Effect of surface roughness on the ultrashort pulsed laser ablation fluence threshold of zinc and steel

    Research output: Contribution to conferencePoster

    Abstract

    Laser ablation is a subtractive micromachining technique, which can be employed to improve the surface functionality of a product by applying a laser-induced texture to the surface. It is a flexible and precise manufacturing process compared to other techniques like electric discharge texturing, chemical etching, shot blasting and electron beam texturing [1,2]. The absorption of laser light and subsequent heating of the material being machined depends not only on the optical properties of the material, but also on its initial surface condition. This means features such as roughness, oxidation or defects etc., of the targeted material play a major role in the efficiency of material removal and ultimately the resulting quality of the machined surface. For continuous wave (cw) laser processing, a higher surface roughness typically results in better absorption of laser energy through scattering from surface irregularities [3,4,5]. In the case of ultra short laser pulses, with pulse durations in the picosecond regime, or shorter, the absorption of laser energy (photons) and modification of the material such as ablation take place at different time scales. That is, absorption of photons typically takes place on the femto- to picosecond time scale, whereas modification of material takes place on the nanosecond timescale or longer [6]. To study the effect of surface roughness on the fluence threshold above which ablation occurs in metals in ultrashort pulse regimes, ablation of bulk zinc, galvanized steel and mild steel is performed with single, as well as multiple picosecond laser pulses at wavelengths of 1030 nm and 515 nm and at different preliminary surface roughness (Ra) values ranging from 0.03 µm to 1.5 µm. Using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), the morphologies and crater dimensions of thousands of ablated craters is studied, by varying the laser fluence over a wide range, as well as varying the number of pulses (N) on the same location between N=1 and N=50. From the analysis, it can be concluded that, within the boundaries of our experimental (laser) conditions, the ablation threshold increases with increasing surface roughness. In addition, the surface roughness of the underlying substrate of a coated material (galvanized steel) also affects the crater morphology and ablation threshold.
    Original languageEnglish
    Publication statusPublished - 10 Sep 2018
    Event11th International Conference on Photo-Excited Processes and Applications (ICPEPA 2018) - Radisson Blu Hotel Lietuva, Vilnius, Lithuania
    Duration: 10 Sep 201814 Sep 2018
    Conference number: 11
    http://icpepa11.com/

    Conference

    Conference11th International Conference on Photo-Excited Processes and Applications (ICPEPA 2018)
    Abbreviated titleICPEPA-11
    CountryLithuania
    CityVilnius
    Period10/09/1814/09/18
    Internet address

    Fingerprint

    ultrashort pulsed lasers
    laser ablation
    surface roughness
    fluence
    zinc
    steels
    thresholds
    ablation
    lasers
    craters
    pulses
    electric discharges
    continuous wave lasers
    photons
    micromachining
    irregularities
    machining
    shot
    pulse duration
    roughness

    Keywords

    • ultrashort pulsed laser
    • ablation threshold
    • surface roughness
    • polycrystalline zinc
    • titanium stabilized ultra low carbon steel
    • galvanized steel

    Cite this

    Mustafa, H., Mezera, M., Matthews, D. T. A., & Römer, G. R. B. E. (2018). Effect of surface roughness on the ultrashort pulsed laser ablation fluence threshold of zinc and steel. Poster session presented at 11th International Conference on Photo-Excited Processes and Applications (ICPEPA 2018), Vilnius, Lithuania.
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    title = "Effect of surface roughness on the ultrashort pulsed laser ablation fluence threshold of zinc and steel",
    abstract = "Laser ablation is a subtractive micromachining technique, which can be employed to improve the surface functionality of a product by applying a laser-induced texture to the surface. It is a flexible and precise manufacturing process compared to other techniques like electric discharge texturing, chemical etching, shot blasting and electron beam texturing [1,2]. The absorption of laser light and subsequent heating of the material being machined depends not only on the optical properties of the material, but also on its initial surface condition. This means features such as roughness, oxidation or defects etc., of the targeted material play a major role in the efficiency of material removal and ultimately the resulting quality of the machined surface. For continuous wave (cw) laser processing, a higher surface roughness typically results in better absorption of laser energy through scattering from surface irregularities [3,4,5]. In the case of ultra short laser pulses, with pulse durations in the picosecond regime, or shorter, the absorption of laser energy (photons) and modification of the material such as ablation take place at different time scales. That is, absorption of photons typically takes place on the femto- to picosecond time scale, whereas modification of material takes place on the nanosecond timescale or longer [6]. To study the effect of surface roughness on the fluence threshold above which ablation occurs in metals in ultrashort pulse regimes, ablation of bulk zinc, galvanized steel and mild steel is performed with single, as well as multiple picosecond laser pulses at wavelengths of 1030 nm and 515 nm and at different preliminary surface roughness (Ra) values ranging from 0.03 µm to 1.5 µm. Using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), the morphologies and crater dimensions of thousands of ablated craters is studied, by varying the laser fluence over a wide range, as well as varying the number of pulses (N) on the same location between N=1 and N=50. From the analysis, it can be concluded that, within the boundaries of our experimental (laser) conditions, the ablation threshold increases with increasing surface roughness. In addition, the surface roughness of the underlying substrate of a coated material (galvanized steel) also affects the crater morphology and ablation threshold.",
    keywords = "ultrashort pulsed laser, ablation threshold, surface roughness, polycrystalline zinc, titanium stabilized ultra low carbon steel, galvanized steel",
    author = "Hasib Mustafa and Marek Mezera and Matthews, {David Thomas Allan} and R{\"o}mer, {Gerardus Richardus, Bernardus, Engelina}",
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    Mustafa, H, Mezera, M, Matthews, DTA & Römer, GRBE 2018, 'Effect of surface roughness on the ultrashort pulsed laser ablation fluence threshold of zinc and steel' 11th International Conference on Photo-Excited Processes and Applications (ICPEPA 2018), Vilnius, Lithuania, 10/09/18 - 14/09/18, .

    Effect of surface roughness on the ultrashort pulsed laser ablation fluence threshold of zinc and steel. / Mustafa, Hasib ; Mezera, Marek ; Matthews, David Thomas Allan; Römer, Gerardus Richardus, Bernardus, Engelina.

    2018. Poster session presented at 11th International Conference on Photo-Excited Processes and Applications (ICPEPA 2018), Vilnius, Lithuania.

    Research output: Contribution to conferencePoster

    TY - CONF

    T1 - Effect of surface roughness on the ultrashort pulsed laser ablation fluence threshold of zinc and steel

    AU - Mustafa, Hasib

    AU - Mezera, Marek

    AU - Matthews, David Thomas Allan

    AU - Römer, Gerardus Richardus, Bernardus, Engelina

    PY - 2018/9/10

    Y1 - 2018/9/10

    N2 - Laser ablation is a subtractive micromachining technique, which can be employed to improve the surface functionality of a product by applying a laser-induced texture to the surface. It is a flexible and precise manufacturing process compared to other techniques like electric discharge texturing, chemical etching, shot blasting and electron beam texturing [1,2]. The absorption of laser light and subsequent heating of the material being machined depends not only on the optical properties of the material, but also on its initial surface condition. This means features such as roughness, oxidation or defects etc., of the targeted material play a major role in the efficiency of material removal and ultimately the resulting quality of the machined surface. For continuous wave (cw) laser processing, a higher surface roughness typically results in better absorption of laser energy through scattering from surface irregularities [3,4,5]. In the case of ultra short laser pulses, with pulse durations in the picosecond regime, or shorter, the absorption of laser energy (photons) and modification of the material such as ablation take place at different time scales. That is, absorption of photons typically takes place on the femto- to picosecond time scale, whereas modification of material takes place on the nanosecond timescale or longer [6]. To study the effect of surface roughness on the fluence threshold above which ablation occurs in metals in ultrashort pulse regimes, ablation of bulk zinc, galvanized steel and mild steel is performed with single, as well as multiple picosecond laser pulses at wavelengths of 1030 nm and 515 nm and at different preliminary surface roughness (Ra) values ranging from 0.03 µm to 1.5 µm. Using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), the morphologies and crater dimensions of thousands of ablated craters is studied, by varying the laser fluence over a wide range, as well as varying the number of pulses (N) on the same location between N=1 and N=50. From the analysis, it can be concluded that, within the boundaries of our experimental (laser) conditions, the ablation threshold increases with increasing surface roughness. In addition, the surface roughness of the underlying substrate of a coated material (galvanized steel) also affects the crater morphology and ablation threshold.

    AB - Laser ablation is a subtractive micromachining technique, which can be employed to improve the surface functionality of a product by applying a laser-induced texture to the surface. It is a flexible and precise manufacturing process compared to other techniques like electric discharge texturing, chemical etching, shot blasting and electron beam texturing [1,2]. The absorption of laser light and subsequent heating of the material being machined depends not only on the optical properties of the material, but also on its initial surface condition. This means features such as roughness, oxidation or defects etc., of the targeted material play a major role in the efficiency of material removal and ultimately the resulting quality of the machined surface. For continuous wave (cw) laser processing, a higher surface roughness typically results in better absorption of laser energy through scattering from surface irregularities [3,4,5]. In the case of ultra short laser pulses, with pulse durations in the picosecond regime, or shorter, the absorption of laser energy (photons) and modification of the material such as ablation take place at different time scales. That is, absorption of photons typically takes place on the femto- to picosecond time scale, whereas modification of material takes place on the nanosecond timescale or longer [6]. To study the effect of surface roughness on the fluence threshold above which ablation occurs in metals in ultrashort pulse regimes, ablation of bulk zinc, galvanized steel and mild steel is performed with single, as well as multiple picosecond laser pulses at wavelengths of 1030 nm and 515 nm and at different preliminary surface roughness (Ra) values ranging from 0.03 µm to 1.5 µm. Using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), the morphologies and crater dimensions of thousands of ablated craters is studied, by varying the laser fluence over a wide range, as well as varying the number of pulses (N) on the same location between N=1 and N=50. From the analysis, it can be concluded that, within the boundaries of our experimental (laser) conditions, the ablation threshold increases with increasing surface roughness. In addition, the surface roughness of the underlying substrate of a coated material (galvanized steel) also affects the crater morphology and ablation threshold.

    KW - ultrashort pulsed laser

    KW - ablation threshold

    KW - surface roughness

    KW - polycrystalline zinc

    KW - titanium stabilized ultra low carbon steel

    KW - galvanized steel

    M3 - Poster

    ER -

    Mustafa H, Mezera M, Matthews DTA, Römer GRBE. Effect of surface roughness on the ultrashort pulsed laser ablation fluence threshold of zinc and steel. 2018. Poster session presented at 11th International Conference on Photo-Excited Processes and Applications (ICPEPA 2018), Vilnius, Lithuania.