Precise femtosecond laser crater fabrication in hard nanolayered AlTiN/TiN coating on steel substrate
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AuthorsGaković, Biljana M.
Milovanović, Dubravka S.
Mihailescu, Ion N.
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Processing of AlTiN/TiN multilayered hard coatings by femtosecond (fs) laser pulses has been investigated. Irradiation was performed in air with linearly polarized laser radiation with pulses of 200 fs duration at 775 nm wavelength. Single or 1000 subsequent laser pulses were directed at normal incidence towards target surface. Laser energy per pulse was adjusted from 0.5 to 50 mu J and corresponding fluence was 0.17-17.5 J cm(-2). The as deposited and laser-ablated samples were characterized by optical confocal microscopy, optical profilometry and scanning and transmition electron microscopy. In case of the AlTiN/TiN coating, a single-pulse damage threshold of 0.41 J cm(-2) was estimated. Well defined holes/craters with diameters from 7 to 35 mu m, up to 40 mu m depth were drilled, depending on laser pulse energy and number, after 1000 laser pulses. For small energy/fluence, laser induced periodical surface structures were observed. A model is discussed which can account for these fea...tures by the accumulation effect during multi-pulse irradiation. The forming craters can prove useful for fabrication of micron solid state lubricant reservoirs in the protective coating-steel system.
Keywords:AlTiN/TiN coating / Femtosecond pulses / laser ablation / Damage threshold / LIPSS
Source:Optics and Laser Technology, 2017, 89, 200-207
- Fabrication and characterization of nano-photonic functional structrues in biomedicine and informatics (RS-45016)
- STSM visit grants in the framework of COST Action Developing the physics and the scientific community for inertial fusion [MP 1208], National Authority for Research and Innovation in the frame of Nucleus programme [4N/2016, 304/2011, PN-II-ID-PCE-2012-4-0539]