Search Results (140)

Development of forming methods for surface-coated metals is a current concern due to their economic and environmental advantages. For a successful forming operation, it is necessary that both components, the substrate and the coating, are able to withstand stress without damage until the final shape and dimensions are reached. This goal can be achieved through good knowledge of the elastic and plastic properties of the substrate and the coating, the compatibility between them, the appropriate surface treatment, and the rigorous control of technological forming parameters. Our study was carried out with flat specimens of pre-painted Al 99.0 sheet that were electromagnetically formed by bulging. Forming behavior was investigated as depending on the initial thickness of the substrate, on the aluminum sheet pretreatment, as well as on the plastic deformation path of the metal–paint structure. To verify the damage to the paint layer, tests with increasing strains were performed, and the interface between the metal and the coating layer was investigated by scanning electron microscopy. The obtained results indicate that electromagnetic forming of pre-painted sheets can be a feasible method for specific applications if the forming degree of the substrate is tightly correlated with the type of desired coating and with the pretreatment method used for the metal surface. Full article

The present investigation highlights the importance of evaluating the painting process on a composite material, namely the Kevlar validation process. Kevlar, a synthetic fabric, is well known for its remarkable strength and durability. Kevlar is used in the construction of spaceships and airplanes because it is lightweight and five times stronger than steel. This paper will present the methods for measuring paint layer thickness in accordance with EN ISO 2808:2019, confirming that organic coatings have fully cured, and coating thickness will be measured using magnetic currents. This study will also address the topic of determining liquid resistance. The protocols for manufacturing the Kevlar specimen are in accordance with ISO 2812-2:2018 using the water immersion method and structural testing. The investigation also demonstrates the progress of the framing test following immersion in Airbus PTP metal test tubes. Full article

To improve the laser cleaning surface quality of composite layers on Al alloy surfaces, a method of determining the optimal cleaning parameters is proposed that is based on the response surface methodology. It involves constructing a mathematical model of the input variables (laser power, scanning speed, repetition frequency, and defocusing amount). Laser cleaning experiments were conducted to analyze the effects of process parameters on paint removal performance. Using the response surface methodology (RSM), a relationship model was developed to link key factors, including paint layer removal thickness and surface roughness. The results indicate that the optimal process parameters are as follows: a laser power of 291 W, frequency of repetition of 166 kHz, scanning speed of 8425 mm/s, and defocusing amount of −17 mm. A verification test was performed to confirm the optimal parameters for the process. The error ranges for the thickness and roughness of the laser paint removal were within 1.9 μm~3.8 μm and −0.573 μm~−0.419 μm, respectively, indicating that the response surface method can be used to predict and optimize the quality of laser paint removal. These findings provide valuable insights into the laser treatment of composite paint layers on Al alloys and contribute to advances in surface treatment technology for Al alloys. Full article

The growing volume of plastic waste from end-of-life vehicles presents environmental concerns, driving efforts to integrate recycled plastics. This study investigates the possibility of using recycled plastic from automotive parts (painted and unpainted bumpers, fuel tanks) as a 10% filler in the core layer of three-layer particleboards (P) and evaluates its impact on physical properties (water absorption—WA and thickness swelling—TS), mechanical properties (internal bonding strength—IB, modulus of rupture—MOR, modulus of elasticity—MOE and screw driving torque—SDT) and volatile organic compounds—VOC emissions. The boards were produced using conventional hot-pressing technology and analyzed according to applicable standards. Based on the results, the density of the reference (P) was 0.72 g·cm⁻³, while wood–plastic composites ranged from 0.70 g·cm⁻³ to 0.72 g·cm⁻³. After 24 h, WA reached 40% for reference (P) and from 36.9% (for (P) containing unpainted bumpers) to 41.9% (for (P) containing fuel tanks). TS reached 18% for (P) and from 16.8% (for (P) containing unpainted bumpers and fuel tanks) to 18.1% (for (P) containing painted bumpers). Plastic is a hydrophobic material and it is assumed that by increasing the proportion of plastic filler in the particleboards, the WA and TS of prepared boards will decrease. From the point of view of mechanical properties, values for (P) containing plastic filler were slightly lower compared to reference (P). The lowest value of IB (0.39 MPa) were reached for (P) containing painted bumpers. Plastic surface treatment could interfere with adhesion between the plastic and adhesive, weakening the bond in the core layer. For this reason, is preferable to use unpainted fillers, which provide better adhesive properties and higher structural integrity. VOC emissions from wood components consisted primarily of monoterpenes such as α-pinene, 3-carene and limonene. Adding 10% plastic to the particleboard did not increase overall VOC emissions. On the other hand, combining wood and plastic particles resulted in a reduction in overall VOC emissions. The findings confirm that recycled automotive plastics can be effectively incorporated into particleboards, maintaining standard performance while reducing reliance on virgin wood materials, making them a viable and sustainable alternative for furniture and interior applications. Full article

The use of CFRP composite increased significantly since the last 40 years for aircraft structure. Unfortunately, such structures are subjected to significant damages if struck by lightning compared to metallic structure. This is mainly due to the low conductivity of this material, which cannot evacuate the current without high Joule heating. Lightning strike-induced damage in a composite laminate is composed of in-depth delamination, fibre breakage, and resin deterioration due to the surface explosion and the core current flow linked to interaction of the arc with the surface. But very rare previous studies dedicated to the analysis of damage as a direct effect of lightning have considered the spurious effect of the paint that always covers real aeronautic structures neither on the thermal nor the mechanical loads that are the root cause of these damages. We present in this paper a coupled non-destructive and destructive damage analysis to support the proposition of damage scenarios depending on the presence and thickness of the paint. The mechanical and thermal sources contribution in the global loading on the core damage is discussed, which confirms previous studies’ analysis and modelling and is in accordance with existing works in the literature. Full article

This paper presents numerical studies of the viscous droplet impact on dry and wetted solid walls for spray painting applications, focusing on air entrapment, film structure, and flake (flat pigment) orientation. The results were compared with experimental observations using various high-speed camera arrangements. For paint droplet impact on dry substrates, a dynamic contact angle model was developed and used in numerical simulations. This contact angle model was verified with experimental observations. For the droplet impact on wet surfaces, characteristic crater sizes (diameter and depth) were defined considering also the effect of the film thickness. A strong correlation with the droplet impact Reynolds number was observed. In addition, a user-defined 6DOF (6-degrees-of-freedom) solver was implemented in a CFD program to perform calculations of rigid body motions within the impacting droplet, technically relevant for the resulting effect of flakes in metallic effect paints. The developed models were applied in parameter studies to further clarify the existing dependencies on application and fluid parameters more quantitatively. The simulation results are helpful to understand and to improve painting processes with respect to the final quality parameters. Full article

The air spray gun model for painting robots is a mathematical model that describes the performance and behavior of the air spray gun in a spray-painting system and simulates the spraying process. Currently, film uniformity and spraying efficiency are key factors in evaluating the spray performance of this model. To further enhance the accuracy and controllability of spray gun modeling, this study used the elliptical double-beta spray pattern model to investigate the key parameters influencing its performance. Fan air pressure was selected as the optimization variable. A fixed-point spraying experimental platform was established where spraying experiments were conducted under six different pressures, and coating thickness data were collected. The optimal fitting function was obtained using data processing software. Experimental verification showed that the amplitude error was within 3 mm and the film thickness error was within 4 µm. The results indicate that fan air pressure can accurately predict film thickness, significantly improving paint utilization, with a high engineering application value. This provides new theoretical support for precise control in the spraying process and optimization of automated spraying systems. Full article

Money Art is a growing contemporary practice where artists transform banknotes into unique visual works. While conceptually powerful, these artworks present significant conservation challenges due to their fragile substrates and complex material compositions. This study investigates the degradation behaviour of UniPosca acrylic markers applied on zero-euro banknotes, drawing on the techniques of artist RichardHTT, and explores bio-based protective strategies suitable for their preservation. Laboratory samples were prepared to replicate the original artwork and subjected to accelerated ageing. A multi-analytical approach was employed, including multispectral imaging, Fourier trasform infrared (FTIR) and Raman spectroscopy, and scanning electron microscopy (SEM-EDS) colorimetric analysis. Thickness and adhesion properties were assessed with contact micrometry and peel tests, while wettability was evaluated through static contact angle measurements. Four biopolymer coatings, chitosan and chitosan–nanocellulose films with varying CNC concentrations, were evaluated for their transparency, mechanical stability, and compatibility with the substrate. Results showed that painted areas, especially those with blue and black pigments, experienced marked degradation, while, after coating application, samples demonstrated improved chromatic stability, hydrophobicity, and adhesion. Importantly, all coatings were fully removable via enzymatic cleaning with α-amylase, confirming their reversibility. This research highlights the potential of chitosan-based biocomposites as conservation materials for non-traditional artworks and contributes to developing tailored, reversible strategies for contemporary art preservation. Full article

This study focuses on the nameplate of Vila D. Bosco, a modern building in Macau from the time of Portuguese rule, and looks at the types of metal materials and surface coatings used, as well as how they corrode due to the tropical marine climate affecting the building’s metal parts. The study uses different techniques, such as X-ray fluorescence spectroscopy (XRF), scanning electron microscopy/energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), attenuated total internal reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and cross-sectional microscopic analysis, to carefully look at the metal, corrosion products, and coating of the nameplate. The results show that (1) the nameplate matrix is a resulfurized steel with a high sulfur content (Fe up to 97.3% and S up to 1.98%), and the sulfur element is evenly distributed inside, which is one of the internal factors that induce corrosion. (2) Rust is composed of polycrystalline iron oxides such as goethite (α-FeOOH), hematite (α-Fe₂O₃), and magnetite (Fe₃O₄) and has typical characteristics of atmospheric oxidation. (3) The white and yellow-green coatings on the nameplate are oil-modified alkyd resin paints, and the color pigments are TiO₂, PbCrO₄, etc. The surface layer of the letters is protected by a polyvinyl alcohol layer. The paint application process leads to differences in the thickness of the paint in different regions, which directly affects the anti-rust performance. The study reveals the deterioration mechanism of resulfurized steel components in a subtropical polluted environment and puts forward repair suggestions that consider both material compatibility and reversibility, providing a reference for the protection practice of modern and contemporary architectural metal heritage in Macau and even in similar geographical environments. Full article

The lack of an in-depth understanding of electrical conduction behaviour in anisotropic carbon fibre-reinforced laminates was reflected by the fact that there was no measurement standard. Various ad hoc experimental techniques were used, involving a range of extrinsic parameters with little or no rigorous control. Not only were widely varying values of electrical conductivity, if not incorrect values, generated, but also the effects of extrinsic parameters were attributed erroneously to those of intrinsic parameters. This predicament was compounded by different techniques used in measurements of volume and surface electrical conduction. This paper formulated the most effective experimental method, using two well-argued solid electrodes, to evaluate electrical conduction with rigorous control of all extrinsic parameters. Its main objectives were to investigate anisotropic volume and surface electrical conduction with a focus on the effects of electrode–specimen contact resistance, clamping pressure, conductive paint, contact face preparations, lay-ups, and specimen dimensions. Unique results and data trends provided the step-changing understanding of electrical conduction, such that the contributions of extrinsic factors were clearly established. The specifical findings showed that (1) the two-probe method was the only viable technique to measure both volume and surface conductivities, (2) all conductivity values were dependent on clamping torques and contact face machining, (3) the conductive paint enhancement effect was an artefact, and (4) obtaining surface conductivities by multiplying volume conductivities with laminate thickness was incorrect. Full article

Beautimeter is a new tool powered by generative pre-trained transformer (GPT) technology, designed to evaluate architectural and urban beauty. Rooted in Christopher Alexander’s theory of centers, this work builds on the idea that all environments possess, to varying degrees, an innate sense of life. Alexander identified 15 fundamental properties, such as levels of scale and thick boundaries, that characterize living structure, which Beautimeter uses as a basis for its analysis. By integrating GPT’s advanced natural language processing capabilities, Beautimeter assesses the extent to which a structure embodies these 15 properties, enabling a nuanced evaluation of architectural and urban aesthetics. Using ChatGPT4o, the tool helps users generate insights into the perceived beauty and coherence of spaces. We conducted a series of case studies, evaluating images of architectural and urban environments, as well as carpets, paintings, and other artifacts. The results demonstrate Beautimeter’s effectiveness in analyzing aesthetic qualities across diverse contexts. Our findings suggest that by leveraging GPT technology, Beautimeter offers architects, urban planners, and designers a powerful tool to create spaces that resonate deeply with people. This paper also explores the implications of such technology for architecture and urban design, highlighting its potential to enhance both the design process and the assessment of built environments. Full article

This research examines the inter-relationship between the deposition time, degreasing temperature, and applied voltage in the cataphoretic painting process, focusing on their cumulative effects on the thickness of the formed layers. A series of experiments was conducted, systematically varying deposition time effects through voltage levels (200 V to 300 V) and degreasing temperatures (40 °C to 80 °C). The results demonstrate that the maximum layer thickness is achieved at longer cataphoretic times, with significant thickness increments observed at optimal voltage levels. Conversely, the study reveals that lower degreasing temperatures lead to increased layer thickness, while elevated temperatures tend to diminish it. Notably, the thickness variations are consistent across different voltage applications, with a discernible threshold at which the layer thickness stabilizes. Additionally, energy-dispersive X-ray spectroscopy (EDX) was utilized to characterize the elemental composition of the cataphoretic layer, providing deeper insights into the coating structure and its relationship to process parameters. This work provides valuable insights into the optimization of cataphoretic processes, offering a framework for enhancing the quality and uniformity of coatings in industrial applications. The findings underscore the importance of the precise control over process parameters to achieve the desired material characteristics, thereby advancing the field of surface engineering and coating technologies. Full article

Spray-on fireproofing materials (SFRMs) and intumescent paints are commonly used to enhance the fire resistance of steel structures. Despite extensive studies on the performance of SFRMs and intumescent paints, there remains a significant lack of research on the material properties of certified products used in real-world applications, especially according to exposed temperatures. In this study, heating experiments were conducted to investigate the material properties of two widely used certified materials in Korea, focusing on their application thickness and exposure temperature. The experiments set target temperatures ranging from room temperature to 900 °C in increments of 100 °C. Additionally, various material properties, such as changes in shape and the insulation performance of the SFRM and intumescent paint, were observed at each temperature. Notably, the moisture content and discoloration depth of the SFRM displayed a consistent trend under different exposure temperatures, a material property that has not been previously reported. Furthermore, the insulation performance of the two materials differed by approximately 17% to 25% compared to an uncoated specimen exposed to the same temperature. The findings on the properties of SFRMs and intumescent paint relative to the exposure temperature presented in this study can serve as valuable data for selecting materials to improve fire resistance performance across various construction sites in the future. Additionally, they can act as key reference data in the diagnostic evaluation process for assessing the impact of fire on steel structures. Full article

This study presents a method for measuring the thickness and adhesion status of paint sensors using pulsed terahertz (THz) waves. Traditional measurement techniques, such as optical, X-ray, ultrasonic (UT), eddy current, and mechanical methods, are prone to accuracy issues and potential sample damage, particularly when evaluating adhesion. The pulsed THz wave approach enables the high-resolution, nondestructive evaluation of both thickness and adhesion status. The analysis of pulsed THz wave reflections from the interfaces of the paint sensor enables accurate measurements of thickness and the detection of adhesion issues. Validation against traditional thickness gauges and UT devices demonstrates the superior performance of the THz-wave-based method, particularly for identifying significant changes in thickness and adhesion defects. Furthermore, a full-field visualization technique is developed to map thickness variations across the entire sensor surface, offering detailed insights into the sensor conditions. The THz-wave-based method represents a significant advancement in nondestructive testing, providing a precise and comprehensive analysis of paint sensors while overcoming the limitations of conventional techniques. Full article

Multilayer samples are used in a wide range of sectors for their functionality. In the field of cultural heritage, multilayer samples are also common, as in the case of gilded or silvered alloys in the pigment layers in paintings. The X-ray ratios Lα/Lβ, Kα/Kβ, or K/L for an element or for different elements in a multilayer sample depend on the chemical composition and thickness of the superimposed layers and on the chemical composition and thickness of the layer in which the element is situated. Gold decorations of paintings on wood represent examples of multilayered structures and, for this reason, it is important to be able to determine the thickness of the gold layer. In the present paper, gold coatings of several paintings on gilded wood, by Italian artist Taddeo Gaddi (1300–1366 AD), were examined using portable energy-dispersive X-ray fluorescence (ED-XRF) in order to calculate the thickness of the gold layer on ochre by measuring the intensity ratio of the Au-L_α/Fe-K_α X-ray. The experimental results obtained showed that the gold leaves used by the artist have a thickness of approximately 0.3 to 0.4 µm; this also demonstrates the artist’s remarkable ability in creating the gilding. Full article