Passivation is mainly performed on stainless steel parts. Non-ferrous metals, such as titanium or aluminum, are self-passivating; i.e. they react with the oxygen in the air and form a natural passivation layer. Stainless steels also have natural passive layer with often is not fully closed, however. By means of passivation, the free iron particles are removed from the surface of the steel and a thicker chromium oxide layer than what the natural passivation has is developed. This therefore increases corrosion resistance as well as the live time of a work piece. Types of passivation are listed in the US Norm ASTM A967/A967M which describes how to proceed and test. Acc. to this norm, both nitric acid as well as citric acid can be used.
PASSIVATION AT ADD'N SOLUTIONS
add’n solutions decided to passivate with citric acid due to the better results and the safer handling of this acid. The process takes place in our fully automated and validated cleaning and passivation machine. We laid out and tested the parameters such as time, concentration and temperature according to ASTM A967/A967M in such a fashion that we achieve both optimal corrosion resistance as well as a guaranteed readability of the marking. After laser marking our passivation of stainless steel products in combination with a thorough cleaning offers an optimal added value for your products.