In the paper, the effect of CoCrMoW high entropy alloy (HEA) binder in cemented carbide on the microstructure and wear-resistant and oxidation-resistant properties of the coating is investigated to ...provide reference for the exploration and development of new wear resistance and oxidation-resistant materials. The results indicate that the coated WC-HEA has a dense coating structure and possesses excellent high-temperature wear resistance. Compared with the Ni or Co binder phase, the coated cemented carbide containing HEA binder phase has a large difference in the matrix microstructure, cross-section morphology, mechanical properties and friction and wear properties. It is also found that a significant amount of W in the substrate diffuses through grain boundaries into the TiN coating and TiCN coatings and forms a TixWxN solid solution at the interface between the TiN coating and the matrix. In particular, the uniformity of the distribution of HEA binder in the matrix directly affects the nucleation growth of the coatings. Nanohardness results indicate that the wear resistance of TiN/TiCN/Al2O3 coating is in the order of WC-Ni < WC-HEA < WC- Co. These differences come from the effect of binder on the nucleation growth and textured orientation of the coating. The comprehensive mechanical properties of the WC-HEA are similarly that of WC- Co, and it has great potential to replace WC- Co. Compared with Ni and Co binder phases, the WC-HEA coating sample is more wear-resistant at 750 °C.
•The effect of CoCrMoW binder phase on the friction characteristics of coated cemented carbide are studied at different temperatures.•The friction characteristics of the coating are affected by the hardness difference between the coating and the substrate.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the present study, a nickel-zinc (Ni–Zn) alloy coating has been selected as the foundational coating, and the formation of a composite Ni–Zn-titanium dioxide (Ni–Zn–TiO2) coating, along with the ...factors influencing its development, has been thoroughly examined. The influential factors explored in this research encompass applying ultrasonic waves, current density, and incorporating varying concentrations of TiO2 nanoparticles (NPs). X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy, and a wear test apparatus were utilized to assess the characteristics of these coatings. The findings indicate that the concentration of TiO₂ NPs in the plating bath profoundly impacts the morphology and coating properties. An increased TiO₂ concentration in the plating bath led to a finer morphology. Applying ultrasonic waves during the plating process enhanced the dispersion and finer distribution of NPs within the coating, resulting in improved wear resistance due to the confinement of irregularities. Applying ultrasonic waves up to 60 W improved the properties; however, a reduction in elemental levels was observed when the ultrasonic waves were increased to 120 W. This decrease in elemental levels can be attributed to the high-intensity ultrasonic waves, resulting in diminished wear resistance.
•Investigated Ni–Zn–TiO2 coating properties under varying conditions.•XRD patterns showed limited TiO2 NPs, impacting crystal size.•Higher TiO2 NPs concentrations enhanced wear resistance.•Ultrasonic waves improved grain boundaries and coating compaction.•40 W ultrasonic waves led to agglomerates, influenced by power levels.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
3.
Superlubricity between MoS2 Monolayers Li, He; Wang, Jinhuan; Gao, Song ...
Advanced materials (Weinheim),
July 19, 2017, Volume:
29, Issue:
27
Journal Article
Peer reviewed
The ultralow friction between atomic layers of hexagonal MoS2, an important solid lubricant and additive of lubricating oil, is thought to be responsible for its excellent lubricating performances. ...However, the quantitative frictional properties between MoS2 atomic layers have not been directly tested in experiments due to the lack of conventional tools to characterize the frictional properties between 2D atomic layers. Herein, a versatile method for studying the frictional properties between atomic‐layered materials is developed by combining the in situ scanning electron microscope technique with a Si nanowire force sensor, and the friction tests on the sliding between atomic‐layered materials down to monolayers are reported. The friction tests on the sliding between incommensurate MoS2 monolayers give a friction coefficient of ≈10−4 in the regime of superlubricity. The results provide the first direct experimental evidence for superlubricity between MoS2 atomic layers and open a new route to investigate frictional properties of broad 2D materials.
A method for friction tests between atomic layers of 2D materials is developed based on the in situ scanning electron microscopy technique. Friction tests on the sliding between MoS2 monolayers give an ultralow friction coefficient of ≈10−4, providing the first direct experimental evidence for the superlubricity between atomic layers of hexagonal MoS2.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The anisotropic friction properties of biomimetic Cf/ZrB2-SiC ceramic composites with fibers disposed along Bouligand structures are analyzed. First, the friction properties parallel to and vertical ...to the hot-pressing surfaces are analyzed for the Cf/ZrB2-SiC ceramic composites with different carbon fiber contents. The anisotropy of friction properties of the biomimetic Cf/ZrB2-SiC ceramic composites with Bouligand structures is analyzed based on the microstructures of wear surfaces. Second, the anisotropic friction properties of biomimetic Cf/ZrB2-SiC ceramic composites with Bouligand structures under high speed and wet conditions are also explored. Under various working environments, the wear mechanisms including abrasive wear, adhesive wear, oxidation wear, and fatigue wear are analyzed in detail based on the microstructures of the wear surfaces. This paper provides a good reference for analyzing the anisotropic friction properties of ceramic composites with Bouligand structures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, copper composite foams reinforced with Al2O3 decorated graphene oxide (AG) were prepared via chemical plating and electrodeposition. Subsequently, copper powders were filled into the ...pores of the composite foams and then spark plasma sintering (SPS) was employed to fabricate the 3D skeleton-reinforced composites. The tensile strength reached 365 MPa for AG/Cuf®Cu composites, which was 47.1%, 33.7%, and 13% higher compared with the pure copper, Cuf®Cu, and GO/Cuf®Cu composites, respectively. Additionally, improved friction properties with obviously decreased friction coefficient and wear rate were shown in the AG/Cuf®Cu composite. The structure study and strengthening mechanism analysis indicated that the decoration of Al2O3 on the graphene oxide resulted in enhanced interface bonding, higher load transfer efficiency for the mechanical and friction properties improvement.
•Copper composite foams reinforced with Al2O3 decorated graphene oxide (AG) were prepared.•Copper composites reinforced by AG/Cu composite foams were designed and prepared.•Enhanced mechanical and friction properties were shown in the composites.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Mesocarbon microbead-silicon carbide (MCMB-SiC) composites are promising candidates for mechanical seals of nuclear reactor main pumps due to their adaptability to severe environments. However, the ...weak bonding strength between MCMB and SiC matrix causes an unstable dry friction coefficient, which limits its further development. Herein, the interface-modified MCMB-SiC composites were prepared by hot-pressing sintering using liquid vinyl hydrido polycarbosilane (VHPCS) coated raw material powder for the first time. The pyrolytic VHPCS was loaded on the surface of MCMB particles. The effects of VHPCS content on the microstructure, mechanical properties, and dry tribological properties of MCMB-SiC composites were systematically studied. The results show that the MCMB-SiC composites with 1 wt% VHPCS (MS-P1) had good comprehensive mechanical properties. Meanwhile, compared to MCMB-SiC composites without VHPCS (MS-P0), MS-P1 exhibited improved dry friction properties, with a dry friction coefficient (μ) reduced by ∼25% (0.18) and a wear rate (WR) reduced by ∼35% (7.69 ×10−7 mm3·N−1·m−1). It was considered to be due to the nano-SiC grains generated by VHPCS after sintering improved the interface strength between MCMB and SiC matrix, which inhibited the detachment of hard SiC particles during the friction process. In addition, sufficient C-Si-O lubricating film can fill the pits, which acts as a self-healing effect. This study provides an effective route to improve the tribological properties of MCMB-SiC self-lubricating composites with high carbon content.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
By incorporating the dual ceramic elements TiB2/B4C, we investigated their impact on the mechanical properties, thermal properties, and friction performance of copper-based powder metallurgy ...materials, and elucidated the friction wear mechanism. Additionally, machine learning algorithms were employed to predict the friction coefficient and stability coefficient. The conclusions are as follows:With the increase in the TiB2/B4C ratio, the trend of mechanical properties initially increases and then decreases, with the optimum ratio being 5:3 for TiB2 and B4C, exhibiting superior mechanical properties. Moreover, B4C enhances the thermal conductivity of copper-based friction materials more effectively than TiB2. In terms of overall friction performance, the ratio of TiB2 to B4C at 5:3 yields better frictional properties. The primary components of the friction surface friction film are CuO, Cu2O, Fe2O3, and B2O3, transitioning from a ceramic film to a metallic film as the TiB2/B4C ratio increases. The friction wear mechanism shifts from abrasive wear to severe fatigue wear as the TiB2/B4C ratio increases, accompanied by oxidative wear. Furthermore, an AdaBoost algorithm model was developed to effectively predict the friction coefficient and stability coefficient, with accuracies of 0.9993 and 0.8739, respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
