The occurrence of phosphating on the surface of steel structure screws and nuts is mainly caused by the chemical reaction between the nut surface and the surrounding environment or contact materials. During the construction process, corresponding measures can be taken to effectively reduce the probability of phosphating of the nuts and ensure the safety and quality of the steel structure.
Author: Marisa
I. Causes of phosphating of steel structure screws
Steel structure screws and nuts are commonly used fasteners in steel structure construction. Exposed nuts are prone to oxidation and corrosion. Phosphating is a special chemical conversion process that is common on metal products such as steel and magnesium alloys. The iron ions on the surface of the nut are combined with phosphoric acid to form an iron-phosphorus compound, which can lock the surface of the nut and form a phosphating film to prevent corrosion.
However, when the phosphating degree of the surface of the steel structure screws and nuts is too large or too deep, the film layer will fall off and the surface will harden. There are two main reasons for the phosphating of nuts:
1. Related to the environmental atmosphere: At room temperature and pressure, the surface of metal products such as screws and nuts constantly interacts with the surrounding air. The moisture and oxygen in the water and air will react chemically with the nuts, resulting in oxidation and phosphating on the surface of the nuts.
2. Related to the contact material: If the material or substrate used for fastening is strongly acidic or oxidizing, the nut may react chemically during the longitudinal passivation process to form a phosphide, resulting in phosphating problems on the nut.
II. Solution to phosphating of steel structure screws
1. Surface treatment: You can choose to chemically treat or galvanize the surface of the screws and nuts first to reduce the occurrence of corrosion and phosphating.
2. Choose nuts that are not prone to environmental reactions: Some protective measures may highlight the effect of one aspect, but cannot avoid the influence of other unstable factors on the nuts. For example, choosing stainless steel nuts with strong oxidation resistance can improve the corrosion resistance of the nuts.
3. Control the ambient temperature: The phosphating of some nuts is related to temperature. In this case, the construction personnel should control the ambient temperature and avoid using the nuts at too low or too high ambient temperatures.
III. The occurrence of phosphating on the surface of steel structure screws and nuts is mainly caused by the chemical reaction between the surface of the nuts and the surrounding environment or contact materials. During the construction process, corresponding measures can be taken to effectively reduce the probability of phosphating of the nuts and ensure the safety and quality of the steel structure.