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"CitriSurf® is a perfect and environmentally friendly alternative to passivating with nitric acid!"

Dieter Fuchs, Boehringer Ingelheim Pharma GmbH & Co. KG

CitriSurf®: the solution for corrosion problems

In order to comply with the international technical standards, all stainless steel has to be passivated in order to ensure the required rust protection. Appropriate passivation should also be carried out in order to protect the products themselves. Stainless steel is indeed able to spontaneously form a passive layer; however, this process takes several hours or days, and it can be interfered with by contamination and variability in the concentrations in the steel’s composition. This natural passive layer is relatively thin and can be damaged by just light mechanical stresses, and though it contains passive chromium oxide the original surface iron is still present also.

These days, the admixture of in-part inferior-quality steel results in contamination by inclusions. Free iron on the surface leads to pitting and rust.

The CitriSurf® passivation method dissolves iron and contamination on the surface, and the formation of the passive layer is accelerated. This improved passive layer contains no surface iron and is more durable compared to the natural passive layer or the passive layer obtained by the use of nitric acid.

In particular, laser-engraved products should be passivated after engraving because the surface integrity is destroyed by the laser. Time and again rusting occurs, particularly at these locations.

The CitriSurf® method can be used with all stainless-steel types; other materials combined within the work piece, such as plastics, aluminium or brass, are not corroded by the organic acid.

The CitriSurf® method is superior to all other methods, in particular nitric acid, with regard to safety at work and reliability of the application, as well as environmental compatibility, because citric and other biologically compatible chemicals are being used.

In order to simplify application for parts that cannot be flushed through or immersed in a bath, we have managed to expand the successful passivation concept for stainless steel in collaboration with our developer in the United States.