Passivation

TYPE VII – SPEC. QQ-P-35C

Metal Finishing offers Nitric Passivation. Nitric Passivation improves the corrosion resistance properties of mechanisms made of different kinds of steels. Dipping stainless steel components in a solution of nitric acid this will improve the surface condition of the stainless steel. By doing this it dissolves iron that may have been implanted as a result of grinding, machining or other manufacturing operations. If allowed to remain, the iron can corrode and give the stainless steel an appearance of rust. In dissolving the embedded iron, passivation restores the original surface by forming a transparent oxide film.

There are three major fluctuations that must be reflected and controlled for the passivation process they are time, temperature and concentration.

The following preparations will reduce any undefined contamination during manufacturing and increase the chances of successful passivation and test results:
* Never use grinding wheels, sanding materials, or wire brushes made of iron, iron oxide, steel, zinc, or other unwanted materials that may cause contamination of the stainless steel surface.
* The use of carbide or other non-metallic tooling is recommended whenever possible.
* Use only clean, unused abrasives such as glass beads or iron-free silica or alumina sand for abrasive blasting. Never use steel shot or grit, or abrasives which have been used to blast other materials.

Controlled atmosphere ovens are highly recommended for all thermal processes.

Advantages of Nitric Passivation
•    Maximum stainless steel corrosion protection without plating.
•    Superior clean surface.
•    Eliminates iron contamination reactions with other materials.
•    No rust discoloration.