How is the passivation of the screw done?

First, let’s first understand the passivation mechanism of the screw: we know that iron and aluminum can dissolve quickly in dilute HNO3 or dilute H2SO4, but the dissolution in concentrated HNO3 or concentrated H2SO4 almost completely stops. Carbon steel is usually very easy. Rusting, if an appropriate amount of Ni and Cr are added to the steel, it becomes stainless steel. The phenomenon that the metal or alloy is affected by some factors and the chemical stability is obviously enhanced is called passivation. Metal passivation caused by certain passivating agents (chemicals) is called chemical passivation. For example, concentrated HNO3 concentrated H2SO4, HClO3, K2Cr2O7, KMnO4, and other oxidants can passivate the metal. After the metal is passivated, its electrode potential moves in the positive direction, causing it to lose its original characteristics. For example, the passivated iron cannot replace the copper in the copper salt. In addition, the metal can be passivated by electrochemical methods. For example, Fe is placed in the H2SO4 solution as an anode, and the anode is polarized by an applied current. The iron potential is raised to a certain extent by a certain instrument, and Fe is passivated. The phenomenon of metal passivation caused by anodic polarization is called anode passivation or electrochemical passivation.

The passivation state of the screw protects the screw from corrosion, but sometimes it dissolves in order to ensure that the metal can participate in the reaction properly, and must also prevent passivation, such as electroplating and chemical power.

The stainless steel screws of the Shi Shi Tong screw factory can be used for passivation of screws according to your needs. Please contact Shenzhen Shi Shi Tong Metal Products Co., Ltd. for custom screws.

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