Surface Treatment Research Articles

Shear bond strength of orthodontic brackets to single-shade composite surfaces: An in-vitro comparative study of different surface preparations

Purpose > The primary objective of this study was to determine which single-shade composite surface yielded clinically acceptable shear bond strength (SBS) to metal orthodontics brackets. The secondary objectives were to identify the best composite surface treatment to enhance SBS and determine which surface treatment produced the least surface damage at debond.Methods > Forty dental composite samples were selected from four different manufacturers (n=160) and grouped by manufacturer, one standard multi-shade dental system (FilTek™ Supreme Ultra) and three single-shade dental composites systems (OmniChroma®, SimpliShade™and Venus® Diamond One). Each group of forty samples was randomly divided into four sub-groups (n=10). Each sub-group was identified by the surface treatment used, hydrofluoric acid (HFA), micro-etching (MIC), or phosphoric acid (PA). Shear bond strength testing and adhesive remnant index (ARI) were performed. Statistical analyses included Kruskal-Wallis, Wilcoxon rank-sum, and two-factorial ANOVA.Results > OmniChroma® had statistically significant lower shear bond strength than the other composite materials tested. The control groups had statistically significant lower shear bond strength than Group 1/HFA (p<.001) and Group 2/MIC (p<.001). Group 1/HFA had the lowest distribution ARI score overall, while MIC had the highest ARI score distributions.Conclusions > The results of this in vitro study found that all tested composite materials achieved clinically acceptable shear bond strengths. The utilization of micro etching produced higher SBS. Significant Adhesive Remnant Index scores (< 0.001) were only found for OmniChroma® without any surface preparation.

Precision defect integrated graphene as reliable support membrane for high-resolution cryo-transmission electron microscopy

Graphene is an excellent support film for high-resolution transmission electron microscopy (TEM) but its use with biological samples, notably in cryo-TEM, is hindered by its inherent hydrophobicity. Whereas surface treatments have been proposed to render graphene hydrophilic, they are often difficult to reproduce due to a lack of information on the structural changes that modify the wetting properties of graphene. This study aims to correlate the atomic structure of graphene with its wetting properties to allow a reproducible protocol to advance its application in cryo-TEM. We follow the change in the atomic structure of graphene as a function of low-energy hydrogen plasma treatment duration on monolayer graphene transferred onto TEM grids. With finely controlled plasma exposure, partial hydrogenation, monoatomic vacancies, and pores of a few nanometers are realized in the graphene. The introduction of defects (vacancies and pores) enables the formation of continuous layers of vitreous ice on TEM grids. Grids with defect-integrated graphene are reproduced and used in the vitrification of the mouse serotonin 5-HT3 receptor, a membrane protein. Single particle analysis of the membrane protein on graphene compared to conventional holey carbon film give insight into the strengths and discretions in using graphene membrane for protein structural studies.

Research on the bonding performance and mechanism of hot-rolled Ti/steel clad plates based on surface state

The interfaciale bonding strength of Ti/steel clad plates is a crucial factor that affects their application. However, the effect of the surface state, which is a significant determinant, is often neglected. In this study, various surface treatment processes were employed to create different surface states based on the hot-rolling of double-layer steel billets, and the effects and mechanisms of these surface states on the bonding performance of hot-rolled Ti/steel clad plates were systematically examined. The results showed that the Ti/steel clad plates pretreated with a louver wheel exhibited the highest bonding performance, with the average bonding strength peaking at 328.67MPa and stabilising at approximately 300MPa. This strength was approximately 50% greater than that achieved with wire brush treatment and significantly surpassed the results obtained with sanding belts and diamond grinding discs. The analysis of the surface properties and microstructural characteristics revealed that various surface treatments led to different levels of work hardening and lattice distortion at the surface, and the interface bonding strength depended on the degree of matching between these factors. Proper surface hardening can promote the transformation of lattice distortion energy into a diffusion-driving force of elements on both sides of the interface during rolling, enabling sufficient diffusion of elements on both sides of the interface and obtaining good interface bonding performance. A phenomenological prediction mechanism-based model was established to quantify the relationship between the surface state and the bonding strength. This study elucidats the mechanism by which the surface state of materials influences the interfacial bonding performance of hot-rolled Ti/steel clad plates. These findings have significant implications for enhancing the interfacial properties of these composite plates and for selecting suitable pre-rolling surface treatment processes.

Effect of WC addition on microstructure and properties of laser melting deposited Ti6Al4V

Titanium alloys are generally characterized by low surface hardness, poor thermal conductivity, high friction coefficients and susceptibility to adhesive wear, which significantly hinder their industrial applications. To address this issue, we enhance the wear resistance of titanium alloys by incorporating nano WC particles. However, the optimal amount of WC to be added to titanium alloys remains unexplored. In this study, we prepared Ti6Al4V-xWC (wt%) (x = 0, 10, 20) coatings on Ti6Al4V substrates using laser melting deposition, specifically examining the effects of WC content on the microstructure and properties of the coating. The experimental findings indicate that the introduction of WC particles resulted in the formation of a TiC reinforced phase within the composite coating which promoted the equiaxialization of lamellae α phase. The hardness of the coatings increased significantly with the increase of the mass fraction of WC nanoparticles. Notably, the Ti6Al4V-10WC and Ti6Al4V-20WC coatings exhibited wear resistance that was 2.5 and 3.4 times greater, respectively, compared to the Ti6Al4V coatings. This enhancement in wear resistance can be attributed to the reinforcing phase (TiC) formed by the addition of WC. This experiment demonstrates a viable approach to improving the wear resistance of the Ti6Al4V titanium alloy through surface treatment.

Convex structure formation on a Cu substrate by friction stirring using a tool wrapped with Ti foil

The bond strength between Cu substrate and epoxy resin is required to be improved in power modules. Surface modification of the Cu substrate improves the bond strength due to the anchor effect. In this study, we propose a new surface modification method using friction stirring. A convex structure was formed on a Cu substrate by friction stirring using a tool wrapped with Ti foil. The microstructure of the modified surface and adhesion with epoxy resin were evaluated. Friction stirring formed a Ti-derived convex structure on the Cu substrate, and Cu and Ti were mixed at the microscale and bonded strongly. The shear bond strength between the modified surface and epoxy resin was 7.9 ± 1.7 MPa, which was twice as strong as that without surface treatment. The Ti-derived convex structure formed on the Cu substrate improved adhesion with epoxy resin.

Dynamic damage behavior of auxetic textile reinforced concrete under impact loading

To investigate the dynamic compression behavior of Textile-reinforced concrete (TRC) under impact load, low speed and high speed impact tests were performed using a ball drop test and a split Hopkinson pressure bar (SHPB) with ϕ50mm, respectively. In view of the advantages of auxetic materials in impact resistance and energy absorption, the auxetic fiber preforms with negative Poisson's ratio effect were woven into meshes and added to the cement-based materials to obtain the auxetic textile-reinforced concrete. Thus, the auxetic textile reinforced cement-based material is obtained. In this paper, TRC with different textile types, laying layers and surface treatments were prepared, and impact tests with different impact speeds were carried out to evaluate the impact resistance of TRC. The impact damage behavior of TRC was analyzed through the method of digital scattering analysis, and then the impact damage mechanism of TRC was investigated. The results show that the auxetic effect of auxetic textiles can still be stabilized under impact loads of different velocities, which provides better control of deformation and energy consumption in the matrix material. Under different impact heights of falling balls, the impact fracture energy of cementitious materials reinforced with auxetic textiles was increased by up to 22.5 and 20 times, respectively, compared with that of blank samples.

Field evaluation of symbiont-targeted control of Halyomorpha halys in hazelnut crop

Halyomorpha halys has emerged as one of the most damaging pests for hazelnut production. Due to the continuous reduction of available options for chemical control, alternative strategies are required. A promising and sustainable alternative is the use of symbiont-targeted control. Treatment of the egg surface with a biocomplex containing copper, zinc, and citric acid has been shown to effectively prevent the acquisition of the endosymbiont ‘Candidatus Pantoea carbekii’ by H. halys nymphs, resulting in high nymph mortality under laboratory conditions. The aim of this work was to assess the field efficacy treatments targeting the H. halys symbiont in hazelnut orchards to optimize spray applications. Treatments with the anti-symbiont biocomplex were performed in an orchard infested with H. halys during 2022 and 2023. To assess product efficacy, H. halys egg masses were glued on cardboard tags and hung on different positions of plants canopy before the treatments. The wetting percentage of egg masses according to the position of the egg on the plant canopy was measured; eggs were then reared to evaluate nymphal mortality after hatching. Symbiont acquisition was measured by quantitative PCR. A preliminary test to set the spraying conditions revealed that a higher fan speed induced higher mortality of the newborns from treated egg masses, although it did not affect the wetting rate of cardboards. In addition, cardboard tags hung in the central part of the canopy and those closer to the sprayer showed the highest egg coverage, whereas those in the peripheral row were less covered. However, nymphal mortality was not correlated with the percentage of cardboard tags coverage, although it was correlated with symbiont acquisition. A significant reduction in the percentage of damaged hazelnuts was observed in the treated plot compared to an untreated control, confirming the efficacy of symbiont-targeted control in hazelnut orchards.

Laser-induced surface reconstruction to enhance interfacial bonding reliability of CFRP/titanium hybrid joints

Adhesive bonding is widely used in aeronautical carbon fiber-reinforced polymer (CFRP)/titanium (Ti) alloy hybrid structures to satisfy the demands of high-strength and lightweight. The physicochemical properties of adherend surfaces significantly impact the bonding performance. In this study, laser-induced surface reconstruction (LISR) was designed for the reliable joining of Ti alloy and CFRP. A three-level-three-factor central composite design (CCD) approach-based response surface methodology (RSM) analysis was applied to statistically specify parameter optimization of the laser energy output. Surface morphology and wettability of CFRP ablated were studied. Chemical compositions were determined by X-ray photoelectron spectroscopy (XPS). Tensile-shear tests were performed, and fractured surfaces were analyzed. The tensile shear strength with LISR process has been improved by 19.1%, in comparison with that of mechanical grinding treatment. The cross-like texture based on designed geometric configuration was fabricated without damaging the underlying fibers, thus increasing the surface roughness and contact area at interface. The wettability transition mechanism was investigated, demonstrating that the hydrophilicity of reconstructed surfaces primarily attributes to the more polar groups (C−O, C=O, etc.) on CF surfaces. This study provides a reliable surface treatment method for fabricating high-performance composite structures by adhesive bonding.

Optimization design of asphalt emulsion with rejuvenator towards a uniform distribution inside the damaged porous asphalt mixture for a better ravelling resistance

Porous asphalt (PA) pavements usually meet the ravelling disease after opening to traffic for several years. Spraying surface treatment (ST) emulsion to PA pavement is a feasible preventive maintenance technology to alleviate this problem. However, the void clogging, nonuniform distribution and low diffusion efficiency of ST residue might hinder its widespread application. Therefore, this study aims to optimize the ST emulsion formula to improve the ravelling resistance of damaged PA. Usages of adding rejuvenators into ST emulsions were discussed. The orthogonal design method was used to determine the appropriate parameter values for preparing rejuvenator emulsions. The viscosity, contact angle and water boiling tests were then conducted to determine the optimal dosage of rejuvenator emulsion within ST emulsion. Cantabro abrasion test was performed to verify the ravelling resistance of damaged PA mixtures treated with optimized ST. Results showed that a stable and homogeneous rejuvenator emulsion could be produced by precisely controlling the PH value, emulsified temperature and emulsifier dosage. Adding rejuvenator emulsions to ST emulsions significantly improved the wettability. The optimal dosages of aromatic oil and tall oil emulsions are 10% and 5% by mass of ST emulsions. Optimized ST containing rejuvenator emulsions showed better ravelling resistances than pure asphalt emulsion.

Simple and reversible method to control the surface energy of ITO branched nanowires for tuning wettability of micro/nanoscale droplets

Reversible control of hydrophobic and hydrophilic surfaces has gained attention due to their potential applications in microfluidic devices, membranes for electrochemical cells, and sensors. While external stimuli such as temperature and electric field can regulate surface properties, they cannot be selectively applied to specific regions, which limits the patterning of areas with different surface energies. Here, we present a simple and reversible method for converting hydrophobic and hydrophilic properties through surface treatments involving nonpolar (−CFx) or polar groups (–OH) on indium tin oxide branched nanowires (ITO BRs). The formation of nonpolar groups results in superhydrophobic surface. Subsequent ultraviolet ozone treatment, using a shadow mask, induces the exposed area to transition into a superhydrophilic state, while the unexposed area retains superhydrophobicity. This demonstrates the potential for selective-area surface energy patterning. Furthermore, we investigate the wetting behavior of nanoscale Ag nanoparticles (NPs) on surface-modified ITO BRs. It is observed that size and shape of Ag NPs depend on the surface energy of ITO BRs. Consequently, controlling the surface energy leads to the formation of unique geometric structure of Ag NPs, enhancing plasmonic light absorption and scattering at specific resonant wavelengths.

Fostering rehydration and facilitating bioactive release through cellulose-assisted leaf surface treatment

Glyphosate is a widely used herbicide in weed control and crop protection. However, its low bioavailability on leaf surfaces of weeds led to excessive use of glyphosate, inducing herbicide-resistant development and major sustainable agricultural and environmental concerns. This study addresses these challenges by developing cellulose-assisted glyphosate formulations using superior rehydration and sustainable release capability of nanocelluloses. We prepared glyphosate-loaded nanocellulose particles (CNP) and cellulose nanofibers (CNF) to enhance the rehydration and sustained release of glyphosate on leaf surfaces. Our results have demonstrated that nanocelluloses significantly improved water capture on the leaf surface and gradual release of glyphosate, with CNP and CNF formulations showing an 8.75-fold increase in water adsorption on cotton leaves compared to the control group over 12 h. Furthermore, incorporating an inorganic salt improved moisture adsorption efficiency. The formulations exhibited high compatibility with existing spray technologies, offering substantial economic and environmental benefits for agriculture practices. This approach highlights the potential application of polysaccharides in revolutionizing agrochemical applications and environmental sustainability, providing great potential in agricultural spraying practices.

Influence of electrophysical characteristics of plasma electrolytic treatment of 16MnCr5 structural alloy steel on structural and phase changes in the surface and its tribological properties

The possibility of using plasma electrolytic technologies for surface treatment of 16MnCr5 steel in order to increase its wear resistance is shown. The influence of electrophysical characteristics of plasma electrolytic treatment on structural-phase changes of the surface and its tribological properties is studied. A comparison of anodic and cathodic variants of diffusion saturation, as well as subsequent polishing on the results of surface modification is carried out. The complex effect of surface layers strengthened above 1100 HV, including iron carbide and nitride, martensite and retained austenite, to a depth of up to 250 μm with the preservation of a viscous core and the formation of a relatively homogeneous surface with reduced roughness on increasing wear resistance has been revealed. The features of tribological behavior of surfaces formed under different electrophysical parameters of processing, mainly related to the difference in surface microrelief, are shown. The correlation of the Kragelsky-Kambolov criterion as a complex assessment of surface roughness with its wear resistance is shown. The influence of changes in sliding speed and friction load on the occurrence and development of leading processes that determine the intensity and nature of destruction of friction surfaces is established.

Effect of faying surface treatments and bolt tightened levels on fretting fatigue performance of slip critical connections with high strength bolts

Effect of faying surface treatments and bolt tightened levels on fretting fatigue performance of slip critical connections with high strength bolts

Evaluation of accurate measurement methods for radon exhalation rate with advection effect and application in field

In decommissioning of a uranium tailings pond, radon exhalation rates on a beach surface should meet regulatory standards. Accurate measurements of the radon exhalation rate are demanded. However, current studies fail to consider the impact of advection under temperature variations or pressure gradients caused by gas movement on measurements using an accumulation chamber. Two proposed methods were therefore evaluated to accurately measure radon exhalation rates on the loose medium surface under advective conditions. Repeated experiments were conducted on a laboratory experimental platform filled with uranium tailings sand under advective flow rates of 0.03 and 0.3L/min to validate the stability and reliability. Deviations between measured and true values were 0.1–6.1% and 6.3–29.2% for the two methods, respectively. Subsequently, numerical simulation was used to analyze defects of traditional methods and mechanisms of the new methods. In a field study, all methods were compared, and a predictive map of radon exhalation rates was created using interpolated data from 20 random sites using the new method. Results from the proposed methods, compared with traditional ones, were closer to true values under advective conditions, and accurate assessment of beach surface treatment was expected. Environmental ImplicationRadon, a naturally occurring radioactive gas, is exhaled from radium-containing porous media and is present in indoor and outdoor environments, posing potential risks to humans. In decommissioning uranium tailings pond, radon exhalation rates on a beach surface must meet regulatory standards. However, traditional chamber-based measurements methods, e.g., a closed-loop method, are unreliable under advective conditions. Positive pressure difference inside a chamber can be observed due to temperature variations or pressure gradients induced by gas transport. Our proposed methods are capable of accurately measuring radon exhalation rates with sensing advection and estimating advection velocity.

Low-Temperature Performance of Acrylonitrile-Butadiene-Styrene and Crumb Rubber Compound–Modified Asphalt Activated by Waste Cooking Oil Surface Treatment

Low-Temperature Performance of Acrylonitrile-Butadiene-Styrene and Crumb Rubber Compound–Modified Asphalt Activated by Waste Cooking Oil Surface Treatment

The impact of surface treatment on Al foil for Cu2ZnSnS4 thin films

The impact of surface treatment on Al foil for Cu2ZnSnS4 thin films

Effect of adhesives and mechanical surface treatments on the hard relining of CAD-CAM denture bases.

The aim of this study was to evaluate the impact of mechanical roughening, adhesive applications, and aging on the bonding between CAD-CAM denture base materials with distinct chemical contents and hard relining material. A total of 300 denture base specimens were produced by additive, subtractive, and conventional heat-polymerization techniques (N=100). The specimens have been classified into five subgroups based on the particular surface treatments administered (n=20): (1) Hard relining material's adhesive application (control); (2) Tungsten carbide bur application for 1min, and hard reline material's adhesive application; (3) Airborne-particle abrasion (APA) with 110 μm Al2O3, and hard reline material's adhesive application; (4) Scotchbond Universal application; and (5) Visio.link application. Representative specimens from each subgroup were examined under a Scanning Electron Microscope (SEM). Subsequently, self-cure hard relining material was condensed in the center of the specimens. Half of the specimens were thermally aged with 5000 cycles at 5°C-55°C. The shear bond strength (SBS) test was performed, and failure loads were recorded. The data was evaluated by Robust ANOVA and Bonferroni test (p<0.05). No statistically significant difference was obtained between the production techniques (p = 0.051). The lowest SBS was observed in the control group among surface treatments, while mechanical surface treatments and universal adhesive showed the highest SBS for both aged and non-aged groups. Aging caused a significant decrease for all test groups (p=0.001). Mechanical surface treatments and universal adhesive applications are more effective for maintaining adhesion across all production techniques.

Progress in Application of Silane Coupling Agent for Clay Modification to Flame Retardant Polymer.

Polymer composites are widely used in various fields of production and life, and the study of preparing environmentally friendly and flame retardant clay/polymer composites has gradually become a global research hotspot. But how to efficiently surface modify clay and apply it to the field of flame retardant polymers is still a potential challenge. One of the most commonly used surface modification methods is the modification of clay with silane coupling agents. The hydrolysable groups of the silane coupling agent first hydrolyze to generate hydroxyl groups. These hydroxyl groups then undergo a condensation reaction with the hydroxyl groups on the surface of the clay, allowing for organic functional groups to be grafted onto the clay surface. The organic functional groups and polymer matrix react to generate chemical bonds so that the composite material's interface is more closely combined. Thus, the dispersion of clay in the organic polymer material and the compatibility of the two is better, which improves the flame retardant effect of the composite material. This paper introduces the classification of a silane coupling agent and the mechanism and process of silane coupling agent-modified clay, outlines the mechanism of silane coupling agent-modified clay flame retardant polymers, reviews the research results on flame retardant polymers of various clays after surface treatment with silane coupling agents in recent years, and highlights the synergistic flame retardant effect of clay and flame retardant organized by silane coupling agents. Finally, it is found that the current research in the field of silane coupling agent-modified clay in flame retardants is focused on the modification of montmorillonite, sepiolite, attapulgite, and kaolinite by KH-550, KH-560, and KH-570, and the development trends in this field are also prospected.

A comparison of conventional sodium fluoride varnish and nano-sodium fluoride varnish regarding enamel microhardness of deciduous teeth: an in-vitro study.

Dental caries is the most common chronic disease worldwide, and various forms of fluoride are considered useful preventive tools. The production of nanoscale materials can significantly improve their mechanical and chemical properties. The present study compared the microhardness of primary tooth enamel after applying sodium fluoride varnish (conventional) and nano-sodium fluoride varnish. Sixty-eight sound canine teeth were selected in this experimental study. The teeth were mounted so that the buccal surface was exposed. A 3 × 3mm square was obtained on the buccal surface of the crown of each tooth. Enamel surfaces were polished using sandpaper in the presence of water as a coolant. The samples were randomly divided into four groups (n = 17): G1, conventional 5% NaF; G2, 1% nano-NaF; G3, 5% nano-NaF; G4, control. The initial microhardness was measured. Before surface treatment with different fluoride compounds, the samples were placed in a demineralizing solution for two days, and the microhardness of all the samples was re-measured. Then G1, G2, and G3 were treated with the fluoride type specified for each group, and G4 was treated as a control (without treatment). Finally, pH cycling was applied, and the microhardness was measured again. Data were analyzed with SPSS 20, using Repeated measure ANOVA and post-hoc Tukey tests. P < 0.05 was considered significant. Repeated measure ANOVA showed that microharness of G1, G2, G3, and G4 was statistically significant different. Tukey tests showed that the microhardness of G1, G2, and G3 were not significantly different. However, these three groups exhibited significantly more microhardness than the control group (P = 0.024, P = 0.027, and P = 0.010). There was no significant differences in enamel microhardness of deciduous teeth between conventional 5% NaF,1% nano-NaF and 5% nano-NaF.

Evaluation of a Commercial MoS2 Dry Film Lubricant for Space Applications

Molybdenum disulfide coatings, particularly Microseal 200-1, have been extensively used as dry film lubricants for actuating mechanisms in space applications. Although Microseal 200-1 has historically been a popular choice for space missions, recent assessments indicate a need for reexamination. This study evaluates sliding friction in air and dry gaseous nitrogen atmospheres at ambient temperatures with both linear reciprocating and rotary unidirectional tribo-tests. Measurements are performed for Microseal 200-1 applied on substrates and surface treatments commonly used in aerospace components, particularly stainless steel and a titanium alloy. Our findings indicate that the friction of stainless steel balls sliding on Microseal 200-1-coated disks is significantly influenced by the environment as well as the disk substrate material. The average friction coefficient ranges from 0.12 to 0.48 in air and from 0.04 to 0.41 in dry gaseous nitrogen, and the amount of friction is consistently much higher for the Microseal 200-1 on the stainless steel than on the titanium alloy. Microscopy and surface analyses, including scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray fluorescence, of the coatings on stainless steel substrates reveals that the coatings are sparse and relatively thin, likely a key factor contributing to their high friction. This insight underscores the substrate dependence of this widely used coating and highlights the importance of detailed tribological testing in accurately assessing the tribological performance of commercial dry film lubricants, a key step towards improving the reliability and effectiveness of actuating mechanisms for space applications.