Search Results (78)

Ti-6Al-4V alloy possesses excellent specific strength, corrosion resistance, and biocompatibility, rendering it widely applicable in aerospace, marine engineering and biomedical fields. Selective laser melting (SLM) serves as an effective technique for manufacturing complex Ti-6Al-4V components. However, SLM-formed specimens generally suffer from surface defects such as high surface roughness, adhered powders, spheroidized particles, and localized spatter, which degrade their service performance and limit further practical applications. Therefore, effective surface modification is urgently required. This work systematically explores the synergistic effects of sandblasting at various angles followed by acid pickling on the surface characteristics of SLM-formed Ti-6Al-4V alloy. The SLM Ti-6Al-4V samples were first treated by sandblasting at different impact angles and then subjected to acid pickling. Material mass loss, micro-morphology, surface roughness, contact angle, surface microhardness, abrasive-particle embedment and surface residual stress were measured and analyzed. The results show that sandblasting angle exerts a remarkable influence on material removal behavior, abrasive-particle embedment and near-surface mechanical response. Scanning electron microscopy (SEM) observations indicate that sandblasting at different angles can not only effectively eliminate surface-adhered powders, but also generate impact pits, cutting grooves, and ploughing marks whose morphologies vary with sandblasting angles. The subsequent acid pickling process further removes loose particles and sharp protrusions, and promotes the formation of microscale surface structures. Benefiting from the combined effects of mechanical sandblasting and chemical acid pickling, the alloy samples exhibit substantially reduced surface roughness and enhanced surface wettability. Meanwhile, sandblasting induces work hardening and thus increases surface microhardness and surface residual stress, while acid pickling regulates surface morphology and the state of the work-hardened layer to a certain degree. Overall, this study provides an economical, efficient, and industrially feasible composite surface modification approach to reduce surface roughness, enhance hydrophilicity, and tailor surface hardness of SLM Ti-6Al-4V alloy. Full article

In this study, zirconia specimens were subjected to Al₂O₃ airborne-particle abrasion and Er laser irradiation to investigate their effects on surface characteristics. The treated and untreated zirconia surfaces were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), qualitative elemental analysis by laser-induced breakdown spectroscopy (LIBS), energy-dispersive X-ray spectroscopy (EDS), Raman spectroscopy, XRD analysis, and power spectral density (PSD) analysis. The Er laser-treated group showed the highest mean surface roughness (Sa: 7.763 ± 2.449 µm), compared with the Al₂O₃-treated group (3.640 ± 2.164 μm); however, the differences in Sa among the experimental groups were not statistically significant (Kruskal–Wallis, p = 0.095). Likewise, no statistically significant differences were observed for Sz (one-way ANOVA, p = 0.567). SEM, AFM, and PSD analyses provided complementary information on the morphological and spatial characteristics of the surfaces produced by the different treatments. Under the experimental conditions evaluated, Er laser irradiation produced distinct surface topographic features and a descriptive trend toward higher mean Sa values, but statistical superiority over Al₂O₃ airborne-particle abrasion or the untreated control was not demonstrated. Further studies are required to determine whether these surface modifications translate into functional or clinical benefits. Full article

Polyetheretherketone (PEEK) has emerged as a promising biomaterial for orthopedic and craniofacial implants due to its favorable mechanical properties and fatigue resistance; however, its inherent chemical inertness limits effective osseointegration. In this study, femtosecond laser surface modification is explored as a strategy to enhance the bioactivity of PEEK. Based on a previously performed parametric study, controlled micro- and nanoscale surface textures were fabricated using femtosecond laser processing, enabling precise tuning of surface roughness and wettability without the need for additional chemical treatment. The modified surfaces were systematically characterized in terms of morphology, composition, and topography using scanning electron microscopy (SEM), 3D profilometry, and water contact angle measurements. Four optimized femtosecond laser-generated surface architectures were selected for the present investigation and comprehensively characterized, followed by in vitro evaluation of dental pulp stem cell adhesion, morphology, and proliferation. The results indicate that laser-induced micro/nanostructuring enhances the surface properties of PEEK, while supporting cellular attachment and favorable cell–surface interaction. Differences in the biological response were observed among the optimized laser-textured surfaces. These findings highlight the feasibility of femtosecond laser texturing as a clean, reproducible, and scalable approach for the development of next-generation, personalized orthopedic implants. Full article

This study presents an Artificial Neural Network (ANN) approach for predicting laser-induced material modifications during femtosecond laser micromachining of aluminum. Experimental investigations were carried out to determine the influence of the average laser power and scanning speed on the width of the ablation groove and the size of the optically determined surface-discoloration width used as a proxy for the Heat-Affected Zone (HAZ). The collected dataset, consisting of 100 samples, was used to develop, train, validate, and test an ANN predictive model with two inputs, two outputs, and two hidden layers. Despite its simplicity and the relatively small dataset, the developed model achieved relatively good prediction accuracy, with an overall correlation coefficient (R) of approximately 0.95 on the test dataset. The predicted values showed reasonable agreement with the experimental results, indicating that the ANN approximated the relationship between laser processing parameters and the resulting material modifications. The presented methodology may provide a useful tool for predicting surface morphology changes and thermal effects in femtosecond laser processing of aluminum. Full article

Background/Objectives: Acorus tatarinowii Schott volatile oil (ATVO), a bioactive component of traditional Chinese medicine, is susceptible to light-induced oxidation and compositional changes. This study aimed to develop a chitosan-modified Saigae Tataricae Cornu particle (MSTC)-stabilized Pickering emulsion (PE) to improve the light-oxidative stability and in vivo disposition of ATVO. Methods: Saigae Tataricae Cornu particles were modified with chitosan and used to prepare an oil-in-water PE encapsulating ATVO. Particle wettability, morphology, structural interactions, emulsion type, interfacial distribution, droplet size, and zeta potential were characterized. The light-oxidative stability of ATVO was evaluated under light using peroxide value, malondialdehyde content, and gas chromatography-mass spectrometry (GC-MS) analysis. The pharmacokinetic behavior of α-asarone and β-asarone was further investigated in rats. Results: Chitosan modification increased the contact angle of Saigae Tataricae Cornu particles from 65.37° to 83.23°, indicating improved wettability and interfacial affinity. The resulting PE showed good physical stability, with a droplet size of 2.51 μm and a zeta potential of +32.00 mV. Confocal laser scanning microscopy (CLSM) confirmed that MSTC particles adsorbed at the oil–water interface and encapsulated ATVO within the oil droplets. Compared with free ATVO and the physical mixture, the PE reduced peroxide and malondialdehyde formation, slowed light-induced changes in volatile components, and better preserved major bioactive constituents. Pharmacokinetic analysis showed that the plasma concentration-time curve from 0 to t (AUC_0–t) and maximum plasma concentration (C_max) of α-asarone increased by 2.02- and 2.47-fold, respectively, whereas the effect on β-asarone was relatively limited. Conclusions: MSTC-stabilized PE provides an effective interfacial-barrier strategy for protecting ATVO against light-oxidative deterioration. This study highlights the potential of modified natural medicinal particles as green stabilizers for improving the stability, quality consistency, and delivery performance of volatile-oil-containing traditional Chinese medicine preparations. Full article

Ultra-High Molecular Weight Polyethylene (UHMWPE), the standard base material in ski manufacturing, offers excellent gliding performance but exhibits limited mechanical and scratch resistance on hard and icy snow conditions. In this work, stainless steel is proposed as a mechanically robust alternative, and its inherently higher friction against snow is addressed through surface engineering. The snow friction behavior of 301H stainless steel surfaces decorated with fishbone-like microstructures combined with Laser-Induced Periodic Surface Structures (LIPSSs) was investigated using a custom-built snow tribometer. Several pattern designs, with different pitch distances and depths, were engraved using femtosecond laser pulse irradiation. We conducted morphological, physical, and chemical investigations through microscopy, static contact angle measurements, and X-ray Photoelectron Spectroscopy analyses. Results indicate that the gliding performance is not directly related to the modifications in surface chemistry and wetting behavior of the samples but is affected by the geometry and orientation with respect to the sliding direction of the specific micro- and nano-features. Overall, we achieved friction coefficient values comparable to those found in UHMWPE with a fast and economically sustainable single-step laser-texturing process. This approach allows the industrial up-scaling of the fishbone-texture design to real-size alpine ski prototypes. Full article

Ballistic para-aramid fabrics are widely used in personal protection and defense applications due to their high strength-to-weight ratio, thermal stability, and durability. This study investigates the influence of laser-based surface modification on graphene-modified Kevlar^® KM2-600 (600 dtex) fabrics, with a particular focus on surface morphology and topographical characteristics of para-aramid fabrics used in ballistic applications. The deposition of graphene onto para-aramid fibers introduces new opportunities for surface engineering, while laser processing enables localized and controlled modification of the fiber surface without compromising the integrity of the bulk material. In this work, graphene-modified Kevlar^® KM2-600 fabrics were subjected to controlled laser processing under various parameter settings, and the resulting surface modifications were systematically analyzed. Three-dimensional laser microscopy was employed to characterize surface morphology and roughness, providing detailed insight into laser-induced topographical changes. The results demonstrate that optimized laser processing enables controlled surface restructuring while avoiding severe thermal damage, particularly when appropriate mechanical stabilization and focal conditions are maintained. Under identical laser processing conditions (Matrix II, q = 3.65 × 10⁴ W/cm²), the mean arithmetic roughness increased from 4.57 ± 1.04 µm for the unmodified fabric to 5.54 ± 1.05 µm for the graphene-modified fabric, while the mean root mean square roughness increased from 5.76 ± 1.41 µm to 6.95 ± 1.39 µm. These findings contribute to an improved understanding of laser–graphene–aramid interactions and provide a foundation for future studies addressing the potential functional implications of surface modification in lightweight protective textiles. Full article

Modification of PLA with functional nanoparticles is a promising approach for imparting new properties to the material. In this work, titanium nanoparticles (Ti NPs) and titanium dioxide nanoparticles (TiO₂ NPs) were synthesized by laser ablation and characterized by dynamic light scattering, spectrophotometry, and transmission electron microscopy. The average hydrodynamic diameter of Ti NPs was 12 nm, while that of TiO₂ NPs was 24 nm; both dispersions possessed a positive zeta potential (23–27 mV) and spherical morphology. L-PLA composite films containing 0.1 wt.% Ti NPs or TiO₂ NPs were obtained by solution casting. Atomic force and modulation-interference microscopy confirmed the uniform distribution of nanoparticles within the polymer matrix, although partial aggregation was observed. The introduction of TiO₂ NPs increased the water contact angle. Mechanical testing revealed a significant reinforcing effect: the addition of 0.1 wt.% NPs increased the Young’s modulus by 62–68% and the ultimate tensile strength by 16–18% while maintaining a ductile fracture pattern with elongation at break up to ~8%. Both types of composites generated reactive oxygen species (ROS) in aqueous solutions: Ti NPs increased H₂O₂ production by 5.5 times and TiO₂ NPs by 4.9 times, and they also induced the formation of hydroxyl radicals. The accumulation of 8-oxoguanine in DNA and long-lived oxidized protein species confirmed the materials’ ability to cause oxidative damage to biomacromolecules. For E. coli, growth inhibition reached 40.5% (for composites with Ti NPs) and 71% (for composites with TiO₂ NPs). The effect was even more pronounced for S. aureus, where inhibition levels were approximately 70% and 80%, respectively; flow cytometry confirmed the strong bactericidal effect, showing that materials containing TiO₂ NPs increased the proportion of dead cells to 25% for E. coli and ~68% for S. aureus. Cytotoxicity assessment on human fibroblasts (HSF) demonstrated the high biocompatibility of neat L-PLA and composites with Ti NPs (viability > 95%) and with TiO₂ NPs (viability ~93%). The obtained results indicate that L-PLA-based composites with Ti NPs and TiO₂ NPs exhibit pronounced ROS-mediated antibacterial activity without additional UV irradiation. These findings position these materials as highly promising candidates for active biodegradable food packaging to extend shelf-life and for biomedical devices, such as wound dressings and implants, where reducing the risk of bacterial colonization is critical. Full article

Laser Powder Bed Fusion (LPBF) enables the fabrication of complex titanium alloy components with high geometric freedom; however, surface integrity and tribological performance remain critical limitations for sliding-contact applications in biomedical and aerospace systems. In this study, the influence of in-layer laser remelting on the microstructure, surface topography, and dry sliding tribological behavior of LPBF-fabricated Ti-6Al-4V ELI (Grade 23) is systematically investigated. Disc-shaped specimens were produced using single-scan (SS) and double-scan (DS, in-layer remelting) strategies and tested in ball-on-disc configuration against AISI 52100 steel at a constant normal load of 10 N and three sliding speeds of 0.10, 0.15, and 0.20 m·s⁻¹. Microstructural and phase-related characteristics were analyzed by X-ray diffraction combined with Rietveld refinement and Warren–Averbach analysis, revealing that the DS strategy increases retained β-phase fraction (up to 5.2%) and promotes crystallite coarsening relative to the SS condition, without significantly altering bulk hardness. Surface morphology examined by SEM/EDS and AFM revealed a more homogeneous near-surface topography in the DS condition. Tribological results indicate that sliding speed governs steady-state friction and wear, with specific wear rates increasing progressively from 5.13 to 5.44 × 10⁻⁴ mm³·N⁻¹·m⁻¹ for SS and from 6.47 to 7.52 × 10⁻⁴ mm³·N⁻¹·m⁻¹ for DS across the investigated speed range. The DS specimens exhibited higher wear rates than the SS condition across all tested speeds, while steady-state COF values remained comparable between strategies, indicating that remelting-induced microstructural modifications affect material removal mechanisms without proportionally destabilizing the frictional regime. These findings suggest that in-layer laser remelting represents a process-integrated parameter with measurable consequences for surface integrity and tribological performance, though the generalizability of these results warrants validation across broader experimental conditions. Full article

This study aims to reveal the mechanism of a novel method for fabricating hierarchical microstructured hydrophobic surfaces. Specifically, plasma shock waves induced by laser ablation are applied to the workpiece to replicate the microstructures on the mold surface, thus obtaining primary microstructures. Meanwhile, the material splashing effect induced by laser ablation is utilized to form secondary microstructures on the basis of the primary microstructures. Subsequently, fluorination treatment and aging treatment are adopted to alter the chemical composition of the hierarchical microstructures on the workpiece surface, thereby reducing the surface energy and enhancing hydrophobicity. In addition, this study investigates the effects of a different number of laser shocks, laser fluence and mold periods on the forming results. Under a laser fluence of 28.97 J/cm², within the range of one to five laser shocks, the forming effect of the aluminum foil workpiece improves with the increase in the number of laser shocks. When the number of laser shocks is set to 3, within the laser fluence range of 19.1–76.39 J/cm², the forming result of the aluminum foil workpiece is enhanced as the laser fluence increases. The larger the mold period, the better the forming effect of the workpiece. An analysis of aging treatment and fluorination treatment reveals their impacts on the workpiece through assessments of wettability, surface chemical composition, and surface morphology. The findings reveal that both aging and fluorination treatments significantly enhance the contact angle of the aluminum foil workpiece, all while preserving its original surface structure. The main changes occur in terms of element content and chemical composition, and a large number of non-polar groups are generated on the workpiece surface after the modification treatments. Full article

Combined pulse laser systems combining continuous-wave (CW) lasers and nanosecond pulsed lasers have shown clear advantages in metal ablation and surface modification. However, the plasma shielding effect induced by nanosecond pulses and the associated shock-wave phenomena in hybrid laser systems remain insufficiently investigated, particularly regarding their influence on CW laser energy coupling. In this study, the ablation behavior of metal targets under the combined irradiation of a 500 W CW laser and nanosecond pulsed lasers with pulse energies ranging from 0.4 J to 1.0 J was investigated. High-speed plasma imaging was employed to analyze laser–material interaction characteristics, including absorption behavior and molten material ejection, while high-speed infrared thermography was used to monitor transient temperature evolution during combined pulse laser processing. Macroscopic and microscopic analyses were conducted to characterize damage morphology, and a three-dimensional surface profilometer was used to quantitatively evaluate ablation efficiency. The results show that, under combined pulse laser irradiation, the removed volume increased from 0.05 mm³ to 0.618 mm³ and the ablation depth increased from 0.136 mm to 0.776 mm. Compared with CW laser processing alone, the ablation efficiency was markedly enhanced. This improvement is attributed to the combined effects of optimized energy deposition, thermal distribution, and material response. In addition, the plasma shielding effect was observed to vary with nanosecond pulse energy, indicating that precise energy control is critical for performance enhancement. This study demonstrates the potential of combined pulse laser technology for high-efficiency and high-precision metal surface processing and micro–nano fabrication. Full article

Laser Powder Bed Fusion (L-PBF) can enable in situ microstructural tailoring of metallic components by precisely controlling the layer-wise processing parameters. Layer rescanning is one such strategy used to induce localized microstructural modification. In this study, we investigated the effect of a lattice-based selective rescanning approach applied to different base scan strategies for Ti-6Al-4V samples. The lattice regions were selectively rescanned at 50% reduced laser power relative to the initial scan along the same laser path. Relative density, porosity, martensitic α′ morphology, phase fraction, and Vickers microhardness were compared with those of non-rescanned reference counterparts. Different scan strategies, including unidirectional, stripes, and chess, exhibited distinct responses to selective rescanning, resulting in localized variations in martensitic phase formation and hardness values. The extent of localized microstructural modification and hardness enhancement was strongly governed by the underlying scan strategy. Selective rescanning using the stripes strategy yielded the largest contrast between non-rescanned and rescanned regions. The unidirectional strategy showed strong effects of rescanning, but the heat-affected zones extended to the non-rescanned regions. In contrast, the chess strategy exhibited comparatively moderate changes owing to its inherent thermal-management characteristics. These findings demonstrate that selective rescanning can provide an effective, localized approach for tailoring microstructure and hardness enhancement in L-PBF Ti-6Al-4V, with its effectiveness strongly dependent on the underlying scan strategy. Full article

The effect of CO₂ laser treatment on the surface composition and properties of a woven fabric (polyester (PET) fiber (59 wt%)/cotton (CO) fiber (31 wt%)/stainless-steel (SS) metal fibers (10 wt%)) was investigated across a range of laser intensities (19.1 × 10⁶ to 615.0 × 10⁶ W/m²). Elemental analysis using wavelength-dispersive X-ray fluorescence (WD-XRF) revealed that for an intensity up to 225.4 × 10⁶ W/m², the carbon content on the fabric surface increased while the oxygen content decreased, indicating thermally induced surface modification. Fourier transform infrared (FT-IR) spectroscopy confirmed that no new chemical bonds were formed, suggesting that the changes observed were predominantly physical in nature. High-resolution scanning electron microscopy (HR-SEM) showed progressive fiber fusion and surface smoothing with increasing laser intensity, consistent with polyester melting. Tensile testing demonstrated a significant decline in peak load and elongation at peak load with rising laser fluence, indicating mechanical embrittlement. Overall, CO₂ laser treatment alters the morphology and elemental composition of the fabric surface without inducing major chemical decomposition, markedly reducing its mechanical strength. Full article

Mg alloys show great potential in biomedical fields due to superior biocompatibility and biodegradability. Additive manufacturing (AM) provides opportunities in fabricating metallic implants with complex geometries while inherent defects during AM limit its further applications. In this work, laser shock peening (LSP) was employed as a post-processing technique to tailor the surface integrity and corrosion resistance of additively manufactured AZ91 Mg alloy by selective laser melting (SLM). The surface morphology, microstructure and porosity, surface hardness and residual stress, and corrosion resistance of the SLMed alloy before and after LSP were examined. The results show that a gradient structure is formed along the depth direction after LSP and high-density dislocations and high-fraction low-angle grain boundaries are induced. The porosity is gradually reduced in number and size and the highest density of 1.794 g/cm³ is obtained after two impacts of LSP. The surface hardness and residual compressive stress both increase with LSP number and the highest values of 135.26 HV and 40.13 MPa after four impacts, respectively. All of the SLMed alloy samples show improved corrosion resistance after LSP. This work provides a promising route for enhancing the performance of additively manufactured Mg alloys through laser materials surface modification. Full article

The increasing prevalence of orthopedic disorders and technological advances have significantly improved the design and functionality of orthopedic implants, fostering the growth of the orthopedic implant market. Polyetheretherketone (PEEK) has emerged as a promising alternative to the gold standard of metallic implants due to its favorable biocompatibility and mechanical properties, comparable to those of bone tissue. However, its chemical inertness results in poor osseointegration. This study investigates femtosecond (fs) laser-induced micro- and nanoscale surface modifications of PEEK, aiming to develop surface modifications potentially favorable for bioactivity enhancement of the as-created transient cellular scaffolds. Various texturing designs were fabricated by precisely controlling the laser parameters applied (laser beam power P = 20–80 mW, hatch spacing dx = 45–100 µm, scanning velocity V = 3.44–32 mm/s). The resulting morphologies were characterized by SEM, EDX, XRD, micro-Raman, 3D profilometry, water contact angle measurements, and evaluated for preliminary biological response. The main achievement of the research indicates that the hierarchical topography created by fs laser microprocessing significantly increased surface morphology, which may subsequently provide surface conditions supporting successful osseointegration. These findings demonstrate the feasibility of femtosecond laser structuring as a promising, reproducible, and environmentally friendly method for sustainable surface biofunctionalization of PEEK in orthopedic applications. Full article