Formation Of Continuous Film Research Articles

Inhibition of interfacial cracks in 304L-Inconel718 bimetal fabricated via laser powder bed fusion

Multi-material additive manufacturing is crucial for intricate component fabrication, yet challenges, such as interfacial cracks and weak bonding, persist. This work investigated the laser powder bed fusion (L-PBF) of bimetallic components (stainless steel 304L-nickel-based alloy Inconel718) crucial in aerospace and nuclear applications. It is found that the interfacial cracks predominantly occur within the compositional transition zone where the proportion of 304 L is between 45 wt% and 75 wt%, characterized by brittle Laves phases along grain boundaries. Experimental and finite element simulations of melt pool reveal that a higher ratio of temperature gradient (G̅) to the grain growth rate (R̅) (G̅/R̅) results in straight grain boundaries with underdeveloped secondary dendrites. This leads to the formation of continuous liquid film and strip-like Laves phase at grain boundaries, causing interfacial cracks during L-PBF. To suppress these cracks, this work proposes manipulating grain boundaries into a tortuous morphology through promoting the growth of secondary dendrites. By controlling the G̅/R̅ ratios below the critical value (<147.9×106 K∙s/m2) and combining with a high cooling rate (G̅×R̅) during L-PBF, a well-developed secondary dendritic structure and grain refinement are achieved, significantly enhancing grain boundary tortuosity and forming discretely distributed Laves phases. As a result, interfacial cracks are completely suppressed, enabling the successful manufacturing of crack-free 304L-Inconel718 bimetallic components. The approach of tailoring the distribution of brittle precipitates through manipulating grain boundary morphology proposed in this work provides a novel and practical pathway for inhibiting cracks in multi-material additive manufacturing.

Manipulating photoelectric properties at ZnO/Ag/ZnO sandwich structure by Ag intercalation

We investigated the relationship between the thickness of Ag and the photoelectric properties of ZnO/Ag/ZnO sandwich structure. The experiments show the Haacke figure of merit (FOM) of ZnO/Ag/ZnO increases and then decreases with the increase of Ag thickness, and the maximum value appears at the thickness of 10 nm, indicating the formation of continuous films of Ag is the key to enhance the performance of transparent conductive electrodes (TCEs) of sandwich structure. Furthermore, density functional theory (DFT) simulations were used to investigate Ag/ZnO heterojunctions with different coverage and thickness of Ag. It was found that the two-dimensional monolayer Ag/ZnO heterojunctions with 100 % coverage had the highest interfacial charge transfer values as well as visible transparency, which confirmed the idea of reducing the thickness of Ag by two-dimensional growth to enhance the performance of ZnO/Ag/ZnO as TCE.

Probing Pt-CeO2 interfacial interactions through adsorption characteristics of small molecules

In this study, we prepared a Pt/CeO2/Cu(111) model catalyst and investigated CO and CO2 adsorption using infrared reflection absorption spectroscopy (IRRAS) and temperature-programmed desorption (TPD) techniques to gain insight into the interaction between Pt nanoparticles and the CeO2 support surface. Our observations revealed that the deposition of CeO2 at 700 K results in island formation on the Cu(111) surface, whereas at 520 K it leads to a more continuous film formation. Reducing the CeO2/Cu(111) surface enhances the CO and CO2 uptakes on CeO2. Pt nanoparticles deposited on these surfaces remained in a metallic form, and during CO desorption, they facilitate the oxidation of CO to form CO2 by utilizing lattice oxygen from the interface between them and CeO2.

Microstructure characteristics and degradation behaviors of medical rare-earth Mg-10.6Gd-0.3Ag-x(Y/Zn) alloys in vitro

Due to excellent biological-functionality, unique/suitable elastic-modulus as well as spontaneous degradation behaviors, Mg alloys acted as medical implants have shown enormous potential in surgical operation and bone-fixation fields. Unfortunately, the extreme mass loss and unmarked-fracture could easily induce the implant failure. In the present study, the microstructure characteristics and degradation behaviors of the Mg-10.6Gd-0.3Ag-x(Y/Zn) alloys were investigated through the XRD, TEM, EPMA, XPS, 3D/CLSM and SECM. Results revealed that with the increment of Y/Zn contents, the amount of Mg24(Gd/Y)5 precipitates increased, which were mainly distributed in grains and on grain boundaries. The addition of Zn and Y increased the undercooling and Y had a large mismatch degree with Mg atoms, which could promote the precipitation of second phases. Additionally, the corrosion rates of Mg-10.6Gd-0.3Ag-x(Y/Zn) increased firstly and then reduced. Also, the best corrosion resistance was achieved in the Mg-10.6Gd-0.3Ag-Y-Zn, with the current intensities of 58.49 μA/cm2, attributed to the formation of continuous reticular structure oxide film, which can act as physical barriers and impede the corrosion process.

Tribological synergy of copper‐based metal–organic frameworks, carbon fibers and SiO2 in modifying the friction and wear properties of epoxy composites

AbstractCopper‐based metal–organic frameworks is anticipated to find applications in the field of friction materials owing to its plentiful surface‐active groups and distinctive framework structure. In this study, copper‐based metal–organic frameworks was synthesized through ultrasound‐assisted method and incorporated alone into carbon fiber reinforced epoxy composites or together with SiO2 nanoparticles towards the goal of improving the composites' friction and wear properties. It is revealed that copper‐based metal–organic frameworks alone cannot improve the friction and wear of carbon fiber reinforced epoxy composites simultaneously. The combination of copper‐based metal–organic frameworks and SiO2 nanoparticles was more effective in enhancing both the mechanical and tribological properties of studied composites. The composite material exhibits a friction coefficient of 0.104 under the specified test conditions of 10 MPa and 3.75 m/s. Additionally, the specific wear rate is impressively low, measuring only 5.64 × 10−7 mm3 N/m. Through morphological and chemical analysis on the worn surfaces and transfer films, the functioning mechanism of copper‐based metal–organic frameworks in modifying the mechanical and tribological properties was discussed. It was discovered that a tribological synergy exists between short carbon fibers, copper‐based metal–organic frameworks, and SiO2 fillers, leading to a shift in the wear mechanism of the composite materials from abrasive wear to adhesive wear. Concurrently, a shear‐prone transfer film forms on the surface of the counter steel surfaces. Findings of the present study pave a new route of designing high performance epoxy based tribo‐composites by using metal–organic frameworks.Highlights Cu‐BDC nanosheets were synthesized using ultrasound‐assisted techniques and incorporated as tribological fillers in EP composites. The combined use of Cu‐BDC, SiO2, and SCF fillers synergistically enhances the mechanical and tribological properties of EP composites. The composite material exhibits a friction coefficient of 0.104 under the specified test conditions of 10 MPa and 3.75 m/s, the specific wear rate is impressively low, measuring only 5.64 × 10−7 mm3N/m. During the sliding friction process of the composite materials, Cu‐BDC and SiO2 play a crucial role in reducing SCF pull‐out wear through their anchoring effect. The dynamic coordination bond structure of Cu‐BDC contributes to the formation of uniform and continuous transfer films on counter metal surfaces.

Graphene films grown by chemical vapor deposition and their applications

In this article we provide the results of the synthesis of graphene films and discuss their potential applications in electronic structures. Graphene films were synthesized on copper foil using the CVD method at 1050 °C. During the initial stage of synthesis, graphene domains with hexagonal shapes and an average size of 10 μm were formed. The orientation and size of the graphene domains are based on the synthesis parameters and the copper foil. As the synthesis time increases, domain cross-linking occurs, resulting in polycrystalline continuous graphene film formation. Graphene films have areas up to 100 cm2 and thicknesses ~ 1 nm to 5 nm. To measure the Raman spectra, graphene films were transferred to SiO2/Si substrates. Graphene films exhibit an intense 2D peak that significantly exceeds the G peak of crystalline graphite. Flexible transparent conductive touch panels were created on the basis of the grown graphene films. A lamination method has been used to create graphene films that can be transferred from copper foil to polymer substrates. A laboratory touch screen with a graphene film acting as a capacitive touch sensor was constructed on the basis of the transferred film, and transparent electrodes for molybdenum disulfide-based photosensitive elements were also created. Resistive humidity sensors based on graphene films were developed and transferred to SiO2/Si and epoxy/Si substrates. The graphene humidity sensor has a low response, high temperature stability, and is highly reliable.

High enhancement, low cost, large area surface enhanced Raman scattering substrates all by atomic layer deposition on porous filter paper

We successfully developed an atomic layer deposition (ALD) method for making Ag noble nanoparticles on cheap, commercial filter paper consisting of three-dimensional porous glass fibers and investigated the evolution of Ag nanostructures with some key process parameters. By tuning Ag particle sizes and controlling the cycle numbers of ALD deposited Ag films, we were able to obtain high-density isolated Ag nanoparticles with average sizes in 3–9 nm without the formation of agglomerates and continuous Ag films. We proved the presence of strong localized surface plasmon resonance peaks near a target wavelength of 632 nm. We further proved the presence of surface enhanced Raman scattering (SERS) signals on the Ag coated filter paper substrates using pyridine as the test analyte. Our results demonstrate that ALD is a very promising technique for a rational design of SERS substrates and, thus, has great potential for the fabrication of large-area, low-cost SERS substrates for future commercial applications, as compared to other existing techniques.

Self‐lubricating epoxy composite coating with linseed oil microcapsule self‐healing functionality

AbstractCured epoxy resins have poor abrasion resistance, which shortens the service life of the material. This work aims to improve the tribological properties of epoxy resins by coupling self‐lubrication and auto‐healing. In this study, linseed oil microcapsules with an average particle size of 38.57 μm and good thermal stability were successfully prepared by in situ polymerization. The effects of microcapsule content on the tribological, mechanical, and self‐healing properties of the composite coatings were studied. It was demonstrated that the composite coating has outstanding self‐lubricating properties. The coefficient of friction reduced from 0.634 (pure epoxy resin) to 0.0459 (epoxy resin with 10 wt.% linseed oil microcapsules). Wear rate reduced from 7.16 × 10−4 mm3/(N m) to 1.74 × 10−5 mm3/(N m). The self‐lubricating mechanism of the coating was investigated by SEM and EDS, which indicated that the formation of uniform and continuous lubricating film on the surface of the friction pairs was the key to improving the wear resistance of the material. In addition, the linseed oil released after the microcapsules rupture can repair the abrasion marks by reacting with oxygen during the friction process. The dual‐functional effect of linseed oil microcapsules prolongs the life of epoxy resin coating and expands its application range.

Tailoring the corrosion behavior and mechanism of Mg-Gd-Zn alloys via Sc microalloying

The Sc microalloying can decrease the corrosion rates of Mg-Gd-Zn alloys by about two orders of magnitude, and thus significantly improving corrosion resistance of Mg-Gd-Zn alloys. Notably, the Sc microalloying can inhibit the precipitation of (Mg, Zn)3Gd phase with high potential while promote the precipitation of 14H-LPSO phase with low potential under the premise of reducing the total amount of second phases. Thus, the micro-galvanic corrosion effect can be effectively weakened. Additionally, the Sc microalloying can lead to the grain refinement, which can act as barriers to corrosion propagation and promote the nucleation and growth of oxides. Also, the activity of Gd, Zn and Sc in α-Mg phase can be increased with the Sc microalloying, which facilitates the formation of related continuous and compact oxide films. The continuous and compact films can effectively protect the alloy matrix from corrosion. Furthermore, the stacking faults distributed in different grains with different orientations in Sc-contained alloys can lead to a more uniform corrosion. The synergistic effects resulted by Sc microalloying contribute to the significantly improved corrosion resistance of Mg-Gd-Zn alloys.

Cracking behaviour and its suppression mechanisms with TiB2 additions in the laser additive manufacturing of solid-solution-strengthened Ni-based alloys

This study systematically investigated the cracking mechanisms in the laser powder bed fusion (LPBF) of GH3230 solid-solution-strengthened Ni-based alloy (GH0). The results show that the micro-cracks that formed in GH0 specimens included both solidification and solid-state cracks. The initiation of solidification cracks was associated with the formation of continuous liquid films on high-angle grain boundaries at the final stage of solidification, while the solid-state cracks were found to be ductility-dip cracks, associated with a reduction in the material's plasticity within the heat-affected zone. The study also found that the residual stresses decreased with increasing LSS values, leading to reductions in crack length. The introduction of 1 wt% TiB2 particles to GH3230 (GH1-composite) was found to suppress cracking by promoting grain refinement and generating special high-angle grain boundaries, although residual thermal stresses increased. The ultimate tensile strength values of the GH0 and GH1-composite specimens at 900 °C were found to be 213 and 352 MPa, respectively. These findings provide significant insights into the LPBF of high-performance crack-free Ni-based superalloys.

Effect of fiber orientation on tribological properties of fiber‐reinforced C/C–SiC composites mated with ceramic ball

AbstractCarbon fiber–reinforced SiC ceramic matrix composites (C/C–SiC composites) with advantages of high wear resistance and corrosion resistance are of high application potential as ceramic bearings. In this study, the frictional and wear behaviors of C/C–SiC with different fiber orientations mating with Al2O3 and SiC balls, respectively, have been investigated. Results reveal that fiber orientation effectively affects the friction and wear properties of carbon–ceramic composites in paired friction experiments with ceramic balls. In comparison to C/C–SiC with unidirectional fiber orientation, C/C–SiC pads with randomly arranged fibers exhibited a more stable coefficient of friction and lower volume wear, presenting the best performance among the pads considered herein, which may have the potential to be applied to bearing materials. The factors affecting the formation of continuous tribo‐film, which influence the comprehensive performance, are researched. It is proposed that the amount of wear debris and the formation of SiC/SiC micro‐hard frictional pairs may inhibit or promote the formation of continuous friction film. The dominant wear mechanisms for friction pairs of C/C–SiC and ceramic are abrasive wear and oxidation wear.

Hot corrosion behavior of a novel TiC/GTD222 nickel-based composite prepared by selective laser melting

In this study, a novel TiC/GTD222 nickel-based composite with enhanced hot corrosion resistance was designed by incorporating appropriate amounts of C, Al, and Ti elements into the GTD222 superalloy. The composite was successfully prepared using the selective laser melting (SLM) technique. The hot corrosion behavior of GTD222 superalloy and the TiC/GTD222 composite in a salt mixture of 75% Na2SO4 + 25% NaCl (wt%) at 900 °C was systematically studied. The results show that the TiC/GTD222 composite exhibits much better hot corrosion resistance than the GTD222 superalloy. This is because a continuous and dense double-layer oxide film is formed in the composite (The inner layer is TiO2 and the outer layer is Cr2O3), while oxide film of the superalloy is loose and porous, and has a discontinuous TiO2 and Al2O3 distribution. The adding alloy elements can promote the formation of more γ' phase and TiC particles in the TiC/GTD222 composite, and also result in the refined grain and formation of more dislocations. The above microstructures increase the diffusion channels of elements, and the higher contents of Al and Ti can enhance the diffusion potential energy of these elements, leading to the formation of continuous and dense double-layer oxide film of the composite. This work provides new ideas for the design of additive manufactured superalloy.

Nucleation and Layer Closure Behavior of Iridium Films Grown Using Atomic Layer Deposition.

Understanding the initial growth process during atomic layer deposition (ALD) is essential for various applications employing ultrathin films. This study investigated the initial growth of ALD Ir films using tricarbonyl-(1,2,3-η)-1,2,3-tri(tert-butyl)-cyclopropenyl-iridium and O2. Isolated Ir nanoparticles were formed on the oxide surfaces during the initial growth stage, and their density and size were significantly influenced by the growth temperature and substrate surface, which strongly affected the precursor adsorption and surface diffusion of the adatoms. Higher-density and smaller nanoparticles were formed at high temperatures and on the Al2O3 surface, forming a continuous Ir film with a smaller thickness, resulting in a very smooth surface. These findings suggest that the initial growth behavior of the Ir films affects their surface roughness and continuity and that a comprehensive understanding of this behavior is necessary for the formation of continuous ultrathin metal films.

Flexible Transparent Electrodes Formed from Template-Patterned Thin-Film Silver.

Template-patterned, flexible transparent electrodes (TEs) formed from an ultrathin silver film on top of a commercial optical adhesive - Norland Optical Adhesive 63 (NOA63) -are reported. NOA63 is shown to be an effective base-layer for ultrathin silver films that advantageously prevents coalescence of vapor-deposited silver atoms into large, isolated islands (Volmer-Weber growth), and so aids the formation of ultrasmooth continuous films. 12 nm silver films on top of free-standing NOA63 combine high, haze-free visible-light transparency (T ≈ 60% at 550nm) with low sheet-resistance ( ≈ 16 Ω sq-1), and exhibit excellent resilience to bending, making them attractive candidates for flexible TEs. Etching the NOA63 base-layer with an oxygen plasma before silver deposition causes the silver to laterally segregate into isolated pillars, resulting in a much higher sheet resistance ( > 8 × 106 Ω sq-1) than silver grown on pristine NOA63 . Hence, by selectively etching NOA63 before metal deposition, insulating regions may be defined within an otherwise conducting silver film, resulting in a differentially conductive film that can serve as a patterned TE for flexible devices. Transmittance may be increased (to 79% at 550nm) by depositing an antireflective layer of Al2O3 on the Ag layer at the cost of reduced flexibility.

Numerical Simulation on Preparing Uniform and Stable Perovskite Wet Film in Slot-Die Coating Process.

Slot-die coating is regarded as a reliable and potential technology for preparing large-area perovskite solar cells with high efficiency and low cost. Therein, the formation of continuous and uniform wet film is of significance to obtain a high-quality solid perovskite film. In this work, the rheological properties of the perovskite precursor fluid are analyzed. Then, the ANSYS Fluent is introduced to establish an integrated model of internal and external flow fields during the coating process. The model is applicable to all perovskite precursor solutions with near-Newtonian fluids. Based on the theoretical simulation of finite element analysis, the preparation of 0.8 M-FAxCs1-xPbI3, one of the typical large-area perovskite precursor solutions, is explored. Accordingly, this work indicates that the coupling process parameters like the fluid supply velocity (Vin) and coating velocity (V) determine the uniformity that the solution flows out of the slit and is coated onto the substrates, and the coating windows for a uniform and stable perovskite wet film is obtained. For the upper boundary range of the coating windows, the maximum value of V and Vin follows V = 0.003 + 1.46Vin (Vin ≤ 0.1 m/s), while for its lower boundary range, the minimum value of V and Vin is V = 0.002 + 0.67Vin (Vin ≤ 0.1 m/s). When Vin is higher than 0.1 m/s, the film will break due to the excessive V. Finally, the real experiment verifies the accuracy of the numerical simulation. Hopefully, this work is of reference value for the development of the slot-die coating forming process on the perovskite precursor solution approximating Newtonian fluid.

Solution-Processed NiPS3 Thin Films from Liquid Exfoliated Inks with Long-Lived Spin-Entangled Excitons.

Antiferromagnets are promising materials for future opto-spintronic applications since they show spin dynamics in the THz range and no net magnetization. Recently, layered van der Waals (vdW) antiferromagnets have been reported, which combine low-dimensional excitonic properties with complex spin-structure. While various methods for the fabrication of vdW 2D crystals exist, formation of large area and continuous thin films is challenging because of either limited scalability, synthetic complexity, or low opto-spintronic quality of the final material. Here, we fabricate centimeter-scale thin films of the van der Waals 2D antiferromagnetic material NiPS3, which we prepare using a crystal ink made from liquid phase exfoliation (LPE). We perform statistical atomic force microscopy (AFM) and scanning electron microscopy (SEM) to characterize and control the lateral size and number of layers through this ink-based fabrication. Using ultrafast optical spectroscopy at cryogenic temperatures, we resolve the dynamics of photoexcited excitons. We find antiferromagnetic spin arrangement and spin-entangled Zhang-Rice multiplet excitons with lifetimes in the nanosecond range, as well as ultranarrow emission line widths, despite the disordered nature of our films. Thus, our findings demonstrate scalable thin-film fabrication of high-quality NiPS3, which is crucial for translating this 2D antiferromagnetic material into spintronic and nanoscale memory devices and further exploring its complex spin-light coupled states.

The synergistic action of Ag and MoS2 on tribological properties of Al2O3/Ag(MoS2) composite coatings

Based on the inherent pores and cracks inside of Al2O3 coating and Al2O3/Ag coating which were sprayed by atmospheric plasma spraying technology, Al2O3/MoS2 and Al2O3/Ag/MoS2 composite coatings were manufactured by means of the vacuum impregnation and in-situ hydrothermal synthesis in this study. The microstructure and mechanical properties of Al2O3(MoS2) coating and Al2O3/Ag(MoS2) coating were analyzed. The synergistic action of Ag and MoS2 on the tribological properties of Al2O3(MoS2) and Al2O3/Ag(MoS2) coatings was discussed in detail. There were more defects and holes inside of Al2O3/Ag coating than Al2O3 coating, so the mechanical properties and wear rate of Al2O3/Ag coating were poorer than those of Al2O3 coating. Al2O3/MoS2 coating showed the great lubricating effect, but this effect cannot maintain a long time since the lubricating substance MoS2 would be consumed under repeat frictional action. The combined introduction of Ag and MoS2 into the defects inside of Al2O3/Ag/MoS2 coating not only reduced the wear rate, but also enhanced the lubrication effect further. The synergistic action of Ag and MoS2 could bring the excellent long-time lubricating effect to Al2O3/Ag/MoS2 composite coating effectively due to the formation of continuous lubricating film.

Direct atomic layer deposition of ultra-thin Al2O3 and HfO2 films on gold-supported monolayer MoS2

In this paper, the atomic layer deposition (ALD) of ultra-thin films (<4 nm) of Al2O3 and HfO2 on gold-supported monolayer (1L) MoS2 is investigated, providing an insight on the mechanisms ruling the nucleation in the early stages of the ALD process. A preliminary multiscale characterization of large area 1L-MoS2 exfoliated on sputter-grown Au/Ni films demonstrated: (i) a tensile strain (from 0.1 to 0.3%) and p-type doping (from 1 × 1012 to 4 × 1012 cm−2) distribution at micro-scale; (ii) an almost conformal MoS2 membrane to the Au grains topography, with some locally detached regions, indicating the occurrence of strain variations at the nanoscale; (iii) atomic scale variability (from ∼ 4.0 to ∼ 4.5 Å) in the Mo-Au atomic distances was detected, depending on the local configuration of Au nanograins. Ab initio DFT calculations of a free-standing MoS2 layer and a simplified MoS2/Au(111) interface model showed a significant influence of the Au substrate on the MoS2 energy band structure, whereas small differences were accounted for the adsorption of H2O, TMA (co-reactant, and Al-precursor, respectively) molecules, and a slight improved adsorption was predicted for TDMAHf (Hf-precursor). This suggests a crucial role of nanoscale morphological effects, such as the experimentally observed local curvature and strain of the MoS2 membrane, in the enhanced physisorption of the precursors. Afterwards the nucleation and growth of Al2O3 an HfO2 films onto 1L-MoS2/Au was investigated in detail, by monitoring the surface coverage as a function of the number (N) of ALD cycles, with N from 10 to 120. At low N values, a slower growth rate of the initially formed nuclei was observed for HfO2, probably due to the bulky nature of the TDMAHf precursor as compared to TMA. On the other hand, the formation of continuous films was obtained in both cases for N > 80 ALD cycles, corresponding to ∼ 3.6 nm Al2O3 and ∼ 3.1 nm HfO2. Current mapping on these ultra-thin films by conductive-AFM showed, for the same applied bias, a uniform insulating behavior of Al2O3 and the occurrence of few localized breakdown spots in the case of HfO2, associated to a less compact films regions. Finally, an increase of the 1L-MoS2 tensile strain was observed by Raman mapping after encapsulation with both high-κ films, accompanied by a reduction in the PL intensity, explained by the effects of strain and the higher effective dielectric constant of the surrounding environment.

Solventless Polymer-Grafted Mesh for Rapid and Efficient Oil–Water Separation

We report a solventless bilayer strategy for grafting hydrophilic poly(methacrylic acid) (PMAA) onto metal meshes. The bilayer nanocoating consisted of ultrathin PMAA brushes grafted onto a highly crosslinked primer that binds to each mesh wire. The enrichment of hydrophilic functionalities on the PMAA-grafted mesh surface improved the surface hydration and underwater oil repellency over the PMAA-crosslinked mesh, which contributed to the formation and stabilization of continuous water films between mesh wires to reject oil penetration in repeated uses. The vapor-based nanocoating process maximized the retention of pore openings for high-flux oil–water separation. The retained permeability, together with the enhanced oil repellency, enabled the PMAA-grafted mesh to achieve excellent gravity-driven oil–water separation, with an oil rejection rate higher than 99%, water flux exceeding 50,000 L m–2 h–1, and flux decay less than 3% after 20 cycles of reuse. More importantly, the PMAA-grafted mesh preserved high separation efficiency and flux stability under conditions of high salinity and extreme pH.

Improving the tribological performance of polyphenylene sulfide by incorporating irradiation treated polytetrafluoroethylene powders

AbstractIn this work, the efficacy of using irradiation treated polytetrafluoroethylene (i.e., i‐PTFE) powders on the tribological properties of polyphenylene sulfide (PPS)‐based composites was systematically investigated. The results showed that the addition of i‐PTFE powders significantly improved the friction and wear properties of PPS. The average friction coefficient and specific wear rate of PPS/i‐PTFE 20 wt% composite reached 0.129 and 1.75 × 10−5 mm3 N−1 m−1, which were 77.4% and 99.5% lower than those of pure PPS, respectively. SEM observations indicated that the i‐PTFE powders exhibited a relatively uniform distribution within PPS, which favored the formation of intact, uniform and continuous transfer film on the surface of friction pair, thereby resulting in a significant improvement of tribological properties for PPS/i‐PTFE composites. The worn surface of the testing specimen turned smoother and the wear debris became smaller with increasing addition of i‐PTFE powders, which was related to the improvement of tribological performance by forming transfer film at the sliding interface. This work provided a strategy to fabricate high performance self‐lubricating polymer composites that demonstrate potential applications in engineering sectors.