Search Results (991)

The aim of this study was to investigate the effects of surface treatments and thermocycling on the shear bond strength of a 3D-printed permanent crown resin. A total of 120 disc-shaped specimens (10 × 3 mm) were fabricated using a 3D printer and randomly assigned to four groups according to surface repair protocols: airborne-particle abrasion with Al₂O₃, bur roughening, 37% orthophosphoric acid etching, and a control group with no surface treatment. All specimens received a silane coupling agent followed by an adhesive resin application, and repair was performed using a highly filled flowable composite. Each group was divided into three subgroups and subjected to 1000, 5000, or 15,000 thermal cycles. Shear bond strength was measured, failure modes were analyzed, and data were evaluated using two-way ANOVA and Tukey’s post hoc test (p < 0.05). The sandblasting group exhibited the highest bond strength (18.7 ± 5.0 MPa), which was significantly higher than the control (12.6 ± 3.7 MPa) and acid-etching (14.2 ± 3.8 MPa) groups (p < 0.05). Aging periods had no significant effect on bond strength (p > 0.05). Additionally, the interaction between surface treatment and thermocycling had no significant effect (p = 0.823). Under the tested conditions, airborne-particle abrasion resulted in the highest shear bond strength of 3D-printed permanent crown resin. Full article

As the primary carrier for oil and gas transportation, pipelines are critical for the entire industry. Pipelines are continuously subjected to corrosion and abrasion in the oil and gas delivery process, leading to gradual wall thickness reduction, shortened service life, and deteriorated operational safety. Ultrasonic testing has been widely adopted for monitoring pipeline wall thickness. Conventional ultrasonic transducers possess rigid configurations, which hinder large-area inspection and exhibit poor adaptability to complex curved components. In contrast, flexible ultrasonic sensors show prominent advantages, with their small size, light weight, and excellent conformal contact with curved surfaces. Flexible piezoelectric thin-film sensors have been used in a wide range of fields. As one of the most representative piezoelectric polymers, poly(vinylidene fluoride–trifluoroethylene) (P(VDF-TrFE)) combines favorable piezoelectric coefficients and intrinsic flexibility, making it popular. Some research groups have investigated the influences of modified filler particles, doping ratios, and fabrication process optimization on the performance of P(VDF-TrFE)-based piezoelectric composites, while others have concentrated on the practical applications of existing flexible piezoelectric sensors. This study emphasizes a rapid customized fabrication strategy for flexible sensors instead of single-specification standardized probes; hence, it does not share the same comparison benchmark as conventional fixed-dimension sensors. Systematic research on flexible piezoelectric thin-film sensors is presented, including piezoelectric material modification, substrate design, laminated structural design, fabrication workflows, establishment of the testing platform, and the development of matched circuit systems. The material preparation and manufacturing processes are optimized, and a scalable technical route for fabricating flexible piezoelectric sensors is proposed. Using this route, flexible piezoelectric thin-film sensors can be rapidly tailored for different application scenarios to satisfy diverse engineering demands. Multiple experiments were conducted on pipeline samples with varying wall thicknesses and curvatures. The results verify that the sensor reaches a measurement precision of 0.01 mm, meeting the demands of high-precision pipeline structural health monitoring. Full article

Efficient abrasive blasting requires precise control of abrasive mass flow, which is governed by both the metering system design and the flow properties of the abrasive material. This study investigates the influence of particle size distribution on the flow behaviour of brown fused alumina during discharge through a commercially available Thomson TV II metering valve. Four abrasive fractions (F220, F80, F46 and F24) were characterized in terms of particle size distribution, bulk density, moisture content, angle of internal friction, and flow function. The discharge behaviour was experimentally evaluated using a custom-built test stand for four valve opening positions. The results showed that the smallest valve opening caused unstable flow conditions, arching, and complete flow blockage for the coarsest fraction, whereas stable and repeatable discharge was achieved for various valve openings. Although the finest fraction exhibited the highest flowability according to the flow function, it did not achieve the highest mass flow rate, indicating that flowability alone was insufficient to explain the observed discharge performance. Instead, the F80 fraction provided the highest discharge performance under all stable operating conditions. These findings indicate that laboratory flowability indices alone cannot reliably predict abrasive feeding performance and should be evaluated together with bulk density and particle size distribution. The results provide practical guidelines for optimizing abrasive metering systems and contribute to improved process stability, abrasive utilization, and operational efficiency in automated abrasive blasting applications. Full article

The surface of nodular cast iron is susceptible to wear failure under high-load conditions. In this study, Fe-Cr-Ni wear-resistant coatings were developed on the surface of nodular cast iron using laser cladding technology. The influence of laser power (P), powder feeding rate (F), scanning speed (V), and overlapping rate (φ) on the microhardness and dilution rate of the coatings was analyzed by response surface methodology, while the model’s accuracy was evaluated through analysis of variance. Subsequently, the multi-objective particle swarm optimization algorithm was utilized to identify the optimal process parameters (P = 1350 W, V = 12.5 mm/s, F = 9 g/min, and φ = 45%) based on non-destructive testing results. The predictive model values closely matched the experimental results. The average microhardness of the Fe-Cr-Ni cladding layer was 620.3 HV, which was 2.8 times that of the nodular cast iron substrate. Importantly, the laser cladding layer demonstrated a significant improvement in wear resistance compared to the substrate. The wear mechanisms for the coating predominantly involved mild abrasive wear and adhesive wear, while the substrate primarily experienced severe adhesive wear. This study offers valuable insights for optimizing laser cladding process parameters for nodular cast iron. Full article

Coatings based on polyvinylidene fluoride (PVDF) and poly(dimethylsiloxane) (PDMS)-based polymeric microspheres can be easily fabricated via non-solvent-induced phase separation (NIPS) and electrostatic spraying (ES) techniques. Both techniques are promising strategies for constructing superhydrophobic surfaces on various substrates. However, PVDF and PDMS inherently suffer from severe aggregation, which generates oversized particles and inhomogeneous microstructures. Conventionally, costly and environmentally hazardous dispersants are required to alleviate this issue, severely restricting the industrial scalability and practical application of such coatings. In this work, methyltrimethoxysilane-modified cellulose nanocrystals (Si-CNCs) were introduced as a green multifunctional modifier to tackle these issues. The results revealed that as structural building blocks and dispersants, Si-CNCs inhibited polymer aggregation via electrostatic repulsion and steric hindrance, refined the particle size and formed uniform micro/nano hierarchical structures. Increasing Si-CNC loading further improved polymer dispersion and superhydrophobic performance. Coatings fabricated by ES showed better hydrophobicity than those fabricated by NIPS. ES achieved a water contact angle (WCA) of 160–166° and a sliding angle (SA) near 1° on cotton fabric, while NIPS had a WCA of 153.8–158° and an SA of around 2°. Wood and glass substrates also obtained favorable superhydrophobicity, with WCAs above 150° and SAs below 1°. Furthermore, all modified surfaces exhibited excellent abrasion resistance. This work provides a relatively eco-friendly, environmentally sustainable, scalable and substrate-flexible strategy for fabricating high-performance PVDF/PDMS-based superhydrophobic coatings. Full article

Aluminum matrix composites (AMCs) reinforced with natural mineral ilmenite offer a cost-effective and thermally stable alternative to conventional cast iron brake drum materials. This study investigates the synergistic effect of fine (32–50 µm) and coarse (75–106 µm) ilmenite particles at four fine-to-coarse weight ratios (1:4, 2:3, 3:2, and 4:1) and three reinforcement contents (5, 10, and 15 wt.%) on the thermal stability and dry sliding wear behavior of stir-cast LM30 Al composites. Ilmenite reinforcement progressively reduces the coefficient of thermal expansion of the LM30 matrix, with the 15 wt.% 4:1 fine-to-coarse ratio composite (15DRP41) exhibiting the lowest coefficient of thermal expansion of ~16.54 × 10⁻⁶/°C, a ~33.3% reduction relative to the unreinforced alloy (~24.8 × 10⁻⁶/°C). The 15DRP41 composite demonstrates the lowest wear rate of all the fabricated composites, 1.82 × 10⁻³ mm³/m at 9.81 N and 9.56 × 10⁻³ mm³/m at 68.67 N at 200 °C. Under the most severe load condition (68.67 N, 200 °C), the coefficient of friction of 15DRP41 is reduced by up to 44% compared with the LM30 alloy. A comparative test against commercial grey cast iron shows that 15DRP41 has a similar wear rate up to 200 °C, while its density (~2.9 g/cm³) is significantly lower and it has excellent dimensional stability. Scanning electron microscopy and energy-dispersive X-ray spectroscopy of worn surfaces and debris confirm a progressive change from oxidative and mild abrasive wear at low loads and temperatures to severe wear by delamination at 68.67 N and 300 °C, as evidenced by the presence of a multi-component mechanically mixed layer. The results have confirmed that the optimum fine-to-coarse ratio for the reinforcement was 4:1, which led to the maximum wear resistance and thermal stability in ilmenite-reinforced LM30 composites for lightweight automotive brake drum applications, and that the optimum weight percentage for the reinforcement was 15 wt.%. Full article

Cantilever roadheaders are widely used in medium-soft rock tunneling. However, conventional pick cutters suffer from high rock-breaking load, excessive energy consumption, and severe abrasion, which restrict the performance of roadheader vehicle-end intelligent control systems. Existing ultrasonic rock-breaking studies mainly focus on drilling and polycrystalline diamond compact (PDC) cutters, while calibrated EDEM simulation and experimental studies of synchronous ultrasonic-vibration-assisted pick cutter cutting remain limited. This study investigates the rock-breaking behavior of synchronous ultrasonic vibration coupled with pick cutter cutting using 21 MPa artificial rock-like specimens. A calibrated EDEM simulation model was developed based on the Hertz–Mindlin with Bonding contact model and validated by uniaxial compression and Brazilian splitting tests. Meta-particle technology was applied to analyze fragmentation characteristics. The effects of ultrasonic frequency, cutting angle, and cone angle on rock-breaking load, debris production, and specific energy consumption were investigated through simulations and experiments. An ultrasonic-assisted cutting test system equipped with force sensors was established for validation. Results show that 30 kHz ultrasonic vibration effectively reduces rock-breaking load under the investigated operating conditions. A relatively favorable parameter combination obtained from the numerical simulations consists of an ultrasonic frequency of 30 kHz, a cutting angle of 40°, and a cone angle of 60°. Compared with conventional cutting, the optimized scheme reduces average cutting load by 74.69%, increases debris yield by 54.71%, and decreases mass-specific mechanical cutting energy consumption by 83.63%. This study provides quantitative data support for roadheader vehicle-end intelligent control systems. Full article

Background and Clinical Significance: Peri-implantitis is an inflammatory condition associated, among other factors, with biofilm accumulation, affecting peri-implant soft and hard tissues and potentially leading to implant loss. Its treatment remains challenging because no single decontamination or regenerative protocol has demonstrated clear superiority. This case report describes a comprehensive surgical and regenerative approach aimed at preserving an affected implant and restoring peri-implant tissue stability; Case Presentation: A systemically healthy 30-year-old patient presented with peri-implant bone loss around an implant in position 25, restored with a lithium disilicate crown and functioning for three years. Treatment included flap elevation, mechanical debridement and air-polishing of the implant surface, followed by thorough irrigation with sterile saline to remove residual abrasive particles and debris, photodynamic antimicrobial therapy, and laser therapy. Bone regeneration was performed using a bone substitute combined with injectable platelet-rich fibrin to produce sticky bone, which was covered with an advanced platelet-rich fibrin membrane. A provisional crown was placed without occlusal contact. After four months, a definitive crown with a modified emergence profile was delivered to improve hygienic access and reduce biofilm retention. Clinical and radiographic follow-up over five years demonstrated stable peri-implant tissues and maintained bone levels; Conclusions: The combined use of surgical decontamination, PRF-assisted regeneration, sticky bone, and prosthetic modification resulted in stable clinical and radiographic outcomes over five years. Identification and elimination of contributing factors were essential for long-term treatment success. Full article

Bamboo is a renewable and mechanically robust bio-based material with potential for sand-barrier construction; however, its long-term outdoor use is limited by ultraviolet-induced photoaging, moisture uptake, wind-sand abrasion, and biological colonization. In this study, a fluorine-free EP/TiO₂/ODTMS superhydrophobic coating was deposited on moso bamboo using a simple spraying process. Rutile TiO₂ was incorporated as a roughness-building and ultraviolet-shielding filler, waterborne epoxy resin served as a film-forming binder to improve particle anchoring and coating cohesion, and octadecyltrimethoxysilane was used to reduce the surface energy. The formulation containing 50–100 nm rutile TiO₂ and 2 wt.% epoxy resin provided the best overall balance between surface wettability and mechanical durability, with a water contact angle of 156.4° and a sliding angle of 6.9°. SEM observations revealed a hierarchical surface composed of TiO₂ particles and microscale agglomerates immobilized within the epoxy matrix. EDS and FTIR results supported the incorporation of TiO₂- and ODTMS-derived components, while UV–Vis–NIR diffuse-reflectance measurements showed an improved optical response in the ultraviolet region. The coating retained superhydrophobicity after sandpaper abrasion, gravel impact, and tape-peeling tests. After 672 h of xenon-lamp aging, the coated bamboo maintained a water contact angle above 150°, exhibited a total color difference of approximately 7.65, and retained 91.1% of its initial flexural strength. In addition, qualitatively reduced visible mildew colonization was observed during 45 days of high-humidity exposure. These results demonstrate that the spray-deposited coating provides a fluorine-free and potentially scalable approach for improving the water repellency, mechanical durability, and accelerated-weathering resistance of bamboo sand-barrier materials. Full article

Background/Objectives: To compare the effects of different surface treatments on the color and translucency of three types of zirconia ceramics. Methods: Ninety CAD/CAM-milled zirconia disks (10 mm diameter, 1 mm thickness) were fabricated from Cercon HT (3-YTZP), IPS e.max ZirCAD MT (4-YTZP), and Cercon XT (5-YTZP). Baseline CIE Lab* coordinates were measured using a digital spectrophotometer. The disks underwent one of three surface treatments: 50 µm alumina air-particle abrasion (AAA), Zircos-E etching (ZE), or 100 µm glass bead air-particle abrasion (GBA). Post-treatment CIE Lab* measurements were obtained, and color change (ΔE₀₀, CIEDE2000) and translucency change (ΔTP₀₀) were calculated. Results: Regarding color change (ΔE₀₀), 50 µm AAA produced the greatest change, followed by ZE, while GBA caused the smallest change. Surface treatment and its interaction with material type were found to exert a significant effect, whereas material type alone was not significant. Cercon XT showed the highest numerical ΔE₀₀ value among the materials, although the difference was not statistically significant. All ΔE₀₀ values were below the clinical acceptability threshold (<1.8). No significant effects of surface treatment, material type, or their interaction were observed for translucency change (ΔTP₀₀) after surface treatment. Baseline translucency values (TP₀₀) differed significantly, with Cercon XT being the most translucent, followed by ZirCAD MT and Cercon HT, but these differences did not result in significant ΔTP₀₀ changes post treatment. Conclusions: Surface treatments and their interaction with material type significantly affected zirconia color change, with 50 µm alumina air-particle abrasion producing the most pronounced effect. Material type alone did not significantly influence ΔE₀₀, though Cercon XT showed the highest numerical value. Translucency change (ΔTP₀₀) after treatment was unaffected by surface treatment or material–treatment interaction. Full article

Hard and brittle material components with complex curved surfaces are widely used in critical foundational parts within aerospace, optoelectronics, and other fields. Their machining quality directly determines the performance and reliability of high-end equipment. However, the inherent properties of hard and brittle materials make them prone to surface/subsurface damage during traditional polishing processes, and maintaining the form accuracy of complex curved surfaces is challenging. Although abrasive waterjet polishing enables non-contact flexible processing, its energy efficiency is low. Additionally, although ultrasonic-assisted polishing can improve material removal, its spatial localization is insufficient, limiting energy utilization efficiency. To address these issues, this paper proposes a novel method of focused, ultrasonic, vibration-assisted abrasive waterjet polishing. The influence of the radiation force and cavitation force of the focused ultrasonic field on abrasive particle motion is analyzed, and analytical equations for abrasive particle velocity are established. Subsequently, single-factor and response surface methodologies are employed to systematically evaluate the influence of process parameters on machining quality and efficiency. The material removal process during FUAP involves both plastic shearing/chip formation and localized brittle fracture. Focused ultrasonic assistance promotes micro-cutting and plastic shearing, while localized crushing pits indicate that brittle fracture remains non-negligible. The focused ultrasound superimposes alternating stress onto the impact action, mitigating microscale crushing pit defects during the brittle removal process of monocrystalline silicon. Furthermore, appropriately increasing ultrasonic power, enlarging abrasive particle size, and raising abrasive concentration all contribute to enhanced material removal from monocrystalline silicon. Adjusting the nozzle height to the effective region of the focused ultrasonic energy field promotes material removal via chip formation while avoiding pit defects caused by excessive fracture. These results suggest that focused ultrasonic energy can be effectively integrated into abrasive waterjet polishing to enhance material removal while suppressing brittle surface defects, thereby offering a promising strategy for the ultra-precision finishing of hard and brittle components with complex curved surfaces. Full article

The rapid transition toward electric mobility is widely recognized as a key strategy for improving urban environmental quality. However, while electric vehicles eliminate tailpipe emissions, they continue to contribute to environmental pressures through non-exhaust sources such as tire wear, road surface abrasion, and particle resuspension. This study develops a composite index framework for assessing road-segment-level operational environmental burdens associated with electric traffic, focusing on traffic operations, electric vehicle load characteristics, non-exhaust emission potential, and meteorological dispersion conditions. The framework does not constitute a life-cycle assessment and does not include battery production, electricity-generation mix, or other upstream environmental impacts. The framework combines four dimensions of influence: traffic operations, electric vehicle characteristics, non-exhaust emission processes, and meteorological dispersion conditions. Indicator selection was performed using the Delphi method, while indicator weights were determined through the Analytic Hierarchy Process (AHP). The methodological contribution lies not in the individual methods applied, but in their integration into a road-segment-level assessment framework specifically designed to identify and prioritize environmentally sensitive locations under traffic electrification scenarios. The resulting model incorporates sixteen indicators aggregated into a single environmental impact index that enables the ranking, classification, and prioritization of urban road segments according to their environmental burden. A case study conducted on selected urban streets demonstrates that non-exhaust emission indicators, particularly tire wear and particle resuspension, represent the most influential factors in the assessment process. Within the illustrative five-segment case study, the relative road-segment ranking remained unchanged under the electrified-traffic scenario, while the structure of the assessed burden shifted toward non-exhaust processes. The proposed framework provides a practical decision-support tool for urban planners and transport authorities by enabling the identification of environmentally sensitive locations, prioritization of infrastructure interventions, and support for sustainable mobility strategies in increasingly electrified urban transport systems. Full article

This study investigated the structure and properties of flame-sprayed composite coatings based on ultra-high molecular weight polyethylene (UHMWPE) modified with Al₂O₃ and SiC ceramic fillers. The results of the composite coatings showed that the filler particles were preserved within the polymer matrix, covered by polymer fibers, and strongly bonded to the matrix. The X-ray diffraction analysis showed that for the samples containing Al₂O₃, the degree of crystallinity decreased from 77% to 64%, while for the SiC-containing samples, it remained in the range of 71–76%. The maximum microhardness was achieved in the coating with 15 wt.% Al₂O₃, reaching 8.15 ± 0.5 HV0.03, which represents a 50.9% increase compared with the initial UHMWPE coating. In the case of the SiC filler, the maximum microhardness was achieved at a content of 20 wt.%, reaching 7.40 ± 0.4 HV0.03. The abrasive wear test results demonstrated that both fillers enhanced the wear resistance of the coatings. The coatings containing 15–20 wt.% SiC exhibited the highest wear resistance, with a mass loss of approximately 0.02 g. In the case of the Al₂O₃ filler, the minimum mass loss was achieved at a content of 20 wt.%, reaching approximately 0.032 g. Full article

To achieve accurate prediction of surface roughness (Ra) in magnetic abrasive finishing (MAF) of the inner wall of Co–Cr alloy vascular stent tubing, and to obtain the optimal process parameter combination for improving the inner surface quality, iron-based diamond magnetic abrasive powders (MAPs) were prepared via plasma melting, centrifugal spraying and rapid solidification. MAF experiments were conducted on Co–Cr alloy vascular stent tubing with an inner diameter of 1.6 mm and an outer diameter of 1.8 mm, and the effects of tube rotational speed, magnetic pole feed rate, abrasive particle size and working gap on surface roughness were investigated. An orthogonal experiment was designed, and a surface roughness prediction model based on particle swarm optimization (PSO) and support vector machine (SVM) was established. Simulation results indicate that the proposed PSO-SVM surface roughness prediction model achieved a coefficient of determination (R²) of 0.96771, a root-mean-square error (RMSE) of 0.0012756 μm, and a mean absolute percentage error (MAPE) of 1.061%. The optimal parameter combination obtained by PSO-SVM optimization was a tube rotational speed of 832.6384 r·min⁻¹, a magnetic pole feed rate of 129.6784 mm·min⁻¹, a working gap of 0.5324 mm, and an abrasive particle size of 132.4185 µm. Under these conditions, the experimentally obtained surface roughness was 0.0949 μm, with a relative error of 0.58% compared to the model-predicted value. The results demonstrate that the established PSO-SVM surface roughness prediction model possesses favorable predictive capability, and its combination with MAF technology enables superior surface quality. Full article

Agricultural soil contact components, including ploughshares, rotary blades, and furrow openers, form the active interface between machinery and complex field media. Operating in multiphase environments, these tools face severe abrasive wear, impact fatigue, and interfacial adhesion. These destructive forces irreversibly alter edge geometry and drastically degrade macroscopic operation quality. This review integrates tillage and precision seeding components into a unified tribological framework. It highlights the nonlinear relationship between microscopic material removal and geometric edge retention. Profile degradation is heavily dictated by soil texture, where sandy soils cause micro-cutting, clay soils induce severe adhesion, and gravelly soils produce impact fracture. To predict these complex wear behaviours accurately, coupled multiphysics numerical simulation using the discrete element method for particle flow dynamics and finite element analysis for transient contact stress provides a highly robust methodology. Mitigating these failures requires a functionally zoned surface engineering approach. Carbide hardfacing offers localized abrasion resistance, while polymer composite layers and bionic nonsmooth structures effectively interrupt continuous liquid films in wet cohesive soils. Ultimately, integrating online multidimensional sensing with full life cycle digital-twin models represents the future trajectory for developing adaptive and highly durable agricultural equipment. Full article