The composition analysis of stainless steel pickling passivation paste adopts modern large-scale spectrometer [infrared, NMR, GC-MS, TGA, DSC, SEM,]; [component analysis of stainless steel pickling passivation paste] combined with the sealant industry for many years engaged in stainless steel pickling passivation Experts from universities in research on paste composition analysis, using rich standard raw material library and mass production experience, reversely reduced the composition analysis of stainless steel pickling passivation paste; the composition analysis of stainless steel pickling passivation paste is widely used in automobile, electronics, electrical appliances and other industries .
Process Control in Pickling and Passivation Operation
Nitric acid solution alone is effective for removing free iron and other metal contaminants, but it is ineffective for removing iron oxide scale, thick corrosion products, tempering films, etc. HNO3+HF solution should generally be used. For convenience and operational safety, fluorine can be used. compound instead of HF. The HNO3 solution alone can be used without corrosion inhibitor, but Lan-826 needs to be added when HNO3+HF pickling. Use HNO3+HF pickling, in order to prevent corrosion, the concentration should be kept in a ratio of 5:1. The temperature should be lower than 49℃, if it is too high, HF will volatilize.
For the passivation solution, HNO3 should be controlled between 20% and 50%. According to electrochemical tests, the quality of the passivation film treated with HNO3 concentration less than 20% is unstable and prone to pitting corrosion, but the HNO3 concentration should not be greater than 50%. To prevent overpassivation.
The one-step method is used for degreasing and pickling passivation. Although the operation is simple and man-hours are saved, the pickling passivation solution (paste) contains aggressive HF, so the final protective film quality is not as good as the multi-step method.
During the pickling process, the acid concentration, temperature and contact time can be adjusted within a certain range. With the increase of the use time of the pickling solution, it is necessary to pay attention to the changes of acid concentration and metal ion concentration, and care should be taken to avoid over-pickling, and the titanium ion concentration should be less than 2%, otherwise it will lead to serious pitting corrosion. In general, increasing pickling temperatures will speed up and improve cleaning, but may also increase the risk of surface contamination or damage.
