Tougher to go the distance

ArmorGalv is an alternative to hot-dip or electrolytic galvanising.

Strengthening the metals that quite literally keep a mine running is crucial. ArmorGalv corrosion protection not only improves durability, but can help mines achieve their sustainability goals.

ArmorGalv corrosion protection is a galvanising process unique and exclusive to ArmorGalv Australia, the only plant of its kind in the country.

Rather than simply being a coating on ferrous and non-ferrous metals, ArmorGalv is a zinc-iron alloy, with the layers of thermal diffusion galvanising typically exhibiting hardness values greater than that of the parent material.

Surface hardness results typically exceed 35 Rockwell C, as referenced within ASTM A 1059/A 1059M – 08 (ASTM International, 2008).

Using a thermal diffusion galvanising process, multiple layers of zinc-iron alloy are formed, from a super corrosion-resistant gamma layer to a compact delta layer and then the zeta layer.

Each layer is harder, more corrosion-resistant and more abrasion-resistant than the previous one, helping to increase the life of the part.

By strengthening the metal itself, the process creates a more durable material that can withstand harsh mining conditions by delivering better defence against deterioration.

ArmorGalv is an alternative to hot-dip or electrolytic galvanising that was developed to replace cadmium and chrome in plating.

This cost-effective, environmentally-friendly and durable galvanising technique was designed in Israel in 1993. However, it did not find its way to our shores until ArmorGalv Australia was born in 2010.

ArmorGalv Australia general manager Clive Jones said the ArmorGalv diffusion process means the sacrificial layers are diffused deeper into the substrate to ensure it lasts longer.

“It’s embedded inside the material as well as on the top, so it’s harder, it’s flexible, and it’s a smart mixture of a zinc oxide which gives much more endurance to the finished product,” Jones told Australian Mining.

“It reduces internal stresses to the base material and removes any hydrogen embrittlement rather than inducing it like hot-dip galvanising does.”

The process creates a more durable material that can withstand mining conditions.

Material fracturing as a result of hydrogen embrittlement is a safety issue on mine sites, a risk ArmorGalv eliminates.

Mine sites are hotbeds of high-ambient temperatures, extremely high humidity, acid and dust, which results in high demands being placed on the need for corrosion-resistant machines and materials.

Corrosion resistance can be substantially increased through the application of a thicker coating or a top coating.

“With hardened and high-tensile steel, we don’t need to have it as thick as the softer zinc coatings because it’s a hard coating. So it’s not going to chip off so easily.”

When customers are looking for a longer lifespan, they’ll generally look for the thicker coating first, with the option to implement the ArmorPlex solution beyond that, where an epoxy coating will be placed over the top of the ArmorGalv corrosion protection without any further preparation.

“The thicker coating is sufficient for most mines, as it has quite a significant lifespan. It will be fairly extreme conditions, which may be heavily acidic ground, that sort of thing, where the customer might opt for the additional ArmorPlex,” Jones said.

ArmorGalv went through a series of salt spray tests that showed the lifespan of the corrosion protection can be from 1500 to 3000 hours, compared to approximately 500 hours with hot-dip galvanising.

“Heavy equipment components used in mining environments such as cable trays, high-tensile fixings and anchors, rock bolts, small structural steels, springs for vibratory equipment, and conveyor components are all critical parts,” Jones said.

“When these parts are treated with ArmorGalv, they won’t be affected by hydrogen embrittlement, and instead will have the tensile strength customers can rely on to be serviceable for much longer.”

The machinery parts are also exempt from galling when galvanised with ArmorGalv.

Galling is defined as when two surfaces in contact seize up, and the materials gain their corrosion resistance from a passive oxide layer over their surface. Under high contact-force sliding this oxide can be deformed, broken and removed from parts of the component, exposing the bare reactive metal. 

When the two surfaces are the same materials, these exposed surfaces can easily fuse together, causing seizure or galling.

Due to increased hardness and wear-resistant properties, the Thermal Zinc Diffusion process provides good anti-galling properties, predominantly facilitated by the absence of free zinc at the outer surface. 

When it comes to sustainability, ArmorGalv Australia has worked hard to continuously improve its footprint both internally and for its customers.

The ArmorGalv thermal diffusion galvanising process provides important environmental benefits in comparison to other corrosion protection methods. It is a completely non-toxic and heavy metal free, environmentally responsible protection against corrosion and wear and tear.

“The mines that are looking into being more environmentally-friendly and reaching net-zero carbon emissions, they need to be considering ArmorGalv,” Jones said. 

This feature appeared in the April issue of Australian Mining.

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