Prediction of Thermal Damage upon Ultrafast Laser Ablation of Metals

Cangueiro, Liliana; Ramos-de-Campos, José A.; Bruneel, David

doi:10.3390/molecules26216327

Cited by 11 publications

(7 citation statements)

References 32 publications

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“…Asymmetricity of graphitization in pockets for the vertically oriented map is caused by two factors. The rst is hatching strategy (from bottom to top), resulting in heat accumulation phenomena [38], [39]. The second factor is the fact that hatching lines were uncentered on the pocket contour, which created different gaps between the bottom part of the contour and rst hatching line (up to 0.0025 mm) and the top part of the contour and last hatching line (up to 0.0015 mm).…”

Section: Discussionmentioning

confidence: 99%

Femtosecond laser texturing of DLC-based coatings by DLW method with sub-micrometer precision

Čermák

Simonovic

Бондарев

et al. 2022

Int J Adv Manuf Technol

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The enhancement of functional surfaces by laser texturing has been investigated in many studies; however, it has been often applied to the substrate. New laser technologies, such as the direct laser writing (DLW) method using a femtosecond laser, allow the production of extremely precise textures into both substrates and thin lms. This paper investigates two distinct methods producing various textures:(i) the substrate is textured before the deposition of the diamond-like carbon coating (DLC), and (ii) the texture is produced into DLC coating deposited on a polished substrate. Our goal was to achieve identical topography in both cases; the textured area was as large as 170 mm 2 . The textured topography was assessed by 3D laser scanning microscope, which con rmed the repeatability of fs laser processing. Raman spectroscopy mapping, SEM, and XPS were combined to investigate the effect of laser processing on DLC coating in terms of oxidation or structural changes. 1. Introduction Many industrial areas face various pressure such as cost-effectiveness, environmental aspects, substitutability of different technologies and its consequent exibility of change. Surface treatments, namely surface texturing by ultra-short pulsed (USP) lasers has been already used in many industrial elds: in the cutting tool industry [1] to improve the cutting process, in piston rings [2], dies preparations for metal forming [3], in bearings [4] for friction reduction; and in other elds such as biomedical equipment [5] or storage devices [6]. Many scienti c papers [7]-[13] dealt with laser surface texturing of DLC coatings, which consisted of dimple shapes limited by applied laser spots from d = 10µm [12] up to 30µm [8] in rectangular/square patterns. The performed experiments showed the coe cient of friction (CoF) reduction when using ultrashort pulsed laser processing [8], [11],[13], instead of short-pulsed laser processing [14], where the heataffected zone (HAZ) seems to be limiting improvement in tribological properties. Other studies [15]-[17] aimed to fabricate different textures, e.g., squares, lines, or circles in many possible patterns.These studies were mainly focused on the impact of various densities of geometrical entities, but not on the achieved depth of textures, which did not allow a proper insertion of laser texturing into various places of the technological production chain. In the study of Dumitru et al. [10], laser texturing was performed in two variants: into the substrate before deposition of DLC coating and after the deposition.However, the depths of the texture were not provided.This study focuses on the fabrication of textures with de ned geometrical entities and conditions by ultra-short pulsed (USP) laser system tuned to a pulsed length of 240fs. Our main goal is to compare the feasibility of two texturing processes. In the rst case, designed textures were micromachined directly into the substrate (tool steel 1.2379) and then the samples were deposited by DLC coating (hereinafter textured-coated). In the second...

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Section: Discussionmentioning

confidence: 99%

Femtosecond laser texturing of DLC-based coatings by DLW method with sub-micrometer precision

Čermák

Simonovic

Бондарев

et al. 2022

Int J Adv Manuf Technol

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“…In addition, a decreasing influence of the applied fluence at very high repetition rates and a decreasing ablation threshold were observed, without any reduction in the resulting quality as a result of heat accumulation. Due to the importance of avoiding heat accumulation for fast industrial USP laser-based machining processes, it is often investigated by thermal simulations focusing the heating of the material adjacent to the ablation [17][18][19][20][21] . Bornschlegel et al also investigated the heat distribution during USP laser ablation of 1.4301 stainless steel by measuring the workpiece temperature.…”

Section: Introductionmentioning

confidence: 99%

Computational optimization of borehole sequences for the reduction of heat accumulation in drilling processes using ultrashort pulse lasers

Lutz,

Helm,

Esen

et al. 2024

Laser-Based Micro- And Nanoprocessing XVIII

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We report on laser drilling of borehole arrays using a high-power ultrashort pulse laser with particular focus on reducing heat accumulation in the workpiece by optimizing the drilling sequence, particularly for highly efficient multi-spot drilling. Different optimization approaches are chosen to improve the drilling sequence, also comparing a simplex algorithm and an evolutionary algorithm. From a laser application point of view, we also compare drilling sequences using a single spot and up to 16-fold multi-spots generated by a spatial light modulator, as to accelerate the drilling process in terms of the number of drilled holes per second.To evaluate the temperatures generated during drilling of up to 40,000 holes in less than 76 seconds in stainless steel foil, temperatures are measured by a thermal imaging camera and subsequently compared to a COMSOL-based simulation for all optimized drilling sequences. With respect to an average temperature of 706 °C without optimization, a reduction by 252 °C, i.e., a reduction by nearly 36 % based on the Celsius scale, is achieved using a 4 × 4 beam splitter and an optimized drilling sequence with a drilling rate of 526 holes per second. In addition, using a 2 × 2 beam splitter, a temperature reduction of up to 40.5 % is achieved for a drilling process with a rate of 129 holes per second using an optimized drilling sequence.

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“…Numerous commonly used materials, including metals [7], exhibit low reflectivity in the ultraviolet (UV) spectrum; thus, nanosecond material processing in UV is advantageous compared to IR and green pulses [8,9]. The advantages are inherently tighter focusing, better efficiency, and lower heat-related impact on the surrounding material [10,11].…”

Section: Introductionmentioning

confidence: 99%

Pulse-on-Demand Operation for Precise High-Speed UV Laser Microstructuring

Kočica

Mur

Didierjean³

et al. 2023

Micromachines

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Laser microstructuring has been studied extensively in the last decades due to its versatile, contactless processing and outstanding precision and structure quality on a wide range of materials. A limitation of the approach has been identified in the utilization of high average laser powers, with scanner movement fundamentally limited by laws of inertia. In this work, we apply a nanosecond UV laser working in an intrinsic pulse-on-demand mode, ensuring maximal utilization of the fastest commercially available galvanometric scanners at scanning speeds from 0 to 20 m/s. The effects of high-frequency pulse-on-demand operation were analyzed in terms of processing speeds, ablation efficiency, resulting surface quality, repeatability, and precision of the approach. Additionally, laser pulse duration was varied in single-digit nanosecond pulse durations and applied to high throughput microstructuring. We studied the effects of scanning speed on pulse-on-demand operation, single- and multipass laser percussion drilling performance, surface structuring of sensitive materials, and ablation efficiency for pulse durations in the range of 1–4 ns. We confirmed the pulse-on-demand operation suitability for microstructuring for a range of frequencies from below 1 kHz to 1.0 MHz with 5 ns timing precision and identified the scanners as the limiting factor even at full utilization. The ablation efficiency was improved with longer pulse durations, but structure quality degraded.

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Prediction of Thermal Damage upon Ultrafast Laser Ablation of Metals

Cited by 11 publications

References 32 publications

Femtosecond laser texturing of DLC-based coatings by DLW method with sub-micrometer precision

Femtosecond laser texturing of DLC-based coatings by DLW method with sub-micrometer precision

Computational optimization of borehole sequences for the reduction of heat accumulation in drilling processes using ultrashort pulse lasers

Pulse-on-Demand Operation for Precise High-Speed UV Laser Microstructuring

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