Increase In Adhesion Strength Research Articles

Self-Growing Hydrogel Bioadhesives for Chronic Wound Management.

Hydrogel bioadhesives have emerged as a promising alternative to wound dressings for chronic wound management. However, many existing bioadhesives do not meet the functional requirements for efficient wound management through dynamically mechanical modulation, due to the reduced wound contractibility, frequent wound recurrence, incapability to actively adapt to external microenvironment variation, especially for those gradually-expanded chronic wounds. Here, a self-growing hydrogel bioadhesive (sGHB) patch that exhibits instant adhesion to biological tissues but also a gradual increase in mechanical strength and interfacial adhesive strength within a 120-h application is presented. The gradually increased mechanics of the sGHB patch could effectively mitigate the stress concentration at the wound edge, and also resist the wound expansion at various stages, thus mechanically contracting the chronic wounds in a programmable manner. The self-growing hydrogel patch demonstrated enhanced wound healing efficacy in a mouse diabetic wound model, by regulating the inflammatory response, promoting the faster re-epithelialization and angiogenesis through mechanical modulation. Such kind of self-growing hydrogel bioadhesives have potential clinical utility for a variety of wound management where dynamic mechanical modulation is indispensable.

Enhancement of adhesion strength in viscoelastic unsteady contacts

We present a general energy approach to study the unsteady adhesive contact of viscoelastic materials. Under the assumption of infinitely short-range adhesive interactions, we exploit the principle of virtual work to generalize Griffith’s local energy balance at contact edges to the case of a non-conservative (viscoelastic) material, subjected to a generic contact time–history. We apply the proposed energy balance criterion to study the approach–retraction motion of a rigid sphere in contact with a viscoelastic half-space. A strong interplay between adhesion and viscoelastic hysteretic losses is reported which can lead to strongly increased adhesion strength, depending on the loading history. Specifically, two different mechanisms are found to govern the increase of pull-off force during either approach–retraction cycles and approach – full relaxation – retraction tests. In the former case, hysteretic losses occurring close to the circular perimeter of the contact play a major role, significantly enhancing the energy release rate. In the latter case, instead, the pull-off enhancement mostly depends on the glassy response of the whole (bulk) material which, triggered by the fast retraction after relaxation, leads to a sort of ‘frozen’ state and results in a flat-punch-like detachment mechanism (i.e., constant contact area). In this case, the JKR theory of adhesive contact cannot be invoked to relate the observed pull-off force to the effective adhesion energy, i.e. the energy release rate G, and strongly overestimates it. Therefore, a rigorous mathematical procedure is also proposed to correctly calculate the energy release rate in viscoelastic dissipative contacts.

How Static and Cyclic Loading Affect the Mechanical Properties of the Porcine Annulus Fibrosus.

This study sought to evaluate the effects of prolonged cyclic loading on the tissue-level mechanical properties of the spinal annulus fibrosus. Functional spinal units (FSUs) were obtained from porcine cervical spines at the C3-C4 and C5-C6 levels. Following a 15-min preload of 300 N of axial compression, the FSUs were split into three groups: the cyclic loading group cycled between 0.35 MPa and 0.95 MPa for 2 h (n = 8); the static loading group was compressed at 0.65 MPa for 2 h (n = 10); and a control group which only underwent the 300 N preload (n = 11). Following loading, samples of the annulus were excised to perform intralamellar tensile testing and interlamellar 180 deg peel tests. Variables analyzed from the intralamellar test were stress and strain at the end of the toe region, stress and strain at initial failure (yield point), Young's modulus, ultimate stress, and strain at ultimate stress. Variables evaluated from the interlamellar tests were lamellar adhesion strength, adhesion strength variability, and stiffness. The analysis showed no significant differences between conditions on any measured variable; however, there was a trend (p = 0.059) that cyclically loaded tissues had increased adhesion strength variability compared to the static and control conditions. The main finding of this study is that long-duration axial loading did not impact the intra- or interlamellar mechanical properties of the porcine annulus. A trend of increased adhesion strength variability in cyclically loaded samples could indicate a potential predisposition of the annulus to delamination.

Fully Recycled Polyolefin Elastomer-Based Vitrimers with Ultra-High, Universal, Stable, and Switchable Adhesion.

Achieving both robust adhesion to arbitrary surfaces and thermal-switchable/recyclable properties has proven challenging, particularly for commodity polyolefins. Herein, a simple and effective route is reported to transform polyolefins elastomer (POE) into a fully recycled epoxy-functionalized POE vitrimers (E-POE vit) with ultra-high, universal, stable, and switchable adhesion via facile free radical grafting and dynamic cross-linking. The resultant E-POE vit exhibits increase in adhesion strength on glass exceeding three to ten times compared to those commonly used polymers, due to the synergy of dense hydrogen (H)-bonds and strong interfacial affinity. In addition, E-POE vit also displays strong adhesion on diverse surfaces ranging from inorganic to organic while maintaining good stability in various harsh environments. More importantly, temperature-sensitive H-bonds allow E-POE vit to switch between attachment-detachment at alternating temperatures, resulting in reversible adhesion without adhesion loss, even after 10 cycles. Moreover, E-POE vit is able to be fully recycled and reused more than ten times via thermo-activated transesterification reactions with negligible change in structure and performance. This work may unlock strategies to fabricate high-performance commercial polymer-based adhesives with adhesion and recyclable features for intelligent and sustainable applications.

Effect of multiple environmental conditions on the formation process and adhesion strength of ice on asphalt binder surface

Road icing caused by freezing rain significantly impacts driving safety. Since asphalt binder plays a pivotal role in pavement infrastructure, understanding the formation process and adhesion strength of ice on asphalt binder surfaces is crucial for assessing road icing risk. This work investigated the effect of different environmental conditions on asphalt-ice interface adhesion strength via a self-designed low-temperature adhesion testing system. In addition, the icing process on asphalt binder surfaces was observed to analyze the asphalt-ice adhesion strength formation mechanism. Results show that the completion time of water-ice phase transition signified the initial development of asphalt-ice adhesion strength. Moreover, as the internal structure of the ice evolved from transparent to needle-like fine lines to dense, the asphalt-ice adhesion strength gradually increased until it reached stability. At asphalt-ice adhesion began forming after 40 min and stabilized after 80 min, whereas at −8°C, adhesion strength started forming after 20 min and stabilized by 60 min. The growth rates of asphalt-ice adhesion strength for temperatures ranging from −2°C to −10°C were approximately 7.92 kPa/°C, 6.56 kPa/°C, 5.14 kPa/°C, 3.29 kPa/°C, and 1.49 kPa/°C, respectively, showing a positive correlation with temperature and a negative correlation with time. According to heterogeneous nucleation theory, the influence mechanism of temperature and water depth on the nucleation icing process and asphalt-ice adhesion strength is analyzed. lower temperatures lead to asphalt-ice adhesion strength increase originating from the larger supercooling, which reduces the critical nucleation energy and thus accelerates the ice nucleation rate. In addition, the increase in water depth promotes the formation of nucleation sites and further enhances the asphalt-ice adhesion strength. Finally, an asphalt-ice adhesion strength prediction model was developed, with PSO-SVM-G achieving over 90 % accuracy. These results provide insights for evaluating ice adhesion behavior on asphalt surfaces and designing anti-icing asphalt materials.

Effect of Cow Dung Additions on Tropical and Mediterranean Earth Mortars-Mechanical Performance and Water Resistance.

Cow dung (CD) is a material that has been used for millennia by humanity as a stabilizer in earth building techniques in vernacular architecture. However, this stabilization has been little addressed scientifically. In this study, the effect of CD additions was assessed on earth mortars produced with one type of earth from Brazil and two other types from Portugal (from Monsaraz and Caparica). The effect of two volumetric proportions of CD additions were assessed: 10% and 20% of earth + sand. The German standard DIN 18947 was used to perform the physical and mechanical tests, and classify the mortars. In comparison to the reference mortars without CD, the additions reduced linear shrinkage and cracking. An increase in flexural and compressive strengths was not observed only in mortars produced with earth from Monsaraz. In mortars produced with the earth from Caparica, the addition of 10% of CD increased flexural strength by 15% and compressive strength by 34%. For mortars produced with the earth from Brazil, the addition of 10% of CD increased these mechanical strengths by 40%. The increase in adhesive strength and water resistance promoted by the CD additions was observed in mortars produced with all three types of earth. Applied on ceramic brick, the proportion of 10% of CD increased the adherence by 100% for the three types of earth. Applied on adobe, the same proportion of CD also increased it more than 50%. For the water immersion test, the CD additions made possible for the mortar specimens not to disintegrate after a 30 min immersion, with the 20% proportion being more efficient. The effects of the CD on mechanical performance, including adhesion, were more significant on the tropical earth mortars but the effects on water resistance were more significant on the Mediterranean earthen mortars. CD has shown its positive effects and potential for both tropical and Mediterranean earthen plasters and renders tested, justifying being further studied as an eco-efficient bio-stabilizer.

Mitigation mechanisms of ash deposition and adhesion by different coatings on heated surfaces at macro and molecular scales

Research on the mitigation of ash deposition on coals rich in alkali and alkaline earth metals using coatings is limited. Existing research methods, mainly focusing on ash composition and melting characteristics, cannot fully elucidate the key mechanisms underlying ash adhesion properties on various coated surfaces. Therefore, this study explored the mitigation mechanisms of nickel and chromium coatings on ash deposition using a drop tube furnace, custom-made ash adhesion strength tester, and molecular dynamics. The results revealed that nickel and chromium coatings effectively mitigated ash deposition, with a more significant effect at temperature less than 1000 °C. Above 1000 °C, the ash melting led to a significant increase in ash adhesion strength, diminishing the inhibitory effect of coatings. The key minerals, Na2SO4, Ca2MgSi2O7, and Ca2Al2SiO7, mainly physically adsorbed onto the NiO(001) and Cr2O3(001) surfaces. The binding energy of these minerals with NiO(001) and Cr2O3(001) was significantly lower than that on α-Fe2O3(110) surfaces. The α-Fe2O3(110) system was more stable, and minerals readily adhered to the α-Fe2O3(110) surface, whereas none of these minerals readily bound to NiO(001) and Cr2O3(001), maintaining their adhesion state. Consequently, nickel and chromium coatings demonstrated excellent resistance to ash adhesion and deposition, with nickel coatings being more effective.

3D printing of thick film NTC thermistor from preceramic polymer composites for ultra-high temperature measurement

Integrating thick/thin film sensors into component systems has emerged as a prevalent approach for monitoring in extreme environments. However, traditional vapor deposition methods face obstacles, including complex fabrication processes and the degradation of sensitive materials at extremely high temperatures. This work delineates the development of a polysilazane composite dual-layer thick-film Negative Temperature Coefficient (NTC) thermistor characterized by its suitability for extreme temperatures and robust bond strength achieved through an advanced near-net-shape printing methodology. High-temperature resistant La(Ca)CrO3/polysilazane films were printed as the sensitive layer, while a dense layer formed by Cr2O3/polysilazane was used as the protective layer. The bilayer structure resulted in a 2.5-fold increase in adhesion strength compared to the single-layer La(Ca)CrO3/polysilazane films. Experimental results indicate that the dual-layer thick-film NTC thermistor can be operated long-term at 1300 °C with a resistance drift rate of 0.9 %/h and survive short-term exposure to temperatures up to 1550 °C. As a proof of concept, this work applied 3D printing technology to fabricate a polysilazane composite dual-layer thick-film NTC thermistor on the surface of turbine blades and demonstrated its functionality under flame impingement at nearly 1300 °C. Such flexible 3D printing techniques pave the way for a new paradigm in manufacturing sensors capable of withstanding ultra-high temperatures.

Модифицирующая добавка для повышения качества асфальтобетона

The paper describes the production of modifying additive on the basis of waste - deferrization sludge of waste groundwater of Nekrasovskoye settlement, Yaroslavl region. The authors found that the predominant components of this waste are trivalent and divalent colloidal iron in the ratio of 3:1. The authors propose to use this waste as a modifier of asphalt concrete mixture to increase the adhesion of bitumen to mineral components of asphalt concrete based on the study of its physical and chemical properties. The authors have conducted studies of asphalt concrete mixes of various grades and selected optimal conditions for the use of deferrization sludge in the technological process of asphalt concrete production. The use of modifying additive allows to increase shear stability and water holding capacity of asphalt concrete, which indicates the increase of adhesive strength of bitumen bond with mineral components of asphalt concrete.

Probing local adhesion: A miniaturized multi-photon lithography design demonstrated on silanized vs. untreated surfaces

As multi-photon lithography technology matures, advanced integrated device design concepts become possible, positioned onto small surfaces, such as optical fibres. Only local adhesion anchors the printed object on the surface and ensure proper print-development without structure loss and long-term usability. Although surface treatments such as silanization are well known to considerably increase adhesion strength, quantification of adhesion is not straightforward and commonly assessed indirectly by surface characteristics and technological methods. The present work aims to quantify adhesion on a micrometer scale through SEM in situ tension experiments, that utilize a newly developed specimen geometry. Multiple specimens, with various footprints, were manufactured on both silanized and untreated fused silica substrates, allowing the comparable quantification of adhesion stresses between different surface conditions. Specimens on an untreated substrate failed with a high scatter in detaching force, whereas specimens on a silanized substrate tend to fail within the photoresist, either at the gauge section or just above the substrate, rather than at the interface itself. Thus, the adhesion stress was increased at least by a factor of 1.4 by the silanization treatment. Generally, a novel approach was developed, that can quantify local adhesions properties in realistic packaging or integrated circuits.

A Single-Component Janus Zwitterionic Hydrogel Patch with a Bionic Microstructure for Postoperative Adhesion Prevention.

The development of anti-adhesion hydrogels for preventing postoperative adhesions is an ongoing challenge, particularly in achieving a balance between exceptional antifouling properties and effective in situ tissue retention. In this study, we propose a unique approach with the design of a single-component Janus zwitterionic hydrogel patch featuring a bionic microstructure. The Janus patches were prepared through free radical polymerization of sulfobetaine methacrylate with N, N'-methylenebis(2-propenamide) as the cross-linker. The incorporation of hexagonal facets separated by interconnecting grooves on one side imparts durable and reliable in situ retention capabilities to the Janus hydrogel patch when it is applied to traumatized tissues. The opposing flat surface exhibits outstanding resistance to bacteria, proteins, and cell adhesion, due to the superhydrophilicity and excellent antifouling characteristics of zwitterionic polymers. This dual functionality empowers the Janus hydrogel patch to mitigate adhesions between traumatized and surrounding tissues. The hexagonal and groove bionic microstructures facilitate rapid drainage, promoting swift contact with the tissue for increased adhesion strength, while independent hexagonal microfacets enhance the peeling energy. In an in vivo setting, Janus zwitterionic hydrogel patches with surface microstructures form mutually embedded structures with the cecum surface, minimizing the likelihood of slippage and detachment. Remarkably, in vivo experiments involving abdominal wall cecum injuries illustrate the Janus zwitterionic hydrogel patch's superior anti-adhesion effectiveness compared to commercial controls. Thus, the Janus hydrogel patch, distinguished by its bionic microstructure surface, presents substantial potential in the biomedical field for averting postoperative adhesions.

Impact of Screw Geometry and Solids Content on the Properties of Continuously Produced Si Anodes

Within the realm of lithium‐ion batteries, there is a growing emphasis on achieving high energy density and environmentally friendly production at a low cost. To address these demands, the battery slurries in this study incorporate the high‐energy anode material silicon. They are systematically produced through continuous extrusion, aiming to realize cost reductions by significantly reducing the overall process time. In this study, it is demonstrated that the choice of screw configuration and solids content during kneading influences the specific energy input and the stress intensity during processing significantly. The stress intensity, represented here by the specific torque, has a great influence on the slurry properties as well as the electrochemical performance of the battery. An increased stress intensity leads to an increase in adhesive strength and ionic resistance. In the results, it is indicated that carbon black decomposition increases significantly, but when a critical specific stress intensity in form of the specific torque is reached, delamination and fracture of the graphite particles occur, leading to a loss of lithium‐ion storage capacity, favoring lithium plating and severely degrading both capacity by up to 40% at 1C and long‐term performance by up to 10% after 50 cycles.

Disulfiram Reduces Atherosclerosis and Enhances Efferocytosis, Autophagy, and Atheroprotective Gut Microbiota in Hyperlipidemic Mice.

Pyroptosis executor GsdmD (gasdermin D) promotes atherosclerosis in mice and humans. Disulfiram was recently shown to potently inhibit GsdmD, but the invivo efficacy and mechanism of disulfiram's antiatherosclerotic activity is yet to be explored. We used human/mouse macrophages, endothelial cells, and smooth muscle cells and a hyperlipidemic mouse model of atherosclerosis to determine disulfiram antiatherosclerotic efficacy and mechanism. The effects of disulfiram on several atheroprotective pathways such as autophagy, efferocytosis, phagocytosis, and gut microbiota were determined. Atomic force microscopy was used to determine the effects of disulfiram on the biophysical properties of the plasma membrane of macrophages. Disulfiram-fed hyperlipidemic apolipoprotein E-/- mice showed significantly reduced interleukin-1β release upon invivo Nlrp3 (NLR family pyrin domain containing 3) inflammasome activation. Disulfiram-fed mice showed smaller atherosclerotic lesions (~27% and 29% reduction in males and females, respectively) and necrotic core areas (~50% and 46% reduction in males and females, respectively). Disulfiram induced autophagy in macrophages, smooth muscle cells, endothelial cells, hepatocytes/liver, and atherosclerotic plaques. Disulfiram modulated other atheroprotective pathways (eg,efferocytosis, phagocytosis) and gut microbiota. Disulfiram-treated macrophages showed enhanced phagocytosis/efferocytosis, with the mechanism being a marked increase in cell-surface expression of efferocytic receptor MerTK. Atomic force microscopy analysis revealed altered biophysical properties of disulfiram-treated macrophages, showing increased order-state of plasma membrane and increased adhesion strength. Furthermore, 16sRNA sequencing of disulfiram-fed hyperlipidemic mice showed highly significant enrichment in atheroprotective gut microbiota Akkermansia and a reduction in atherogenic Romboutsia species. Taken together, our data show that disulfiram can simultaneously modulate several atheroprotective pathways in a GsdmD-dependent as well as GsdmD-independent manner.

Studying and Characterization of Coating of Zein-CaSiO3 Composite on Polyetheretherketone Implant Material.

Material-coated implants are placed in the bone and play an essential role in bone regeneration and rapid healing around implants. Polymeric matrix reinforced with ceramic materials is a promising composite material for coating implants. This study aims to determine the effect of mixing various concentrations of zein with CaSiO3 on polyetheretherketone (PEEK) as implant material. The coating was performed using the electrospray method. PEEK disks were used as a control group. The coated disks with different concentrations of zein-CaSiO3 (Group 1: 10% wt, 90% wt), (Group 2: 20% wt, 80% wt), and (Group 3%: 30% wt, 70% wt) were the experimental group. Each group was characterized by atomic force microscopy, field emission scanning electron microscope, Fourier-transform infrared spectroscopy, water contact angle, and adhesion strength. The lowest water contact angle was obtained for Group 1: 10% wt and 90% wt were (26.64° and 27.13°, respectively), and increasing amounts of zein in comparison to quantities of CaSiO3 resulted in increased adhesion strength of the composite material to the substrate. The current study suggested that the higher amount of zein compared to the amount of CaSiO3 mixture coating is achieved by electrospraying, a favorable candidate for coating implants compared to uncoated and coated disks with low concentrations of zein compared to concentrations of CaSiO3.

Synthesis and characterization of poly (methyl methacrylate)/ silver-doped hydroxyapatite dip coating on Ti6Al4V

This study intends to analyze the properties and potential applications of a novel composite coating composed of poly (methyl methacrylate) (PMMA) and silver-doped hydroxyapatite (HAPAg) produced from waste eggshells, which was dip-coated onto Ti6Al4V substrates. Medical implants frequently made of the titanium alloy Ti6Al4V can benefit greatly from surface coatings in terms of biocompatibility and performance. In order to add antibacterial and osteoconductive characteristics, silver-doped hydroxyapatite nanoparticles were dispersed within a PMMA matrix to create the PMMA/HAPAg composite coating. The coated samples report an average contact angle (CA) between 70 and 750 and total surface free energy (SFE) between 35 and 50 mJ/m2, which signifies its improved wettability. The 7.03% change in hydrophilicity was observed between PMMA/H0 (75.270 ± 1.690) and PMMA/H20 (700 ± 1.440) coated samples. The increase in adhesion strength and coating thickness with the increase in HAPAg reinforcement was observed. The surface morphology of the defective zones was examined using scanning electron microscopy (SEM), and information on the elemental composition of synthesized was obtained using Inductively Coupled Plasma Mass Spectroscopy (ICPMS), Fourier Transform Infrared spectroscopy (FTIR) and X-ray diffractogram (XRD). Atomic force microscopy (AFM) reveals the surface roughness; root mean square roughness, roughness profile, skewness and kurtosis of the coated samples. The contact angle reports the hydrophilicity and SFE. Finally, the results conclude that the composite coating had a consistent distribution of HAPAg nanoparticles incorporated within the PMMA matrix. The minimal presence of Ag ions on the surface indicates the coating's potential antibacterial properties, and it is highly recommended for dental applications.

Clay composition patterns and their influence on the adhesive strength of earthen plasters

The clay fraction of earthen plasters is the part responsible for the acquisition of cohesion and adherence that they possess against deterioration factors. Adherence is the property responsible for keeping the plaster together with the wall and is influenced by the percentage content of clay as well as by its mineralogy and the heterogeneity of minerals that may be present. However, it is still unknown in depth how clay minerals perform in the adherent properties of earthen plasters when the composition is heterogeneous in the material. The objective of this study is to evaluate the incidence of the mineralogical complexity of clay mineralogy in the variability of the adherence of earth plasters. To evaluate the variability, considering that the mineralogy of the soils depends directly on the place and the formation processes, eight soils from Tucumán (Argentina) corresponding to different physiographic units were analyzed. A methodology was designed for sample preparation that allows soils to be compared through adhesion tests. They were characterized by XRD to determine their mineralogical composition and by the hydrometric method to determine their granulometry. To evaluate the adherence of mixtures made with the respective soils, it was proposed in the first instance to compensate the granulometry of the soils to equate them and, once the plasters were made, this property was evaluated through shear and pull-off tests. The results showed that they allowed us to identify that the soils presented a pattern of mineralogical composition common to all the physiographic units, made up of the Ill and K pair, the former being predominant. For this pattern, it was observed in particular that there is a positive correlation between the increase in Ill content with the increase in the adhesive strength of the plasters. Clay minerals from the Sm group also contribute to the increase in adherence when the percentage is greater than or equal to 11%. On the contrary, K and Cl do not influence the increase in adhesive strength.The clay fraction of earthen plasters is the part responsible for the acquisition of cohesion and adherence that they possess against deterioration factors. Adherence is the property responsible for keeping the plaster together with the wall and is influenced by the percentage content of clay as well as by its mineralogy and the heterogeneity of minerals that may be present. However, it is still unknown in depth how clay minerals perform in the adherent properties of earthen plasters when the composition is heterogeneous in the material. The objective of this study is to evaluate the incidence of the mineralogical complexity of clay mineralogy in the variability of the adherence of earth plasters. To evaluate the variability, considering that the mineralogy of the soils depends directly on the place and the formation processes, eight soils from Tucumán (Argentina) corresponding to different physiographic units were analyzed. A methodology was designed for sample preparation that allows soils to be compared through adhesion tests. They were characterized by XRD to determine their mineralogical composition and by the hydrometric method to determine their granulometry. To evaluate the adherence of mixtures made with the respective soils, it was proposed in the first instance to compensate the granulometry of the soils to equate them and, once the plasters were made, this property was evaluated through shear and pull-off tests. The results showed that they allowed us to identify that the soils presented a pattern of mineralogical composition common to all the physiographic units, made up of the Ill and K pair, the former being predominant. For this pattern, it was observed in particular that there is a positive correlation between the increase in Ill content with the increase in the adhesive strength of the plasters. Clay minerals from the Sm group also contribute to the increase in adherence when the percentage is greater than or equal to 11%. On the contrary, K and Cl do not influence the increase in adhesive strength.

Cementless Compositions for the Restoration of White Stone Based on Lime Binder and Silicon Dioxide.

The condition of architectural monuments is directly influenced by various factors, such as anthropogenic, natural, and technological, leading to the degradation of both structures and construction materials, ultimately resulting in irreversible damage. These factors diminish the quality of construction materials, contributing to alterations and the destruction of the appearance and structure of white stone. The primary objective of this research is to develop cement-free compositions for restoring ancient masonry materials. Tests were conducted at the BM Department of VlSU using modern equipment. New material compositions for restoration have been devised, combining lime and silicon dioxide with chemical additives to enhance adhesive and strength properties. Adhesive strength increases by 1.5 times with the addition of white soot (silicon dioxide). Moreover, the incorporation of silicon dioxide positively impacts compressive strength (from 10.6 to 15.6 MPa), surpassing the strength of composites without white soot by 1.5 times. XRD confirms the developed composite's similar phase composition to white stone, supported by optical microscopy and SEM results. Restoration composites based on these compositions exhibit homogeneous structures compatible with white stone and demonstrate high adhesion levels. These results make the proposed compositions promising for white stone restoration, ensuring structural and chemical compatibility with the restored surface.

Exploring salt-mist corrosion resistance of GPTMS functionalized graphene oxide reinforced epoxy resin composite coating on shot-peened Ti-15333 titanium alloy

The purpose of this work was to research the effects of 3-Glycidyloxypropyltrimethoxysilane (GPTMS) incorporation and shot peening on the salt-mist corrosion resistance and adhesion property of GO-epoxy coating over Ti-15,333 alloy. Herein, in order to increase the adhesion strength between the organic coating and the metal matrix, the surface roughness of Ti-15,333 alloy was improved by the shot peening technology, and graphene oxide (GO) could reduce the micro defects in the epoxy resin matrix to enhance anti-corrosion properties. In addition, the coating was doped with GPTMS to improve active corrosion protection. The treated Ti-15,333 alloy's corroded surface has been characterized by SEM, EDS and XPS techniques. The barrier capabilities and adhesion efficiency of different protective layers were further analyzed by polarization curve, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) tests. According to the fitting results of the polarization curve, after 312 h of salt-mist, the corrosion current densities of the GO-epoxy and f-GO-epoxy coating samples were 2.692 × 10−7 and 3.990 × 10−8, respectively, the calculation result showed that their protection efficiency reached 63.76% and 94.63%, respectively. Meanwhile, according to the EIS and EN results, f-GO-epoxy coating sample's corrosion protection properties increased significantly. The pull-off results showed that the f-GO-epoxy coating had the most significant increase in adhesion strength compared to the GO-epoxy coating sample. The results reveal that the synergistic effect of GPTMS incorporation and shot peening significantly enhance the corrosion resistance and adhesion strength of GO-epoxy coating over Ti-15,333 alloy.

Magnetically controlled interface weaving of dual-layer heterogeneous coatings with active and passive anti-corrosion protection

Polydimethylsiloxane (PDMS) elastomer exhibiting remarkable corrosion resistance and fouling release properties. However, their performances are often compromised due to the weak interfacial adhesion with rigid substrates. Herein, we have developed an innovative dual-layer heterogeneous coating via magnetic-controlled interface weaving technology, achieving a seamless integration of PDMS with a rigid epoxy (EP) substrate. Magnetic nanoparticles (Fe3O4@MPDA-MBT) were strategically incorporated into the coating system, guided by a magnetic field to facilitate their interfacial migration. This controlled migration of nanoparticles resulted in the formation of interface layer between the EP primer and PDMS topcoat, leading to a sharp increase in PDMS adhesion strength (3.0 MPa), which is over 7 times greater than that of control counterpart (0.4 MPa). Additionally, Fe3O4@MPDA-MBT were selectively enriched adjacent to the metal substrate, thereby endowing the coating with outstanding corrosion resistance, due to the quick releasing of enough MBT inhibitors, as confirmed by electrochemical tests with high corrosion resistance value (2.2 × 108 Ω·cm2). Also, the topcoat PDMS enabled the dual-layer heterogeneous coating to achieve fouling-release and cavitation resistance.

Enhanced adhesion and thermal stability of thick (Al,Cr)2O3 coatings on hot work steel

Al2O3 coatings deposited by chemical vapor deposition (CVD) at temperatures T ˃ 1000 °C are commonly used for wear and oxidation protection in manufacturing processes. Physical vapor deposition (PVD) gained also great interest to synthesize crystalline Al2O3 at lower temperatures by modification using Cr. High Speed PVD has the potential to synthesize thick crystalline (Al,Cr)2O3 coatings. However, previous studies showed that increasing adhesion strength is necessary for corresponding applications. This study evaluated various interlayer systems to enhance the adhesion strength between (Al,Cr)2O3 functional layer and steel X40CrMoV5-1. AlCrN interlayers of varying thicknesses were deposited, as well as two graded AlCrNg interlayers at different bias voltages. Afterwards, AlCrN/(Al,Cr)2O3 coatings were produced. Hereby, the functional layer thickness is varied. The AlCrNg/(Al,Cr)2O3 compounds show no spallation at the edge of Rockwell imprints and scratches at higher normal forces. The thermal stability of the coatings was investigated by annealing in vacuum at T = 1000 °C and T = 1200 °C. Moreover, no diffusion processes leading to chemical and structural changes was obtained after annealing. Therefore, thick (Al,Cr)2O3 coatings, s ≈ 30 μm, with a graded AlCrNg interlayer provide high potential for protecting hot-work steel against thermal loads up to T = 1200 °C.