From the perspective of metal corrosion cleaning, the modification layer and the substrate belong to a homogeneous layer, and the film material contains a base layer element or a derivative of the base layer, that is, various corrosion products or decay products. The green laser pointer method is used for removal. The main cleaning mechanism is the gasification mechanism. The cleaning effect is achieved after the laser energy density reaches the ablation threshold of the rust layer. Specific removal methods are divided into two types: direct gasification and recoil pressure.
The rust generated by iron and steel in the atmospheric environment is a kind of crevice corrosion, which forms a layer of loose and porous oxide scale on the surface of the steel substrate, which cannot serve as a seal protection. The infiltration of water, oxygen and other gases causes the substrate to be constantly rusted. However, based on the characteristics of the rust layer of steel, it has facilitated the removal of rust by laser.
In essence, the laser cleaning of metal materials is a physical removal. It is mainly caused by the vaporization of the rust layer, the existence of a temperature gradient between the rust layer and the substrate to induce thermal stress at the interface, and the expansion of the gas or liquid phase between the rust layer. Decomposition and interstitial phase expansion and fracture alternately, the thickness of the rust layer gradually decreases, and finally the green laser pointer clears the rust effect.