Effect of nanosecond laser pulse scanning beam on the microtopography of Al ceramic coatings2O3
The possibility of changes in Al2O3 ceramics surface microtopography under the action of nanosecond laser pulses has been investigated. Results of the surface modiication are presented for lasers operated in a pulse-periodic mode (10 ns pulse duration, 100 Hz repetition frequency): ArF-excimer laser (193 nm wavelength) and solid-state Nd:YAG laser (355 nm wavelength, third harmonic). Ceramic specimens were irradiated in air by series of laser beam (350 mm in diameter) pulses with luences from 0.2 to 0.7 J/cm<sup>2</sup> with scanning speed up to 1 mm/s. Formation of new laser-induced periodic surface structures was is to be ascertained. The surface microstructure shape and size parameters were studied with the help of atomic force microscopy. Efects of absorbed energy density and laser radiation wavelength on the characteristic dimensions of the structures formed have been studied. The laser pulse luence and wavelength were found to be the key parameters determining the resulting surface structure dimensions. Laser treatment with a shorter wavelength results in a decrease in the characteristic period of the microstructures.