With the increasingly strict requirements of environmental protection regulations in China and the increasing awareness of environmental protection and safety, many shortcomings of the traditional cleaning industry are becoming more and more obvious. Laser cleaning is considered to be the most reliable and effective solution for cleaning features such as cleaner, non-contact, efficient and flexible, and suitable for various materials.
Metallic surfaces react chemically or electrochemically with the surrounding medium to cause corrosion of the metal. Metal corrosion is a waste of resources, the extent of which is very alarming. Among the corrosion of various metals, the corrosion of iron is the most serious. The annual steel loss caused by corrosion in the world accounts for 1/5 to 1/4 of the total steel. At present, there are many researches on laser cleaning and rust at home and abroad. Since the invention of the laser, the idea of laser cleaning has been proposed. In recent years, research work on laser derusting has been carried out in China, and useful progress has been made. The efficiency of dry laser cleaning is lower than that of wet cleaning, but the wet film is introduced into the liquid film, which results in low process stability and inflexible industrial applications. If improperly handled, it will cause secondary corrosion and other factors. Dry laser cleaning Research is even more important for industrialization.
Laser cleaning embroidering mechanism
From the viewpoint of metal rust cleaning, the modifying layer and the matrix belong to the homogenous layer, and the film material contains the basal layer element or the derivative of the basal layer, that is, various corrosion products or decay products. The laser is used for removal, and the main cleaning mechanism is a gasification mechanism, which achieves cleaning after the laser energy density reaches the ablation threshold of the rust layer. The specific removal methods are divided into direct gasification and recoil pressure.
The rust generated by steel in the atmospheric environment is crevice corrosion, and a loose porous oxide scale is formed on the surface of the steel substrate, which cannot function as a seal. The infiltration of water, oxygen and other gases keeps the substrate rusted. However, based on this feature of the steel rust layer, it is convenient for the laser to remove rust.
In essence, the rust laser cleaning of metal materials belongs to physical removal, mainly through the vaporization of the rust layer, the thermal stress generated at the temperature gradient induced interface between the rust layer and the substrate, the vapor phase of the rust layer gap or the expansion force generated by the liquid phase, and vaporization. Decomposition and gap phase expansion and rupture alternately, the thickness of the rust layer is gradually reduced, and finally the rust removal effect is achieved.