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What is Passivation?

Passivation is a non-electrical metal finishing process to help prevent metal surfaces from corrosion and pitting. The chemical treatment for stainless steel and other alloys makes the metal more resistant to rust and reduces chemical reactivity.

How Does Passivation Work?

Passivation involves immersing stainless steel parts in an acid bath (usually nitric or citric acid). This process removes free iron from stainless steel surfaces. When the stainless steel is exposed to oxygen-containing environments, a thin chromium oxide film layer then forms. While most stainless steels naturally form this protective oxide layer, the passivation process thickens the layer and significantly speeds up the process. The oxide layer creates a passive surface that acts as protection from corrosive environmental stimuli.

Why Passivation?

Passivation removes outside free iron and iron compounds from the surface of metal, removing surface contamination, but leaving the integrity of the stainless steel intact. Improving the quality as well as sterilization of stainless steel, the passivation process is ideal for a variety of industries including aerospace & defense, medical, food & beverage, and oil & gas.

The 300 series stainless steel alloys are best suited for passivation. However, some of the 400 and other high sulfide series alloys are not the best candidates for the passivation process. For assemblies that will need to be passivated, all components should be made of the same alloy as different alloys may have different appearances after the passivation process.

With over 20 years’ experience and a commitment to quality standards and processes, Electro-Max, Inc. provides the best service, unsurpassed quality and superior passivation services. EMI is NADCAP accredited, fully registered to ISO9001:2015 and complies with ASTM A380, ASTM A 967, AMS 2700, QQ-P-35, SPS-1001, PS 2026, or customer specific standards.

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