How to prevent polycarboxylate superplasticizer from rusting? Check the relevant information of the polycarboxylate superplasticizer storage tank. The corrosion of 304 austenitic stainless steel is generally divided into the following categories: First, due to insufficient solid solution treatment or use in the temperature range of carbides, carbides in the grain boundary Precipitation and grain boundary corrosion caused by chromium deficiency.
Secondly, due to the inclusions on the surface of the material, the surface uniformity of the material is destroyed, thereby causing localized corrosion. Third, stress corrosion occurs in the presence of ions with strong penetrating power, such as chloride ions. Stainless steel fasteners are usually pickled and passivated after cold rolling and twisting. The main purpose is to clean all kinds of grease, scale and scars on the surface.
At the same time, the metal surface exposed to the air is rapidly passivated, forming a new layer of chromium-rich passivation film, which plays an anti-rust role. Therefore, passivation treatment is very important in the processing of stainless steel fasteners. If the acid passivation treatment is not done properly, the residual acid on the surface cannot be cleaned, which may lead to localized corrosion on the surface of the material. Locally high CI, low PH value, etc., accelerate material corrosion.
The presence of CI- was also found in the corrosion samples, and the higher velocity of the local CI on the surface accelerated the corrosion of the material. In order to prevent corrosion, three measures have been taken: one is to strengthen the control of the raw material procurement process and reduce the content of S element in the finished product; the other is to wash with weak alkaline solution before passivation.