Abstract
In laser peening, a transparent overlay called the plasma confinement layer is typically employed to suppress
the expansion of the plasma such that a high-pressure shock wave is generated. Water is usually used
as a plasma confinement layer. However, for metallic materials that are sensitive to water, solid media can
substitute for water. In this study, laser peening was performed in a dry environment using silicone rubber
(polydimethylsiloxane, PDMS) as a plasma confinement layer. Instead of using rigid solid media such as
glass, PDMS has been used, which is softer and can effectively adhere to metal surfaces to improve the
acoustic impedance mismatch. Because of laser-induced damage, it is difficult to use solid media repeatedly
as a plasma confinement layer, which ultimately reduces the efficiency of the laser peening process.
Experiments were conducted to explore the appropriate process window for laser irradiation by varying
the laser intensity and number of laser shots.
