Search Results (1,007)

In this study, polysiloxane-containing polyimide (si-PI) composite coatings containing hexagonal boron nitride (hBN) particles of four different sizes and at different contents were prepared, and their mechanical and tribological properties were investigated. The coatings were deposited on steel substrates via dip coating and cured at 160 °C. Their tribological properties were measured using reciprocating sliding tests under unlubricated conditions against a steel ball. The composite coatings containing nano-hBN with the smallest mean primary particle size of 0.05 μm exhibited the lowest wear. Subsequently, coatings containing 1–15 wt% nano-hBN were prepared to examine the effect of filler content. The results showed that the coatings with low nano-hBN contents (1–2 wt%) had relatively high friction coefficients and significantly reduced wear on both the coating and the counterpart. Cross-sectional scanning electron microscopy (SEM) observations revealed that dispersed small hBN aggregates suppress crack propagation through dispersion strengthening. Coatings with low nano-hBN contents (1–2 wt%) also exhibited sufficient electrical insulation. However, as the hBN content increased further, hBN agglomeration was promoted, weakening the crack-propagation suppression effect and increasing wear. These findings indicate that low-content nano-hBN/si-PI composite coatings are promising electrical erosion-resistant coatings for the outer rings of the bearings used in electric vehicle motors. Full article

We report the fabrication and electrochemical characterization of TiO₂-based impedimetric sensors for the analysis of artificial sweat compositions. Two-electrode topologies were patterned on indium tin oxide (ITO) substrates: an interdigitated electrode (IDE) configuration and a Hilbert fractal electrode (HFE) geometry. TiO₂ thin films with thickness up to 350 nm were deposited by dip-coating and evaluated as photoactive sensing layers. The impedimetric response of the sensors was investigated by electrochemical impedance spectroscopy in artificial sweat with composition varied in terms of ionic content (0–100 mM Na⁺) and organic content (2.5–30 mM lactic acid and 5–50 mM urea). Regardless of TiO₂ thickness, the high-frequency response is predominantly governed by electrode topology, with the HFE design exhibiting up to 2.5-fold higher modulation compared to the IDE configuration. Under UV illumination, a low-frequency, photo-assisted response emerges, influenced by the TiO₂ layer thickness and primarily sensitive to the organic components of the solution, particularly lactic acid. These results suggest that frequency-resolved impedance measurements in TiO₂|ITO structures may enable partial differentiation between ionic conductivity and organic contributions in sweat, providing a promising basis for multi-parameter sweat analysis. Full article

This review provides a comprehensive overview of high-wear-resistant metal–ceramic surface engineering technologies based on Directed Energy Deposition (DED) for high-temperature industrial applications. In high-temperature processes such as continuous hot-dip coating, critical components (e.g., rollers and sleeves) are exposed to severe wear and chemical reactions, leading to rapid degradation and frequent replacement, which results in significant economic losses. This review focuses on the fundamental characteristics of DED processes and their advantages over conventional surface modification techniques such as HVOF, PVD/CVD, and arc-based methods. Particular attention is given to the process–structure–property relationships governing coating performance, including coating thickness, bonding characteristics, and high-temperature stability. Representative material systems, particularly WC-based metal–ceramic composites (e.g., Co–WC), are systematically discussed in terms of their wear resistance and applicability under severe operating conditions. Quantitative tribological performance metrics, including wear rate and friction coefficient, are also reviewed to provide a more rigorous understanding of coating performance. The analysis highlights that DED offers unique advantages in achieving thick coatings with strong metallurgical bonding and high applicability to repair and remanufacturing of large-scale components. In addition, recent advances in DED technologies, such as closed-loop control, self-regulating effects, and data-driven process optimization, are examined to highlight emerging trends in the field. The review also identifies current technical limitations and outlines future research directions, emphasizing the need for improved process control, defect mitigation, and integration of advanced monitoring techniques. Full article

Surgical site infections (SSIs) remain a major clinical challenge, particularly due to bacterial adhesion and biofilm formation on suture materials. In this study, we developed a dual drug-eluting suture incorporating chlorhexidine (CHX) and dexamethasone (DEX), with lauric acid used as a binding agent to enhance drug adhesion. The exact composition of the system was CHX/DEX/Lauric Acid, designed to enable localized delivery of both therapeutic agents at the implantation site. Vicryl sutures were dip-coated and characterized by means of FTIR-ATR and HPLC to confirm drug incorporation and release. Mechanical integrity was preserved, with no significant difference in tensile strength between coated and uncoated sutures. Antimicrobial activity was confirmed against Gram-positive and -negative bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), in addition to the yeast Candida albicans. Cell viability assays demonstrated acceptable biocompatibility, with values exceeding 70%. These findings support the potential of dual-functionalized sutures to reduce SSIs and modulate inflammation, offering a promising strategy for improving postoperative outcomes. Full article

Objective: This work aims to reduce the surface tension of an aluminum–silicon alloy melt by adding different amounts of the Zn element, thus improving the coatability and coating quality of hot-dip aluminum plating on steel plates. Method: Wetting experiments were conducted at 1023 K using a modified sessile drop method. Conclusions: The addition of the Zn element can reduce the surface tension of the Al-Si alloy, thus decreasing the wettability of the Al-Si alloy. Zn vapor can break down the surface oxide film to expose the fresh melt. The wettability of the Al-10Si alloy on interstitial-free (IF) steel and surface tension were investigated using the modified sessile drop method at 1023 K. Axisymmetric Drop Shape Analysis software was utilized to calculate the contact angles of the Al-10Si-xZn/Al₂O₃ and Al-10Si-xZn/IF steel systems (x ranges from 0 wt.% to 5 wt.%). Moreover, the microtopography and microstructure of surfaces and cross-sections were analyzed by means of an energy-dispersive spectrometer and scanning electron microscope. The results indicated that the surface tension of the alloy melt gradually decreases with an increase in Zn content, ranging from 874 to 760 mN/m. The contact angle of the Al-10Si-xZn alloy melt on IF steel also progressively decreases with increasing Zn content, which is attributed to the lower surface tension of Zn. This study also discovered that the Zn element can disrupt the oxide film of the Al-10Si alloy, exposing the fresh melt and thereby reducing the surface tension of the alloy liquid, thus enhancing wettability. The addition of Zn might be capable of improving the hot-dip aluminizing coatability of steel plates and the quality of the coating. Full article

Nd₂NiO_4+δ was investigated as a Ruddlesden–Popper (RP) cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs), with particular emphasis on its electrochemical performance and oxygen reduction reaction mechanism. The material was synthesized via a polymeric sol–gel route derived from Pechini’s method and evaluated in symmetric cells using Ce_0.9Gd_0.1O_2−δ (GDC) as the electrolyte. X-ray diffraction confirmed the formation of a single RP phase and good chemical compatibility with GDC after thermal treatments at 800 °C. Cathode layers with thicknesses of 8–12 µm were deposited by dip-coating. Electrical conductivity measurements revealed a thermally activated semiconducting behavior governed by Ni²⁺/Ni³⁺ small-polaron hopping, with an activation energy of ~1.08 eV. Electrochemical impedance spectroscopy showed a strong temperature dependence of the area-specific resistance, decreasing from 9.18 Ω·cm² at 600 °C to 0.39 Ω·cm² at 800 °C. Distribution of relaxation times (DRT) analysis enabled the identification of the dominant electrochemical processes, indicating that oxygen surface exchange reactions are more favorable than charge transfer at the cathode–electrolyte interface, which remains the main limiting step. These results demonstrate that Nd₂NiO_4+δ is a promising cathode for IT-SOFC operation, while further optimization of the electrode–electrolyte interface is required to enhance its oxygen reduction kinetics. Full article

Corrosion resistance of steel wires can be achieved through several approaches, one of the most established being hot-dip galvanizing. The effectiveness of anticorrosive protection of a galvanized wire is considered to depend not only on the galvanizing process itself, namely bath composition, temperature, and immersion duration—but also on the post-galvanizing wiping method, which ultimately determines the final thickness and uniformity of the zinc coating. This study describes and quantifies the resulting parameters of the Zn layer, systematically comparing two technical variants. Four parameters were analyzed to characterize the coating: the effective thickness of the constituent layers, their morphology (examined by SEM), their compositional profile (EDX mapping), and their microhardness. To comprehensively assess the influence of the wiping method on the anticorrosion performance of the galvanized wire, the final corrosion tests, fifth in the sequence, will be conducted in a salt fog environment using an Erichsen chamber, in accordance with standardized procedures. Full article

The use of additive manufacturing for rapid prototyping of near-infrared and terahertz components provides seamless and error-free production. This article discusses the additive manufacturing and post-processing of axicons and their performance evaluation using attenuation and near-field-measurements based fundamental techniques. The axicons are manufactured using the materials cyclic olefin copolymer (TOPAS) and polymethyl methacrylate (PMMA), for their respective use in terahertz and near-infrared applications. The optical and terahertz components manufactured using traditional 3D-printing processes, e.g., fused filament fabrication or stereolithography apparatus exhibit high surface roughness in the range of 15 ± 2.5 µm, resulting in undesired propagation and scattering in the near infrared wavelengths. This research work proposes an economical post-processing technique for additively manufactured terahertz and near-infrared axicons for applications in multispectral characterization, e.g., bio-sensing. The authors used an enhanced method of dip-coating, which involves interval dipping and intermittent hardening to achieve better surface finish. An emphasis is placed on interval dipping and intermittent hardening, which lead to excellent transparency in case of additively-manufactured near-infrared axicons. The dip-coated samples exhibit surface roughness below 10 nm. With the use of heated resin material as the coating layer, due to reduced viscosity, the resin material distributes uniformly over the surface of the 3D-printed terahertz and near-infrared axicons. The authors also observed that the DOF length deviation between unprocessed and enhanced dip-coated axicons remains within the measurement error estimation from analytical calculations. In addition to the improved surface finish and transparency, the coatings are also closely matched in refractive index to the axicon material. Such post-processed axicons pave the way for producing a wide array of systems in the fields of communication, imaging, and bio-sensing. Full article

Titanium dioxide (TiO₂) nanotube arrays (NTAs) were constructed on Ti foil to immobilize Cu₂ZnSnS₄-TiO₂ (CZTS-T/NTAs) via the sol–gel dip-coating technique. The films were characterized by X-ray diffraction (XRD) patterns, field-emission scanning electron microscope–energy dispersive spectroscopy (FESEM-EDX), ultraviolet–visible diffuse reflectance spectra (UV–Vis/DRS), and electrochemical impedance spectroscopy (EIS) techniques. The photocatalytic property of CZTS-T/NTAs was evaluated by the photodegradation of Basic Blue 41 under visible light irradiation. We show that CZTS-T/NTAs have an energy band gap of 2.23 eV, which leads to excellent potential trapping or facilitates the transition of charge carriers under visible light. The parameters R₀ and C₀ of the experimental EIS data, by fitting the proposed electrical circuit, were also discussed. Decreasing R₀ led to an increase in cell capacitance, which resulted in increased carrier generation at the interface between the catalyst and solution and thus an increased photodegradation yield. The response surface methodology (RSM) and central composite rotatable design (CCRD) were used to optimize the effects of the experimental parameters in the degradation process by four key variables (pH, dye concentration, irradiation time, and hydrogen peroxide (H₂O₂) concentration). As a result, the optimized conditions attained a considerable degradation of 95.25%. We also proposed the possible photodegradation mechanism of the photocatalyst. Notably, the proposed catalyst after six consecutive reuse runs retained activity. Full article

Metamaterials possess unique and desirable multiphysical behaviors derived from deliberately arranging conventional materials into designed structural topologies. Multifunctional mechanical metamaterials that can both carry load and provide in situ state awareness are increasingly needed for applications such as structural health monitoring and soft robotic systems. To address the demand for multifunctional metamaterials, this study reports a scalable fabrication strategy for self-sensing lattice metamaterials by conformally dip-coating 3D-printed flexible cells with a carbon nanotube (CNT)–styrene–ethylene–butylene–styrene (SEBS) nanocomposite. Scanning electron microscopy shows that the coating conforms closely to the printed struts with well-dispersed CNT networks. The electromechanical behavior of coated Octet, Kelvin, and auxetic unit cells was characterized under quasi-static cyclic uniaxial compression (0–40% strain). All the coated structures exhibited highly stable, reversible, and repeatable piezoresistive response, with a near-linear relationship between resistance change and strain. Among the tested geometries, the auxetic unit cell achieved the highest strain sensitivity that was approximately four times that of the Octet cell and six times that of the Kelvin cell. To evaluate scalability, auxetic lattices containing eight scaled auxetic unit cells were shown to retain high sensitivity and remained statistically similar to the unit cell. This study demonstrates that the strain sensing performance of nanocomposites can be engineered through lattice topology using a simple dip-coating functionalization approach, enabling scalable self-sensing metamaterials for large-scale and conformal sensing applications. Full article

This paper presents an evaluation of two new approaches to improve the surface quality and the mechanical properties of ceramic parts printed by fused deposition of ceramic (FDC). Dip-coating and aerosol-treatment are performed in order to reduce the staircase effect in the vertical printing direction, which typically represents the weakest orientation in most additive manufacturing processes, particularly in fused filament fabrication (FFF). The post-treatments are applied on two highly filled alumina feedstocks. A commercial aerosol-treatment machine for fused deposition modeling is used with ethanol as solvent. A suspension composition for dip-coating is developed to reduce the surface roughness without compromising the printing resolution. The influence of these post-processing steps on the mechanical properties and surface roughness of the green and sintered parts is investigated using perthometer measurements and four-point bending tests in the vertical build direction on as-processed, aerosol-treated, and dip-coated samples. The mechanical results are compared to extruded strand samples. An improvement in surface quality is achievable by dip-coating despite reduction in the parts strength, with a reduction of 65% of the R_z values in the sintered state compared to untreated samples. Aerosol-treatment neither improves the surface quality nor the mechanical properties of the parts. The feedstock and post-processing steps developed in this research aim at printing dense ceramic parts with high surface quality, serving as a basis for developing ceramic parts with higher strength. This advancement will facilitate the utilization of FDC in structural and aesthetic design applications. Full article

The rapid synthesis of high-performance silicalite-1 membranes was systematically investigated by examining the effects of seed size, solution volume, and reactor configuration on membrane growth, microstructure, and gas separation performance. Silicalite-1 seeds (~100 nm and ~1 µm) were dip-coated onto capillary α-alumina supports, followed by secondary growth under controlled conditions. Small seeds (~100 nm) produced high nucleation density, uniform intergrowth, and defect-free membranes, yielding consistently high ideal separation factor for H₂/SF₆ (181–295) and low SF₆ permeance (~10⁻⁹ mol m⁻² s⁻¹ Pa⁻¹) after only 45 min of synthesis. In contrast, larger seeds (~1 µm) enabled faster growth but resulted in less uniform layers with inferior selectivity. Furthermore, a novel reactor design with enhanced heat transfer enabled the rapid silicalite-1 membrane synthesis on conventional large-diameter tubular supports, producing well-intergrown and uniform membranes with high H₂ permeance (4.7 × 10⁻⁶ mol m⁻² s⁻¹ Pa⁻¹) and high ideal separation factors of up to 349 for H₂/SF₆ and 223 for N₂/SF₆. Overall, this study demonstrates that optimization of seed properties, synthesis parameters, and reactor design enables rapid and scalable fabrication of silicalite-1 membranes with robust molecular sieving performance, highlighting their strong potential for SF₆ purification applications. Full article

Kraft paper, commonly known as brown paper, has been widely used in the preservation of various food products and is increasingly explored in the development of active packaging materials with antimicrobial functionality by incorporating metal nanoparticles. This study aimed to comparatively investigate the surface modification of Kraft paper with silver nanoparticles (AgNPs) using dip-coating and drop-casting techniques. AgNPs were produced via green synthesis and incorporated onto the surface of Kraft paper samples. The modified samples were characterized using physicochemical techniques, including atomic force microscopy (AFM), Raman spectroscopy and light microscopy, as well as nanomechanical characterization via force spectroscopy. The antimicrobial activity of the modified papers was assessed using the disk diffusion method. The results demonstrated that the modification techniques resulted in distinct surface characteristics. Samples treated with the drop-casting method exhibited the highest AgNP surface loading; however, this was accompanied by pronounced surface heterogeneity and a tendency toward reduced load-bearing capacity. Overall, the findings indicate that the choice of deposition technique plays a key role in controlling nanoparticle distribution and surface properties. Within the limitations of the techniques evaluated, the incorporation of nanomaterials with potential antimicrobial activity into Kraft paper may offer opportunities for the development of active food packaging, although further optimization is required. Full article

Silicone-based implants have been widely used in breast reconstruction but have also been associated with poorly understood complications, including pathologic foreign body responses such as capsular contracture. In this study, we leveraged 3D-printing technology to generate silicone-based implants in a novel, anatomically relevant, prepectoral rat model. We used this model to evaluate the response to an extracellular matrix-based product: ovine-derived reinforced tissue matrix (RTM). Two-piece negative molds were developed through computer-aided design and 3D-printed. The molds were filled with various polydimethylsiloxane mixtures and dip-coated to fabricate implants. Implant material characterization revealed that the implants retained the original 3D-printed mold shape and qualitatively demonstrated a shell with an inner solid gel-like structure. Fabricated implants had smooth surfaces, as well as tunable features including implant stiffness (storage modulus). From initial studies in our rat model, placement of bilateral prepectoral implants allowed assessment of both muscle- and skin-facing capsules and were well-tolerated for at least 12 weeks. Comparison of the foreign body response between RTM-covered and uncovered (control) implants in this model revealed that the capsule thickness did not differ between groups at the 12-week endpoint. However, RTM reduced contractile fibroblasts (alpha-smooth muscle actin) and macrophages (Iba1) compared to the control. Our findings suggested that RTM may improve capsule quality by attenuating cells involved in fibrosis, even when total capsule thickness remains unchanged. However, these changes to cells involved in fibrosis were only observed at this early endpoint and may not predict long-term clinical outcomes. Full article

This study investigates the technological and chemical causes of early zinc-coating degradation on cold-formed steel sections produced from DX51D+Z140 galvanized coils. Commercially manufactured products exhibiting early corrosion symptoms were used in this study. The entire processing route, which included strip preparation, cold rolling, hot-dip galvanizing, passivation, multi-roll forming, storage, and transportation to customers, was analyzed with respect to the residual surface chemistry and process-related deviations that affect the coating integrity. Thirty-three specimens were examined using electromagnetic measurements of coating thickness. Statistical analysis based on the Cochran’s and Fisher’s criteria confirmed that the increased variability in zinc coating thickness is associated with a higher susceptibility to localized corrosion. Surface and chemical analysis revealed chloride contamination on the outer surface, absence of detectable Cr(VI) residues indicative of insufficient passivation, iron oxide inclusions beneath the zinc coating originating from the strip preparation, traces of organic emulsion residues impairing wetting and adhesion, and micro-defects related to deformation during roll forming. Early zinc coating degradation was shown to result from the cumulative action of multiple technological (surface damage during rolling, variation in the coating thickness) and environmental (moisture during storage and transportation) parameters. On the basis of the obtained results, a methodology was proposed to prevent steel product corrosion in industrial conditions. Full article