Surface Of Composite Material Research Articles

Microwave-assisted fabrication of 1D/2D CeO2/Bi2MoO6 heterojunction for efficient photocatalytic CO2 reduction to CH3OH

Photocatalytic CO2 reduction to fuels via visible light is regarded as a highly promising sustainable technology to address resource depletion and environmental apprehensions. However, the elevation of photocatalytic performance is limited due to some drawbacks of isolated catalysts such as poor CO2 adsorption performance, inadequate utilization of visible light, and rapid recombination of photo-generated carriers. Herein, a series of novel heterojunction catalysts, 1D/2D CeO2/Bi2MoO6 (CBMO-X), were fabricated utilizing the microwave-assisted method for the photocatalytic reduction of CO2. The CH3OH yield of the optimized CBMO-10 composite material reached 4.31 μmol⋅g−1⋅h−1 with excellent stability and structural integrity. Through a series of characterizations, it was found that the introduced CeO2 nanorods served as bifunctional sites for CO2 adsorption and photoelectron accumulation, effectively promoting CO2 conversion under visible light. In addition, CBMO-X exhibited faster photo-generated carriers migration rate due to the formation of the II-scheme heterojunction, which improved the photocatalytic performance obviously. Furthermore, the density functional theory (DFT) calculations and in situ XPS were used to investigate the carrier migration paths on the surface of composite materials. This work provided a novel strategy for the design of photocatalysts for efficient CO2 conversion.

Wetting, droplet evaporation and corrosion behavior of various composite and textured materials

Experimental studies were conducted on the evaporation rate of a droplet located on the surfaces of various composite and textured materials with different wettability at varying surface temperatures. The maximum droplet evaporation rate was recorded on a textured Cu–SiC composite material with superhydrophilic properties. The minimum droplet evaporation rate corresponded to a superhydrophobic AlMg3 substrate obtained using laser texturing with subsequent hydrophobization procedure. An increase in surface temperature led to a significant deterioration of hydrophobicity for a superhydrophobic substrate and a deterioration of hydrophilicity for a superhydrophilic substrate. As a result, with increasing temperature, the influence of the droplet geometry determined by surface wettability on the droplet evaporation rate for these substrates sharply decreases. Advancing and receding dynamic contact angles, as well as contact angle hysteresis were obtained on all studied substrates. It is generally accepted that a hydrophobic surface exhibits less contact angle hysteresis than a hydrophilic one. However, Cu-SiС composite substrate with a textured hydrophobic surface exhibited the opposite behavior. The contact angle hysteresis on the hydrophobic textured surface was found to be four times higher than that on the hydrophilic polished one. A mechanism was proposed that explains the high contact angle hysteresis and four hysteresis time modes. The minimum hysteresis value corresponded to the superhydrophobic AlMg3 substrate. Anti-corrosion properties were studied for all substrates under consideration. The minimum corrosion current corresponded to a copper substrate with a graphene coating, as well as a superhydrophobic AlMg3 substrate. For a given substrate, there are two corrosion modes with a three-fold difference in the corrosion current. In addition, the wettability behavior of different surfaces was examined using molecular dynamics simulations. The simulation results were found to be consistent with the experimental data.

Inspection of Surface Damage in Composite Materials with Different Techniques

Due to their excellent physical properties and high strength and stiffness relative to density, aerospace industry research is producing high-performance structural materials, such as composites, which are used in many critical structural parts like airframes, wings, rotor blades, propellers, and other components. However, during flight, these materials may be damaged by impact, thermal stress, moisture, and ultraviolet radiation. One of the most prevalent issues with composite materials is their challenging nature in terms of flaw detection during both manufacturing and use. When they are employed in the crucial areas that were previously indicated, this becomes a very serious issue. When evaluating the structural integrity of composites and looking for any damage, microscopes are a very useful instrument. Effective methods for identifying and analyzing damage include microscopic procedures like optical microscopy, stereomicroscopy, scanning electron microscopy (SEM), scanning ion microscopy (SIM), and atomic force microscopy (AFM). A variety of methods may be employed with microscopes to examine and identify deterioration in composite materials. It is often possible to examine overt deterioration on the surface of composite materials under the microscope utilizing a number of different approaches and procedures. Determining the kind, extent, distribution, and impact of the damage requires these inspections. Often employed techniques consist of: SEM is a method for high-resolution imaging of surface damage. It entails shining an electron beam onto the sample's surface and capturing pictures. SEM is a useful tool for identifying erosion, delamination, and microcracks. It is also possible to measure things like the damage's breadth and depth. Optical microscopes have a large field of view and look at damaged regions. This makes it possible to find tiny fractures or cracks that are invisible to the unaided eye. Furthermore, details on the degree of harm, the roughness of the surface, and the breadth and depth of the fractures may be acquired. To see damaged objects, optical microscopy is utilized. Cracks and damage locations are visible with optical microscopy. Optical microscopes can identify different kinds of damage by looking at the surface of the material. Damage like delamination, fiber breakage, cracks, and deformations are a few examples of these. This study examines the efficacy of microscopic methods and non-destructive testing in assessing the different kinds of damage that can occur at the interfaces between holes in composite materials. Composite test materials were chosen from glass fiber reinforced phenolic matrix composites that were produced in compliance with aerospace standards. The measurements led to the conclusion that using microscopic techniques has benefits like speed and field suitability. However, the continuous development and improvement of new methods in this field will contribute to a better understanding of layered composite materials and the development of safer and more durable structures.

Highly sensitive Ti3C2Tx MXenes-RGO humidity sensor for human non-contact respiratory monitoring

In this study, a highly sensitive and stable Ti3C2Tx MXenes-RGO humidity sensor was developed for real-time respiratory monitoring. Ti3C2Tx-RGO composite material increases the interlayer spacing of RGO, further expanding the channels for water molecule transport. Introduction of Ti3C2Tx promotes the generation of more -O, -OH, -F groups on the composite material surface, which can serve as adsorption sites for water molecules to improve response, and they form weak physical adsorption with water molecules, shortening the response and recovery time of the sensor. Ti3C2Tx-RGO composite material increases the interlayer spacing of RGO, further expanding the channels for water molecule transport. Density functional theory (DFT) calculation results indicate that Ti3C2Tx surface -F has higher adsorption energy for water molecules, which is beneficial for enhancing the sensitivity of the humidity sensor. Ti3C2Tx-RGO humidity sensor exhibits high sensitivity (22,117), low humidity hysteresis (1%), relatively short response/recovery time (7/16 s), and good stability and repeatability in the range of 11%− 95% RH. The sensor can also monitor changes in respiratory intensity and frequency, achieving real-time analysis of respiratory patterns, making it demonstrate strong application potential in non-contact human respiratory detection. This study provides new research ideas and methods for preparing high-performance humidity sensors.

Sand Erosion Resistance and Failure Mechanism of Polyurethane Film on Helicopter Rotor Blades.

Polyurethane is widely used on the surface of composite materials for rotor blades as sand erosion protection materials. The failure mechanism investigation of polyurethane film under service conditions is useful for developing the optimal polyurethane film for rotor blades. In this article, the sand erosion test parameters were ascertained according to the service environment of the polyurethane film. The sand erosion resistance and failure mechanism of polyurethane film at different impact angles were analyzed by an infrared thermometer, a Fourier transform infrared spectrometer (FTIR), a differential scanning calorimeter (DSC), a field emission scanning electron microscope (FESEM), and a laser confocal microscope (CLSM). The results show that the direct measurement method of volume loss can better characterize the sand erosion resistance of the polyurethane film compared to traditional mass loss methods, which avoids the influence of sand particles embedded in the polyurethane film. The sand erosion resistance of polyurethane film at low-angle impact is much lower than that at high-angle impact. At an impact rate of 220 m/s, the volume loss after sand erosion for 15 min at the impact angle of 30° is 57.8 mm3, while that at the impact angle of 90° is only 2.6 mm3. The volume loss prediction equation was established according to the experimental data. During low-angle erosion, the polyurethane film damage is mainly caused by sand cutting, which leads to wrinkling and accumulation of surface materials, a rapid increase in roughness, and the generation of long cracks. The linking of developing cracks would lead to large-scale shedding of polyurethane film. During high-angle erosion, the polyurethane film damage is mainly caused by impact. The connection of small cracks caused by impact leads to the shedding of small pieces of polyurethane, while the change in the roughness of the film is not as significant as that during low-angle erosion. The disordered arrangement of the soft and hard blocks becomes locally ordered under the action of impact and cutting loads. Then, the disordered state is restored after the erosion test finishes. The erosion of sand particles leads to an increase in the temperature of the erosion zone of the polyurethane film, and the maximum temperature rise is 6 °C, which does not result in a significant change in the molecular structure of the polyurethane film. The erosion failure mechanism is cracking caused by sand cutting and impact.

Activated carbon synthesized from Arecanut catechu L. as a sustainable precursor intercalated TiO2 modified electrode for the detection of fungicide Dichlorophen

Pesticides, such as dichlorophen (DCP), pose serious threats to the ecosystem and human health. Hence, developing an efficient and sensitive detection method is crucial for environmental monitoring and remediation. In this study, we present a novel composite material comprised of TiO2 intercalated areca nut husk-derived activated carbon for the ultrasensitive detection of dichlorophen. The activated carbon is derived through a well-established activation process using areca nut husk waste, a sustainable biomass material. The material's irregular structure and large surface area provide abundant adsorption sites for the target analyte, DCP. The integration of TiO2 nanoparticles further enhances the detection capability due to their exceptional catalytic properties. Upon exposure to DCP, their interaction with the surface of composite material leads to measurable changes in its electrical and chemical properties. Cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques are used to validate the performance of the fabricated electrode. The developed ultrasensitive detection method exhibits remarkable DL (detection limit, 1.01 × 10−8 M) and QL (quantification limit, 3.36 × 10−8 M) values, hence can be a promising alternative for environmental monitoring, industrial safety, and public health applications. The synergistic effect between activated carbon and TiO2 nanoparticles ensures a highly sensitive and selective response to DCP. Consequently, this advanced sensor system has great potential for detecting and quantifying dichlorophen concentrations in diverse environmental samples.

Effect of laser cleaning on adhesive properties of carbon fiber composite materials

A pulsed fiber laser was used to conduct laser cleaning experiments on the composite paint layer on the surface of carbon fiber composite materials (carbon fiber-reinforced plastic (CFRP)). The influence of laser energy density and laser travel speed on the cleaning effect was studied. The surface morphology, surface roughness and phase composition of the cleaned sample were analyzed. After bonding, tensile testing was conducted on the bonding part to verify the impact of laser cleaning on the bonding performance. The research results indicate that the cleaning effect gradually improves with the increase of laser energy density or the decrease of travel speed. In this experiment, when the laser energy density is 4.00[Formula: see text]J/cm2 and the travel speed is 6.5[Formula: see text]mm/s, the phase composition of the cleaned substrate surface is only C, without TiO2 and BaSO4. This indicates that the paint layer has been completely removed under this process parameter. By selecting reasonable process parameters, the surface paint layer of CFRP can be effectively removed, and a good surface morphology can be obtained without damage to the carbon fiber. Meanwhile, the mechanical properties after bonding can be improved.

Immobilization of β-cyclodextrin onto the surface of electrospun fibers as rapid and highly efficient adsorbent with good recyclability

It is still a big challenge to obtain adsorbents with high adsorption rate and improved adsorption capacity. Herein, we report a novel electrospun fibers adsorbent modified with carboxylated-β-cyclodextrin (CB-β-CD) molecules for the rapid and efficient removal of phenolphthalein (PHP) from water. First, CB-β-CD is synthesized by esterification of β-CD with succinic anhydride. Subsequently, by means of polydopamine (PDA) coating rich in amine groups, CB-β-CD is covalently bonded onto the surface of poly(vinylidene fluoride)@polystyrene/PDA (PVDF@PS/PDA) fibers through the amide linkage to obtain PVDF@PS/PDA/CB-β-CD fibers adsorbent. XPS, WCA and thermal properties results suggest that large amounts of CB-β-CD molecules hang over the surface of PVDF@PS/PDA/CB-β-CD fibers and the cavities of CB-β-CD molecules are well preserved, thus providing more sites to form inclusion complexes with guest molecules. The adsorbent exhibits excellent adsorption properties for PHP, with a saturation adsorption capacity of 39.97 mg/g after 10 min, which is superior to other reported adsorbents containing β-CD. Moreover, PVDF@PS/PDA/CB-β-CD shows good recyclability and highly selective adsorption of PHP, which has potential applications in molecular recognition, organic molecules separation, and water purification. The developed method provides a new strategy for immobilizing more β-CD molecules onto the surface of composite materials to endow superior comprehensive performances.

Preparation and performance of TiO2/ZnO humidity sensor based on TiO2

In this study, TiO2 was selected as the primary material to prepare a humidity sensor. To enhance its sensing performance, it was doped with ZnO, and a TiO2/ZnO composite was synthesized via the hydrothermal method. Based on this composite material, a TiO2/ZnO humidity sensor was designed and fabricated. The sensor properties were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) techniques. The increase in hydroxyl and oxygen vacancy content on the surface of composite materials enhances their sensitivity to water molecules, leading to improved sensor response. The construction of ZTO3 heterojunction promotes the migration of electrons on the sensor surface to improves the performance of the sensor. Humidity sensor based on the TiO2/ZnO composite material exhibits excellent performance, with high response to water molecules, a fast response/recovery time (18/22 s), low humidity hysteresis (1.55 %), and low interference from monochromatic light. Thus, the TiO2-based humidity sensor doped with ZnO shows great potential for practical applications.

Effects of Additives on the Mechanical and Fire Resistance Properties of Pultruded Composites.

Under high temperatures, fiber-reinforced polymers are destroyed, releasing heat, smoke, and harmful volatile substances. Therefore, composite structural elements must have sufficient fire resistance to meet the requirements established by building codes and regulations. Fire resistance of composite materials can be improved by using mineral fillers as flame-retardant additives in resin compositions. This article analyzes the effect of fire-retardant additives on mechanical properties and fire behavior of pultruded composite profiles. Five resin mixtures based on vinyl ester epoxy and on brominated vinyl ester epoxy modified with alumina trihydrate and triphenyl phosphate were prepared for pultrusion of strip profiles of 150 mm × 3.5 mm. A series of tests have been conducted to determine mechanical properties (tensile, flexural, compression, and interlaminar shear) and fire behavior (ignitability, flammability, combustibility, toxicity, smoke generation, and flame spread) of composites. It was found that additives impair mechanical properties of materials, as they the take place of reinforcing fibers and reduce the volume fraction of reinforcing fibers. Profiles based on non-brominated vinyl ester epoxy have higher tensile, compressive, and flexural properties than those based on brominated vinyl ester epoxy by 7%, 30%, and 36%, respectively. Profiles based on non-brominated epoxy resin emit less smoke compared to those based on brominated epoxy resin. Brominated epoxy-based profiles have a flue gas temperature which is seven times lower compared to those based on the non-brominated epoxy. Mineral fillers retard the spread of flame over the composite material surface by as much as 4 times and reduce smoke generation by 30%.

Synthesis of NiCo2O4/CF composites with heterogeneous interfaces as excellent microwave absorbers

The absorbers with strong absorption capacity, wide effective absorption bandwidth (EAB), low filling, lightweight and thin thickness are the future development direction of electromagnetic wave (EMW) absorption field. NiCo2O4/CF composites were synthesized by simple hydrothermal method and calcination method in this study. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and vector network analyzer (VNA) were used to study the crystal structure, microstructure, surface chemical states and microwave absorption properties of the composites, respectively. Carbon fiber (CF) was used as nucleation carrier, and NiCo2O4 formed a dense conductive network on its surface in the shape of nanoneedles. In addition, there are abundant oxygen vacancies and heterogeneous interfaces on the surface of composite materials, which can cause dipole polarization and interface polarization and lead to more dissipation of electromagnetic wave energy. The minimum reflection loss (RLmin) of the NiCo2O4/CF composite is − 59.75 dB at the thickness of 2.01 mm. The maximum effective absorption bandwidth (RL < −10 dB) of the composite is 4.12 GHz (8.84–12.96 GHz) at the thickness of 2.18 mm. In the thickness range of 1.2–5 mm, the effective absorption frequency range of the composite material accounted for 80.78% of the measurement range (3.46–18 GHz), which covered the whole C-band, X-band and Ku-band, as well as a portion of the S-band. NiCo2O4/CF composites have the characteristics of strong absorption and wide absorption bandwidth due to the synergistic effect of dielectric loss and magnetic loss, good impedance matching characteristics and more Debye relaxation processes, which provide new inspiration for the structure and component design of lightweight microwave absorbing materials (MAMs).

Efficient fabrication of infrared antireflective microstructures on a curved Diamond-ZnS composite surface by using femtosecond Bessel-like beams.

Antireflective microstructures fabricated using femtosecond laser possess wide-ranging applicability and high stability across different spectral bands. However, due to the limited aspect ratio of the focused light field, traditional femtosecond laser manufacturing faces challenges in efficiently fabricating antireflective microstructures with high aspect ratio and small period, which are essential for antireflection, on curved surfaces. In this study, we present a robust and efficient method for fabricating high-aspect-ratio and basal surface insensitive antireflective microstructures using a spatially shaped Bessel-like beam. Based on theoretical simulation, a redesigned telescopic system is proposed to flexibly equalize the intensity of the Bessel beam along its propagation direction, facilitating the fabrication of antireflective subwavelength structures on the entire convex lens. The fabricated microstructures, featuring a width of less than 2 µm and a depth of 1 µm, enhance transmittance from 75% to 85% on Diamond-ZnS composite material (D-ZnS) surfaces. Our approach enables the creation of high aspect ratio subwavelength structures with a z-position difference exceeding 600 µm. This practical, efficient, and cost-effective method is facilitated for producing antireflective surfaces on aero-optical components utilized in aviation.

Mechanical and Thermal Properties of Multilayer-Coated 3D-Printed Carbon Fiber Reinforced Nylon Composites

This paper evaluates the mechanical and thermal properties of 3D-printed short carbon fiber reinforced composites (sCFRPs). A numerical analysis was developed to predict the mechanical and thermal properties of the sCFRPs, which were verified via experimental tests. In the experiments, a novel technique was adopted by coating the sCFRPs with carbon fiber fabric and copper mesh to further improve its mechanical and thermal performance. Various copper meshes (60-mesh, 100-mesh and 150-mesh) were integrated with carbon fiber fabric to form a multilayer structure, which was then coated on the surface of Nylon 12-CF composite material (base material) to form a composite plate. The effects of the copper mesh on the mechanical and thermal properties of the composite plate were studied theoretically and experimentally. The results show that the addition of different copper meshes had a significant influence on the mechanical and thermal properties of the composite plate, which contained carbon fiber fabric, copper mesh and the base material. Among them, the mechanical and thermal properties of the composite plate with the 60-mesh copper mesh were significantly improved, while the improvement effect slowly declined with the increase in the thickness of the base material. The composite plate with 100-mesh and 150-mesh copper meshes had improved mechanical properties, whereas the influence on its thermal conductivity was limited. For thermal conductivity calculation, both the thickness and length directions of the heat transfer were considered. The comparative analysis indicated that the calculated values and experimental results are in excellent agreement, meaning that this numerical model is a useful tool for guiding the design of surface lamination for 3D-printed sCFRPs.

Ball-milled sulfide iron-copper bimetals based composite permeable materials for Cr (VI) removal: Effects of preparation parameters and kinetics study

Zero-valent iron (ZVI) and modified ZVI have been investigated extensively for groundwater remediation. However, ZVI based powder was difficult to be applied directly as permeable reactive barrier (PRB) materials due to their low water permeability and usage rate. In this study, sulfide iron-copper bimetal was prepared by ball milling, which is environment-friendly without second contamination. The optimal preparation parameters of sulfide iron-copper bimetal for Cr(VI) removal were determined (Cu/Fe ratio (w/w), 0.018; FeS/Fe ratio (w/w), 0.1213; ball milling speed, 450 rpm; ball milling time, 5 h). A composite permeable material was prepared by sintering a mixture of sulfide iron-copper bimetal, sludge, and kaolin. The parameters for composite permeable material preparation including sludge content and particle size, and sintering time were optimized, which were 60%, 60–75 mesh, and 4 h, respectively. The optimal composite permeable material was characterized by SEM-EDS, XRD, and FTIR. The results demonstrated preparation parameters can affect the hydraulic conductivity and hardness of composite permeable material. High sludge content, small particles size, and moderate sintering time resulted in high permeability of composite permeable material and were beneficial for Cr(VI) removal. The dominant Cr(VI) removal mechanism was reduction, and the reaction followed pseudo-first order kinetics. Conversely, low sludge content and large particle size, and long sintering time lead to low permeability of composite permeable material. Chromate removal was mainly by chemisorption following pseudo-second order kinetics. The hydraulic conductivity and hardness of the optimal composite permeable material achieved 1.732 cm/s and 50, respectively. The results of column experiments indicated that its Cr(VI) removal capacity was 0.54 mg/g, 0.39 mg/g and 0.29 mg/g at pH 5, 7 and 9, respectively. The ratio of Cr(VI) to Cr(III) on composite permeable material surface was similar under acidic and alkaline conditions. This study will provide an effective reactive material of PRB for field application.

Polyoxometalates‐Modulated Hydrophilic‐Hydrophobic Composite Interfacial Material for Efficient Solar Water Evaporation and Salt Harvesting in High‐Salinity Brine

Solar vapor generation (SVG) represents a promising technique for seawater desalination to alleviate the global water crisis and energy shortage. One of its main bottleneck problems is that the evaporation efficiency and stability are limited by salt crystallization under high‐salinity brines. Herein, we demonstrate that the 3D porous melamine‐foam (MF) wrapped by a type of self‐assembling composite materials based on reduced polyoxometalates (i.e. heteropoly blue, HPB), oleic acid (OA), and polypyrrole (PPy) (labeled with MF@HPB‐PPyn‐OA) can serve as efficient and stable SVG material at high salinity. Structural characterizations of MF@HPB‐PPyn‐OA indicate that both hydrophilic region of HPBs and hydrophobic region of OA co‐exist on the surface of composite materials, optimizing the hydrophilic and hydrophobic interfaces of the SVG materials, and fully exerting its functionality for ultrahigh water‐evaporation and anti‐salt fouling. The optimal MF@HPB‐PPy10‐OA operates continuously and stably for over 100 h in 10 wt% brine. Furthermore, MF@HPB‐PPy10‐OA accomplishes complete salt‐water separation of 10 wt% brine with 3.3 kg m−2 h−1 under 1‐sun irradiation, yielding salt harvesting efficiency of 96.5%, which belongs to the record high of high‐salinity systems reported so far and is close to achieving zero liquid discharge. Moreover, the low cost of MF@HPB‐PPy10‐OA (2.56 $ m−2) suggests its potential application in the practical SVG technique.

The investigation of wear properties of nanoparticle-reinforced epoxy composite material surfaces

This study added nano-sized Al2O3, Boron, and TiO2 powders to the epoxy polymer at 0.5% and 1% ratios. Abrasive wear resistance properties of nanoparticle-reinforced epoxy polymers were investigated. First cylindrical specimens with and without additives were prepared for realizing the experimental research. Pin-on discs were used for the wear test of epoxy samples. The mass losses were measured via a precision scale. According to the results, the boron nanoparticles have increased the epoxy specimens’ resistance. As a result of the experimental studies, it was observed that the wear resistance of the epoxy composite increased with each nano-sized powder added to the epoxy. SEM and optical profilometry investigated the composites’ friction coefficient and surface morphology. As a result of friction coefficient and wear weight loss tests, the highest wear resistance was obtained in 1% boron powder nano-reinforced epoxy composites. It was observed that the epoxy friction coefficient was in the range of 0.4–0.6, which decreased to the range of 0.2–0.4 with the addition of nano boron. The surface roughness value after epoxy wear was measured as 1.4 μm. With the addition of nano boron, this value was measured as 0.32 μm. Optical profilometry and SEM imaging results also support these values.

Peroxide-Free Bleaching Gel: Effect on the Surface and Mechanical Properties of Nano- and Micro-Hybrid Restorative Composite Materials

This laboratory investigation was designed to test the influence of a novel bleaching formulation based on phthalimidoperoxycaproic acid (PAP) with additives on the surface and mechanical properties of nano- and micro-hybrid restorative composites. Twenty-four bar-shaped and twelve disk-shaped samples from each restorative composite were prepared. The samples from each restorative composite were randomly divided into two groups according to the treatment, i.e., experimental and control. The treated groups went through the bleaching process: by Opalescence Regular or novel PAP+-containing gel (HiSmile™). The treated group underwent a bleaching process for seven consecutive days (a 10-min session of bleaching application every day) before the properties were tested. A paired sample t-test was performed to compare the results between the experimental and the control groups. The level of significance was set at 0.05. The surface roughness of the nanohybrid composite using Opalescence Regular (p &lt; 0.05) was significant. Additionally, a significant difference in nanohardness and elastic modulus between the experimental and the control groups of the microhybrid composite using Opalescence Regular was observed: p = 0.041 and p = 0.023, respectively. While a marked difference in flexural strength was observed in the experimental and control groups using Opalescence Regular, Hismile™ bleaching gel caused a diminutive and insignificant reduction in tested properties (p &gt; 0.05). It was found that Opalescence Regular bleaching gel affects the surface and bulk properties of restorative composite materials, whereas the novel PAP+ formulation has no deleterious effect on either nano- or micro-hybrid restorative composites.

Study of Air Pressure on Arc Ion Plating on Epoxy Resin Matrix Composites at Meter Range Working Distance

The metal film was deposited on the surface of epoxy resin based composite by arc ion plating technology. The distribution of metal ions at the interface of matrix was simulated. The growth mode of metal ions on the composite surface was analyzed. The deposition rate, surface morphology and membrane base bonding strength were investigated. The results show that the transition layer of nm level will be formed on the surface of composite materials, and the larger the sputtering energy of metal ions, the deeper the distribution on the surface of composite materials. Nucleation occurs at the junction of fiber and resin matrix, and the fusion of nucleated particles grows along the fiber boundary with the increase of deposition time, and extends to the vertical fiber direction. Finally, the particles between fibers and the particles on the boundary gradually expand and merge into layered films. The working pressure decreased, the deposition rate of metal increased, the grain size decreased, the large particles on the surface of the metal coating decreased, and the bonding strength of the film base increased.

Effect of Low-Temperature Plasma Surface Treatment on Bonding Properties of Single-Lap Joint of Thermosetting Composites

Bonding is one of the main forms of composite bonding. In order to investigate the effect of low-temperature plasma surface treatment on the bonding properties of carbon fiber-reinforced epoxy resin composites (CF/EP), a single-lap joint of CF/EP was prepared. The surface of the CF/EP was treated with atmospheric pressure "low-temperature plasma spray" equipment, and the tensile shear strength, surface morphology, surface contact angle and surface chemical composition of the CF/EP before and after plasma treatment were characterized. Finally, the samples were treated with traditional sandblasting, compared and analyzed. The results show that the effect of low-temperature plasma surface treatment on CF/EP joints is better than that of traditional sandblasting treatment. After low-temperature plasma surface treatment, the tensile shear strength of the CF/EP single-lap joint increased by 119.59% at most, and the failure form of the joint changed from untreated interface failure to mixed failure dominated by cohesion failure. Plasma can etch the surface of composite materials, the mechanical interlock between the carbon fiber and glue is enhanced and the bonding performance of the composite is improved. In addition, after low-temperature plasma surface treatment, the introduction of a large number of oxygen-containing active groups such as C-O and C=O can increase the surface free energy, reduce the contact angle and improve the surface activity and wettability of the composites. However, too long a treatment time will lead to excessive plasma etching of carbon fibers, thus weakening the active effect of the oxygen-containing active groups on the surface of the composites, and the surface wettability is no longer improved, but the adhesive properties of CF/EP are reduced. This paper plays a guiding role in the bonding technology of composite materials.

Study on anti-icing performance of carbon fiber composite superhydrophobic surface

The icing phenomenon widely exists in the nature and has become an urgent problem to be solved in the fields of aerospace, wind power generation, and other fields. Scholars have been undertaking much research on surface anti-icing technology, but it has always been a challenge to develop an efficient, energy-saving, environmentally friendly, stable and durable anti-icing surface. In this study, hydrophobic silica nanoparticles were used to hydrophobically modify the matrix material, and a metal screen was used as a template, combined with hot-pressing process. The superhydrophobic surface of carbon fiber composite material with anti-icing property was prepared. The results showed that the water contact angle of the surface was 156 ± 2°, the sliding angle was 2 ± 1.5°, and the number of water drops bouncing on the surface was 7 times. Compared with the untreated test sample, the surface ice content decreased by 4 times, and the ice adhesion strength decreased by 2 times. Besides, the surface also had excellent contact state recovery and mechanical stability. During the process of icing and thawing, the contact state between the droplet and the surface changed spontaneously from Wenzel model to Cassie model. After 30 cycles of icing and de-icing, the surface still maintained a water contact angle of more than 150°and an ice adhesion strength of less than 50 KPa. The preparation method of this study is simply, rapid, low-cost, green and environment-friendly, which provides reliable theoretical guidance and design ideas for surface anti-icing technology and effectively promotes the large-scale production and application of superhydrophobic surfaces in the field of anti-icing.