Search Results (114)

Alkyd resins are among the most common coatings used for exterior wood joinery. In Romania, solvent-borne alkyd coatings are widely used to finish wood. The study aims to compare the performance after 7 years of outdoor exposure of two types of alkyd coatings, a semi-transparent brown stain with micronized pigments (Alk1) and an opaque white enamel (Alk2), applied directly on wood or wood pre-treated with three types of resins: acryl-polyurethane (R1), epoxy (R2), and alkyd-polyurethane (R3). Fir (Abies alba) wood served as the substrate. Cracking, coating adhesion, and biological degradation were periodically assessed through visual inspection and microscopy. Additionally, a cross-cut test was performed, and the loss of coating on the directly exposed upper faces was measured using ImageJ. The results indicated that resin pretreatments somewhat reduced cracking but negatively affected coating adhesion after long-term exposure. All samples pretreated with resins and coated with Alk1 lost more than 50% (up to 78%) of the original finishing film by the end of the test. In comparison, coated control samples lost less than 50%. The Alk2 coating exhibited a film loss between 2% and 12%, compared to an average loss of 9% for the coated control. Overall, samples pretreated with alkyd-polyurethane resin (R3) and coated with alkyd enamel (Alk2) demonstrated the best performance in terms of cracking, adhesion, and discoloration. Full article

Fabric veneer panels were prepared using ethylene-vinyl acetate copolymer film (EVA) as the intermediate layer and poplar plywood as the substrate. Eight fabrics with different compositions were selected for evaluation to screen out fabric materials suitable for poplar plywood veneer. The fabrics were objectively analyzed by bending and draping, compression, and surface roughness, and subjectively evaluated by establishing seven levels of semantic differences. ESEM, surface adhesive properties, and peel resistance tests were used to characterize the microstructure and physical–mechanical properties of the composites. The results show that cotton and linen fabrics and corduroy fabrics are superior to other fabrics in performance, and they are suitable for decorative materials. Because the fibers of the doupioni silk fabric are too thin, and the fibers of felt fabric are randomly staggered, they are not suitable for the surface decoration materials of man-made panels. The acetate veneer surface gluing performance was 1.31 MPa, and the longitudinal peel resistance was 20.98 N, significantly exceeding that of other fabric veneers. Through the subjective and objective analysis of fabrics and gluing performance tests, it was concluded that, compared with fabrics made of natural fibers, man-made fiber fabrics are more suitable for use as surface finishing materials for wood-based panels. The results of this study provide a theoretical basis and process reference for the development of environmentally friendly decorative panels, which can be expanded and applied to furniture, interior decoration, and other fields. Full article

As a core structure within the Qing Changling Mausoleum, a UNESCO World Cultural Heritage site, Long’en Hall preserves a relatively complete set of Qing dynasty imperial lacquered furniture. These furnishings provide critical physical evidence for studying Qing dynasty sacrificial rituals and the craftsmanship of court lacquerware. However, limited research has been conducted on the surface finishing techniques of such furnishings, posing challenges to their conservation and accurate restoration. This study focuses on representative furnishings from Long’en Hall—including an offering table, an incense pavilion, a throne, and a poke lamp—and employed a multi-method analytical approach comprising fluorescence microscopy (FM), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared (FTIR) spectroscopy. The analysis was conducted on the following two levels: the lacquer layer structure and material composition. The results show that the furnishings in the Long’en Hall adopt the typical structure of “lacquer ash layer–color lacquer layer”, and the color lacquer layer is composed of raw lacquer, tung oil, animal glue, and other natural organic ingredients as film-forming materials, supplemented with inorganic mineral pigments such as red lead (Pb₃O₄) and Au metal, which constitutes a stable organic–inorganic composite structure with the lacquer ash layer. The multi-analysis results show a good complementary and cross-corroboration relationship, providing the necessary technical support and a theoretical reference for Qing dynasty palace lacquer wood furniture as cultural relics worthy of scientific protection and imitation. Full article

This research employed triethylenetetramine as a chelating agent to successfully synthesize a chelating-functional waterborne polyurethane (CWPU) dispersion by adjusting the ratio of hard and soft segments and optimizing the molecular structure through the use of a chain extender. This allowed for the establishment of a stable WPU/Ag composite emulsion system upon the addition of silver nitrate, and during the film formation process, the reducing properties of polyols were employed to in situ reduce Ag⁺, resulting in the formation of silver nanoparticles (AgNPs). Structural characterization analyses, including FTIR and XRD, verified that the reduced AgNPs were evenly distributed in the WPU matrix, and SEM observations revealed the presence of reduced AgNPs on the film. Further, contact angle and TG tests were performed to explore the impact of AgNPs on the hydrophilicity and thermal stability of the film. By applying WPU/Ag to cotton fabric through a padding finishing technique, the fabric retained a breathability of over 64.7% and mechanical properties exceeding 70.9%. Following 20 standardized washes, the antibacterial efficacy against Escherichia coli and Staphylococcus aureus remained above 99%. Even after undergoing 1200 abrasion tests, the antibacterial efficacy for both bacteria was sustained at over 93%, and the antibacterial rate continued to exceed 99% after a 6 h immersion in hot water. These findings suggest that the composite material possesses outstanding thermal stability, durability, and mechanical characteristics. This research offers a new methodology for the development of textiles that combine both usability and prolonged antibacterial efficacy. Full article

The study presented in this paper investigates the influence of coating polymers on the acoustic properties of resonant spruce wood. It evaluates absorption, acoustic reflection, and resonance frequency spectrum characteristics in both unvarnished and varnished samples, with the interface between the coating polymer and the wood modifying the acoustic response. The novelty of the research consists in evaluating the acoustic and dynamic parameters of resonant spruce wood boards, varnished with varnishes with different chemical properties (oil-based varnish, spirit varnish, nitrocellulose varnish). The study focuses on the influence of the type of varnish and the thickness of the varnish film on the frequency spectrum, damping coefficient, quality factor, acoustic absorption coefficient, and sound reflection. The sound absorption coefficient increases with the number of varnish layers and is influenced by the sound’s frequency range, the type of varnish, and the quality of the wood—factors that collectively enhance acoustic performance. For instance, oil-based varnish applied in 5 or 10 layers contributes to a fuller sound at a frequency of 1.5 kHz. In contrast, spirit varnish, which has a lower acoustic absorption coefficient at this frequency, and a reduced damping coefficient, can lead to a nasal tone, although the frequency spectrum turns out to have the richest. Applying more than 10 layers of varnish softens the sound when using oil-based varnish but sharpens it with spirit varnish on resonant wood. Thus, the acoustic performance of a soundboard can be tailored by selecting the appropriate varnishing system and number of layers applied. However, a detailed analysis of the timbre of musical instruments finished with these varnishes is necessary to confirm their influence on the acoustic quality of the instruments. Full article

In the casting and stamping process of automobile, ship, aerospace, and other fields, improving the atomization quality of the spray release agent can effectively solve the problems of difficult film removal, low efficiency, and poor surface finish, and greatly improve the efficiency of production and manufacturing. The geometric model of the external mixing nozzle was constructed, and the calculation domain and grid were divided. The atomization flow field velocity, liquid film thickness, particle distribution, and cooling amount were calculated using fluid simulation software. Finally, an experimental platform was set up for verification. With the increase in the distance between the iron plate and the nozzle, the velocity of the flow field decreases from the nozzle exit to the periphery, and the frequency distribution of D_60–70 increases gradually. With the increase in the pressure ratio (K), the particle velocity increases gradually, the liquid film thickness increases first, and then gently decreases, and the D_60–70 frequency distribution decreases. The influence of gas pressure on atomized particle velocity and liquid film thickness is greater than that of liquid phase pressure, and the ion velocity reaches the peak value when K = 2. When K = 1.5, the average thickness increment of absolute liquid film is small, the atomized particle diameter changes the least, the frequency distribution of D₆₅ particles is approximately the same, and the atomization effect is the most stable. When the spraying time is 1 s, the K value is larger, and the smaller the temperature drop will be. In 2–4 s, the change in K value has little influence on the cooling amount. Full article

Vehicle color coatings have long been recognized as a factor influencing road safety, particularly regarding their impact on speed perception and crash risk. This study aims to examine how different vehicle color coatings affect drivers’ perception of speed under nighttime driving conditions, with a specific focus on sustainability and visibility. A controlled laboratory experiment was conducted using a driving simulator to replicate realistic night traffic scenarios. A total of 161 participants evaluated passenger vehicles in four distinct color treatments, white (high-reflective paint), yellow (matte safety film), blue (glossy metallic finish), and black (low-reflective coating), at two speeds: 30 km/h and 50 km/h. Participants’ perceived speeds were collected and analyzed using standardized statistical methods. Results indicated a consistent pattern: speed was overestimated at 30 km/h and underestimated at 50 km/h across all vehicle colors. Lighter-colored vehicles (white and yellow) were perceived as moving faster than darker-colored vehicles (blue and black), with significant differences between black and yellow (30 km/h), yellow and blue (30 km/h), and black and white (50 km/h). Additionally, female participants tended to estimate higher speeds than male participants across most conditions. Other individual factors, such as place of residence, driver’s license type, driving experience, and frequency of driving, also showed measurable effects on speed perception. By using a simulator and accounting for diverse demographic characteristics, the study highlights how perceptual biases related to vehicle color can influence driver behavior. These findings emphasize the importance of considering vehicle color in traffic safety strategies, including driver education, vehicle design, and policy development aimed at reducing crash risk. Full article

Potassium dihydrogen phosphate (KDP) crystals, vital for high-power laser systems, pose significant machining challenges due to their brittleness, low hardness, and hygroscopic properties. Achieving crack-free, high-precision surfaces is essential but complex. Single-point diamond fly-cutting (SPDF) is the primary method, yet it exposes tools to high mechanical stress and heat, accelerating wear. In dry cutting, worn tools develop adhesive layers that detach, causing scratches and degrading surface quality. Traditional wet cutting improves surface finish but leaves residual fluids that contaminate the surface with metal ions, leading to optical degradation and fogging. To address these issues, this study explores mixed-fat-based minimum quantity lubrication (MQL) as a sustainable alternative, comparing two lubricants: biodegradable-base mixed ester lubrication (BBMEL) and hydrocarbon-based synthetic lubricant (HCBSL). A comprehensive evaluation method was developed to analyze surface roughness, tool wear, and subsurface damage under dry cutting, MQL-BBMEL, and MQL-HCBSL conditions. Experimental results show that MQL-BBMEL significantly enhances machining performance, reducing average surface roughness by 27.77% (Sa) and 44.77% (Sq) and decreasing tool wear by 25.16% compared to dry cutting, outperforming MQL-HCBSL. This improvement is attributed to BBMEL’s lower viscosity and higher proportion of polar functional groups, which form stable lubricating films, minimizing friction and thermal effects. Structural analyses confirm that MQL-BBMEL prevents KDP crystal deliquescence and surface fogging. These findings establish MQL-BBMEL as an eco-friendly, high-performance solution for machining brittle optical materials, offering significant advancements in precision machining for high-power laser systems. Full article

Infrared deflectometry is an efficient and accurate measuring method for curved surfaces fabricated via grinding or finish milling. The emitting properties and geometrical configurations of the infrared light source is a core component governing the measurement performance. In this paper, an infrared slit light source is designed based on the cavity structure of a polyimide heating film. This design ensures good stability and uniformity of the light source whilst effectively reducing background noise. Additionally, the light source can be applied as a calibration board for calibrating infrared cameras. The light source is aligned using a theodolite and cubic prism to control the positional deviations during scanning. Experimental results demonstrate that the proposed slit light source and calibration method can achieve a measurement accuracy of 1 µm RMS, which can meet the needs of rapid measurement in grinding. This approach provides a reliable, cost-effective, and efficient tool for surface quality assessments in optical workshops and has a broad application potential. Full article

The study introduces new technologies of microfinishing, which are primarily aimed at cylindrical surfaces but with machining effectiveness, precision, and surface longevity. In the newly proposed dual-zone microfinishing method, symmetrical abrasive film feeding systems are adapted with a lever mechanism and a pivoting pressing assembly to simultaneously conduct processing in two zones. With such a design, uniform force distribution is ensured, while mechanical deformation is reduced to raise the utility of the abrasive film and lower scraps for better economic performance. Also, the application of microfinishing operations combined with carbon layer deposition using graphite-impregnated abrasive films is introduced as a novel method. This process combines surface refinement and the forming of wear-resistant carbon coatings into one single operation, resulting in increased wear resistance and reduced forces of friction. Further stabilization of the conditions for microfinishing is achieved by immersing the processing zone in a fluid medium due to increased lubrication, improvement in heat dissipation, and the optimization of surface properties. It is particularly suitable for high-precision applications and a maintenance-free environment such as military, vacuum, and low-temperature systems. The experimental results show the effectiveness of the proposed methodologies, underscoring their ability to create remarkably smooth surfaces and very robust carbon textures simultaneously. Full article

This research explored the formation and effects of carbon layers on Grade 5 titanium alloy (Ti–6Al–4V) surfaces during a microfinishing process using both traditional abrasive films and graphite-coated abrasive films. The study tried to appraise the effect of using graphite-coated films in the microfinishing process concerning surface roughness. Microfinishing with an abrasive film impregnated with diamond particles and an additional coating of graphite was performed to minimize surface roughness and enhance the overall performance of the surface. As a result, it was shown that after processing, the uniform carbon texture formed by the graphite-coated film significantly improved the lubricating and thermal properties. Energy dispersive spectroscopy (EDS) analysis confirmed the homogeneity of carbon distribution over the whole treated surface. Moreover, the graphite-coated films enabled us to obtain smoother surfaces with improved tribological properties. The study therefore concluded that the inclusion of graphite in the abrasive films is necessary for effecting surface modification in light of considerable improvements in surface quality and performance, especially where the wear needs to be reduced and the integrity of the surface maximized. Full article

The surfaces of beech wood samples were treated with polyethylenimine (PEI) solutions at three different concentrations—0.5%, 1% and 2%—and two molecular weights—low molecular weight (LMW) and high molecular weight (HMW). The effects of PEI surface treatment of wood were characterized by FT-IR spectroscopy, the penetration depth of PEI (EPI fluorescence spectroscopy), the bonding position of PEI (by SEM), the wetting and surface energy, and the water uptake. After PEI treatment, the samples were coated with a water-based transparent acrylic coating (WTAC). The dry film thickness, the penetration depth of the coating, the adhesion strength and the surface roughness of the coated wood surface were evaluated. EPI fluorescence and SEM micrographs showed that PEI HMW chains were deposited on the surface, in contrast to PEI LMW, which penetrates deeper into layers of the wood cells. Treatment with a 1% PEI HMW solution resulted in a 72% reduction in water uptake of the wood (compared to untreated samples after 5 min of applying water droplets to the surface) and a 23.2% reduction in surface energy (compared to untreated samples) while maintaining the adhesion strength of the applied WTAC. The lower water uptake of the treated wood samples reduced the roughness of the coated surface, which is particularly important when the wood surface is finished with water-based coatings. Full article

This work investigates the contact between abrasive particles and workpieces in microfinishing processes with special consideration given to the determination of unit force, unit pressure, and grain, the forces exerted by individual abrasive grains. A detailed methodology was established for measuring the contact area, penetration depth, and circumferences of grain imprints at depths corresponding to multiples of the total height of the abrasive film, represented by the parameter Sz. The following depths were analyzed: 0.05 Sz, 0.15 Sz, 0.25 Sz, and 0.35 Sz. Results show that the areas closer to the central microfinishing zone bear the highest unit pressures and forces and, thus, contribute dominantly to material removal. It was further found that near the edges of the contact zone, the pressure and force have been reduced to lower material removal efficiency. The non-uniform geometry of abrasive particles was found to significantly affect contact mechanics, more at shallow depths of penetration, whereas the shape of the apex defines the nature of the interaction. A parabolic force and pressure distribution were evident for the irregular load distribution of the microfinishing area. The result brings out the need for further refinement in the design of the abrasive film and pressure distribution in order to achieve improvement in uniformity and efficiency during microfinishing. It would bring out valuable insights on how to improve the effectiveness of an abrasive film and ways of optimizing the process conditions. The results provide a founding stone for further advancement of knowledge in the grain–workpiece interaction, enabling better surface quality and more reliable microfinishing processes. Full article

The paper presents the results of experimental and numerical tests on barrel vaults with backfill material. The thickness, internal span, and rise of the vaults were 125 mm, 2000 mm, and 730 mm, respectively. In experimental studies, vaults with backfill of expanded clay aggregate or granite aggregate were tested. Moreover, three types of extrados finishing were considered in the experiments: masonry with flush joints, PVC film, and steel angles attached to the bricks. The numerical simulations increased the number of cases analyzed by conducting a parametric analysis for four additional backfill materials with varying bulk density or internal friction angle, as well as modifying the friction coefficient at the backfill-vault interface for each of the analyzed materials. The main goal of the analyses was to investigate the impact of the bulk density, the internal friction angle of the backfill material, and the friction coefficient between the backfill and the vault on the load-bearing capacity of the buried vault. Both the laboratory tests and numerical simulations indicate a significant impact of the internal friction angle, bulk density of the backfill materials, and the finishing method of the extrados of the vault on the load-bearing capacity of buried vaults. Full article

Austenitic stainless steels are used widely in many fields due to their good mechanical properties and high resistance to corrosion. This work focuses on the reconstruction of the passive film after scratching. The purpose of the study was to compare changes in the rate of passive layer reconstruction and to discuss the effect of both the type of material and its electrochemical treatment on the reconstruction of the passive layer for two types of stainless steel: 304 and 316. The XPS tests performed indicate a significantly higher Cr/Fe ratio for the samples after the electropolishing process of 1.41–1.88 compared to the as-received samples of 0.82–0.86. After 2–3 min of sputtering the surface with Ar+ ions, a decrease in chromium content can be observed, with a simultaneous increase in nickel content, visible especially for the electropolished samples. A new approach in the conducted research was to scratch the test samples under controlled conditions, then evaluate the dynamics of the passive layer reconstruction using the AFM method, and then confront the obtained results with XPS measurements for the corresponding samples. For the as-received samples (2B finish) and those after surface treatment, regardless of the level of contamination of the electropolishing process bath, the reconstruction time was similar, which was approximately 2 h, although certain differences in the process dynamics were noticeable. Full article