Laser Surface Research Articles

Research on Laser Direct Transmission Welding of Transparent Polystyrene and Polycarbonate Based on Laser Surface Modification

The conventional near-infrared laser transmission welding (LTW) process for joining dissimilar transparent polymers is limited by the need to incorporate optical absorbents, which compromises joint performance and raises biocompatibility concerns. To address these issues, this study proposed a surface modification technique using femtosecond laser ablation prior to the welding process. Experiments involved 520 nm femtosecond laser ablation of transparent polymers, followed by LTW of dissimilar transparent polymers using an 808 nm laser, with subsequent characterization and mechanical property evaluations. A maximum joint strength of 13.65 MPa was achieved. A comprehensive investigation was conducted into the physical and chemical mechanisms through which laser ablation improved the welding performance of dissimilar transparent polymers. The results demonstrated that laser ablation generated microstructures that serve as substitutes for optical absorbents while also facilitating the formation of numerous oxygen-containing functional groups. These enhancements improve miscibility and bonding performance between dissimilar polymers, enabling absorbent-free welding between ablated polycarbonate (PC) and polystyrene (PS). This work confirms both the feasibility and potential application of this process for direct LTW of dissimilar transparent polymers.

Surface Modification of Additively Manufactured Ti6Al4V through In-Situ Nitrogen-Assisted Laser Surface Remelting

Abstract Laser surface remelting is a widely used method for surface modification of titanium and related alloys, particularly to enhance its workability in the biomedical industry through surface nitriding. The present work aims to develop the nitride surface over the LPBF-processed Ti6Al4V substrate by introducing the nitrogen environment in the build chamber during the remelting. The effects of different laser power and laser scan speeds were studied over the surface topography and elemental changes of the remelted surface. The result shows an increase in surface roughness with selective laser remelting, which could enhance cell proliferation or osseointegration, which is advantageous for biomedical applications.EDX results show a significant increase in nitrogen content in terms of weight percentage for the in-situ remelted surface. XRD phase analysis shows the presence of titanium(Ti) and aluminium(Al) nitride peaks, and X-ray Photon-electron Spectrometry (XPS) also indicates the formation of nitrogen bonds with Ti and Al, which were initially missing in the substrate. The results reported here confirm the nitride surface formation over the substrate due to the in-situ remelting under the nitrogen environment for the LPBF-processed Ti6Al4V, which could be used for improved biomedical applications.

Impact of Nd: YAG laser, cold plasma, and conventional surface pretreatment on bond strength of 3Y-TZP and 5YSZ ceramics to dentin

Impact of Nd: YAG laser, cold plasma, and conventional surface pretreatment on bond strength of 3Y-TZP and 5YSZ ceramics to dentin

Improving the cell adhesion and antibacterial behaviour on Ti6Al4V through micro and nano hierarchical laser surface texturing

Improving the cell adhesion and antibacterial behaviour on Ti6Al4V through micro and nano hierarchical laser surface texturing

Effect of laser surface treatment on microstructural evolution and mechanical properties of a Co–Cr–Fe–Ni–Mo medium–entropy alloy

In this study, we explored the influence of laser surface treatment on the microstructural evolution and mechanical properties of a Co17.5Cr12.5Fe55Ni10Mo5 medium-entropy alloy. After laser scanning on the cold-rolled alloy, a heterogeneous microstructure with Mo-rich μ-precipitates formed along the depth from the surface. Notably, laser processing parameters, including scanning speed and the number of scans, affected the macroscopic heterogeneity in the microstructure of the alloy, such as the thickness of the columnar, recrystallized, partially-recrystallized, and non-recrystallized layers. Furthermore, the microstructural features of the laser-treated alloys with a heterogeneous distribution of grains, cellular structures, and precipitates, contributed to the mechanical response of the alloys. As the heat input from the laser heat source increases, the grain coarsening and the absence of non-recrystallized layer have a greater impact on the strength of the laser-treated alloys, even if the precipitates distributed deeper from the surface. These microstructural modifications through laser surface treatment are linked to variations in the mechanical performance of the alloys, indicating that it can be an effective method to tailor the mechanical properties of structural materials.

Assessing the influence of laser surface texturing on the fatigue behavior of AISI 301LN stainless steel

Assessing the influence of laser surface texturing on the fatigue behavior of AISI 301LN stainless steel

Microstructure Refinement or Increased Copper Solubility: Factors That Contribute to the Pitting Corrosion Tendency in Aluminum–Copper Alloys

Aluminum–copper alloys are commonly used in the aerospace industry due to their low density and high strength. Pitting corrosion is the major problem of Al-Cu alloys due to the presence of largely separated electrochemical potential difference phases. Microstructure refinement and phase homogenization of the alloys are believed to be the factors that contribute to decreasing the galvanic coupling between phases, hence decreasing the pitting tendency. In this work, we investigate whether microstructure refinement is the only factor that contributes to pitting or whether some other factors are involved in the pitting tendency. The investigation was conducted on two frequently used aerospace aluminum–copper alloys, Al-2024 T3 and Al-2014 T6. The surface refinement was conducted by laser surface melting, and microstructure characterization was conducted by scanning electron microscopy with an energy-dispersive X-ray analysis. Phase identification before and after the laser surface melting was conducted by X-ray diffraction, while pitting tendency was measured by a polarization test in 1 molar sodium chloride solution. These experimental results revealed that the enrichment of copper in the α-matrix phase was the major contributing factor in pitting as compared to the largely believed microstructural phase refinement.

Laser Surface Texturing in Single-Point Incremental Sheet Forming

Abstract Single-point incremental sheet forming (SPIF) offers high flexibility, cost-effectiveness, mass customization, ease of setup, and scalability. However, the process can result in poor surface characteristics, making it important to control them, especially for applications requiring enhanced wettability. To overcome this challenge, the present study introduces a novel technique that uses laser surface texturing (LST) to create micropatterns on the SPIF forming tool and replicate on the planar surface of workpiece. After SPIF process on the opposite side of the workpiece, the replicated micropatterns are maintained without significant effect to the laser textures and keep the surface's wettability. The 3D surface topography of the imprinted micropatterns was characterized. Additionally, a sessile drop test was performed to assess the wettability of the surface both before and after the deformation process. The results showed that a functionalized micropatterned surface can be achieved using the proposed technique without affecting the geometric accuracy. No cracks were observed on the workpiece surface, but during the SPIF process, deformation stretched the imprinted microvalleys, leading to a slight decrease in hydrophobicity compared to the original LST surface.

Texture Analysis of Inconel 718 with Different Modes During Single-Track Laser Surface Re-Melting

Texture Analysis of Inconel 718 with Different Modes During Single-Track Laser Surface Re-Melting

Mechanical properties and deformation mechanism of lightweight Al0.5NbTi3VZr0.5 high-entropy alloy via laser surface melting process

Mechanical properties and deformation mechanism of lightweight Al0.5NbTi3VZr0.5 high-entropy alloy via laser surface melting process

A study on the influence of laser hardening on microstructure, and microhardness of additively manufactured H13

ABSTRACT Laser surface treatment was employed as a promising approach to enhance the fatigue life of additively manufactured samples by increasing the surface hardness of the material. In this study, H13 tool steel was manufactured using the selective laser melting method, and lines of laser treatment were applied to the surface. Experimental and statistical approaches were utilised to investigate the microstructural changes, microhardness variations, and weld geometry resulting from different laser treatment processes. The aim was to control the laser parameters and analyse the behaviour of the microstructure and hardness profile of the laser-treated zone. The results revealed an amelioration in the hardness of the laser-treated surface, except for the heat-affected zone, which exhibited a lower hardness compared to the substrate. Statistical approaches were employed to study the effect of laser parameters on the weld geometry including width and depth of the laser-treated area using ANOVA method, elucidating the impact of each factor on these values. Finally, a predictive method for estimating the width and depth was proposed, to facilitate the adjustment of laser parameters for achieving specific outcomes, such as desired hardness profiles or geometrical characteristics, in the laser surface treatment process.

Comparative Study of the Effects of Different Surface States During the Laser Sealing of 304 Steel/High-Alumina Glass

Laser welding (sealing) is a promising technology for joining metal to glass, but it shows poor joint strength in existing studies. This study conducted the laser sealing of a 304 stainless steel alloy to high-alumina glass using pre-oxidation and laser surface melting as an interlayer. The present investigation aimed to determine the influence of this surface modification strategy on the mechanical behavior of glass-to-metal sealing joints made via laser welding. An experimental campaign was conducted on 304 stainless steel and high-alumina glass. Pre-oxidation and laser surface melting treatment were performed on the 304 steel alloy surface before joining to improve the mechanical interlock and chemical bonding between the substrates. The microstructures of the 304 steel alloy/glass interface were investigated by using scanning electron microscopy (SEM) and an energy-dispersive spectrometer (EDS), and the interface evolution mechanism and the correlation between the steel/glass joining strength and the interface morphology were discussed. Finite element analysis software simulated the temperature field and stress field in the welding process, and the reasons for the differences in the welding strengths of different surface treatment samples were analyzed in depth. The results showed that the laser surface melting strategy used significantly influenced the mechanical behavior of the joints and the failure mode. Adopting a higher number of scans improved the mechanical interlock and, consequently, the mechanical behavior of the joints.

Tribological Analysis of Laser-Textured WC-Co Against Ti6Al4V Under Dry and Lubricated Conditions for Different Sliding Times

Machining titanium alloys, particularly Ti6Al4V, pose significant challenges in manufacturing engineering. The combination of high strength and low thermal conductivity makes Ti6Al4V a particularly difficult material to machine. One of these difficulties is the rapid wear and short tool life of cutting tools, which substantially increases manufacturing costs. To address this issue, the texturing of cutting tools, especially using laser-based techniques, has garnered significant attention due to its potential to enhance the tribological performance of textured surfaces. In this paper, by means of a groove design applied to a tungsten carbide (WC) disc by laser surface texturing (LST), its behavior and wear have been evaluated after subjecting it to tribological pin-on-flat tests by confronting it with Ti6Al4V pins with different reciprocating times (250 s, 500 s, 750 s and 1000 s) in lubricated and dry conditions. In addition, these same tests have been replicated without textures for comparison. Through conducting this research, we expect to gain new insights into texturing processes and their influence on friction and sliding behavior under lubricated conditions. Additionally, the study aims to evaluate how lubricant retention capacity varies to reduce friction and wear across different testing durations. The results show better behavior with textures, reaching a higher rate of volume loss in the titanium pins. The main conclusions obtained after these tests are that textures offer a better performance in tests up to 800 s. In addition, after this time, the lubricant begins to lose its properties, becoming an abrasive paste.

The Effect of Laser Surface Hardening on Microstructure and High Temperature Wear Resistance of H13 Steel for Mandrel of Tube Mill

The Effect of Laser Surface Hardening on Microstructure and High Temperature Wear Resistance of H13 Steel for Mandrel of Tube Mill

Enhanced Tribological Performance of Laser-Textured TiN-Coated Ti6Al4V Alloy Surfaces: A Comparative Study with Untextured Surfaces

Titanium alloy is widely used as a biomaterial due to its strength, lightweight nature, and corrosion resistance. Despite its strength and lightweight nature, its low wear resistance limits its uses in prosthetic components. Laser surface texturing (LST) was used to improve the wear resistance of titanium alloys by creating textured surfaces before applying protective coatings. A biocompatible TiN composite protective coating was applied using physical vapour deposition (PVD) with a thickness of 4 µm. Response surface methodology (RSM) was used to predict the tribological properties by varying input parameters such as material type (TI, T2, T3, and T4), load in N, and sliding velocity in m/s. A pin-on-disc tribometer was used to conduct a unidirectional sliding wear test based on the RSM design. Tribological properties were studied to determine the impact of laser texturing on the bonding strength of the coating. As a result, material type T4 exhibits an improved coefficient of friction and specific wear resistance under varying sliding velocity and load conditions compared to other material types. The study was further supported by an ANSYS simulation, which revealed stress reduction affecting the coefficient of friction and, consequently, wear. The textured surface topography, wear mechanisms, and coating compositions were examined using scanning electron microscopy.

Optimization of laser process parameters and improved corrosion behaviour of LZ/YSZ thermal barrier coating

Abstract Laser processing the surfaces of plasma-sprayed thermal barrier coatings is one of the methods used to improve the corrosion resistance of the coatings. However, laser glazing alone is not sufficient to fully protect coatings from corrosion. In this study, optimum laser surface modification parameters were determined for plasma-sprayed LZ/YSZ double-layer thermal barrier coatings. The coating surface, whose entire surface was scanned with optimum parameters, was modified with nano YSZ using the electrophoretic deposition technique. Thus, the network cracks formed during laser glazing were filled with nano YSZ. The coating modified by laser and electrophoretic deposition processes was subjected to corrosion tests. As a result of the characterizations, it was determined that the optimum laser surface modification parameters for LZ/YSZ thermal barrier coatings were 200 mm laser distance, 120 scan speed, and 28w laser power. With these parameters, discontinuities on the as-sprayed coating surface were eliminated. A dense layer was successfully created on the LZ layer. As a result of the corrosion tests, it was determined that modifying the laser-glazed surface with nano YSZ reduced the penetration depth of corrosive contaminants. Thus, the glassy melt and hot corrosion resistance of LZ/YSZ thermal barrier coatings was increased.

Study on the Tribological Behavior of Laser Surface Texturing on Silicon Nitride Ceramic Under Water Lubrication

The tribological behavior of silicon nitride (Si3N4) ceramic with textured patterns under water lubrication was investigated in this paper. Different textured patterns were fabricated using laser surface texturing (LST). Surface wettability was characterized by contact angle. The original surface and textured Si3N4 ceramic with triangular patterns presented as hydrophobic. However, the textured Si3N4 ceramic with hexagonal patterns presented as hydrophilic. Surface wettability and textured patterns were important factors affecting the friction performance of the Si3N4 ceramic. Our results indicated that symmetrical textured patterns were more beneficial for decreasing the coefficient of friction (COF) at lower reciprocating frequencies. In contrast, better surface wettability played a more important role in reducing the COF at higher reciprocating frequencies. The most severe damage observed on the untextured Si3N4 ceramic led to a higher wear rate. The symmetrical structure of hexagonal patterns was more conducive to decreasing the wear rate than triangular patterns. However, the Si3N4 ceramic with triangular patterns was more suitable for use at high-speed frictions due to better lubrication. The textured patterns had the function of storing lubricants and capturing and cutting debris. Thus, friction performance was improved by introducing textured patterns onto the surface of the Si3N4 ceramic. The friction and wear mechanisms are also discussed in this study.

Laser Surface Nanoalloying of Fe, Si, and C on Aluminum Substrate with Excellent Optical and Electronic Properties

Laser surface alloying of Fe, Si, and C on aluminium is demonstrated using a q-witched Nd:YAG laser as the source of energy. The fundamental wavelength of the laser beam was...

Tunable wavelength laser surface profilometry through tilted interference

Frequency-tunable lasers allow the removal of phase ambiguities in interferometric profilometry through the synthetic wavelength longer than height variations in the sample. The subsequent measurements lowering synthetic wavelengths and updating phase difference values improves the measurement. The surface profilometry on samples with tilted interference can lead to an initial synthetic phase map, though locally unambiguous, getting globally wrapped whose unwrapping can be difficult in the presence of noise. Starting with the synthetic phase map that is locally unambiguous but globally wrapped can still update the phase values through a recursive algorithm. The artefact of 2π jumps in the initial wrapped synthetic phase just gets carried forward which can be easily removed from the final phase map obtained with the shortest possible synthetic wavelength. Choosing a point on the sample surface as the point of comparison, the proposed interferometry scheme can be made immune to surrounding vibrations while tuning wavelengths.

The suppression of liquation cracking in the repair process of non-weldable K447A superalloys by laser surface remelting-assisted laser cladding

The suppression of liquation cracking in the repair process of non-weldable K447A superalloys by laser surface remelting-assisted laser cladding