Corrosion remains one of the most persistent and expensive engineering challenges in Australia. But engineers are working with new materials and advanced coatings to push back against the forces of nature.
By Jonathan Bradley
The failure of vital infrastructure often begins long before there are visible signs. Everything might seem in working order – structures stable, materials sound, surfaces intact – but, beneath that surface, environmental forces are at play.
Exposure to moisture, stress and chemical agents gradually initiates corrosion, undermining the integrity of materials over time. Minor imperfections expand, connections weaken, and what starts as a slow, silent process can escalate into sudden, costly failure.
It’s not a dramatic fiction but a constant, complex problem engineers must anticipate and manage in the real world.
“Corrosion is a bit like corruption,” Professor Srdjan Nesic, Director of Ohio University’s Institute for Corrosion and Multiphase Flow Technology, and an affiliated scholar at Western Australia’s Curtin Corrosion Centre, told create. “It’s destructive. It can lead to complete collapse.”
However, he said, while corruption eats away at the social fabric, corrosion does its work on infrastructure.
It’s a problem that no-one, whether politicians, business or the broader population, likes to think about until it’s too late.
“Corrosion is the last thing on the list until it becomes the first – when something fails,” he said. “A lot of those things we can prevent and solve upfront in the design and operational phases. We don’t have to wait for failures.”
By the numbers
Estimated global cost of corrosion:
Of the global GDP, this is equivalent to:
Land and sea
Research from the US’s National Association of Corrosion Engineers estimated the global cost of corrosion to be $3.9 trillion – equivalent to 3.4 per cent of the global gross domestic product.
That amounts to a high of $78 billion each year in Australia alone, according to the Australasian Corrosion Association. Its impact affects sectors economy-wide, including oil and gas, water and wastewater, defence, construction and infrastructure.
Monash University’s Professor Nick Birbilis said public safety and cost reduction are reasons to make transportation more corrosion-resistant and therefore more resilient, but he sees environmental opportunity too.
“If we can make infrastructure that lasts a really long time, we don’t need to replace it, and then we start being much better in terms of sustainability,” he said. “There’s an old saying that either you call the corrosion engineers in early, or you’ll definitely call them in later.”
With the process of corrosion taking place at the intersection between materials and the environment, when it comes to transportation, urban infrastructure has different challenges to rural, and coastal locations require a different approach to those inland.
“In an urban setting, with a lot of cars, there’s more carbon dioxide, which increases the type of corrosion called carbonation. So buildings in the inner city are far more prone to this than those in rural areas.
“Similarly, coastal structures near the water are far more prone [to corrosion] because of the amount of chlorides that are in the environment and airborne particles that contain salt.”
That means Australia, a country whose population is largely confined to cities along the coast, is particularly susceptible.
“A huge proportion of Australia’s population and infrastructure is in what we call the marine environment, which extends some tens of kilometres inland,” Birbilis said. “The aerosol spray from the ocean penetrates quite far inland, so most of Australia’s critical infrastructure is in marine environments.”
As a result, much of the land-based infrastructure faces similar corrosion challenges to infrastructure at sea.
“For port structures, and [other] structures that are absolutely critical, we do very regular early inspections to try and understand if corrosion is happening,” Birbilis said.
These inspections will often be matched by ongoing repairs
and maintenance.
In rare cases, costly stainless steel might be used as the reinforcement for a structure’s concrete foundations, said Birbilis, citing the Sydney Opera House as an example. With the much-older Sydney Harbour Bridge, however, the solution is to repeatedly repaint the structure to safeguard it from the sea air.
The right choice
“The best thing is to choose the right material for the given environment,” Associate Professor Kod Pojtanabuntoeng, of the Curtin Corrosion Centre, told create.
“If we build everything from gold, platinum or titanium, it may be okay from a corrosion perspective, but the cost and the strength of the material won’t match what we need from these materials in that given environment. That’s when you have to compromise.
“That’s why carbon steel is the most used in all of the cases: because it’s the cheapest type of material, and then you couple it with the prevention, such as a [protective] coating.”
Birbilis said selecting a corrosion-resistant material is ideal.
“And if you’ve got a material that might be corrosion-prone, but is in an inert environment, you’re also okay.”
Even when using corrosion-resistant alloys, you still need to ensure that they are appropriate to the relevant environment, Pojtanabuntoeng said.
“In a high-chloride environment, which Australia is known for, corrosion can manifest in a different way. When we look at carbon steel, it corrodes everywhere – everything turns red. But stainless steel would [experience] pitting – pinholes here and there.”
In an attempt to devise ever more innovative corrosion-resistant materials, researchers have recently turned to AI, Birbilis said.
“There have only been a few developments in the history of corrosion-resistant materials,” he said. “A good example is stainless steel, which was a discovery rather than an invention.”
Devising new materials that match the properties corrosion engineers seek is complicated by the sheer number of potential alloys that can be created.
AI, Birbilis said, allows researchers to speed-run a mix-and-match process.
“If you were to experimentally make alloys and try them with a traditional production of materials, you’d need as long as the universe has been in existence to do all the experiments,” he said.
“In machine learning and AI, we have the ability to accelerate materials design digitally and screen a large list of candidates. This area has been emerging globally in the last couple of years.”
Beyond material solutions, corrosion experts are continuing to refine electrochemical responses.
“Cathodic protection is a way of protecting steel from corrosion through either sacrificial anodes or through an impressed current method, where you supply some electrons – you literally plug your structure into a wall – and you supply electrons to it,” Birbilis explained.
“If you supply electrons to a metal, it drives down the driving force for corrosion because it has a surplus of electrons and it doesn’t want to oxidise.”
An early example of this technique, he said, was pioneered in Australia’s transit networks.
“Some of the earliest use of cathodic protection was in inner Melbourne, because infrastructure was corroding as a result of stray current from the tram network.”
And it’s an area in which Australia has remained innovative. Just this year, a closed-loop smart cathodic protection technology developed by Deakin University’s Dr Mike Yongjun Tan was awarded the Materials Performance Corrosion Innovation of the Year Award at the Association for Materials Protection and Performance conference in Nashville.
The technology monitors materials in real time and automatically adjusts protection levels to mitigate complex and localised forms of corrosion.
Aerial stress
While transit by land and sea is subject to a broad range of corrosive environments, air travel must endure all of these and more. In the sky, material failure from hard-to-detect flaws such as stress-corrosion cracking can have particularly catastrophic effects.
Air transport has distinct features that shape the kinds of corrosion to which it is susceptible: planes operate in harsh environments and in a wide temperature range, move rapidly between high altitudes and ground-level, and can be exposed to fuel leaks and pollutants.
“Corrosion can target a small location, a very small micro-structure that we cannot see,” explained Tan, who is Professor of Applied Electrochemistry and Corrosion Technologies at Deakin.
“We’ve had in the past a lot of aircraft incidents due to this stress-corrosion cracking, so in the corrosion engineering area, we have spent a lot of time and a big effort has been made to investigate it – how to stop it and how to change the material.”
One engineer working to strengthen the material we use to keep our planes in the sky is Dr Mukesh Bhasin, who conducted his doctoral research into graphene-reinforced aerospace polymers at RMIT University.
He told create he keeps three aims in mind when it comes to aircraft materials.
“Number one is safety, number two is maintenance cost, and number three is weight and performance.”
Traditionally, planes have been constructed from aluminium to address the weight and performance metric. It’s a light metal and, when used in alloyed form, a strong one.
But aluminium alloys are susceptible to corrosion, usually addressed through coatings and surface treatments. When aircraft engineers began introducing stiffer and lighter carbon composites into aircraft design, they were looking to improve performance.
“Because of the change of material, we were inadvertently also working to reduce corrosion – but that was not the primary goal,” Bhasin said. “Composite is a carbon-fibre reinforced plastic.”
And while plastic doesn’t rust, composites are still at risk from galvanic corrosion, such as might occur where plastic meets metal inserts or fasteners, and stress corrosion that forms cracks in which moisture can collect.
Bhasin wants to improve the next generation of carbon composites by integrating into their structure the nanomaterial graphene, which he describes as having “phenomenal properties”.
“Because graphene is one single layer of carbon, it creates a barrier which is impermeable to any gas or liquid,” he said. “We are able to block the agents for corrosion, which can be moisture, oxygen or other electrolytes which have to come into contact with the metal.”
Although graphene is usually highly conductive, it can be engineered to act as an insulator, meaning it prevents galvanic corrosion through electrical isolation.
“Galvanic corrosion requires two different elements or two metals to contact with electron flow between them,” Bhasin said. “If we put a layer of graphene in between them, that can prevent the electron flow and hence stop corrosion.”
There is also potential for graphene to be adapted as a smart material that stops cracks from growing after they appear, and even self-heal. Some experimental forms are even being adapted to act as indicators of other problems, letting engineers and maintenance crews know to investigate a material before a problem gets out of hand.
“If we put nanoparticles within the matrix, we can make it generally conductive,” Bhasin said. “Any separation of material can be sensed through the reduction in the electrical conductivity.”
Return to form
When talking about their life’s work, corrosion engineers can sometimes sound fatalistic; their outlook almost turns philosophical.
“Corrosion is unavoidable. It is a process that returns the metals to the original mineral state in which they came from,” Nesic said. “It’s just progression. You can’t stop it, but you can slow it down so that things can last for as long as we need them to last.”
We might live in a corroded world, but that’s what inspires Nesic and others to continue innovating.
“It’s that thermodynamic driving force that wants metals to go back to basically being ores,” Birbilis said. “But we do know enough now for designing how to stop that. That’s where we need to do really well, so our infrastructure can last.”
Nesic said he wants to equip engineers with the best possible knowledge to help them produce infrastructure that lasts longer.
“We are constantly fighting to understand and research what corrosion does and how it does it,” Nesic said. “My goal is to understand the enemy in order to be able to fight it.”
This story was originally published in the August 2025 issue of create with the headline “Material issues”.
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