Surface treatments for aluminium and other metals: types and advantages

Applying specific surface treatments to aluminium enhances the material with high anti-friction properties, wear resistance and corrosion protection, while improving its appearance.

The metal and aluminium surfaces used to coat machinery in industrial and commercial contexts are subject to wear and tear, damage and heavy physical and mechanical stresses, reducing the performance of the machinery over time. Suitable surface treatments can be applied, however, to improve the physical and mechanical properties of the material, making it stronger, more durable and more aesthetically pleasant.

The surface treatments offered by Argos, such as anodizing and hard anodizing, enable improved production performance and longer equipment life.

For some treatments, such as painting, preparatory treatments including electroless nickel plating or phosphating yield optimal results in terms of brilliance and colour uniformity.

Argos surface treatments

Anodizing

Anodizing is a particular surface treatment that creates an oxide finish on surfaces. It is made of aluminium and titanium alloys and can be applied to aluminium and aluminium alloys.

The great advantage of anodizing is that it performs a dual protective action resulting in:

• Wear resistance: the aluminium oxide layer is so hard and compact that it compares to hard chrome. Excellent resistance to abrasion and adhesive wear.
• Corrosion resistance: the elevated anti-corrosion properties mean the surface can withstand long exposures to aggressive substances and weathering.

Hard anodizing

In the hard anodizing process, a hard oxide finish is created on the aluminium surface by passing a current through a tank at sub-zero temperatures.

It is therefore possible to achieve a notable increase in surface hardness and reduced roughness, resulting in greater corrosion resistance, moderate insulation and reduced friction (if hard anodizing is combined with a PTFE coating, also provided by Argos).

The applications for Argos surface treatments include the automotive, aeronautics, chemical/pharmaceutical, food, oil & gas, textiles, printing and packaging industries.

Among the various metal treatments, electroplating stands out.

Electroplating treatments are split into three stages: surface preparation, metal coating and finishing work.

Preparation of the aluminium surface involves chemical degreasing (through simple immersion) and electrolytic degreasing (the treated parts are bonded as anodes or cathodes). An additional step, pickling, is used to remove traces of oxidation or rust.

The next step involves deposition of the metal coating (zinc, copper, tin, etc.) by passing a continuous current through an aqueous solution containing ions of the metal to be deposited.

The last stage is finishing, a passivation process that lends the surface greater resistance and enhances the appearance of the item.

Types of surface treatments

Different processes exist to treat the surface of steel, aluminium and other metals such as iron, copper and special alloys. Each has its own unique characteristics as well as features common to other treatments. The aim is to improve production performance and extend the life of systems and machinery.

Non-stick and anti-friction treatments facilitate sliding along the surfaces, treatments for corrosion resistance protect them from chemical or atmospheric agents; and hardness treatments increase their resistance to damage, while electrical and thermal insulation treatments allow for safe working conditions in the presence of high temperatures or possible electrical discharges. Let’s examine them in detail.

Corrosion-resistance treatments – (Visit the page)

Used in the automotive, chemical and oil & gas industries, treatments for corrosion resistance are applied to metal surfaces (systems and machinery) for greater resistance to wear and chemical aggressors. The thickness of the coating can be selected (from 30 microns to 1 mm) to suit your individual needs.

Anti-friction treatments – (Visit the page)

With their non-stick properties, treatments to reduce friction can be applied to ensure better sliding over metal surfaces. The presence of solid lubricants makes the surface self-lubricating. Such treatments are usually used in production lines to make materials slide better; reducing friction also means less energy is needed.

Non-stick coatings – (Visit the page)

Used in a variety of markets, including mechanical engineering, food processing, packaging and rubber and plastics, non-stick treatments give metal surfaces hydrophobic and non-stick properties against a variety of substances, such as rubber, paint, ink, leather, adhesives, pills, etc. The use of special treatments means they can work at high temperatures (up to 270°C), so they are very popular in the food sector (pasta, coffee, chewing gum, sweets and cakes).

Antimicrobial treatments

The presence of harmful bacteria and germs on surfaces creates a breeding ground for the development and spread of infectious diseases. To overcome this issue, especially in environments such as the healthcare sector, Argos has developed an antimicrobial treatment that hinders the formation of fungi, bacteria, viruses and other dangerous parasites that can lurk on surfaces.

Wear-resistance treatments – (Visit the page)

Wear-resistant coatings can dramatically extend the life of machinery subject to abrasion due to certain processed products. With coatings and treatments that give the base material low friction and smoothness, the production efficiency of the machinery is extended over time, especially in sectors where particularly abrasive materials are processed, potentially leading to premature wear of the machinery and the consequent reduction in production capacity.

Electrical insulation – (Visit the page)

To make surfaces safe from sudden electrical discharges, it is necessary to create an impermeable, insulating barrier with coatings that also provide high heat, moisture and shear resistance.