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Why PEO is the superhero of surface treatments

Surface treatments are applied to billions of pounds’ worth of metal components and products around the world, to protect and strengthen them. Most of these products will never be treated with PEO (Plasma Electrolytic Oxidation).

Why? Because in many circumstances, traditional surface treatments like anodising, thermal spraying or plating will do. Manufacturers have been successfully anodising surfaces to improve strength and durability for a hundred years.

However, in industries like aerospace, energy, hi-tech, transport and biomedical, where performance and environmental requirements are more intense, manufacturers are turning to a newer, more advanced process to solve their toughest challenges.

Product designers and materials engineers in these sectors are discovering that PEO is the superhero of surface treatments.

What is PEO?

PEO is a surface treatment that improves the performance of alloys of aluminium, magnesium and titanium (substrate). The PEO process involves oxidising components in an electrolyte bath (much like traditional anodising). Millions of short-lived plasma discharges – like microscopic bolts of lightning – transforms the substrate into an oxidised ceramic layer to introduce unique characteristics. Finally, elements of the electrolyte bath are incorporated into the ceramic layer in different proportions depending on the desired result.

Here are five challenges PEO is helping leading organisations overcome.

Challenge 1: Reduce weight without impacting other performance criteria

In sectors like aviation and transport, steel has always been the go-to material for strength and durability. Because PEO dramatically enhances the properties of light alloys, product designers are now able to swap out heavy steel for lighter alternatives.

In new air mobility concepts such as vertical take-off and landing (VTOL), electric planes and drones, using PEO-treated, lighter components can dramatically improve an aircraft’s range and fuel efficiency.

In automotive, heavy parts like brake discs increase the amount of fuel or electricity needed to power the vehicle. Switching to aluminium treated with PEO offers automotive manufacturers the same performance as steel, with less impact on the environment. Significant reduction in brake emissions can be achieved (simulation test bench results project circa 78%) , using PEO.

Challenge 2: Lower emissions and reduce overall environmental impact

As we’ve already seen, using PEO means manufacturing lighter components, which can reduce energy consumption. But the PEO process helps organisations become more environment friendly in other ways too.

Manufacturers are bound by ever more stringent regulations. These include restrictions on the use of chemicals which are harmful to the environment, such as REACH (the registration, evaluation, authorisation and restriction of chemicals), and RoHS which covers hazardous substances in electrical and electronic equipment.

Traditional anodising techniques typically use sulphuric acid in their production – an extremely corrosive, toxic substance which harms aquatic and animal life if released into the environment. Black anodising – a process used in optical applications to absorb light – requires the use of carbon monoxide, which has been shown to contribute indirectly to climate change.

Organisations looking to improve their sustainability and comply with environmental regulations are shifting to PEO: a clean technology which doesn’t rely on harmful acids, solvents or gases.

Challenge 3: coat very large, very small, or intricate-shaped items

Wherever liquid can pass, PEO can treat. The treatment can be directed with a high level of precision, to coat some surfaces and not others. Unlike – say – thermal spraying, almost any size or shape of item can be treated with uniform coverage. And because the finished surface is part of the component itself, rather than a coating, there’s no risk of particles becoming dislodged.

These properties make PEO ideal for the biomedical sector, to treat everything from micro-surgical instruments to bioactive coatings for implants and stents.

Equally, precision instruments of any shape, created through additive manufacturing (AM) or computer numerical control (CNC) engineering, can be treated with no loss of consistency.

Challenge 4: increase the durability or longevity of an item beyond typical surface coating capabilities

PEO’s adherent qualities and conformability mean fewer maintenance cycles for repair and resurfacing, compared to less sophisticated solutions. Where manufacturers need to reduce downtime for equipment, they are electing to use PEO, rather than treatments which fatigue more quickly (such as plasma nitriding and anodising); which don’t bond as well to the component (plating, painting); or which don’t offer high enough load-bearing capacity (physical vapour deposition (PVD)).

Challenge 5: increase thermal and electrical protection

A frequent challenge in sectors such as aerospace, space, transport and electronics is managing temperature. To function correctly, components must be protected from the heat produced by a circuit board, for instance, or the enormous variations of temperature encountered by a satellite in space.

Often external coatings or pieces of electrical tape are applied to parts where heat must be dissipated. Because these types of protection are distinct from the component itself, they risk flaking or coming unstuck, meaning they must be replaced regularly. They can also contain glues or chemicals which are harmful to the environment or impact recycling potential.

Dielectric insulation is also an important quality in many components – i.e. the ability to absorb electromagnetic energy. The density of PEO improves dielectric breakdown, meaning manufacturers can ditch inferior fixes like insulating tape for an inorganic coating which produces better insulation.

Why Keronite PEO?

Keronite is the world leader in Plasma Electrolytic Oxidation. Our team collaborates with design and materials engineers from the early stages of the R&D process to help produce the best possible finished product.

The electrolytes used in our PEO process are patented and we use proprietary power supply units. Because PEO is all we do, we’re able to focus 100% of our energy and resource into creating the ideal solution for our clients.

Benefits of Keronite PEO include:

  • Fully inorganic, very low outgassing (<0.1 TML%) and no particle shedding
  • Consistent and stable properties (e.g. solar absorptivity and emissivity)
  • Resistant to extreme UV loads, charged particles, radicals
  • High temperature (>450˚C) and thermal shock resistant
  • Resists cold welding and corrosion
  • Stable range of optical and other properties

Get in touch to find out how Keronite PEO, the superhero of surface treatments, could improve your components’ performance.

CWST Keronite is now part of the CWST engineered coatings business.