Applied Surface Science, Vol.434, 582-587, 2018
Selective generation of laser-induced periodic surface structures on Al2O3-ZrO2-Nb composites
Laser-induced periodic surface structures (LIPSS) were selectively fabricated on the metal phase of Al2O3-nZrO(2)-Nb (78.3-1.7-20 vol.%) ceramic matrix composites. For this purpose, sample surfaces were irradiated with fs-laser pulses (tau = 300 fs, lambda = 1025 nm) of different laser peak fluences ranging from 0.23 to 0.40 J/cm(2). The structured surfaces were characterised by scanning electron microscopy (SEM), atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and by measuring the water contact angle. Well-pronounced LIPSS with a period of Lambda approximate to 750 nm and a height of h approximate to 263 nm were found solely on the metal phase of the composite when applying the highest fluence whereas no structural and chemical modifications were found on the surface of the ceramic matrix. This can be explained by the different light absorption behaviour of both phases, which results in different ablation thresholds. The water contact angle of composite surfaces was successfully reduced from 68.4 degrees for untreated samples to 40.9 degrees for structured samples. Selectively structured composites with adjustable wettability are of particular interest for biomedical and tribological applications. (C) 2017 Elsevier B.V. All rights reserved.
Keywords:Fs-laser;Laser-induced periodic surface structures (LIPSS);Selective surface structuring;Ceramic matrix composites;Wettability