Blackening treatment, also known as oxidation treatment or bluing treatment, is a chemical reaction that forms an oxide film on the surface of screws and bolts. This process usually involves placing screws and bolts in a chemical solution containing an oxidant, heating them to form a layer of Fe3O4 film on the surface, which appears black or blue black in color.
Features and advantages:
Low cost: Blackening treatment is a relatively economical surface treatment method.
Improving corrosion resistance: Although the oxide film formed by blackening treatment is relatively thin, it can still improve the corrosion resistance of screws and bolts to a certain extent.
Appearance effect: After treatment, the surface of the screws and bolts presents a uniform black or blue black color, which has a certain aesthetic appeal.
limitations:
Limited anti-corrosion performance: The anti-corrosion performance of blackening treatment is relatively weak, especially in harsh environments where it is prone to failure.
Poor consistency in torque and preload force: The blackened screws and bolts exhibit poor consistency in torque and preload force.