Enhanced Passivation

The corrosion of stainless steel is counteracted by passivation. Without passivation iron or iron oxide exists on the surface of stainless steel. When any machining or fabrication operations are performed, the condition is worsened. Aside from iron being deposited by tooling, it is also being entrapped underneath the "smeared skin" created by the mechanical operation. This is why GEMLUX® processing is so valuable. The salt spray corrosion tests shown below clearly illustrate the superior results provided by GEMLUX® processing. A 5% salt-fog environment was used in accordance with ASTM B117. All of the tests on these pages have been conducted by independent laboratories.

Surface passivation by nitric acid immersion only attacks iron at the surface. This only partially solves the problem. The remaining iron under the skin will now corrode both inwardly and outwardly. The inward corrosion is known as I. G. A. or intergranular attack. The results are metal fatigue and surface corrosion. The photographs above indicate how passivation by nitric acid immersion actually raises the microfinish of a surface because it leaves pits where iron had existed. Any applications requiring a clean environment such as gas or liquid valves and pumps, bearings, vacuum systems, or fuel supplies would be subject to detrimental effects without thorough passivation.

GEMLUX® processing resolves this problem entirely. Surface contaminants and the false skin which entraps iron are removed electrochemically. the surface that remains after processing is positively the cleanest, most passive surface possible. The microfinish is lowered and dimensions with close tolerances do not pose a problem. The rate of metal removal is controllable with this process.