Inorganic Fullerene-like Tungsten Disulfide Research Articles

Addressing Irreversibility and Structural Distortion in WS2 Inorganic Fullerene-Like Nanoparticles: Effects of Voltage Cutoff Experiments in Beyond Li+-Ion Storage Applications.

Large interlayer spacing beneficially allows Na+- and K+-ion storage in transition-metal dichalcogenide (TMD)-based electrodes, but side reactions and volume change, which pulverize the TMD crystalline structure, are persistent challenges for the utilization of these materials in next-generation devices. This study first determines whether irreversibility due to structural distortion, which results in poor cycling stability, is also apparent in the case of inorganic fullerene-like (IF) tungsten disulfide (WS2) nanocages (WS2IF). To address these problems, this study proposes upper and lower voltage cutoff experiments to limit specific reactions in Na+/WS2IF and K+/WS2IF half-cells. Three-dimensional (3D) differential capacity curves and derived surface plots highlight the continuation of reversible reactions when a high upper cutoff technique is applied, thereby indirectly suggesting restricted structural dissolution. This resulted in improved capacity retention with stable performance and a higher Coulombic efficiency, laying the ground for the use of TMD-based materials beyond Li+-ion storage devices.

Inorganic Fullerene-Like WS2 Reinforced Polyamide Powders for Improved Mechanical Properties in Laser Sintered Nanocomposite Parts

Polyamide (PA) is a widely utilized engineering polymer, and its thermal and mechanical properties can be further improved by adding nanofillers. However, adding inorganic fullerene-like tungsten disulfide (IF-WS2) nanoparticles (NPs) to PA to produce composite precursor powders for additive manufacturing is challenging. Here, we report a novel and cost-effective method for fabricating PA-12 based nanocomposite (NC) powders with fixed/partially encapsulated IF-WS2 nanoparticulate fillers utilizing an advanced mixing technique because simple wet mixing (WM) can only attach fillers weakly to the powder surfaces when compared to the proposed method. The resulting nanocomposite powders maintained nearly the original particle size distribution of PA-12. They also exhibited improved rheological properties, melting, and crystallization behaviors compared with those prepared by the WM method. The laser-sintered PA-12 nanocomposite specimens revealed enhanced powder thermal stability and higher tensile strengths than pristine PA-12, validating the advantages of the novel technique for the fabrication of polyamide nanocomposite powders and their suitability for utilization in laser sintering additive manufacturing. These results demonstrate that high-performance engineered PA-12 nanocomposite components can be directly laser sintered, and this technique can potentially be extended to fabricate other engineered polymeric nanocomposite powders.

Inorganic fullerene-like tungsten disulfide/waterborne polyurethane reinforced Spectra® composites with improved mechanical properties and tensile energy absorption

Fiber-based nanocomposites play a significant role in bullet-resistant, anti-impact, and aerospace applications. This research was conducted to (1) determine the feasibility of preparing inorganic fullerene-like tungsten disulfide (IF-WS2)/waterborne-polyurethane (WPU) dispersions in varying water/ethanol mediums and (2) study the effects of IF-WS2/WPU impregnation on mechanical and tensile energy absorption properties of ultra-high molecular weight polyethylene (UHMWPE) fibers. The characterization results indicate that the WPU showed poor solubility in ethanol causing low distribution uniformity of IF-WS2 and WPU on fibers. Comparable mechanical properties were obtained for the optimal samples prepared with water and water/ethanol mediums. The maximum load, energy to break, and normalized energy to break increased by 26.5%, 44.9%, and 31.1% for the 2 wt% IF-WS2/10 wt% WPU/UHMWPE composite prepared with water medium, respectively. Neat UHMWPE fibers showed failure mechanisms of fiber breakage, delamination, fibrillation, and splitting, while additional ductile breakage and matrix debonding were observed on WPU/IF-WS2 incorporated UHMWPE composites.

Selective laser sintering of functionalized carbon nanotubes and inorganic fullerene-like tungsten disulfide reinforced polyamide 12 nanocomposites with excellent fire safety and mechanical properties

More effective and safe fire prevention solutions for polymer derivatives are necessary to address rising environmental and health concerns. In this study, the novel and simple chemically modified multi-walled carbon nanotubes (H-CNT) and PEGylated inorganic fullerene tungsten sulphide (P-IF-WS2) reinforced PA12 nanocomposites are synergistically prepared via selective laser sintering (SLS). The PA12/H-CNT/IF-WS2 nanocomposites show a wider sintering window than blank PA12. The formed hydrogen bond network of inter-chain contacts and compatibility in PA12/H-CNT/P-IF-WS2 matrix is proved. Furthermore, a dense carbon layer is developed by further dehydrating the oxygen-rich functional groups on the surface of H-CNT and P-IF-WS2 during carbonization at high temperatures. The PA12/H-CNT/P-IF-WS2 nanocomposites fabricated by incorporating hydrogen and carbon bonds in the PA12-based nanocomposites demonstrate good fire safety, thermal, and mechanical properties. The significant reduction in total heat release (20.14%), peak heat release (38.9%), and total smoke emission (22.6%) showed the improved fire safety of PA12. The H-CNT and P-IF-WS2 nanofillers also enhanced the mechanical (tensile and dynamic mechanical) capabilities. This technique of introducing nano-additives to SLS samples changes offers a practical, long-lasting, and effective way to improve the flame retardancy of laser-sintered polymer nanocomposites.

Tribological and Friction-Induced Vibration Behaviors of Inorganic Fullerene-Like Tungsten Disulfide and Three-Dimensional Graphene as Lubricant Additives

Abstract Friction and friction-induced vibration have a great impact on the service life of mechanical systems. In this study, the tribological performances and vibration characteristics of three-dimensional graphene nanosheets (3D GNS), inorganic fullerene-like tungsten disulfide (IF-WS2), and their mixed additive lubricants are investigated by experiments. The results show that IF-WS2/3D GNS (1:1) mixed additive can improve the friction-reduction and anti-wear of base oil by 62.9% and 71.4%, respectively. In terms of vibration damping, the mixed additive has an extremely strong dampening effect on vibration acceleration in all directions, especially in the Z-axis direction, where the amplitude is reduced by about 90%. The vibration damping should be attributed to the filling effect of 3D GNS and IF-WS2, which greatly flattens the friction surface, thus reducing the number of collision micro-bumps in the relative movement of the friction pair and suppressing the vibration. In addition, the unique ductile deformation of IF-WS2 makes the two additives form a flexible ball-bearing damper between the two contact surfaces, thus greatly reducing the vibration.

Mechanical and thermal degradation behavior of inorganic fullerene-liked tungsten disulfide reinforced perfluoroalkoxy/poly(ether-ether-ketone) nanocomposites

Enhancing the mechanical, thermal properties and obtaining the thermal degradation mechanism of polymers is crucial for designing advanced polymer composites. Here, an inorganic fullerene-like tungsten disulfide nanoparticle reinforced perfluoroalkoxy and poly(ether-ether-ketone) (PFA/PEEK/IF-WS2) nanocomposites were developed using solution mixing and polymer blending techniques. This work investigated the mechanical, thermal properties and thermal degradation behavior of PFA/PEEK blends and PFA/PEEK/IF-WS2 nanocomposites. FTIR analysis demonstrated the interacting hydrogen bonds. SEM and TEM showed the compatibility of the incompatible PFA/PEEK blend was improved with the introduction of IF-WS2. TG analysis indicated that IF-WS2 enhanced the thermal stability of PFA/PEEK blends. The PFA/PEEK/IF-WS2 nanocomposites exhibited better mechanical properties, especially tensile properties, with a 37.9% increase in tensile strength and a 106% increase in storage modulus. DSC showed that compared with pure PFA, the initial melting temperature of the 80/20/1% sample was increased by 8.64 ℃, and the crystallinity was increased by 9.44%. TG-IR analysis showed that IF-WS2 delayed the time of thermal decomposition products and reduced the yield of organic volatiles. Excellent barrier properties and good compatibility of IF-WS2 in the PFA/PEEK blends are considered to be the keys to enhance mechanical and thermal performances.

Impact of Ionic Liquid Additives and Inorganic Fullerene-Like Tungsten Disulfide on Friction and Wear under Aqueous Environments.

Aqueous lubricants are gaining attention due to significant advantages such as being environmentally friendly, tunable, and thermally stable. The oil and gas industry can use such additives to utilize in water-based fluids for applications where small sliding velocities and large lateral forces require enhanced lubrication. This investigation aims to compare the effects of two different additives: (i) inorganic fullerene-like tungsten disulfide (IF-WS2) and (ii) an alkanolamine ionic liquid denoted as AA-IL. Both additives were paired with three different base fluids, deionized water (DIW), aqueous NaCl, and aqueous CaCl2, to measure the impact on fluids commonly utilized in the field. The addition of IF-WS2 to all three solutions resulted in a 30-60% decrease in the coefficient of friction (COF) and wear. Surface analysis by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDS) showed that the formation of a tribofilm (tungsten oxide layer) is primarily responsible for tribological improvements. The AA-IL did not show evidence of any chemical interaction. Instead, a physically bonded film of the AA-IL on the steel surface enabled the improved COF (40-50% reduction) and wear response. Both additives are effective in very small amounts and provide excellent wear and friction reduction properties.

The Influence of Sample Preparation on SEM Measurements of Anodic Oxide Layers

Abstract Coatings with high wear, corrosion resistance and sliding properties are desirable in tribological applications, especially for oil-free nodes. In order to obtain such coatings on aluminium alloy the anodizing process is one of the methods which is commonly used. In the present research two kinds of anodic oxide layer were prepared. One series of samples comprised amorphous oxide layer Al2O3 obtained on aluminium alloy EN AW 5251. The second one was the composite oxide layer Al2O3 with inorganic fullerene-like tungsten disulfide (IF-WS2). The addition of IF-WS2 to an acid bath is used to reduce the friction coefficient of the oil free friction pair. The aim of the study is the analysis of the surface and fresh cross section of the samples depending on the kind of conductive metal used for SEM examination. Gold and carbon were used in order to prevent the charging of a specimen with an electron beam in the conventional SEM mode. Significant differences in the interpretation of results were found.

Synergistic low friction effect and mechanism of inorganic fullerene-like tungsten disulfide and talcum at the interface of steel tribo-pairs under severe conditions

Poor lubrication can lead to sever wear of mechanical equipment and even cause its failure, nevertheless, lubricating additives are able to effectively alleviate the negative results. In this work, nano-additive lubricants used in the interface of steel tribo-pairs are prepared by inorganic fullerene-like tungsten disulfide and talcum nanoparticles, which can improve the friction-reduction and wear-resistance performances of base lubricant by as much as 25% and 50%, respectively. On the one hand, the macroscopic characterization reveals that the improved tribological performance comes from the synergistic effect of the two nano nanoparticles. On the other hand, the phenomenon has been further explored by molecular dynamics. The macroscopic and microscopic interface interaction mechanism between the nano-additives, investigated in the study, indicate valuable reference for the investigation of improved nano-additive lubricating oil in the future.

Three-body abrasive wear in the presence of inorganic fullerene-like tungsten disulfide and ionic liquid containing alkanolamines and phosphates

In coiled tubing applications, common constraints e.g., high friction, lateral drag and restricted flow rate increase the demand for friction modifiers. These modifiers also face the inevitable intrusion of abrasive particles in the wellbore that impair the drilling efficiency and accelerate wear of the sliding components. This study shows the tribological effect of sand particles in plain deionized (DI) water, resulting in a high friction environment with the risk of particles embedding in a two-body sliding behavior. To mitigate the drilling system’s performance degradation, two additives, inorganic fullerene-like tungsten disulfide (IF-WS2) and an ionic liquid with alkanolamines named “Base,” were added and their synergic tribological effects with sand were investigated. The presence of sand particles offered a reduction in coefficient of friction (COF) by 22% in the presence of DI water + IF-WS2, and a slight increase in wear. The Base additive was not as efficient as IF-WS2 at the same sand content, resulting in an increase in the COF and wear. In addition to the rolling friction, the gradual exfoliation of the IF-WS2 played an important role in alleviating friction and wear, leading to formation of tungsten-based tribolayer on sand particles.

Design and Evaluation the Anti-Wear Property of Inorganic Fullerene Tungsten Disulfide as Additive in PAO6 Oil

Inorganic fullerene-like tungsten disulfide particles have been proved to have good anti-friction and anti-wear properties as lubricating materials. As far as we know, however, when it is used as a lubricant additive, its behavior and action mechanism in the friction process are rarely studied. Herein, IF–WS2 particles were synthesized by a Chemical Vapor Deposition (CVD) method. The effect of IF–WS2 particle concentrations in the PAO6 oil on the tribological behaviors was investigated with a four-ball wear machine at both 75 and 100 °C. Additionally, the analyzed morphology and composition of nanomaterials and worn surfaces were analyzed by Scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The friction behavior in actual working conditions was studied by a wear testing machine. The experimental results show that compared with the original PAO6 oil, at a dispersion of 0.25 wt% in PAO6 oil, the IF–WS2 particles showed the best performance in terms of coefficient of friction, wear scar diameter and wear mass, which significantly reduced by 27%, 43% and 87%, respectively. At the same time, in the process of friction, it was found that IF–WS2 particles accumulated in the depressions to fill the scratches, and adsorption films and chemical films, including FeS2, WS2 and WO3, were formed on the worn surfaces to avoid the direct contact among the friction pairs more effectively, resulting in the improved anti-wear performances. Additionally, the addition of IF–WS2 particles effectively delayed the rise of lubricating oil temperature. In addition, dispersant span 80 can effectively improve the dispersion and stability of IF–WS2 in PAO6. This work provides us for understanding the effective lubrication mechanism of IF–WS2 particles in more detail and having a new acknowledge of the comprehensive performance of IF–WS2/PAO6 oil.

Employment of Micro- and Nano-WS2 Structures to Enhance the Tribological Properties of Copper Matrix Composites

Friction and wear are responsible for around 23% of the energy consumption in transportation, manufacturing, power generation, and residential sectors. Employed components are exposed to a wide range of operational conditions, therefore a suitable material design is fundamental to decreasing tribological issues, energy consumption, costs, and environmental impact. This study aims to analyze the effect of different solid lubricants on the suitability of copper matrix composites (CuMCs) as a potential solution to reduce the depletion of sliding electrical contacts working under extreme conditions. CuMCs samples are produced by cold-pressing and sintering to merge a high electrical conductivity with the lubricant effect supplied by different species, namely tungsten disulfide micro-powder (WS2), inorganic fullerene-like (IF) tungsten disulfide nanoparticles, and graphene nanoplatelets (GNP). The crystalline structure of the pristine and composite materials is characterized via XRD. The electrical tests show a small decrease of conductivity compared to pure copper, due to the insulating effect of WS2; however, the measured values are still adequate for conduction purposes. Micro-scratch and wear tests highlight the positive effect of the combination of WS2 structures and GNP. The friction coefficient reduction leads to the possibility of extending the lifetime of the components.

Novel Hybrid Nanostructures of Carbon Nanotube/Fullerene-like Tungsten Disulfide as Reinforcement for Aramid Fabric Composites

Multilayered composites based on aramid fabrics are widely used in impact protection. The objective of this study is creating a new kind of multiaxial aramid fabric composites with inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS2) and single walled carbon nanotubes (SWCNT) used as nanoreinforcement to enhance the dynamic mechanical and anti-stabbing properties of the composites. The four composites of the Kolon fabric forms were impregnated with 10 wt.% poly(vinyl butyral) (PVB)/ethanol solution which contained different forms of IF-WS nanoparticles. The surfaces of IF-WS2 were coated with silane coupling agent (m-IF) and the SWCNT were oxidized (o-SWCNT) for the fabrication of the o-SWCNT/m-IF hybrid nanoparticles. The mechanical testing showed that the Kolon/PVB/o-SWCNT/m-IF sample produced nearly 62 % of improvement in the tensile strength and 51 % of improvement in the tensile energy absorption compared to the Kolon/PVB sample. Furthermore, the sample with the o-SWCNT/m-IF hybrid nanoparticles demonstrated 24 % of enhancement in the impact toughness and 48 % of improvement in the absorbed energy after knife penetration in comparison with the Kolon/PVB sample.

Nanofluids for Performance Improvement of Heavy Machinery Journal Bearings: A Simulation Study.

Nanofluids have extensive applications in hydrodynamic journal bearings used in heavy industry machinery. Inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS2 NPs) are the most common additive for lubrication purpose due to their excellent mechanical characteristics along with their effect on reducing friction and wear. In this work, a computational simulation approach with discrete phase modeling (DPM) of suspended nanoparticles was used to evaluate the application of the IF-WS2 nanofluid lubricant on load carrying capacity of high-load journal bearings where the normal loads are high, considering the bearing dimensions. For accurate simulation, nanofluid viscosity was calculated considering the aggregation effect of NPs by using scanning electron microscopy (SEM) imaging of the nanofluids. A benchmark study was first performed to assess the model accuracy. Hydrodynamic lubrication was simulated under different nanofluid weigh fractions. The simulated pressure distribution was then employed to determine the load capacity of the bearing. The results show an approximately 20% improvement of load carrying capacity at 5% weight fraction of WS2-oil nanofluid.

Fabrication of nanocomposite powders with a core-shell structure

This study presents a new process for producing nanocomposite powders for use in various manufacturing processes such as laser sintering or dry powder impregnation techniques for thermoplastic composites manufacture. Polyetherimide (PEI) was used as a polymeric coating/shell to encapsulate nanoparticles on the surface of poly ether ether ketone (PEEK) particles, which were used as a core matrix. Nanoparticles with different morphologies, known to enhance thermal and electrical performance of polymers: 2D graphene nanoplatelets (GNPs) and inorganic fullerene-like tungsten disulfide (IF-WS2) in different concentrations (0.1, 1, and 5 wt%) were incorporated in the shell structures. The coated powders had approximately the same particle size distribution as the uncoated, plain powders, which is an indication that the shell was in nm size and the coating process did not affect the overall size of the particles. Furthermore, the core-shell particles exhibit a smoother surface and an improved flowability after coating. The Transmission Electron Microscopy (TEM) images of the nanocomposite particles cross-section area confirmed the formation of core-shell structure, and the presence of the nanoparticles embedded into the shell layer. The scanning electron microscopy (SEM) images showed a homogeneous distribution of nanoparticles within the coating layer at lower nanoparticle concentrations (0.1 and 1 wt%).

Influence of the Size of Nanoparticles on the Microstructure of Oxide Coatings

The microstructures and structures of composite coatings prepared on aluminum substrates are studied. Amorphous oxide layers Al2O3 are obtained on EN AW 5251 aluminum alloy. In the Al2O3 coatings, two kinds of inorganic fullerene-like (IF) tungsten disulfide (WS2) nanoparticles (NPs) are introduced by a dip coating method. In order to show the difference between the possibilities of introducing NPs in the microstructure of Al2O3, we carried out the scanning electron microscopy and transmission electron microscopy analyses. The image processing and analysis were performed in order to study the shapes and sizes of the IF-WS2 nanoparticles. Visual comparative analysis reveals the difference in the quality of nanopowders that greatly affects their ability to form agglomerates and, hence, strongly affects the possibility of introducing NPs into nanopores.

Aramid hybrid composite laminates reinforced with inorganic fullerene-like tungsten disulfide nanoparticles

Abstract Combination of phenolic resin with poly (vinyl butyral), PVB, is often used as impregnation of aramid fabrics in prepregs for the ballistic protection products. In this study an effect of inorganic fullerene-like tungsten disulfide nanoparticles (IF-WS 2 ) in aramid/phenolic resin/PVB composite for improving its viscoelastic and mechanical properties is examined. The effect of IF-WS 2 on mechanical properties improvement was first proved by nanoindentation on thin film samples PVB/IF-WS 2 . The quality of aramid fabrics impregnation with PVB/phenolic resin/IF-WS 2, and the nanoparticles dispersion were analyzed by scanning electron microscope with energy dispersive spectrometer. Viscoelastic properties of the composites were examined by dynamic mechanical thermal analysis, observing the storage and loss modulus, mechanical loss factor and glass transition temperature versus temperature and frequency. Time-temperature superposition principle was applied for the construction of master curves. IF-WS 2 causes increase of glass transition temperature and improvement in mechanical properties of examined composites.

Inorganic fullerene-like IF-WS2/PVB nanocomposites of improved thermo-mechanical and tribological properties

The subject of this research is to explore the possibility of preparation of nanocomposite material of improved thermo-mechanical and tribological properties, using inorganic fullerene-like tungsten disulfide nanostructures (IF-WS2) as reinforcement in poly(vinyl butyral) (PVB). This paper also reports investigation of the effects of using different solvents in preparation of PVB/IF-WS2 nanocomposite on the thermo-mechanical behavior of the resulting material. PVB was dissolved in ethanol, isopropanol, n-butanol and ethyl acetate. IF-WS2 nanoparticles were added to these PVB solutions and dispersed by different deagglomeration techniques. Samples were dried and thin films were obtained. Their microstructure and the quality of IF-WS2 dispersion and deagglomeration in PVB matrix was analyzed by scanning electron microscope (SEM). The reinforcing effect of IF-WS2 is examined by determining hardness, reduced modulus of elasticity and coefficient of friction, by nanoindentation and nanoscratch test, in terms of the different solvents applied in preparation of the samples, mode of stirring and different contents of IF-WS2. The glass transition temperature (Tg) was determined for the prepared samples using differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMA). Storage modulus and mechanical loss factor were observed in a defined temperature range using DMA.

Tribological behaviour of Al<SUB align="right">2O<SUB align="right">3/inorganic fullerene-like WS2 composite layer sliding against plastic

With the aim of proposing new materials with good properties for dry sliding contact, aluminium oxide layers Al2O3 with inorganic fullerene-like tungsten disulfide IF-WS2 - were obtained and tested. The results of tribological tests, surface topography measurements and SEM analysis are presented. The top layer of the anodised (porous) aluminium-oxide film was loaded with fullerene-like nanoparticles (NP) of WS2 (IF-WS2). Ethanol (method A) and glycol ethylene (method B) were used as dispersive liquids. The tribological properties were investigated by conducting wear tests of Al2O3/IF-WS2 (inorganic fullerene-like tungsten disulfide) coatings against a TG15 plastic (politertrafluotoethylene - graphite) counter-body under pin-on-plate reciprocating motion in dry contact conditions. Non-parametric statistical ANOVA (by Kruskal-Wallis) showed that Al2O3/IF-WS2 layers (method B) had a higher dispersion of the results of both the friction coefficient and the wear intensity of TG15 material while they were in contact. A lower value of wear intensity and a smaller spread of data predispose the Al2O3/IF-WS2 layer produced by method A more to a sliding contact compared to the layer obtained by method B.

Preliminary analysis of the possibility of preparing PVB/IF-WS2 composites. Effect of nanoparticles addition on thermal and rheological behavior of PVB

A possibility of using inorganic fullerene-like tungsten disulfide, IF-WS2, nanoparticles as a filler in poly (vinyl butyral), PVB, for improving its thermal and rheological properties is examined. PVB is a thermoplastic polymer with excellent properties, widely used: in ballistic protection, for protection of safety glass, in metal primers and coatings, temporary binders. Two different molecular weights of PVB were previously examined in this research: Mowital B60H and B75H. Both grades of PVB were dissolved in different solvents: ethanol and 2-propanol. Thin films were prepared by solvent casting technique. The glass transition temperature (Tg) of the tested samples was determined using differential scanning calorimetry (DSC), at three different heating rates (5°C/min, 10°C/min and 20°C/min). After choosing a solvent and PVB grade, IF-WS2 nanoparticles were added to PVB solutions and dispersed by ultrasonic irradiation. Compatibility, i.e. interaction of IF-WS2 with the dissolved PVB was examined by microcalorimetry method. The nanoparticles dispersion and deagglomeration in matrix of PVB was analyzed by scanning electron microscope (SEM). The effect of IF-WS2 on rheological properties of the chosen samples has been examined using Dynamic Mechanical Thermal Analysis (DMTA), observing storage modulus, loss modulus and the loss factor as functions of temperature for the tested composites.