Improving the electrical conductivity and structural integrity of Si/C anodes is of great concern for lithium-ion batteries which can be effectively achieved by doping graphene. However, it is ...difficult to achieve graphene-doped Si/C composites with good interface contact and conductive architecture. Herein, an in-situ graphene-doped carbon coated silicon nanoparticles (SiNPs) with multilayer architecture is designed. SiNPs is firstly modified and coated by polymethyl methacrylate (PMMA) shell. Multilayer carbon architecture is constructed via co-pyrolysis method using PMMA and citric acid as carbon sources. It displays an excellent lithium storage performance with a reversible discharge capacity of 2117.5 mAhg−1 at 200 mAg−1. These impressive anodic properties are chiefly benefited from the ingenious carbon architecture coated SiNPs involving in-situ graphene with a strong interfacial bonding interaction. Overall, this investigation can not only broaden the application potential in LIBs for advanced Si/C anodes but also provide an alternative route on designing a graphene-related material.
To improve the electrical conductivity and structural integrity of silicon-based anodes, an in-situ graphene-doped carbon substrate coated silicon nanoparticles (SiNPs) with a multilayer architecture (SiNPs@MC) is designed via emulsion polymerization coupled with co-pyrolysis methods. Before this, the surface of SiNPs is modified by silanization reaction to strengthen interfacial bonding interaction between SiNPs and PMMA shell. The multilayer architecture is derived from co-pyrolysis of citric acid and PMMA as double carbon sources. Due to the differences between two carbon sources, in-situ graphene is successfully prepared, boosting good electrical conductivity and structural stability of Si/C anode for advanced LIBs. This method also provides an alternative way to study in-situ graphene-involved materials. Display omitted
•Surface modification of Si nanoparticles (SiNPs) is conducted for PMMA coating.•In-situ graphene-doped SiNPs/C anode is prepared for boosting Li-storage capacity.•Multilayer architecture is designed via double-carbon-source co-pyrolysis method.•It displays a prominent Li-ion storage ability with a strong bonding interaction.•This work broadens the application potential of in-situ graphene-doped Si/C anode.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Diamond-like carbon (DLC) coatings, frequently used to reduce wear and friction in machine components as well as on forming tools, are often subjected to cyclic loading. Doping of DLC coatings with ...metals or metal carbides as well as the usage of multilayer architectures represent promising approaches to enhance toughness, which is beneficial for the coatings' behavior under cyclic loading. In this study, we utilized cyclic nanoindentation to characterize the tribologically induced surface fatigue behavior of single-layer tungsten-doped (a-C:H:W) and multilayer silicon oxide containing (a-C:H:Si:O/a-C:H)25 amorphous carbon coatings under cyclic loading. Columnar growth was observed for both coatings by focused ion beam microscopy and scanning electron microscopy, while the multilayer architecture of the (a-C:H:Si:O/a-C:H)25 coating was verified by the silicon content using glow-discharge optical emission spectroscopy. In cyclic nanoindentation of the (a-C:H:Si:O/a-C:H)25 multilayer coating, stepwise small changes in indentation depth were observed over several indentation cycles. The surface fatigue process of the single-layer a-C:H:W covered a smaller number of indentation cycles and was characterized by an early steep increase of the static displacement signal. Microscopical analyses hint at grain deformation, sliding at columnar boundaries, and grain detachment as underlying fatigue mechanisms of the a-C:H:W coating, while the (a-C:H:Si:O/a-C:H)25 multilayer coating showed transgranular crack propagation and gradual fracturing. In case of the (a-C:H:Si:O/a-C:H)25 multilayer coating, superior indentation hardness (HIT) and indentation modulus (EIT) as well as a higher HIT3/EIT2 ratio suggest a higher resistance to plastic deformation. A high HIT3/EIT2 ratio, being an indicator for hindered crack initiation, combined with the capability of stress relaxation in soft layers contributed to the favorable surface fatigue behavior of the (a-C:H:Si:O/a-C:H)25 multilayer coating observed in this cyclic nanoindentation studies.
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•Cyclic nanoindentation of single- and multilayer coatings to assess surface fatigue•Favorable fatigue behavior for multilayer (a-C:H:Si:O/a-C:H)25 with high HIT3/EIT2•Surface fatigue of (a-C:H:Si:O/a-C:H)25 relied on transgranular, gradual fracturing•Fatigue-related grain deformation, sliding and detachment for single-layer a-C:H:W
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
In order to better fulfill the requirements high-performance dielectric devices for low insertion loss, compact size, and excellent temperature stability, we propose a strategy to maximize the ...comprehensive regulation of microwave dielectric properties. Since TiO2 has a relatively large and positive τf value, direct addition of TiO2 has often been utilized to modify the negative τf value in previous studies. In this paper, TiO2 and the laminated co-firing technique are applied to monoclinic wolframite structural ceramics. Tri-layer architectural ZnZr1−xHfxNb2O8-yTiO2-ZnZr1−xHfxNb2O8 (0.000 ≤ x ≤ 0.030, 0.01 ≤ y ≤ 0.06) ceramics were synthesized by the laminated co-firing technique. Firstly, Hf4+ ions substituted for Zr4+ ions to significantly enhance the Q×f value of ZnZrNb2O8 system. The modulation effect of Hf4+ on the crystal structure and the influence on the dielectric constant (εr), Q×f, and τf values were reasonably demonstrated by combining several characterization approaches with complex chemical bond theory. Compared with pure ZnZrNb2O8, the ZnZr0.990Hf0.010Nb2O8 ceramic achieved a nearly 65% increase in the Q×f value without excessive deterioration of other dielectric parameters. The laminated co-firing technique was then used to further modulate its εr and τf values. Notably, the ZnZr0.990Hf0.010Nb2O8-0.05TiO2-ZnZr0.990Hf0.010Nb2O8 tri-layer architectural ceramic achieved prominent comprehensive microwave dielectric characteristics: εr = 34.34, Q×f = 53,860 GHz, and τf = + 2.29 ppm/°C, making the tri-layer architecture ceramics attractive for usage in modern microwave communications.
•A series of ceramics with the composition ZnZr1−xHfxNb2O8 (x = 0.000, 0.005, 0.010, 0.020, and 0.030) are synthesized using the traditional solid-state reaction approach.•A two-step strategy is proposed for the first time to improve the comprehensive microwave dielectric properties of ZnZrNb2O8 systems.•The effects of Hf4+ substitution on the crystal structure, microstructure, bonding properties, and microwave dielectric characteristics of ceramics with monoclinic wolframite structure were comprehensively investigated.•The εr value is influenced by the bond ionicity of Nb-O bond. The Q×f value is determined by the lattice energy of Nb-O bond, and the FWHM values of Raman spectra. The τf value is mostly dependent on the bond energy and bond valence of Nb-O bond.•The microwave dielectric characteristics of the ZnZrNb2O8 system were comprehensively adjusted by the laminated co-firing technique, and the excellent microwave dielectric characteristics were obtained: εr = 34.34, Q×f = 53,855 GHz, and τf = + 2.29 ppm/°C.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
Material‐independent and bioinert hierarchical polymer multilayer coatings are presented. Chemically active catecholic hyperbranched polyglycerols (hPGs) form a foundation layer on a versatile ...surface via multivalent anchoring and crosslinking, the activity of which is shielded by the bioinert catecholic hPGs. Mono‐catecholic hPGs finally terminate all of the free catechols to build a flexible bioinert top layer. These coatings perfectly prevent protein and cell adhesion.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The mechanical properties, microstructure, adhesion and wear behavior of a Ti0.41Al0.48Ta0.11N monolithic coating and Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 and Ti0.41Al0.48Ta0.11N/Ta multilayers were ...investigated. The coatings were deposited on titanium substrates by reactive DC magnetron co-sputtering. The hardness and reduced elastic modulus of the coatings were determined by nanoindentation. The multilayer coatings were found to exhibit the lower mechanical characteristics than those of the monolithic coating due to the contribution of the softer metal interlayers to their measured values. Adhesion evaluation was performed by scratch testing. The Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 multilayer was characterized by stronger adhesion to the titanium substrate than the monolithic coating, whereas the Ti0.41Al0.48Ta0.11N/Ta multilayer exhibited poorer adhesion. In contrast, both the multilayers showed improved wear resistance compared with the monolithic coating. The best wear performance was demonstrated by the Ti0.41Al0.48Ta0.11N/Ti0.45Al0.55 multilayer that was attributed to stronger bonding between the layers as well as the lower hardness of the Ti0.45Al0.55 layers, which allowed for the accommodation of a larger amount of deformation via their plastic flow.
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•Growth of columnar grains in TiAlTaN coatings is interrupted by TiAl and Ta layers.•TiAl layers enhance adhesion of TiAlTaN-based coatings to Ti substrate.•TiAlTaN/TiAl and TiAlTaN/Ta multilayers exhibit improved wear resistance.•TiAl layers provide benefits over Ta layers for wear performance of TiAlTaN coatings.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
A cofired trilayer ceramic architecture showing as MgTiO3/TiO2/MgTiO3 was designed to realize temperature-stable and ultrahigh-Q microwave dielectrics in the typical MgTiO3-TiO2 system. The effects ...of TiO2 content on the microwave dielectric properties of cofired trilayer ceramics were studied. Through the design of cofired trilayer architecture, the chemical reactions between MgTiO3 and TiO2 were limited within a narrow region of MgTiO3/TiO2 interfaces (~ 15 µm in width), which could be beneficial for optimizing the microwave dielectric properties. Excellent characteristics of εr ~ 18.38, Q×f value ~ 169,900 GHz and τf ~ − 1 ppm/°C were gained for the MgTiO3/TiO2/MgTiO3 ceramic architectures stacked with 1.63 vol% TiO2. The current work could serve as new strategies to develop high-performance dielectric resonators and multilayers for 5G wireless communication applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Several multilayer architectures, based on ZrC-SiC system, were fabricated on SiC-coated carbon/carbon composites by plasma spraying and tested using an oxyacetylene torch. A remarkable variance in ...scale evolution was found in these multilayer coatings, referring to close correlation between multilayer architecture and ablation behavior. The multilayer coating made of consecutive sublayers of ZrC-10, 30, 10 and 70 vol% SiC survived three repeated ablation cycles with mass ablation rate of −0.467 mg/s and linear ablation rate of − 0.411 µm/s. Detailed phase analysis and morphology investigation attributed its preferable ablation performance to the formation of multifunctional scale and modest thermal stress.
•Various ZrC-SiC multilayer coatings were prepared on SiC-coated C/C composites by plasma spraying.•The relationship between coating architecture and ablation behavior was studied using oxyacetylene torch.•Ablation mechanism was analyzed systematically as well as the roles of different sublayers.•Theoretical analysis was adopted to compare the stress level within these multilayer coatings.
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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, TiN coatings with favorable phase stability were introduced to CrAlNbN coatings for stabilizing the structure of CrAlNbN coatings during annealing. The structure, mechanical properties ...and thermal stability of CrAlNbN/TiN multilayers and the monolithic counterparts were comparatively studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and nanoindentation. All coatings exhibit face-centered cubic structure, and CrAlNbN/TiN multilayer with smaller bilayer period reveals superlattice structure. The coherent growth of CrAlNbN sublayers along with TiN template layers, and the relatively higher binding energy of Ti–N bonds than Cr–N retards the thermal decomposition procedure of CrAlNbN/TiN multilayers, where the initiation temperatures of w-AlN precipitation and N-loss are elevated by 100 and 200 °C, respectively. The architecture of CrAlNbN/TiN multilayers effectively improves the capability of corresponding monolithic layers to maintain hardness upon thermal load, which is beneficial for their high-temperature applications.
•CrAlNbN/TiN multilayers reveal coherent interface.•CrAlNbN/TiN multilayers reveal higher hardness than calculated values by mixing rule.•The TiN insertion layer retards the thermal decomposition process of CrAlNbN.•CrAlNbN/TiN multilayers show milder declining trend of hardness during annealing.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Graphene, a 2D sp2‐hybridized carbon sheet is a hot topic in the fields of materials science and chemistry. Here, a symmetrical multilayer architecture of graphene is designed by grafting of ...sulfonated 4,4′‐ diaminodiphenyl sulfone (SDDS) with the ample sulfonate groups and tunable interlayer spacing to exhibit the Li+ extraction from ionic mixtures with Na+, Mg2+ and Ca2+. Under the application of an electric field, the selective separation of cations can be achieved by controlling the flow channels of negatively charged ions (≈0.48 nm) during the synthesis of rGO‐SDDS‐rGO membrane. The result shows that the ion selectivity of the rGO‐SDDS‐rGO membrane is Na+ > Li+ > Ca2+ > Mg2+ and the absolute separation efficiency values of Li+/Mg2+ and Li+/Ca2+ are as high as 85.32 and 80.81%, respectively.
A symmetrical multilayer architecture of graphene is designed by synthesizing sulfonated 4,4′‐diaminodiphenyl sulfone with the ample sulfonate groups and tunable interlayer spacing to exhibit the Li+ extraction from ionic mixtures with Na+, Mg2+ and Ca2+.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
AlCrSiN coatings with exceptional oxidation resistance are promising protective layers for cutting tools. Due to the inferior tribological properties at elevated temperatures, recently, tailoring of ...AlCrSiN by alloying has attracted widespread attention. The addition of Ni is a practical method to reduce friction and increase toughness. Whereas, the lower hardness of Ni-containing AlCrSiN coatings leads to poor wear resistance. Here, to optimize the phase structure of monolithic AlCrSiN–Ni for synergistic improvement of mechanical and tribological properties, the AlCrSiN–Ni/AlCrN multilayer was deposited by cathodic arc evaporation and investigated by combing X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, nanoindentation, and ball-on-disc tribometer. Without the formation of wurtzite AlN, epitaxially grown AlCrSiN–Ni/AlCrN coatings obtain coherent interlayer interfaces and dual-phase cubic structure involving nitride and metallic Ni. Correspondingly, the hardness increases from 21.6 ± 0.8 GPa of AlCrSiN–Ni to 31.1 ± 0.7 GPa of AlCrSiN–Ni/AlCrN. Also, significant enhancement of scratch toughness was achieved by the multilayer. For wear tests at 600 °C, the multilayer exhibits an average friction coefficient of ∼0.81, which is between ∼0.95 of AlCrSiN and ∼0.61 of AlCrSiN–Ni. Furthermore, the superior mechanical properties upgrade the wear resistance of the coating. The wear rate at 600 °C for the multilayer is 3.9 × 10−6 mm3/N·m, while other monolithic coatings have a wear rate higher than 2.0 × 10−5 mm3/N·m.
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•AlCrSiN–Ni/AlCrN multilayer exhibits epitaxial growth with coherent interfaces.•The multilayer architecture effectively inhibits the formation of wurtzite AlN.•Structural optimization leads to higher hardness and toughness of the multilayer.•The multilayer has the best wear resistance due to superior mechanical properties.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZRSKP
