Not everyone knows that passivation, one of the surface treatments offered by BAMA, is actually a process that already exists in nature. Many materials, in fact, naturally develop a kind of protective film on their surface against aggressive agents: passivation is therefore a treatment that accelerates this phenomenon, making the protective film being formed perfectly thin, dense, and non-porous (fundamental characteristics for the layer to function). However, there is still much to say about passivation: what it is and how it works, for example. Let’s see it together.
What is Passivation
Passivation is, in simple terms, a process that transforms the surface of metals to give them superior resistance to chemical and atmospheric attacks. This chemical metamorphosis is the basis of the resistance of materials such as stainless steel, titanium, nickel alloys, aluminum, and copper. The core of this process lies in the chemical creation of a passive layer, a thin but tenacious oxide barrier that helps the metal protect itself from erosion over time and from the aggression of elements: the artificial passivation process, therefore, consists in the artificial formation of a passivating and protective film and can be considered the ultimate chemical treatment for the protection of metal surfaces.
The Advantages of Passivation
In addition to fighting corrosion, passivation enhances the quality of the material in the long term. For the industry, this means reducing both ordinary and extraordinary maintenance of machinery and surfaces, which consequently reduces operating costs. The ability of the process to extend periods between maintenance interventions is essential, especially in environments where unplanned machine stops can cause production delays and significant economic losses. When performed correctly by experienced personnel, this treatment not only preserves the structural integrity of the metal but also maintains its aesthetic by preventing the formation of stains or patinas that can compromise its appearance. Not bad, right?
Passivation is mainly introduced after mechanical or thermal processes that expose the metal to the risk of oxidation, such as sandblasting or welding. We also recommend it after cleaning or restoring parts that are not freshly welded and already used, as part of a preventive maintenance program to avoid corrosion and prolong the component’s life (and, therefore, the machinery).
How Passivation Works
Let’s now see how the passivation treatment works. The passivation process begins with a thorough cleaning of the piece to remove any machining residue or contaminant, possibly with a pickling or degreasing treatment. Subsequently, the pieces are immersed in chemical baths containing specific acid solutions that react with the metal surface to form the passive layer. This layer is imperceptible to the naked eye but provides important protection against corrosion and wear.
Controlling the immersion time, temperature, and concentration of the solution is crucial to ensure the effectiveness of the process.
The most commonly used methods are immersing the piece in a tank or spray passivation, which involves spraying the acid onto the object using low or high-pressure spray systems.
Various factors influence the success of passivation:
• The composition of the metal alloy
• The presence surface defects (hence why we recommend pickling first)
• The environmental conditions during the treatment
• The professionalism of the company performing the treatment
• The choice of passivating agent.
The choice of passivating agent is particularly important and is linked not only to the type of metal to be treated but also to the sector of destination of the treated component (which can range from the pharmaceutical to the naval, from aerospace to manufacturing, and the agri-food sector).
BAMA Products for Passivation
BAMA S.r.l. offers passivation products developed internally to ensure the highest quality of treatment: the same quality with which we carry out treatments on the artifacts entrusted to us.
Here are our main products for passivation:
• FOSFIRON – A liquid product with a passivating action on carbon steel. It has a dual cleaning and passivating action that eliminates slight oxidations, salts, and grease residues, then passivates the metal surface, making it more resistant to corrosion.
• PICKE-INOX ST. – Specifically designed for stainless steel, Picke-Inox St. is a passivating agent for stainless steel surfaces. The product complies with the standards imposed by ASTM A-380.
• INOX PASS N. – A passivating agent primarily aimed at stainless steel, generally used following pickling treatment. Inox Pass N. complies with the standards of ASTM A-967.
• GEELSTEEL STRONG – A high-viscosity product with a passivating action on austenitic steel (300 series steels), martensitic steel (400 series), and austeno-ferritic steel (duplex and superduplex alloys). The gel removes oxides, salts, and other residues from previous processing from the metal surface, eliminating the risk of localized corrosion. It is particularly effective in removing any traces of weld oxidation.
• GELTITAN STRONG – This is a high-viscosity product with a passivating action on titanium and its alloys. It is particularly effective in removing any traces of weld oxidation and instantly adheres to the surface to be treated without dripping.
Choose the right passivating product: contact us for a consultation!
