Particle Generation from Aluminum Alloy Surfaces Irradiated by 355nm Pulsed Laser and Multi-shots Laser Pretreatment Method at Low Fluences

The studies focus on particle generation from aluminium alloy surfaces irradiated by a Q switched Nd:YAG laser at 355 nm wavelength at low fluencies. The particles number increase with laser fluence but reduces with pulse number. The average initial threshold laser fluence for particles generation is 26.64 mJ/cm2. Larger particle with a diameter more than 5μm are found for fluencies above 76.54 mJ/cm2. After 40 pulsed laser shots at 72 mJ/cm2, it can effectively reduce the generation of metal particles. Our results demonstrated that 7075 aluminum alloy has the best laser resistance and the method of multi-shots laser pretreatment can reduced the generated particles by 76.92%. The SEM results shows that laser pretreatment process lead the passivation effct which smoothed the microstructure on the initial surface. The XPS results shows that zinc aluminate was generated during laser pretreatment process which has good thermodynamic properties. This study has important value for reducing metal particle contamination due to laser irradiation on metal surface in high power laser facilities and improving the service life of optical components.