Anticorrosion working principle of aluminum coating in thermal spraying

       Thermal spraying is a surface strengthening technology. Those technologies that need to achieve surface engineering need to use thermal spraying. It is also an important technology to prevent corrosion of objects. The working principle of its anti-corrosion coating requires workers to understand. an important principle.



The principle is as follows:



1. The isolation effect of blocking corrosive medium.



Enamel and paint anti-corrosion is this mechanism;



2. Anti-hydrogen sulfide corrosion mechanism of aluminum coating



The aluminum-based coating has excellent resistance to hydrogen sulfide corrosion. Al in the coating can form intermetallic compounds and Al2O3, and the internal stress of the generated corrosion product is relatively small, so that the coating can accommodate the plastic deformation it produces without causing Cracking or peeling of the coating; Al2S3 in the corrosion product can inhibit the outward diffusion of iron atoms, and aluminum atoms can preferentially combine with sulfur, which hinders the formation of iron sulfide and ensures that the substrate is not corroded by hydrogen sulfide.



3. Cathodic protection through self-sacrifice of coating materials.



The electrode potential of aluminum and its alloy coatings is lower than that of steel materials. In the presence of electrolyte, these coatings are anodic materials, and steel is cathodic materials, and a corrosion galvanic cell is formed between them. During the corrosion process, the anode material (coating) protects the cathode material (steel) through its own sacrifice. Since the corrosion products of the aluminum coating can effectively slow down the corrosion rate, the consumption of the coating is also very slow, which can protect the steel substrate for a long time.



With these principles of thermal spraying, workers can better understand how thermal spraying works, so as to achieve higher and better work efficiency.