Stainless Steel Passivation Process
The passivation process is the chemical removal of iron contaminates left behind on the stainless steel surface from machining and fabrication. These contaminates, if not removed, could potentially corrode and deteriorate the stainless steel. This process also leaves a thin transparent oxide film that protects the stainless steel from corrosion. It is a combination of cleaning and a protective coating.
Passivation of stainless steel has been widely used for years by the medical, aerospace, electronics, and other high tech industries that require maximum performance from products manufactured from corrosion resistant steels.
Choosing the Best Passivation Process
The effectiveness of passivation is verified via accelerated corrosion tests, such as salt spray, high humidity and water immersion or a copper sulfate immersion.
The type of stainless steel determines the most effective passivation process. Time, temperature and concentration are all determined by the type of alloy being processed.
The two primary types of passivation utilize either nitric or citric acid solution. Although nitric acid is the most popular because of its history of proven results, citric acid is more
Typical specifications for passivation include QQ-P-35 and ASTM A- 967