SurTec 650 treatment is a chromate conversion coating for aluminium surfaces.
Its primary function is to protect aluminium against corrosion without the need for any additional treatments.
At the end of this electrochemical conversion process, the aluminium is highly resistant to attack from external agents.
In fact, this treatment meets the main corrosion-resistance requirements of the U.S. Navy (MIL-C-5541 / MIL-DTL – 81706 / minimum 336 hours in NSS).
It also provides high resistance in salt spray testing, up to 350 hours.
The complete protection of aluminium achieved through SurTec 650 passivation results from an electrochemical process: the metal is coated with a thin, highly resistant passivation layer (passivation film) that covers the entire surface and adheres to it perfectly.
This protective film effectively shields the metal against corrosion and provides long-lasting protection.
In this way, chromates or dichromates inhibit corrosion phenomena in metallic materials, which is why the process is referred to as chromate conversion.
Generally, to achieve high-quality final results, a number of preliminary operations must be carried out before the treatment.
For example, any grease residues must be removed from the aluminium component, the surface must be made uniform and matt, impurities must be eliminated, residual alkalinity must be neutralized, and any film remaining on the surface of the components must be removed.
The process is generally followed by washing and drying stages.
The widespread use of SurTec 650 treatment is due not only to the high level of protection it provides for aluminium, but also to its ability to preserve the material’s high electrical conductivity.
The process withstands temperatures of up to +100°C and provides very low electrical resistance (<< 5,000 ohms per square inch, according to MIL-DTL-81706B), while leaving the material’s properties unchanged.
Furthermore, although the treatment is free from hexavalent chromium (Cr(VI)), it delivers excellent performance while being completely non-toxic, sustainable, and compliant with the European RoHS Directive (Restriction of Hazardous Substances in Electrical and Electronic Equipment).
In addition, this process can also serve further functions.
It prepares the component for subsequent treatments by ensuring excellent adhesion between the metal and the following organic finishing layers, thanks to the support provided by the passivation layer.
For this reason, SurTec 650 treatment is also widely used as an effective pretreatment for the adhesion of paints, coatings, lacquers and other finishes.
Its effectiveness in this respect is confirmed by QUALICOAT and GSB approval.
Given the significant benefits it provides, this process is widely used across many industrial sectors.
Typical applications include the chemical, marine, electronics, medical, railway, aerospace, telecommunications and defence industries.
Overall, SurTec 650 passivation is particularly suitable for industries requiring high levels of resistance, durability and performance, even in harsh and corrosive environments.