's jet engines
could withstand higher temperatures, the engine could operate more
efficiently, resulting in fuel-savings for the aviation industry. Or, if
you can produce steam pipes with better high-temperature capability,
biomass-fired power plants could generate more power per kilogram of
fuel.
Corrosion is one of the key obstacles to material development
within these areas. The Chalmers researchers' article provides new tools
for researchers and industry to develop alloys that withstand higher
temperatures without quickly corroding.
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