查看更多>>摘要：? 2021Recently, a 2-inch-diameter high-quality (001) diamond wafer was prepared that was heteroepitaxially grown on a (001) Ir buffer layer/(112ˉ0) A-plane sapphire substrate. Herein, we investigate residual strain and curvature of diamond in a relation with Ir/sapphire substrate and Ir/(001) MgO substrate. Diamond layers grown on Ir substrates have tensile strain, whereas Ir buffer layers on sapphire or MgO substrates have compressive strain. However, the magnitude of these strains in diamond and Ir layers grown on sapphire is considerably lower than that of the same layers grown on MgO. The lower tensile strain in the diamond on Ir/sapphire leads to the growth of a 2-inch-diameter layer without cracking. The convex curvature radius of the diamond layers grown on sapphire is larger than that observed on the MgO substrate. The difference in the coefficients of thermal expansion between the diamond and sapphire is considerably smaller than that of the MgO substrate. The low tensile strain of diamond is caused by the difference in the lattice constants of the diamond and Ir/sapphire substrate.
查看更多>>摘要：? 2022 Elsevier B.V.Diamond-like carbon (DLC) composite films doped with ceria were synthesized on LY-12 aluminum alloys by electrodeposition. The effects of ceria concentration on the microstructure, microhardness, wear and corrosion behavior of the composite film were investigated via Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), micro-Vickers tester, friction and wear tester and electrochemical workstation. Meanwhile, the growth mechanism of the films was explored. Results proclaimed that the loose honeycomb structure of the films was replaced by a compact granular structure as the ceria concentration increased to 1.16 ×10?3 mol/L. Raman spectra showed the typical amorphous characteristics of DLC film. The intensity ratio of G-line and D-line (ID/IG) diminished from 0.59 to 0.47, the G-line shifted to the lower frequency and the GFWHM increased, demonstrating that the CeO2/DLC composite film deposited at optimal ceria contains the higher sp3-C content. XPS analysis revealed that the binding mode of ceria is physically doped. Furthermore, the CeO2/DLC composite film exhibits superior anti-wear and anti-corrosion ability, which is primarily due to the compact structure and high microhardness. The statement of the new information: Double Ni-Cu interlayer are prepared and CeO2 nanoparticles were successfully encapsulated in diamond-like carbon (DLC) films on LY-12 aluminum alloy substrates by electrodeposition.
查看更多>>摘要：? 2022 Elsevier B.V.Pseudo-vertical diodes on {113} oriented homoepitaxial boron-doped diamond were successfully fabricated using molybdenum as a metal for both the Schottky and ohmic contacts. After metal deposition, diodes were stabilized by annealing for 20 min at 300 °C and their I-V and C-V characteristics were measured at temperatures from 30 to 180 °C. Results show that Mo forms a very good and stable Schottky contact on {113} oriented homoepitaxial boron-doped diamond. At 180 °C, forward current densities higher than 1kA/cm2 are achieved, while the reverse current density stays unchanged at 10?8 A/cm2. The ideality factor of the diode I-V characteristic drops to 1.23 and the barrier height of the Schottky contact increases to 1.71 eV. This effect is attributed to inhomogeneity in the Schottky barrier. These characteristics are fully comparable with those of the best Schottky diodes fabricated on {100} oriented homoepitaxial boron-doped diamond. Results confirm that the use of {113} oriented homoepitaxial boron-doped diamond for the fabrication of high-temperature power devices is advantageous, as it enables high quality Schottky and ohmic contacts.
查看更多>>摘要：? 2022 Elsevier B.V.The reuse of the waste crumb rubber (CR) is of great significance to alleviate the increasingly serious black pollution problem. Herein, low-cost electromagnetic microwave absorption (EMA) CR composites assisted by conductive carbon nanotubes (CNTs) and magnetic Fe3O4 are fabricated with the aid of microwave. The effects of the addition of CNTs and Fe3O4 on the structure and morphology, and EMA properties of the CR@CNT/Fe3O4 composite are evaluated in detail. The resulted composite can exhibit a superior minimum reflection loss (RLmin) of ?60.46 dB at 14.19 GHz with a thickness of 2.3 mm, and a wide effective absorption bandwidth of 5.5 GHz (11.2–16.7 GHz) due to the synergy effect of coordinated dielectric and magnetic losses, good interface impedance matching, and internal multiple reflections. This composite recycling from waste tire rubber is expected to become a potential candidate as a low-cost microwave absorber for reducing electromagnetic and black pollution.
查看更多>>摘要：? 2022SnO2 nanosheets were uniformly dispersed on sunflower seed shell based carbon microspheres by a simple one-step hydrothermal method, and the obtained composite was applied as a high-performance hard carbon anode material for lithium-ion and potassium-ion batteries. The introduction of sunflower seed shell based carbon spheres not only provides the support frame and growth site for SnO2 nanosheets, but also prevents the aggregation of flower-like structures to a certain extent. Moreover, the sunflower seed shell based carbon spheres have superior electrical properties. The results show that the composite can maintain 901.2 mAh g?1 after 400 cycles at 782 mA g?1, demonstrating stable reversible cycling under high current. The potassium ion battery show that the composite can maintain 201.9 mAh g?1 after 350 cycles at 374 mA g?1. This study provides a simple and convenient method for preparing prickly ball-like electrode materials, a promising anode material for potassium-ion batteries (PIBs) and lithium-ion batteries (LIBs).
查看更多>>摘要：? 2022 Elsevier B.V.Herein, by using Cu–Sn–Ti alloys addition zirconium carbide (ZrC) reinforcement to provide a way of enhancing the strength of brazed joint between diamond and solder. Microtopography of brazed segments was observed and interfacial characteristics of the brazing diamond were analyzed in detail via Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The wear machining performance of the diamond segment at different braze process was measured by changing the brazing temperature and holding time, respectively. Experiments indicated the microtopography of brazed segments with composite alloy of 15 wt% ZrC addition was optimal which the diamond edge was obvious, and the brazing filler metal spread more continuously and uniformly around the diamond without cracks and holes. Interfacial characterization results indicated that 10% wt% ZrC addition can promote titanium carbides produced on the diamond surface owing to the capillary force can improve the wettability. 15% wt% ZrC addition can further promote titanium carbides produced and improve the wettability by increasing the capillary force. However, higher ZrC addition (x ≥ 20 wt%) reduced performance of welded joints. Different braze process results showed that the brazed joint with the best grinding performance was obtained when the brazing temperature was 980 °C and the holding time was 15 min.
查看更多>>摘要：? 2022 Elsevier B.V.The influence of graphene nanoplatelets (GNP) surface area and size on the dispersion, electrical percolation behavior, electrical conductivity, thermal conductivity, electromagnetic interference (EMI) attenuation, and EMI attenuation mechanisms of GNP/polylactic acid (PLA) were investigated. The GNP/PLA composite's electrical percolation threshold decreased with the increase in GNP surface area and decrease in GNP size. The higher number of GNP particles associated with the decrease in GNP size and increase in GNP surface area facilitated the creation of a conductive network at a lower GNP content. However, at a GNP loading of 30 wt%, the GNP/PLA composites' electrical, EMI SE, and thermal conductivity decreased with the increase in GNP surface area and decrease in GNP size. At high nanofiller loading, the contact resistance between the nanofiller particles is more important than the nanofiller aspect ratio or size. The smaller filler size means more particles and more filler/filler resistance points. The most exciting finding is the dependence of EMI attenuation mechanisms on the GNP surface area. EMI attenuation by absorption was found to increase with the increase in GNP surface area.
查看更多>>摘要：? 2022 Elsevier B.V.Graphene-based materials present a high surface area and can present several structural defects or heteroatoms depending on the fabrication method. Such properties facilitate the graphene interaction with biomolecules leading to high electrochemical activity. In this context, we synthesize a high-quality dispersed reduced graphene oxide using Lysozyme as a dispersant (Ly-RGO). In this study, we have investigated the graphite oxidation-reduction fabrication process using X-ray Photoelectron Spectroscopy, X-ray Diffraction, and Raman Spectroscopy. We have used the Ly-RGO to fabricate an electrode on an electrochemical cell in which voltammograms show significant transduction of electrical signals. Finally, cyclic voltammetry and chronoamperometry measurements were performed with human saliva and SARS-CoV-2 RNA samples, to calibrate our biosensor. The results indicate that Ly-RGO has great potential in biosensor devices.
查看更多>>摘要：? 2022Plasma technology can be used as a green and novel method for the graphitization of carbon fiber. The effect of graphitization time on the main element content along with microstructure of carbon fiber in the plasma treatment process was investigated. It took an extremely short time (less than 100 ms) for the temperature of the system to increase until a relatively stable stage was reached. Furthermore, compared with the original carbon fiber, the increase in the carbon content and graphitization degree of carbon fiber was observed after microwave plasma treatment. Moreover, the original imperfect turbostratic graphite-like structure transformed to an ordered graphite structure with the escape of non?carbon elements from the disordered region of graphite-like crystallites. With the graphitization time of 180 s and microwave power of 800 W, corresponding to the temperature of 2100 °C, a high graphitization degree (R = 0.61) was observed and the crystallite size was as large as 5.10 nm, which are better than that of M40J and T800H. After 5 mins treatment, the average tensile modulus of samples apparently increased by 23% from 189 GPa to 245 GPa. This work demonstrated that the microwave plasma is an alternative approach for the development of carbon fibers with good microstructure and high graphitization degree.
查看更多>>摘要：? 2022We report the synergistic effects of boron nitride and graphene nanosheets on physical, structural, and nuclear radiation attenuation properties of polyester matrix-incorporated nanocomposites. Some critical material properties are thoroughly evaluated for several types of synthesized samples. Polyester is employed to strengthen graphene and boron nitride nanolayers, and their characteristics are investigated in detail. Additionally, we report the gamma-ray and fast neutron attenuation characteristics of synthesized nanocomposites to get a better understanding of the reinforcing effect as a function of material type and weight percentage. Thermal analysis findings indicate that adding graphene lowers the decomposition temperature but co-adding graphene and BNNS enhances thermal decomposition in comparison to graphene itself. Tensile tests showed that the inclusion of both GRP and GRP/BNNS strengthens the material. Among the polyester composite samples analyzed, the G3 sample with the most GNP reinforcement had the lowest HVL values throughout the broadest range of energy levels investigated. The recent findings may be beneficial to the scientific community in terms of incorporating these reinforcing types and ratios into polyester materials for a variety of applications, including industrial and research purposes.
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