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Vpliv laserske ablacije v različnih tekočinah na funkcionalnost kovinskih površin
ID Senegačnik, Matej (Author), ID Gregorčič, Peter (Mentor) More about this mentor... This link opens in a new window

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Abstract
Težnja po miniaturizaciji naprav in nadzoru nad interakcijo površin motivira poizkuse umetne izdelave površin z izboljšanimi lastnostmi. Ena od možnih metod izdelave takšnih površin je lasersko obsevanje in cilj te doktorske disertacije je ugotoviti (i) dinamiko procesa in (ii) karakteristike površine po takšni obdelavi kovin v nekonvencionalnih pogojih – različnih plinih, kapljevinah, in omejevalnih geometrijah. Od klasičnih raziskav smo se oddaljili prek razvoja primernih metod opazovanja in odkrili, da lahko preboj v kapljevini v bližini ostrega roba vodi do pritrjene kavitacije in povratnega curka v mehurček. Razvili smo novo metodo za izdelavo ukrivljenih meanderskih utorov s podmikrometrskim razmakom, pri čemer smo slednje dosegli z uporabo termokapilarnih sil za nadzor mehurčkov, ki smo jih uporabili kot uklonske objekte. S fokusiranim ionskim snopom smo pojasnili, da lasersko-povzročene periodične površinske strukture pri izdelavi z nanosekundnimi bliski (v primerjavi s pikosekundnimi) sestavlja tanka modulirana plast oksida z zanemarljivo topografsko variacijo osnovnega materiala. Nadalje smo dokazali, da je oksidacija površine, kot posledica lasersko-povzročenega segrevanja brez spremembe topografije, odgovorna za spremembo optičnih lastnosti zaradi interference svetlobe, ki se odbija na tankem oksidnem sloju. Z visoko fluenco bliskov smo prav tako pokazali, da lahko z lasersko obdelavo površin tudi povečamo njihovo omočljivost.

Language:Slovenian
Keywords:laserski inženiring površin, funkcionalnost površine, laserska ablacija v kapljevinah, kavitacijski mehurček, lasersko-povzročene periodične površinske strukture, uklon, obarvanje površine, omočljivost
Work type:Doctoral dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Place of publishing:Ljubljana
Publisher:[M. Senegačnik]
Year:2023
Number of pages:XVIII, 145 str.
PID:20.500.12556/RUL-146802 This link opens in a new window
UDC:621.9.048.7:532.528:544.722.3(043.3)
COBISS.SI-ID:156464387 This link opens in a new window
Publication date in RUL:14.06.2023
Views:675
Downloads:122
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Secondary language

Language:Unknown
Title:The influence of laser ablation in different fluids on metal surface functionality
Abstract:
The quest for device miniaturization and control over surface interactions motivate the rigorous efforts to artificially fabricate surfaces with improved properties. One of the potential methods is laser irradiation and the aim of this thesis is to determine the (i) process dynamics and (ii) surface characteristics after such treatment of metals in unconventional surroundings – different gases, liquids, and confining geometries. We diverge from classical studies through development of appropriate observation methods and discover that a fixed-type secondary cavity followed by re-entrant injection of liquid can occur when breakdown is induced near a sharp edge. We develop a new method for fabricating curved meandering grooves with submicrometer spacing by exploiting thermocapillary forces to manipulate the bubbles, used as circular diffraction objects. In gases, our focused ion beam cross sections clarify that laser-induced periodic surface structures formed by nanosecond pulse irradiation (compared to picosecond) compose of a thin modulating oxide layer with negligible topographical variation of bulk. We further demonstrate that surface oxidation, a consequence of laser-induced heating without topographical alteration, is responsible for changing the optical properties due to interference of light reflected at the thin oxide film and that high fluence irradiation can be implemented to enhance the surface wettability.

Keywords:laser surface engineering, surface functionality, laser ablation in liquids, cavitation bubble, laser-induced periodic surface structures, diffraction, surface coloration, wettability

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