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 . The passivation 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.
The passivation process 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.
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
environmentally friendly.
Typical specifications for passivation include QQ-P-35 and ASTM A- 967
