Nanosecond laser-induced plasma for nondestructive cleaning and substrate strengthening of 7075 aluminum alloy surface coating

This study develops a novel model for plasma-based non-destructive cleaning and substrate reinforcement, employing techniques such as acoustic frequency, LIBS, EDS, SEM, and mechanical property analysis. Theoretical optimization of plasma and shock wave processes for substrate reinforcement is performed. Numerical simulations and experimental results validate the plasma-induced spatial stress distribution process, showing that energy release from multi-pulse combustion waves occurs gradually. Acoustic emission signals during cleaning are monitored to identify the characteristic frequencies of stress elimination and ablation. The combined use of LIBS, EDS, and SEM to analyze surface microstructure and composition changes during cleaning shows that plasma impact and shear wave reflection reduce surface defects, significantly enhancing substrate hardness and durability. Shock-induced martensitic phase transformation increased the local microhardness from 153.5 HV to 206.9 HV. The direct interrelationship of multiple input parameters in the cleaning process was established, and through multidimensional analysis, the physical and chemical reactions in the cleaning process as well as the physical mechanisms of substrate reinforcement after cleaning were revealed.