Metal finishing for aerospace components requires meticulous processes to ensure the removal of contaminants and the highest quality results, including corrosion resistance for improved performance and longevity.

What is Passivation?

Passivation is an option for enhancing the finish and corrosion resistance of metal parts without removing any surface material. It works by using a chemical bath to remove free iron from the surface and fostering the formation of a thin oxide layer that acts as a barrier to protect against  environmental factors that could lead to corrosion, extending the lifespan of the component.

Unlike electropolishing — which also creates a passive layer but removes a precise amount of surface material through an electrochemical process — passivation does not alter the physical dimensions or aesthetics of the part.

Passivation Pre-Cleaning Processes

Before passivation begins, parts must be cleaned to remove lubricants, adhesives and other contaminants. Advanced pre-cleaning processes, including vapor degreasing and reverse alkaline cleaning, effectively removes any oils or residues while also reducing vapor emissions by 99%.

Passivation works to remove free iron, which develops from the transfer of material from carbon steel tooling used in machining to stainless steel components. This cross-contamination introduces foreign particles that can compromise the integrity of the metal surface leaving it  susceptible to corrosion. Passivation effectively removes these superficial iron deposits without removing metal surface material like electropolishing does.

Which is Right for Your Parts? Choosing Between EP & Passivation

The choice of finishing methods depends on the specific requirements of the aerospace component. For parts needing a higher level of corrosion resistance, electropolishing may be the preferred method, leaving parts with 30% more corrosion resistance while also leaving parts in a passivated state. However, for applications where maintaining the component's original dimensions and appearance is critical, passivation offers an effective solution without altering the part's physical properties.

Nitric vs. Citric Acid Passivation

Both nitric and citric passivation are effective for achieving the desired protective oxide layer. While nitric acid has a reputation for being more aggressive, the results are quite similar. However, some prefer citric passivation for its environmental benefits and sustainability considerations.

Able provides both nitric acid and citric acid passivation and can process per AMS 2700, ASTM A967 and ASTM A380 specifications.

Able Electropolishing Quality Control

With an automated German-engineered degreasing system and compartmentalized carriers for rack-passivation, meticulous quality control processes ensure that parts undergo treatment without risking damage from part-to-part contact.

At Able Electropolishing this attention to detail extends to our flexible service offerings, including standard 5-day turnaround times with options for expedited next-day or two-day delivery.

Our team has deep experience in collaboration with engineers across industries and our solutions reflect our role as both a pioneer of the process and an industry leader.  Our expertise in both electropolishing and passivation enables us to provide customized solutions that meet the stringent demands of the aerospace industry, ensuring that every component we treat is optimized for performance, longevity, and reliability.

Contact us to learn more about passivation for aerospace