Oxidation film removing method based on femtosecond laser etching

Abstract

The invention discloses an oxidation film removing method based on femtosecond laser etching. The method is applied to surface oxidation film removing before welding of metal such as aluminum alloy and magnesium alloy. According to the method, with a femtosecond pulse laser serving as a direct tool, transverse or longitudinal progressive scanning of a pulse sequence on the surface of a workpiece is achieved through a scanning galvanometer. Under the effect of the ultra-intense and ultra-short femtosecond pulse laser, an oxidation film vaporizes instantly and is driven by a vapor stream formed on the surface to escape or be desorbed from the surface, and thus the oxidation film is efficiently and precisely removed in a controllable mode; or, in combination with linear motion of the workpiece, the oxidation film in a designated area of the surface of the large-breadth workpiece can be precisely removed through etching, the influence of the heat effect on the structure property of a base material can also be effectively avoided, and meanwhile the oxidation film can be thoroughly removed in an environment-friendly mode. The method has broad application prospects in oxidation film removing for fusion welding of light metal such as aluminum and magnesium.

Description

technical field [0001] The invention belongs to the technical field of light metal welding, and in particular relates to a method for removing oxide films on the surface of light metals such as aluminum and magnesium by using femtosecond pulse laser etching. Background technique [0002] As important light metal structural materials, aluminum and magnesium alloys are widely used in aerospace, rail transit, automobile and other fields. However, due to the strong chemical activity of aluminum, magnesium and other alloys, an oxide film will be formed on the surface under natural conditions. For example, the main component of the oxide film on the surface of aluminum alloy is aluminum oxide, and its thickness is about 4-5nm. This layer of oxide film has a loose structure and poor corrosion resistance. These non-dense oxide films can absorb more water, and the absorbed water can exist in the form of crystal water, such as Al 2 o 3 ·H 2 O or Al 2 o 3 ·3H 2 O, can also exist...

AI Technical Summary

Problems solved by technology

Grinding is currently the most widely used physical method to remove the surface oxide film, but it usually causes physical damage such as scratches on the surface of the substrate. At the same time, the method of mechanical cleaning requires high technical level of the operator, and it is difficult to clean the thickness and width. Precise control, cleaning effect is difficult to guarantee

Although the method of chemically cleaning the oxide film has a good cleaning effect, it is necessary to first protect the area not to be cleaned with glue, and the protective glue needs to be cleaned after corrosion. The process is complicated, the efficiency is low, and there is serious environmental pollution.

The swing arc cathode atomization oxide film cleaning method based on the cathode atomization of the AC or DC reverse arc can control the cleaning position, but the cleaning is not complete because it only breaks the metal oxide film with a high melting point and pushes it to the edge of the molten pool. , on the other hand, limited by the arc swing, it is not suitable for large-scale cleaning

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