Search Results (1,376)

Transparent glazing systems are increasingly required to provide simultaneous control over light transmission, solar heat gain, thermal losses, surface contamination, and environmental durability, creating new challenges for the development of multifunctional coating technologies. This review critically examines advanced optical and self-cleaning coatings developed for transparent glass and polymeric substrates, with particular emphasis on the relationships between materials chemistry, surface/interface chemistry, microstructure, and functional performance. Dielectric multilayers, metal oxides, ceramic coatings, sol-gel-derived hybrid systems, and emerging chromogenic materials are discussed in terms of their chemical compositions, structural characteristics, and mechanisms governing optical, thermal, and surface properties. Particular attention is given to structure–property relationships associated with photosynthetically active radiation (PAR) transmission, near-infrared (NIR) management, thermal emissivity, solar modulation, wettability, and self-cleaning behavior, together with their implications for energy-efficient transparent glazing and greenhouse environments. The influence of coating architecture, porosity, surface roughness, interfacial interactions, and deposition conditions on functional performance and long-term stability is critically evaluated. The advantages and limitations of representative deposition strategies are further compared, considering scalability, process compatibility, substrate sensitivity, and application to heat-sensitive polymeric films. Environmental degradation mechanisms induced by ultraviolet irradiation, moisture, thermal cycling, and mechanical stresses are analyzed to identify the key factors governing coating durability and sustainability. Finally, current knowledge gaps and emerging research directions are identified, highlighting the need for rational materials design, multifunctional integration, scalable fabrication, and improved structure-property-durability correlations for next-generation transparent glazing and greenhouse applications. Full article

To investigate the effect of femtosecond laser scanning path on the surface integrity of 7075 aluminum alloy after paint removal, parallel, Z-shape, and loop-shape scanning were compared in terms of surface morphology, microstructure, chemical composition, roughness, wettability, and corrosion resistance. Parallel scanning effectively removed the paint while maintaining a surface roughness of 0.27 μm, close to that of the original substrate. The resulting regular unidirectional laser-induced periodic surface structures (LIPSS) yielded a water contact angle of 85°, consistent with the Wenzel wetting model. X-ray photoelectron spectroscopy (XPS) showed the lowest C 1s and O 1s peak intensities, the lowest lattice-oxygen fraction in Al₂O₃, the strongest metallic Al⁰ signal, and limited thermal oxidation. Electrochemical measurements showed the most positive corrosion potential (−0.974 V), the highest film resistance and charge-transfer resistance, and the best corrosion resistance for parallel scanning. By contrast, energy accumulation at the ends during Z-shape scanning and thermal accumulation at the corners and center during loop-shape scanning increased pit and recast-defect densities, oxidation, and corrosion degradation. Loop-shape scanning produced a surface roughness of 3.60 μm and a contact angle of 140.7°, indicating superhydrophobicity, but also the highest corrosion current density and the poorest corrosion resistance, showing that superhydrophobicity does not necessarily correspond to high corrosion resistance. The results show that scanning path affects LIPSS evolution, oxide-film integrity, and corrosion resistance through the spatial distribution of laser energy and thermal accumulation. Among the three paths, parallel scanning provided the best combination of paint removal, low substrate damage, and corrosion resistance, supporting its use in femtosecond-laser paint removal from aircraft aluminum alloy skins. Full article

In the present work, we investigated the role of polydopamine coatings in anchoring TiO₂ P25 nanoparticles on gold and ITO surfaces. For this purpose, we studied the adhesion of polydopamine-coated aggregates of TiO₂ nanoparticles on bare substrates and of aggregates of bare TiO₂ nanoparticles on polydopamine-coated substrates. Coating with polydopamine was accomplished by oxidation in air of alkaline aqueous dopamine solutions in which the nanoparticles or the substrates were immersed. Dynamic light scattering, Fourier transform infrared spectroscopy, and transmission electron microscopy were used for the chemical and morphological characterization of aggregates of the nanoparticles. The adhesion of aggregates of the nanoparticles on the substrates was evaluated by means of AFM and XPS. The results of this study suggest that the adhesion of TiO₂ P25 nanoparticles on polydopamine films, as well as of polydopamine-coated TiO₂ P25 nanoparticles, is a balance of several contributions: chemical interactions, electrostatic interactions, and coating roughness. Electrostatic attraction and repulsion between nanoparticles and the substrate appear to play an important role, as indicated by the ζ-potential values of nanoparticles and substrates. Full article

Mechanical reliability is an essential prerequisite for III-nitride thin films throughout device fabrication and processing. However, the availability of nanoindentation data for metastable cubic phases remains limited, making cross-study comparisons particularly challenging. In this context, the present work offers a unified compilation of hardness (H) and Young’s modulus (E) values derived from nanoindentation of cubic epilayers grown by plasma-assisted molecular beam epitaxy (MBE) on MgO(001)-based templates, encompassing c-GaN, c-In_x${Ga}_{1-x}$N alloys ($x = 0.26$–0.72), and c-InN. The three underlying studies utilize consistent metrological approaches: Berkovich indentation with Oliver–Pharr analysis, polished surfaces exhibiting low root-mean-square (RMS) roughness, and a shared MgO/c-GaN-templated stack. This methodological alignment enables a composition-aware comparison across the c-GaN/c-In_x${Ga}_{1-x}$N/c-InN series. Consolidated H and E values are examined as functions of the indium fraction, x, while their depth dependence is used to distinguish the film-dominated response from the increasing influence of the template or substrate. Additionally, a focused comparison with representative wurtzite data situates the cubic results within a broader context, while maintaining emphasis on MgO-based heteroepitaxy. Ultimately, the resulting dataset and analysis provide a practical resource for mechanically informed processing and reliability evaluation in cubic III-nitride systems. Full article

Magnetic molecular thin films provide a platform for nanoscale control of spin density, morphology and low-dimensional magnetism. We use co-deposition of closely isostructural iron phthalocyanine (FePc) and metal-free phthalocyanine (H₂Pc) onto heated substrates to prepare diluted thin films with systematically varied Fe spin densities. Structural and surface characterization shows that H₂Pc incorporation modifies film growth, producing a monotonic dependence of surface roughness on dilution and a grain size minimum for mixed FePc:H₂Pc films. Vibrating sample magnetometry reveals a nonlinear suppression of the magnetic response with increasing H₂Pc content, exceeding the reduction expected from FePc concentration alone. Below 5 K, the saturation magnetization is markedly reduced in diluted films compared with undiluted FePc, suggesting that molecular packing, Fe chain length and nanoscale morphology influence the magnetic coupling strength. These findings provide insight into FePc:H₂Pc co-deposition as a route to chemically tunable magnetic molecular nanomaterials and highlight the importance of structurally compatible molecular dilution for magnetic sensing applications. Full article

In this work, Cu₂CoSnS₄ (CCTS) thin films were deposited on glass substrates by thermal evaporation and investigated for photovoltaic applications. The influence of substrate temperature, varied from 25 °C to 200 °C, on the structural, morphological, and optical properties of the films was experimentally studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) measurements. XRD analysis confirmed the formation of crystalline CCTS with a stannite structure and a preferential orientation along the (112) plane. SEM observations revealed rough and non-uniform surfaces accompanied by an increase in grain size with increasing substrate temperature. Room-temperature PL measurements indicated a band-gap energy of approximately 1.3 eV, suitable for photovoltaic applications, and confirmed the presence of secondary phases in the p-type stannite CCTS films. Despite the promising photovoltaic properties of CCTS, numerical studies on CCTS-based solar cells remain scarce in the literature. In this context, a numerical study of the CCTS-based solar structure grown on glass was also performed using SCAPS-1D, showing good agreement with experimental photovoltaic results and validating the simulation model. Replacing the glass substrate with silicon improved the device efficiency to 5.77%. Further optimization of the series and shunt resistances significantly enhanced the photovoltaic performance, achieving a power conversion efficiency of 16.77%, with FF = 52.94%, V_oc = 0.89 V and J_sc = 35.19 mA/cm². Full article

Surface icing poses a significant risk to unmanned aerial vehicles (UAVs) and compact aerospace platforms, where limited onboard power and space require efficient anti-/de-icing surfaces. In this study, micro/nanostructures were fabricated on TC4 titanium alloy (Ti–6Al–4V) surfaces by femtosecond laser processing at different scanning speeds. The effects of scanning speed on surface morphology, wettability, static freezing, dynamic droplet behavior, and electrothermal de-icing performance were systematically investigated. Increasing the scanning speed induced nonlinear changes in microstructure height and surface roughness, while variations in ablation intensity caused nonuniform material redistribution. The surface processed at 250 mm/s showed the best anti-icing performance, with a water contact angle of 157.5 ± 0.5° and a maximum freezing delay 21.5 times longer than untreated TC4. During electrothermal de-icing, melting initiated at discrete ice–substrate contact points, forming coalesced meltwater films, while interfacial stress concentration promoted crack propagation and rapid ice detachment. Compared with untreated surfaces, ice detachment time (250 mm/s) achieved complete ice detachment at approximately 152 s, whereas ice on the untreated surface remained adhered after 270 s of continuous heating, representing a de-icing time reduction of at least 44%. These results demonstrate that combining laser-fabricated microstructures with electrothermal heating effectively reduces real ice–substrate contact, providing an enhanced anti-/de-icing strategy for lightweight, long-endurance UAV applications under identical electrical input. Full article

Complex surfaces exhibit hierarchical morphological organizations that cannot be fully described by conventional roughness parameters alone. In this study, a fractal–statistical framework is proposed to elucidate the substrate-controlled morphological evolution of 2,6-diphenyl anthracene (DPA) thin films deposited on chemically modified dielectric substrates, including hexamethyldisilazane (HMDS), octyltrimethoxysilane (OTMS), octadecyltrichlorosilane (OTS), and bare silicon dioxide (SiO₂). A multidimensional morphological descriptor vector (M_DPA) is introduced by integrating ISO 25178 areal surface parameters (H_ISO), fractal dimension (D_f), texture direction parameters (T_d), power spectral density (PSD), and scale-sensitive fractal analysis (SSFA) descriptors to quantify amplitude-based, spatial-frequency, and scale-dependent morphological information. Atomic force microscopy (AFM) topographies of 5 nm and 50 nm thick films were analyzed using complementary approaches, including ISO 25178 areal surface parameters, texture direction analysis, peak statistics, morphological envelope fractal analysis, two-dimensional Fourier analysis, power spectral density (PSD), and scale-sensitive fractal analysis (SSFA). The results demonstrate that substrate chemistry governs not only the amplitude of surface roughness but also the lateral organization, spatial frequency distribution, and scale-dependent fractal complexity of DPA morphologies. The fractal dimension analysis revealed substrate-dependent variations in surface complexity, with values ranging from 2.11 to 2.45 for 5 nm films and from 2.19 to 2.52 for 50 nm films. PSD analysis identified distinct substrate-induced modifications in spectral organization, while SSFA revealed significant changes in smooth–rough crossover scales, maximum complexity scales, and fractal surface complexity during film growth. In particular, OTMS promoted the strongest hierarchical organization for thicker films, exhibiting the highest scale-sensitive fractal complexity, whereas OTS generated highly developed but less hierarchically correlated rough structures. The integrated fractal–spectral methodology establishes quantitative relationships between substrate functionalization and multiscale surface evolution, demonstrating that morphological complexity cannot be described solely by conventional height parameters. This framework provides a robust approach for characterizing hierarchical thin-film architectures and can be extended to other organic semiconductor systems where substrate-driven morphological control is critical. Full article

Natural water-repellent surfaces use hierarchical texture and low surface energy to minimize liquid adhesion, and this principle has inspired engineered superhydrophobic surfaces for passive anti-icing. However, whether such bioinspired water-repellent architectures remain beneficial during freezing and ice detachment depends on the stability of the wetting state and on the interaction between surface texture and coating chemistry. This study evaluates the anti-icing performance of smooth and laser-textured 1050A aluminum surfaces functionalized with different hydrophobic agents. Freezing delay measurements at −18 °C and ice adhesion strength measurements at −20 °C were conducted, together with wettability, surface free energy, roughness, and morphology analyses, to compare different coatings on identical morphologies and to isolate the effect of laser-generated texture for the same coating chemistry. On smooth surfaces, fluorinated alkyl phosphonic acid coating provided the largest reduction in ice adhesion strength, decreasing it by approximately 72% relative to the non-functionalized reference, while alkyl phosphonic acid coating reduced it by approximately 50%. In contrast, polydimethylsiloxane showed the longest freezing delay, with a mean value of 907 s, whereas the fatty acid-based coatings exhibited shorter freezing delays than the bare reference surface. On laser-textured surfaces, all coatings initially produced highly water-repellent wetting states. However, the differences in ice adhesion strength were markedly reduced and no longer followed the same ranking as on smooth surfaces. Polydimethylsiloxane again exhibited the most favorable freezing delay, while fluorinated alkyl phosphonic acid showed the poorest performance on the textured substrate. These results show that the bioinspired superhydrophobic state created by laser texturing does not by itself guarantee improved anti-icing performance, as under icing conditions, texture-mediated wetting, local liquid penetration, condensation or frost formation inside the texture, and mechanical interlocking can dominate over the nominal low-surface-energy chemistry. Full article

This study investigates the tribological performance of three commercial PTFE-based Xylan^® coatings—Xylan^® 1425, Xylan^® 1052, and Xylan^® 1010—applied to 18CrNiMo7-6 steel under dry sliding conditions. Ball-on-Disk tests were conducted at normal loads of 5, 7.5, and 10 N, wear-track radii of 12, 16, and 20 mm, and corresponding sliding velocities of 0.31–0.52 m·s⁻¹. The tribological evaluation was complemented by measurements of coating thickness, surface roughness, nanoindentation, wear-track profilometry, scanning electron microscopy, EDS mapping, and post-test cross-sectional microscopy. All coatings reduced the coefficient of friction from approximately 0.49–0.64 for the uncoated steel to 0.09–0.13, corresponding to an average reduction of 78–80%. Xylan^® 1425 exhibited the highest nanohardness of 57.02 MPa, the highest reduced elastic modulus of 3.33 GPa, and the most favorable elastoplastic indices. It also achieved the lowest wear, with a volumetric loss of approximately 0.03 mm³ under the most severe conditions, representing a reduction of more than 99% compared with the substrate. Xylan^® 1010 provided the lowest friction but showed pronounced plastic deformation, whereas Xylan^® 1052 exhibited fragmentation and increased wear. Post-test cross-sectional microscopy confirmed local exposure of the steel substrate in both coatings. Overall, Xylan^® 1425 provided the best balance of low friction, mechanical stability, coating continuity, and wear resistance. Full article

In the field of flexible electronics, traditional composite copper foils generally suffer from weak interfacial adhesion between the copper layer and polymer substrate, poor corrosion resistance, insufficient surface uniformity, and limited functional adaptability. To address these issues, Cu/Cu-CeO₂ composite coatings were deposited on polyimide (PI) substrates via PVD magnetron sputtering using argon as the working gas, aiming to enhance the comprehensive properties of composite copper foils, including interfacial bonding strength and corrosion resistance. Initially, pure Cu coatings were deposited on polyimide (PI), polyethylene terephthalate (PET), and polypropylene (PP) substrates. The deposition parameters were optimized through orthogonal and single-factor experiments, and the optimal process combination was determined as follows: PI substrate, sputtering time of 20 min, sputtering power of 60 W, and argon flow rate of 90 sccm, which achieved a balance between mechanical and electrical properties. Subsequently, comparative studies of Ar plasma treatment (100 s, 200 s, 300 s, and 400 s) and NaOH chemical etching (0 mol/L, 1 mol/L, 2 mol/L, and 3 mol/L) were conducted on the three polymer substrates. Comprehensive analyses of water contact angle, surface energy, bonding strength, and surface roughness demonstrated that the PI substrate treated with Ar plasma for 300 s exhibited superior overall performance, with a water contact angle of 48.5°, surface energy of 61.78 × 10⁻³ J/m², bonding strength of 4.56 N, and surface roughness of 0.89 μm. On this basis, the performance of pure Cu coatings and Cu/Cu-CeO₂ composite coatings prepared under different CeO₂ sputtering powers (20 W, 30 W, 40 W, and 50 W) was further investigated. Combined analyses of SEM, EDS, and XPS characterizations, together with bonding strength, resistivity, electrochemical impedance spectroscopy, polarization curves, and corrosion morphology tests, revealed that the Cu/Cu-CeO₂ composite coating prepared at a sputtering power of 50 W exhibited superior overall performance in terms of interfacial bonding strength and corrosion resistance. Full article

This study focuses on how modulating the electrical pulse frequency alters both the topographic features and corrosion resistance of ceramic coatings produced via micro-arc oxidation (MAO) on an AZ31B magnesium substrate. In a silicate-based electrolyte, MAO treatments were executed utilizing four distinct frequencies: 300, 500, 800, and 1000 Hz. Phase configurations, microstructural features, and surface patterns were thoroughly evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM) integrated with energy dispersive spectroscopy (EDS), and an ultra-depth-of-field microscope. Furthermore, the fabricated coatings underwent rigorous assessments for their porosity, contact angle, Vickers hardness, and electrochemical attributes. The outcomes demonstrate that the surface appearance, phase structure, defect state, and density of the MAO coatings are highly sensitive to variations in pulse frequency. Notably, although the coating prepared at 800 Hz exhibited elevated surface roughness (Ra), it achieved a highly consolidated microstructure and the lowest porosity level, underscoring that roughness alone is not a definitive quality indicator. This structural refinement was driven by the presence of well-crystallized Mg₂SiO₄ and MgO phases. This group recorded a peak inner barrier layer resistance (R_b) of 1.62 × 10⁴ Ω·cm² alongside a minimum corrosion current density (I_corr) of 3.38 × 10⁻⁷ A·cm⁻², confirming its exceptional protective capacity. Consequently, the structural quality and corrosion resistance of MAO coatings can be strategically enhanced by tuning the electrical frequency, offering valuable engineering guidelines for utilizing AZ31B alloy parts under aggressive environmental conditions. Full article

To improve the corrosion resistance of Sn coatings on Cu substrates in chloride-containing environments, pure Sn and Sn–P coatings containing 0.02, 0.05, and 0.08 wt.% P were prepared by hot-dip coating. Their surface morphology, surface-film chemistry, and corrosion behavior were characterized using electrochemical measurements, atomic force microscopy (AFM), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS), and X-ray photoelectron spectroscopy (XPS). The results demonstrate that trace phosphorus addition enhances the electrochemical stability of Sn coatings prepared via the hot-dip method. The corrosion current density decreased from 1.55 × 10⁻⁶ A·cm⁻² for pure Sn to 3.28 × 10⁻⁷ A·cm⁻² for SnP0.02, corresponding to a reduction of approximately 79%. Meanwhile, the total resistance increased from 10.46 to 19.03 kΩ·cm², confirming the enhanced barrier effect of the surface film. AFM results showed that the surface roughness Ra decreased from 13.41 nm for pure Sn to 8.72–12.69 nm for the Sn–P coatings. XPS identified Sn–O, P–O, and Sn–P species, suggesting the formation of a Sn–O/P–O-containing protective film. SnP0.02 exhibited the best overall corrosion resistance, whereas excessive P promoted local P-rich regions and non-uniform film formation, limiting further improvement. Full article

Spherical/aspherical mirrors are widely used in satellite communication and imaging systems, but their reflectivity is affected by the surface roughness value. The vibration of the machine tool system is one of the most important factors affecting the surface roughness. This paper systematically suppresses vibration through different ways, reduces the peak and valley value of workpiece surface roughness, and improves the specular reflectivity (i.e., zero-order diffraction efficiency) of the machined surface. This paper establishes a reflectance model for machined surfaces considering surface aberration using rigorous coupled wave theory. Based on this model, the relationship between reflectivity and processed surface morphology was calculated. According to the influence of different vibration modes on surface morphology, the influence of different vibration morphology on reflectivity is studied. In order to reduce cutting vibration, a new adaptive interpolation point planning algorithm has been innovatively proposed for planning the position of each interpolation point on the meridian of the workpiece. The specular reflectivity of uncoated bare spherical/aspherical mirror surfaces processed by adaptive interpolation point planning algorithm can reach over 90%, providing a high-quality substrate for subsequent high-reflection optical coatings. Full article

316L stainless-steel capillary tubes are important in medical devices, precision fluid transport and micro heat exchangers, but their slender geometry and dense passivation film make inner-surface finishing inefficient. This study proposes a stepwise chemical-assisted magnetorheological finishing (CMRF) process for 316L capillaries. The inner surface was first pretreated with hydrogen peroxide/oxalic acid to form a removable reaction layer, and then finished by magnetorheological abrasives. The effects of the two reagents on material removal and surface integrity were evaluated, and the optimal pretreatment was determined to be 2.25 wt.% oxalic acid and 1.5 wt.% H₂O₂. Compared with conventional magnetorheological finishing, CMRF increased the material removal rate by approximately 54% and reduced the final inner-surface roughness Sa to 0.116 μm. Characterization results show that hydrogen peroxide and oxalic acid generate a dynamic oxidation–complexation–dissolution–reoxidation cycle, converting the dense passive film into an oxygen-rich, porous, low-crystallinity reaction layer and reducing surface hardness by about 30%. This softened layer promotes preferential abrasive removal instead of direct cutting of the metallic substrate, thereby improving finishing efficiency and surface quality. Full article