Special Issue "Laser Surface Modification of Metallic Materials"

A special issue of Coatings (ISSN 2079-6412). This special issue belongs to the section "Surface Characterization, Deposition and Modification".

Deadline for manuscript submissions: 31 December 2021.

Special Issue Editors

Prof. Dr. Juan Manuel Vazquez Martinez
E-Mail Website
Guest Editor
School of Engineering, Department of Mechanical Engineering and Industrial Design, University of Cadiz. Adv. Universidad de Cadiz 10, E11519 Puerto Real, Spain
Interests: Tribology; Surface modification; Mechanical behavior of materials; Surface characterization; Laser surface texturing; Metrology; Machining; Manufacturing processes
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Jorge Salguero
E-Mail Website
Guest Editor
School of Engineering, Department of Mechanical Engineering and Industrial Design, University of Cadiz. Adv. Universidad de Cadiz 10, E11519 Puerto Real, Spain
Interests: laser surface texturing; tribology; surface improvement; machining; manufacturing processes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Currently a high percentage of metallic materials used in strategic areas, such as the aerospace, energy or biomedical industry, are subject to surface modification procedures in order to adapt the initial properties to specific work conditions and improve the performance of the processes where the manufactured parts are involved. Surface texturing techniques used for the modification of the features and mechanical behavior of manufactured elements allows to overcome limitations and improve the properties of the external layers without affecting the remaining material. In this aspect, by laser surface processing methods, specific topographies or microstructural modifications can be developed that can give rise to variations in the initial characteristics of the treated material. In the case of texturized processes on metallic materials, mainly due to the homogeneity of the layers, better results can be obtained, in terms of uniformity and repeatability of the modified layer than in other types of materials such as composites. The ability to generate microgeometries with dimensions and shape adapted to specific applications is widely related to wettability behavior. Therefore, by developing laser surface treatments, hydrophobic and hydrophilic tendencies can be induced on a wide variety of materials. On the other hand, the modification of the microstructure is generally associated with variations in mechanical properties such as hardness or wear resistance under tribological conditions. Additionally, if control is maintained over the laser treatment atmosphere, the appearance of layers with compositional changes becomes possible, giving rise to oxidation or nitriding process, among others. This Special Issue is mainly focused on research lines in the field of laser surface texturing on metallic materials. In this special edition, high interest is maintained on research articles dedicated to improving the performance of texturing processes and their use in specific applications. The improvement of surface conditions and the characterization procedures of the modified layer are very interesting aspects for publication in this issue.

Dr. Juan Manuel Vazquez Martinez
Prof. Dr. Jorge Salguero Gomez
Guest Editors

Manuscript Submission Information

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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. Coatings is an international peer-reviewed open access monthly 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 1800 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 texturing
  • surface modification
  • wetting behavior
  • surface finish
  • surface characterization
  • wear resistance treatment
  • corrosion resistance surface treatment
  • tribological applications.

Published Papers (6 papers)

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Research

Article
Laser Dissimilar Joining of Al7075T6 with Glass-Fiber-Reinforced Polyamide Composite
Coatings 2020, 10(2), 96; https://doi.org/10.3390/coatings10020096 - 22 Jan 2020
Cited by 1 | Viewed by 955
Abstract
Dissimilar joining between metal and composite sheets is usually carried out by mechanical or adhesive joining. Laser dissimilar joining between metal and composite sheets could be an alternative to these methods, as it is a cost-effective and versatile joining technique. Previously, textured metallic [...] Read more.
Dissimilar joining between metal and composite sheets is usually carried out by mechanical or adhesive joining. Laser dissimilar joining between metal and composite sheets could be an alternative to these methods, as it is a cost-effective and versatile joining technique. Previously, textured metallic and composite parts have been held together and heated with a laser beam while pressure is applied to allow the melted polymer to flow into the cavities of the metal part. The main issue of this process relates to reaching the same joint strength repetitively with appropriate process parameters. In this work, both initial texturing and laser joining parameters are studied for Al 7075-T6 and glass-fiber-reinforced PA6 composite. A groove-based geometry was studied in terms of depth-to-width aspect ratio to find an optimal surface using a nanosecond fiber laser for texturing. Laser joining parameters were also studied with different combinations of surface temperature, heating strategy, pressure, and laser feed rate. The results are relatively good for grooves with aspect ratios from 0.94 to 4.15, with the widths of the grooves being the most critical factor. In terms of joining parameters, surface reference temperature was found to be the most influential parameter. Underheating does not allow correct material flow in textured cavities, while overheating also causes high dispersion in the resulting shear strength. When optimal parameters are applied using correct textures, shear strength values over 26 kN are reached, with a contact area of 35 × 45 mm2. Full article
(This article belongs to the Special Issue Laser Surface Modification of Metallic Materials)
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Article
Effect of Scanning Speed on the Interface Behavior and Dendrite Growth of Laser Remelted Fe-Based Ni/WC Coatings
Coatings 2019, 9(10), 677; https://doi.org/10.3390/coatings9100677 - 18 Oct 2019
Cited by 5 | Viewed by 780
Abstract
The flame sprayed Fe-based Ni/WC cermet coating was treated by laser remelting. The influence of scanning speeds on the interface behaviour was investigated. SEM, XRD and EDS were used to analyse the microstructure, phase composition and element distribution of the interface. The results [...] Read more.
The flame sprayed Fe-based Ni/WC cermet coating was treated by laser remelting. The influence of scanning speeds on the interface behaviour was investigated. SEM, XRD and EDS were used to analyse the microstructure, phase composition and element distribution of the interface. The results showed that the interface of the coating contained holes and interlayer cracks and showed typical mechanical bonding features. The coatings mainly consisted of [Fe, Ni], Cr, WC, Cr7C3, Fe0.04Ni0.36, and other phases. After laser remelting, the coatings were smooth and dense due to the existence of well-developed dendrite structures and metallurgical bonding and could reach the optimal performance at 200 mm/s. New phases such as Fe2Si, Cr2Si, and W2C appeared in the remelted layers. With the increase of scanning speed, the half-peak height and average grain size became wider and smaller. At the same time, the measured dendrite spacing decreased with increasing scanning speed. Full article
(This article belongs to the Special Issue Laser Surface Modification of Metallic Materials)
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Article
The Corrosion Resistance of Aluminum Alloy Modified by Laser Radiation
Coatings 2019, 9(10), 672; https://doi.org/10.3390/coatings9100672 - 16 Oct 2019
Cited by 5 | Viewed by 946
Abstract
This study presents an analysis of the impact of the oxide layers, prepared utilizing fiber laser radiation (1062 nm) in ambient air with different process parameters, on the corrosion resistance of EN 5754 aluminum alloy. Due to both high corrosion resistance and high [...] Read more.
This study presents an analysis of the impact of the oxide layers, prepared utilizing fiber laser radiation (1062 nm) in ambient air with different process parameters, on the corrosion resistance of EN 5754 aluminum alloy. Due to both high corrosion resistance and high fatigue strength, a 5754 alloy is used, among others, in the marine, aerospace, automotive, and chemical industries. Nevertheless, it corrodes in aggressive environments (with high chloride ions concentration). The controlled delivery of laser radiation energy in the oxygen environment allows the formation of the oxide layer on the surface of the material. We have determined that it significantly affects the resistance of these materials to corrosion. As a result of laser irradiation, changes in the chemical structure of the surface layer (chemical composition as well as surface development) can be observed. It may exert both a positive and a negative consequence on the corrosion resistance. The electrochemical corrosion tests (potentiodynamic polarization and electrochemical impedance spectroscopy EIS) have been carried out in an aggressive environment (3% NaCl). Moreover, microscopic examination, chemical tests, and roughness were also performed. The study revealed that appropriate control of the laser process can significantly increase the original corrosion resistance of the 5754 aluminum alloy. Full article
(This article belongs to the Special Issue Laser Surface Modification of Metallic Materials)
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Article
Nanosecond Pulsed Laser Irradiation of Titanium Alloy Substrate: Effects of Periodic Patterned Topography on the Optical Properties of Colorizing Surfaces
Coatings 2019, 9(10), 658; https://doi.org/10.3390/coatings9100658 - 11 Oct 2019
Cited by 4 | Viewed by 1058
Abstract
Most of the current works based on surface treatments of metals by laser marking technology are focused on the modification of the color tonality of flat surfaces, or the development of specific topography features, but the combination of both processes is not usually [...] Read more.
Most of the current works based on surface treatments of metals by laser marking technology are focused on the modification of the color tonality of flat surfaces, or the development of specific topography features, but the combination of both processes is not usually evaluated, mainly due to the complexity of controlling the optical properties on rough surfaces. This research presents an analysis of the influence of the micro-geometrical characteristics of periodic patterned laser tracks on the chromaticity and reflectance of Ti6Al4V substrates. The samples were irradiated with an infrared nanosecond pulsed laser in air atmosphere, taking as the control parameter the scan speed of the beam. A roughness evaluation, microscopic inspection, and absorption and chromaticity examination were conducted. Although micro-crack growth was detected in an isolated case (10 mm/s), the possibility of adjusting the result color was demonstrated by controlling the heat-affected zone thickness of the textures. The results of rough/colored combined textures allow new perspectives in industrial design to open, particularly in aesthetic applications with special properties. Full article
(This article belongs to the Special Issue Laser Surface Modification of Metallic Materials)
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Article
Distribution of Al Element of Ti–6Al–4V Joints by Fiber Laser Welding
Coatings 2019, 9(9), 566; https://doi.org/10.3390/coatings9090566 - 05 Sep 2019
Cited by 4 | Viewed by 1072
Abstract
In the process of laser welding, the uneven distribution of solute elements caused by element burning loss and flow of molten pool affects the quality of joints. In this paper, butt welding experiments were conducted on the 3 mm thick Ti–6Al–4V specimens with [...] Read more.
In the process of laser welding, the uneven distribution of solute elements caused by element burning loss and flow of molten pool affects the quality of joints. In this paper, butt welding experiments were conducted on the 3 mm thick Ti–6Al–4V specimens with different preset ratios of Al and Si powders by using 4 kW fiber laser. The distribution of Al solute element and its influence on the microstructure and mechanical properties of the final weld joint were investigated. The results showed that the self-diffusion of Al element and the flow of molten pool affects the alloy elements distribution in laser welding. And the microhardness of the welded joint with Ti–6Al–4V and 90% Al + 10% Si powders was significantly higher than that with only Ti–6Al–4V, with the difference of about 130HV. At the same time, in the joint with 90% Al and 10% Si powders, the acicular α’ size was finer, and basketweave microstructure was present as well. This research is helpful to better understand the distribution of Al solute element and its influence on the joint quality during laser welding of Ti–6Al–4V alloy, which provides a certain reference for improving the weld or surface properties of Ti–6Al–4V alloy during laser processing. Full article
(This article belongs to the Special Issue Laser Surface Modification of Metallic Materials)
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Article
TiBCN-Ceramic-Reinforced Ti-Based Coating by Laser Cladding: Analysis of Processing Conditions and Coating Properties
Coatings 2019, 9(6), 407; https://doi.org/10.3390/coatings9060407 - 24 Jun 2019
Cited by 5 | Viewed by 1246
Abstract
In this paper, TiBCN-ceramic-reinforced Ti-based coating was fabricated on a Ti6Al4V substrate surface by laser cladding. The correlations between the main processing parameters and the geometrical characteristics of single clad tracks were predicted by linear regression analysis. On this basis, the microstructure, microhardness, [...] Read more.
In this paper, TiBCN-ceramic-reinforced Ti-based coating was fabricated on a Ti6Al4V substrate surface by laser cladding. The correlations between the main processing parameters and the geometrical characteristics of single clad tracks were predicted by linear regression analysis. On this basis, the microstructure, microhardness, corrosion resistance, and wear resistance of the coating and the substrate were investigated. The results showed that the clad height, clad width, clad depth, and dilution rate depended mainly on the laser power, the powder feeding rate, and the scanning speed. TiBCN-ceramic-reinforced Ti-based coating was mainly composed of directional dendritic TiBCN phases, equiaxed TiN phases, needle-like Al3Ti phases, and Ti phases. The microhardness gradually increased from the bottom to the top of the coating. The highest microhardness of coating was 1025 HV, which was three times higher than that of the Ti6Al4V substrate (350 HV). Furthermore, the coating exhibited excellent corrosion resistance and wear resistance. The corrosion potential (Ecorr) reached −1.258 V, and the corrosion density (Icorr) was 4.035 × 10−5 A/cm2, which was one order lower than that of the Ti6Al4V substrate (1.172 × 10−4 A/cm2). The coating wear mass loss was 4.35 mg, which was about two-third of the wear mass loss of the Ti6Al4V substrate (6.71 mg). Full article
(This article belongs to the Special Issue Laser Surface Modification of Metallic Materials)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Authors: Eneko Ukar Arrien
Title:  Laser surface texturing of Al 7075T6 and Usibor 2000 for laser direct joining with Tepex102

Authors: Juan Manuel Vazquez Martinez; Jorge Salguero
Title: Nanosecond pulsed laser irradiation of titanium alloy substrate: Effects of periodic patterned topography on the optical properties of colorizing surfaces 

Authors: Yury Korobov, Alexander Vopneruk, Yulia Khudorozhkova, Sergey Burov, Prabu Balu, Alexey Chernov
Title:
Thickness effect on the properties of laser deposited NiBSi-WC coating on Cu-Cr-Zr substrate
Abstract:
For some applications, for example, for the continuous casting machine mold, materials combining high thermal conductivity and wear resistance at elevated temperatures are required. To meet these demands a copper alloy is used as a substrate, and wear and corrosion resistant coating is applied.
          A fabrication of a coating on a copper meets with the following difficulties [1]. Easy oxidation of copper at high temperatures leads to clogging of the weld metal by refractory oxides. A coefficient of thermal expansion is 1.5 times greater than that of steel. Such high value causes increased residual stress and deformation after heating. The combination of high thermal stress with a decrease of the mechanical properties can promote the formation of cracks. Copper in the molten state absorbs considerable quantity of hydrogen. The crystallization of metal weld pool is marked by high rate due to the high thermal conductivity of copper. Accompanied by a sharp solubility decrease of hydrogen in the metal it results in staying atomic hydrogen in the metal. Water vapor is formed at cuprous oxide reducing by hydrogen, which leads to the formation of the weld cracks and pores. Heating above the recrystallization point leads to lower strength. Laser cladding is an attractive method to produce Ni-WC coatings, particularly on copper [2]. It allows keeping the carbides intact with minimal dissolution accompanied by melting the matrix material only.
          Ni/60WC coatings on copper substrate were formed by laser deposition. The structure study by scanning electron microscopy and by microhardness evaluation was done. Two-body abrasive wear tests were carried out by pin-on-plate reciprocating technique. AISI D2 steel with a hardness of 63 HRC was used as a counterpart. The study results were the following:

  • Precipitation of secondary carbides takes place in the thicker layers. Their hardness is lower than that of primary carbides in the deposition (2425 HV vs 2757 HV) because of mixing with matrix material. In the thin layers, the precipitation is restricted due to higher cooling rate;
  • Microhardness value of laser deposited tungsten carbide corresponds to 0.9 of the cast carbides and about 2 times as high comparing to the carbides in HVOF coatings. Wherein for both LD-coatings the carbide’s hardness is increased comparing to initial WC-containing powder (2756 HV vs 2200 HV). Such high microhardness reflects combined influence of low thermal destruction of carbides at laser deposition and forming a boride-strengthening phase from matrix powder;
  • Thicker layer showed a higher wear resistance; weight loss was 20% less in the case of a thicker coating. The reasons for the change in properties for coatings of various thicknesses have been discussed.
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