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Special Issue "Advances in Laser Processing"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: 20 October 2022 | Viewed by 10868

Special Issue Editors

Prof. Félix Quintero Martínez
E-Mail Website
Guest Editor
Department of Applied Physics, University of Vigo, 36310 Vigo, Spain
Interests: laser materials processing; laser synthesis; laser manufacturing
Prof. Dr. Juan Pou
E-Mail Website
Guest Editor
Department of Applied Physics, Universidade de Vigo, Vigo, Spain
Interests: laser deposition; laser materials processing; coatings; biomaterials; nanoparticles, nanofibres
Special Issues, Collections and Topics in MDPI journals
Dr. Antonio Riveiro
E-Mail Website
Guest Editor
Dept. Materials Engineering, Applied Mechanics and Construction, School of Engineering, University of Vigo, Lagoas Marcosende s/n, 36310 Vigo, Spain
Interests: laser processing; laser welding; laser cutting; laser cladding; laser texturing; laser surface treatments; laser microprocessing; laser drilling; laser-based additive manufacturing; biomaterials; nanomaterials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Lasers are routinely used as tools with exceptional capabilities in many applications of materials processing. The development of new laser sources and processes is continuously expanding the use and performance of laser materials processing.

This Special Issue welcomes novel contributions reporting advances in applications of laser materials processing. The processes included in the scope of this Special Issue range from the most conventional applications such as laser cutting, welding, marking, cladding, annealing, or surface treatment, to the most recent ones, such as additive manufacturing, the synthesis of nanomaterials, micro-  and nano-manufacturing, and other new processes. Of great interest are works that support new insights into fundamental mechanisms using experimental, theoretical, or computational methods or combinations of these approaches. Contributions should concern any materials processing application where lasers are an essential tool; contributions dealing with laser processing of metals, ceramics, and biomaterials are especially welcome.

Prof. Félix Quintero Martínez
Prof. Juan Pou
Dr. Antonio Riveiro
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2300 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • laser materials processing
  • laser synthesis
  • laser manufacturing

Published Papers (12 papers)

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Research

Article
Micromachining of Alumina Using a High-Power Ultrashort-Pulsed Laser
Materials 2022, 15(15), 5328; https://doi.org/10.3390/ma15155328 - 02 Aug 2022
Viewed by 160
Abstract
We report on a comprehensive study of laser ablation and micromachining of alumina using a high-power 1030 nm ultrashort-pulsed laser. By varying laser power up to 150 W, pulse duration between 900 fs and 10 ps, repetition rates between 200 kHz and 800 [...] Read more.
We report on a comprehensive study of laser ablation and micromachining of alumina using a high-power 1030 nm ultrashort-pulsed laser. By varying laser power up to 150 W, pulse duration between 900 fs and 10 ps, repetition rates between 200 kHz and 800 kHz), spatial pulse overlap between 70% and 80% and a layer-wise rotation of the scan direction, the ablation efficiency, ablation rate and surface roughness are determined and discussed with respect to an efficient and optimized process strategy. As a result, the combination of a high pulse repetition rate of 800 kHz and the longest evaluated pulse duration of 10 ps leads to the highest ablation efficiency of 0.76 mm3/(W*min). However, the highest ablation rate of up to 57 mm3/min is achieved at a smaller repetition rate of 200 kHz and the shortest evaluated pulse duration of 900 fs. The surface roughness is predominantly affected by the applied laser fluence. The application of a high repetition rate leads to a small surface roughness Ra below 2 μm even for the usage of 150 W laser power. By an interlayer rotation of the scan path, optimization of the ablation characteristics can be achieved, while an interlayer rotation of 90° leads to increasing the ablation rate, the application of a rotation angle of 11° minimizes the surface roughness. The evaluation by scanning electron microscopy shows the formation of thin melt films on the surface but also reveals a minimized heat affected zone for the in-depth modification. Overall, the results of this study pave the way for high-power ultrashort-pulsed lasers to efficient, high-quality micromachining of ceramics. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Optimization of Heat Accumulation during Femtosecond Laser Drilling Borehole Matrices by Using a Simplex Algorithm
Materials 2022, 15(14), 4829; https://doi.org/10.3390/ma15144829 - 11 Jul 2022
Viewed by 241
Abstract
We report on an optimization study of percussion drilling thin metal sheets employing a high repetition rate, high power femtosecond laser with respect to the resulting heat accumulation. A specified simplex algorithm was employed to optimize the spatial drilling sequence, whereas a simplified [...] Read more.
We report on an optimization study of percussion drilling thin metal sheets employing a high repetition rate, high power femtosecond laser with respect to the resulting heat accumulation. A specified simplex algorithm was employed to optimize the spatial drilling sequence, whereas a simplified thermal simulation using COMSOL was validated by comparing its results to the temperature measurements using an infrared camera. Optimization for drilling borehole matrices was aspired with respect to the generated temperature across the processed specimen, while the drilling strategy was altered in its spatial drilling sequence and by using multi-spot approaches generated by a spatial light modulator. As a result, we found that an optimization strategy based on limited consecutive holes in a Moore neighborhood led to reduced temperatures and the shortest process times. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Energy Efficiency in CO2 Laser Processing of Hardox 400 Material
Materials 2022, 15(13), 4505; https://doi.org/10.3390/ma15134505 - 26 Jun 2022
Viewed by 422
Abstract
The use of laser technology for materials processing has a wide applicability in various industrial fields, due to its proven advantages, such as processing time, economic efficiency and reduced impact on the natural environment. The expansion of laser technology has been possible due [...] Read more.
The use of laser technology for materials processing has a wide applicability in various industrial fields, due to its proven advantages, such as processing time, economic efficiency and reduced impact on the natural environment. The expansion of laser technology has been possible due to the dynamics of research in the field. One of the directions of research is to establish the appropriate cutting parameters. The evolution of research in this direction can be deepened by determining the efficiency of laser cutting. Starting from such a hypothesis, the study contains an analysis of laser cutting parameters (speed, power and pressure) to determine the linear energy and cutting efficiency. For this purpose, the linear energy and the cutting efficiency were determined analytically, and the results obtained were tested with the Lagrange interpolation method, the statistical mathematical method and the graphical method. The material chosen was Hardox 400 steel with a thickness of 8 mm, due to its numerous industrial applications and the fact that it is an insufficiently studied material. Statistical data processing shows that the maximum cutting efficiency is mainly influenced by speed, followed by laser power. The results obtained reduce energy costs in manufacturing processes that use the CO2 laser. The combinations identified between laser speed and power lead to a reduction in energy consumption and thus to an increase in processing efficiency. Through the calculation relationships established for linear energy and cutting efficiency, the study contributes to the extension of the theoretical and practical basis. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Ultrashort Pulsed Laser Drilling of Printed Circuit Board Materials
Materials 2022, 15(11), 3932; https://doi.org/10.3390/ma15113932 - 31 May 2022
Cited by 1 | Viewed by 442
Abstract
We report on a comprehensive study of laser percussion microvia drilling of FR-4 printed circuit board material using ultrashort pulse lasers with emission in the green spectral region. Laser pulse durations in the pico- and femtosecond regime, laser pulse repetition rates up to [...] Read more.
We report on a comprehensive study of laser percussion microvia drilling of FR-4 printed circuit board material using ultrashort pulse lasers with emission in the green spectral region. Laser pulse durations in the pico- and femtosecond regime, laser pulse repetition rates up to 400 kHz and laser fluences up to 11.5 J/cm2 are applied to optimize the quality of microvias, as being evaluated by the generated taper, the extension of glass fiber protrusions and damage of inner lying copper layers using materialography. The results are discussed in terms of the ablation threshold for FR-4 and copper, heat accumulation and pulse shielding effects as a result of pulse to pulse interactions. As a specific result, using a laser pulse duration of 2 ps appears beneficial, resulting in small glass fiber protrusions and high precision in the stopping process at inner copper layer. If laser pulse repetition rates larger than 100 kHz are applied, we find that the processing quality can be increased by heat accumulation effects. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Influence of Laser Treatment on End Notched Flexure Bonded Joints in Carbon Fiber Reinforced Polymer: Experimental and Numerical Results
Materials 2022, 15(3), 910; https://doi.org/10.3390/ma15030910 - 25 Jan 2022
Viewed by 689
Abstract
Surface pretreatment for bonding is one of the most important steps for the manufacturing of a reliable bonded joint. In this paper, the effectiveness of an innovative pretreatment by CO2 pulsed laser for bonding Carbon Fiber Reinforced Polymer (CFRP) was investigated. End [...] Read more.
Surface pretreatment for bonding is one of the most important steps for the manufacturing of a reliable bonded joint. In this paper, the effectiveness of an innovative pretreatment by CO2 pulsed laser for bonding Carbon Fiber Reinforced Polymer (CFRP) was investigated. End Notched Flexure (ENF) specimens were made with different densities of laser treatment, and the respective fracture toughness was obtained through the Compliance-Based Beam Method (CBBM). Furthermore, a cohesive model for simulating debonding processes was illustrated, and the cohesive parameters were obtained by an inverse method. The achieved results represent a fundamental step for the development of a numerical model useful for the determination of laser texturing as a function of the applied local stress into the bonded joint. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Study on the Measurement of Laser Drilling Depth by Combining Digital Image Relationship Measurement in Aluminum
Materials 2021, 14(3), 489; https://doi.org/10.3390/ma14030489 - 20 Jan 2021
Viewed by 738
Abstract
In this study, laser processing equipment was used to drill aluminum alloy materials and with different auxiliary mechanisms, the deformation around the holes after processing was observed. The experimental results show that, due to the high temperature generated during laser processing, a large [...] Read more.
In this study, laser processing equipment was used to drill aluminum alloy materials and with different auxiliary mechanisms, the deformation around the holes after processing was observed. The experimental results show that, due to the high temperature generated during laser processing, a large thermal gradient causes thermal stress to be introduced into the test piece and outward expansion deformation occurs. In this study, the digital image correlation and residual stress detection methods were applied. Based on the correlation between the drilled hole depth and the hole deformation, the hole depth of the laser processing was estimated. The average coefficient of determination for all auxiliary mechanisms is 0.82. The experimental results confirm that the digital image correlation method can be used to estimate the hole depth of laser processing. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Microstructure and Mechanical Properties of Laser-Welded DP Steels Used in the Automotive Industry
Materials 2021, 14(2), 456; https://doi.org/10.3390/ma14020456 - 19 Jan 2021
Cited by 10 | Viewed by 1482
Abstract
The aim of this work was to investigate the microstructure and the mechanical properties of laser-welded joints combined of Dual Phase DP800 and DP1000 high strength thin steel sheets. Microstructural and hardness measurements as well as tensile and fatigue tests have been carried [...] Read more.
The aim of this work was to investigate the microstructure and the mechanical properties of laser-welded joints combined of Dual Phase DP800 and DP1000 high strength thin steel sheets. Microstructural and hardness measurements as well as tensile and fatigue tests have been carried out. The welded joints (WJ) comprised of similar/dissimilar steels with similar/dissimilar thickness were consisted of different zones and exhibited similar microstructural characteristics. The trend of microhardness for all WJs was consistent, characterized by the highest value at hardening zone (HZ) and lowest at softening zone (SZ). The degree of softening was 20 and 8% for the DP1000 and DP800 WJ, respectively, and the size of SZ was wider in the WJ combinations of DP1000 than DP800. The tensile test fractures were located at the base material (BM) for all DP800 weldments, while the fractures occurred at the fusion zone (FZ) for the weldments with DP1000 and those with dissimilar sheet thicknesses. The DP800-DP1000 weldment presented similar yield strength (YS, 747 MPa) and ultimate tensile strength (UTS, 858 MPa) values but lower elongation (EI, 5.1%) in comparison with the DP800-DP800 weldment (YS 701 MPa, UTS 868 MPa, EI 7.9%), which showed similar strength properties as the BM of DP800. However, the EI of DP1000-DP1000 weldment was 1.9%, much lower in comparison with the BM of DP1000. The DP800-DP1000 weldment with dissimilar thicknesses showed the highest YS (955 MPa) and UTS (1075 MPa) values compared with the other weldments, but with the lowest EI (1.2%). The fatigue fractures occurred at the WJ for all types of weldments. The DP800-DP800 weldment had the highest fatigue limit (348 MPa) and DP800-DP1000 with dissimilar thicknesses had the lowest fatigue limit (<200 MPa). The fatigue crack initiated from the weld surface. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Stable Superhydrophobic Aluminum Surfaces Based on Laser-Fabricated Hierarchical Textures
Materials 2021, 14(1), 184; https://doi.org/10.3390/ma14010184 - 02 Jan 2021
Cited by 5 | Viewed by 1277
Abstract
Laser-microtextured surfaces have gained an increasing interest due to their enormous spectrum of applications and industrial scalability. Direct laser interference patterning (DLIP) and the well-established direct laser writing (DLW) methods are suitable as a powerful combination for the fabrication of single (DLW or [...] Read more.
Laser-microtextured surfaces have gained an increasing interest due to their enormous spectrum of applications and industrial scalability. Direct laser interference patterning (DLIP) and the well-established direct laser writing (DLW) methods are suitable as a powerful combination for the fabrication of single (DLW or DLIP) and multi-scale (DLW+DLIP) textures. In this work, four-beam DLIP and DLW were used independently and combined to produce functional textures on aluminum. The influence of the laser processing parameters, such as the applied laser fluence and the number of pulses, on the resulting topography was analyzed by confocal microscopy and scanning electron microscopy. The static long-term and dynamic wettability characteristics of the laser-textured surfaces were determined through water contact angle and hysteresis measurements, revealing superhydrophobic properties with static contact angles up to 163° and hysteresis as low as 9°. The classical Cassie–Baxter and Wenzel models were applied, permitting a deeper understanding of the observed wetting behaviors. Finally, mechanical stability tests revealed that the DLW elements in the multi-scale structure protects the smaller DLIP features under tribological conditions. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
The Effect of an External Magnetic Field on the Aspect Ratio and Heat Input of Gas-Metal-Arc-Welded AZ31B Alloy Weld Joints Using a Response Surface Methodology
Materials 2020, 13(22), 5269; https://doi.org/10.3390/ma13225269 - 21 Nov 2020
Cited by 2 | Viewed by 691
Abstract
This study attempted to analyze and optimize the effect of an external magnetic field (EMF) on the aspect ratio and heat input for AZ31B weld joints that were welded using the gas metal arc welding (GMAW) process. The response surface methodology (RSM) was [...] Read more.
This study attempted to analyze and optimize the effect of an external magnetic field (EMF) on the aspect ratio and heat input for AZ31B weld joints that were welded using the gas metal arc welding (GMAW) process. The response surface methodology (RSM) was adopted for the critical analysis, and subsequently, mathematical models were developed based on the experimental results. It was observed that the EMF and its interaction with the wire feed rate significantly affected the aspect ratio and heat input, respectively. At 119 G (magnetic field), 700 mm/min (welding speed), 5.8 m/min feed rate, and 11.5 L/min (gas flow rate), the aspect ratio was 2.26, and the corresponding heat input factor (HIf) was 0.8 with almost full weld penetration. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Large-Beam Picosecond Interference Patterning of Metallic Substrates
Materials 2020, 13(20), 4676; https://doi.org/10.3390/ma13204676 - 20 Oct 2020
Cited by 8 | Viewed by 1656
Abstract
In this paper, we introduce a method to efficiently use a high-energy pulsed 1.7 ps HiLASE Perla laser system for two beam interference patterning. The newly developed method of large-beam interference patterning permits the production of micro and sub-micron sized features on a [...] Read more.
In this paper, we introduce a method to efficiently use a high-energy pulsed 1.7 ps HiLASE Perla laser system for two beam interference patterning. The newly developed method of large-beam interference patterning permits the production of micro and sub-micron sized features on a treated surface with increased processing throughputs by enlarging the interference area. The limits for beam enlarging are explained and calculated for the used laser source. The formation of a variety of surface micro and nanostructures and their combinations are reported on stainless steel, invar, and tungsten with the maximum fabrication speed of 206 cm2/min. The wettability of selected hierarchical structures combining interference patterns with 2.6 µm periodicity and the nanoscale surface structures on top were analyzed showing superhydrophobic behavior with contact angles of 164°, 156°, and 150° in the case of stainless steel, invar, and tungsten, respectively. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Nanosecond Laser Etching of Aluminum-Plated Composite Materials Applied to Frequency Selective Surfaces
Materials 2020, 13(12), 2808; https://doi.org/10.3390/ma13122808 - 22 Jun 2020
Cited by 1 | Viewed by 884
Abstract
High-quality frequency selective surfaces (FSSs) are important for electromagnetic signal absorption/filtration. Usually, they are made from wave-transparent composite materials covered with a thin metal layer. Current machining methods show some disadvantages when performing fabrication on the structure. Based on its flexibility and uncontactable [...] Read more.
High-quality frequency selective surfaces (FSSs) are important for electromagnetic signal absorption/filtration. Usually, they are made from wave-transparent composite materials covered with a thin metal layer. Current machining methods show some disadvantages when performing fabrication on the structure. Based on its flexibility and uncontactable processing characteristics, nanosecond laser etching of aluminum-plated composite materials applied to FSSs was investigated. To observe the influence of the laser light incident angle, etching of a series of square areas with different incident angles was performed. Thereafter, an image processing method, named the image gray variance (IGV), was employed to perform etching quality evaluation analysis. The observed microscopic pictures of experimental samples were consistent with those of the IGV evaluation. The potential reasons that might affect the etching quality were analyzed. Following all the efforts above, an incident angle range of ±15° was recommended, and the best etching result was obtained at the incident angle of 10°. To observe the influence of the laser pulse overlap and focal spot size on the etched area border uniformity and on the potential damage to the base materials, a theoretical equation was given, and then its prediction of area border edge burrs fluctuation was compared with the experiments. Furthermore, SEM pictures of etched samples were examined. Based on the study, a processing window of the laser pulse overlap and focal spot size was recommended. To conclude, optimal etching results of the FSS materials could be guaranteed by using the right laser operating parameters with the nanosecond laser. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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Article
Effect of CeO2 on Impact Toughness and Corrosion Resistance of WC Reinforced Al-Based Coating by Laser Cladding
Materials 2019, 12(18), 2901; https://doi.org/10.3390/ma12182901 - 08 Sep 2019
Cited by 11 | Viewed by 1394
Abstract
WC reinforced Al-based coating with added CeO2 was prepared on the surface of S420 steel by laser cladding. The microstructure and structure of the coatings were analyzed by scanning electron microscope, X-ray diffractometer and optical profiler. The mechanical properties and corrosion properties [...] Read more.
WC reinforced Al-based coating with added CeO2 was prepared on the surface of S420 steel by laser cladding. The microstructure and structure of the coatings were analyzed by scanning electron microscope, X-ray diffractometer and optical profiler. The mechanical properties and corrosion properties of the coatings were studied by microhardness tester, friction and wear tester, Charpy impact tester, and electrochemical workstation. The results show that the coating is mainly composed of Al-phase, continuous-phase, and hard reinforced-phase WC, and the coating and substrate show good metallurgical bonding. When the content of CeO2 is 1%, the fine grain strengthening effect is obvious, and the impact toughness of the coating is obviously improved. Appropriate amount of rare earth CeO2 can significantly improve the hardness of the coating. When the content of CeO2 is more than 1%, the wear resistance of the coating decreases. The coating prepared with different CeO2 content has higher impedance and corrosion resistance than that of the substrate. At 1% CeO2 content, the coating has the best corrosion resistance. Full article
(This article belongs to the Special Issue Advances in Laser Processing)
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