Effect of electrode structure on performance of Si anode in Li-ion batteries: Si particle size and conductive additive

The effects of Si particle size and the amount of carbon-based conductive additive (CA) on the performance of a Si anode in a Li-ion battery are investigated by adopting combinations of two different Si particle sizes (20 and 3 μm on average) and CA contents (15 and 30 wt.%), respectively. The CA contains graphitic flakes and nano-sized carbon black. Cyclic voltammetry, charge–discharge tests, scanning electron microscopy and X-ray diffraction establish that the CA content has a profound effect on the cycle-life and irreversible capacity of the Si anode. The former increases, while the latter decreases significantly with increasing CA content. Reducing the particle size of Si, on the other hand, facilitates the alloying/de-alloying kinetics. For instance a cycle-life of over 50 cycles with >96% capacity retention at a charge capacity of 600 mAh per g-Si has been demonstrated by adopting of 30 wt.% CA and 3 μm Si particles.     

A comparative study on the tribological behaviors of nitrided and sulfur-nitrided 35CrMo steel lubricated in PAO base oil with MoDTC additive

A nitrided layer on 35CrMo steel was prepared by the ion nitriding process, and then a sulfur-nitrided layer was obtained by low temperature ion sulfuration. The results showed that both the nitrided and sulfur-nitrided surfaces improved the wear resistance efficiently under PAO lubrication, and exhibited the best wear resistance and friction-reducing property under PAO with 0.75% MoDTC lubrication. Compared with the plain and nitrided surfaces, the sulfur-nitrided surface exhibited the best synergistic effect with MoDTC displaying the lowest friction coefficient and wear volume. The mechanism of the best effect was due to MoS₂ and FeS formed on the sulfur-nitrided surface.     

Effect of denucleating glass composition on undercooling of Fe83Ga17 alloy melts

Adopting glass fluxing combined with superheating cycling method, the undercooling and its stability of Fe₈₃Ga₁₇ alloy melts were investigated using different kinds of denucleating glass: B₂O₃, 90% NaSiCa + 10% B₂O₃ (simplified as Na–Si–Ca–Al–B) and 70% Na–Si–Ca–Al–B + 30% Na₂B₇O₄. The results showed that different glass has different denucleating mechanism. The purification of B₂O₃ glass is only a physical process, by which the stable bulk undercooling cannot be obtained during superheating–cooling cycles. While taking Na–Si–Ca–Al–B glass as purifying agent, its denucleating mechanism is a comprehensively physicochemical process. But the stability of undercooling is still undesirable because of the separation between melt and glass during cooling process in superheating cycling. A stable bulk undercooling can be obtained by physicochemical denucleating process in the case of 70% Na–Si–Ca–Al–B + 30% Na₂B₇O₄ molten glass owing to its suitable viscosity.     

MoS2/Pb-Ti多层薄膜的结构和摩擦学性能

目的 设计MoS2/Pb-Ti多层薄膜,改善真空和大气环境下的摩擦学性能。方法 采用磁控溅射技术沉积MoS2/Pb-Ti多层薄膜,通过扫描电镜（SEM）、X射线衍射(XRD)、纳米压痕仪、真空和大气摩擦磨损实验,分别评价MoS2/Pb-Ti多层薄膜的表面形貌、微观结构、力学性能、真空和大气环境下的摩擦学性能,并通过光学显微镜、能谱仪（EDS）、Raman光谱仪对磨痕及磨斑进行分析。结果 随着MoS2层厚度的增加,MoS2/Pb-Ti多层薄膜的表面颗粒逐渐细化,变得更加光滑。同时,微观结构由金属相主导转变为由MoS2相主导,弹性模量逐渐降低,硬度则先升高后降低。在真空环境下,MoS2/Pb-Ti多层薄膜的摩擦系数低至0.01,磨损率低至2.2×10?7 mm3/(N?m),大气环境下摩擦系数低至0.07左右,磨损率低至2.7×10?7 mm3/(N?m)。 结论 在真空摩擦磨损实验中,MoS2层厚度过薄时,MoS2/Pb-Ti多层薄膜的磨损机制为粘着磨损,MoS2层厚度增加有助于形成稳定的转移膜,使得摩擦磨损大幅降低。在大气摩擦磨损实验中,Ti保护MoS2的结构免于H2O和O2的破坏,使体系具有低而稳定的摩擦磨损。     

Slag resistance mechanism of MgO–Mg2SiO4–SiC–C refractories containing porous multiphase aggregates

The slag resistance of MgO–SiC–C (MSC) refractories should be improved because of the mismatch in the thermal expansion coefficient between the aggregates and matrix, as well as the defects caused by the affinity between periclase and slag. In this study, MgO–Mg₂SiO₄–SiC–C (MMSC) refractories were prepared using porous multiphase MgO–Mg₂SiO₄ (M-M₂S) aggregates to replace dense fused magnesia aggregates. Compared to MSC, the slag penetration index of MMSC decreased by 43.5%. The structure of the porous aggregates increased the surface roughness, and the multiphase composition of the aggregates decreased the mismatch of the thermal expansion coefficient with the matrix, thus reducing debonding between the aggregates and matrix. The aggregates and matrix in the MMSC formed an interlocking structure, which bound them more tightly to improve the slag resistance. The slag viscosity at different depths from the initial slag/refractory interface was calculated using the Ribond model. The M-M₂S aggregates increased Si_xO_y^z− in the slag, which increased the slag polymerization and slag viscosity. The aggregates and matrix in the MMSC reacted with the slag to form high melting point phases, which reduced the channel of the slag. In addition, the penetration depth and velocity derived from the Washburn Equation were modified for the CaO–SiO₂–Al₂O₃–MgO–FeO slag and magnesia based refractory to accurately evaluate slag penetration.     

Evaluation of biosynthesized nickel oxide nanoparticles from Clerodendrum phlomidis: A promising photocatalyst for methylene blue and acid blue dyes degradation

In the present investigation, nickel oxide nanoparticles (NiO) were biosynthesized utilizing an extract of Clerodendrum phlomidis leaves. Their size, phase study, and shape were investigated using a variety of research methods. In addition, we assessed the photocatalytic effects of NiO nanoparticles on the degradation of methylene blue (MB) and acid blue (AB) dyes. Throughout the research process, we found that these nanoparticles had extraordinary potential for photocatalysis when exposed to UV light. This is a 100% environmentally friendly method that makes no use of any harmful or poisonous solvents. High-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and ultraviolet–visible spectroscopy (UV–Vis) were used to analyze the biosynthesized NiO nanoparticles. The catalytic activity of the newly synthesized nanoparticles was evaluated by seeing how well they degraded dyes called methylene (MB) and acid blue (AB). Following the first-order reaction, kinetics was the photocatalytic effectiveness against the methylene blue (MB) and acid blue (AB) dyes, both of which exhibited a maximum degradation efficiency of 92% and 63%. Because of this, the biosynthesized NiO nanoparticles synthesized utilizing the extract of Clerodendrum phlomidis leaves have the potential to be used in photocatalytic applications.     

Broadband,high-sensitivity self-powered ferroelectric LuMnO3-based photodetector with large photocurrent output

The broadband spectrum detection from ultraviolet to near-infrared is hankered in the photoelectric applications of imaging, sensing and communication. Here, a new self-powered photodetector based on ferroelectric LuMnO₃ thin film with a narrow bandgap of 1.46 eV exhibits high-sensitivity ultraviolet–visible–near infrared photodetection properties. The responsivity (R) and detectivity (D*) in sunlight are 0.4 A/W and 7.05 × 10¹¹ Jones, which are much higher than that of other ferroelectric photodetectors. Moreover, under the monochromatic light (900 nm), the R and D* can reach 0.39 A/W and 6.89 × 10¹¹ Jones. The outstanding photodetection performances owed to the large photocurrent output, where the short-circuit current density can reach 10.5 mA/cm² under 1 sun illumination. The synergistic effect of ferroelectric photovoltaic effect and interface barrier effect demonstrates that the multi-driving forces can achieve high dissociation efficiency for photon-generated carriers. The excellent photodetection performances open up new application of ferroelectric materials in broadband self-powered photodetectors.     

Microstructure and flexural strength of C/HfC-ZrC-SiC composites prepared by reactive melt infiltration method

C/HfC-ZrC-SiC composites were fabricated via reactive melt infiltration (RMI) of the mixed HfSi₂ and ZrSi₂ alloys. The microstructure, infiltration behavior of the hybrid silicide alloys infiltrating C/C composites, and flexural strength of C/HfC-ZrC-SiC composites was studied. Inside composites, there were more Hf-rich (Hf, Zr)C phases distributed in the exterior region, while more SiC and Zr-rich (Zr, Hf)Si₂ in the interior region. There was compositional segregation in (Hf, Zr)C, with the HfC content decreasing from the exterior region to interior region. The RMI process was performed at different temperatures to investigate the structural evolution, and a model for the reactive melt infiltration of the mixed HfSi₂ and ZrSi₂ alloys into C/C composites was established. Compared with C/HfC-SiC and C/ZrC-SiC prepared by same process, C/HfC-ZrC-SiC had the highest flexural strength of 247Mpa and 213Mpa after oxidation at 1200 ℃ for 15 min. Both the unoxidized and oxidized samples presented a pseudo-plastic fracture behavior.     

Copper bonding silicon nitride substrate using atmosphere plasma spray

Silicon nitride (Si₃N₄) is an excellent engineering ceramic with high strength, fracture toughness, wear resistance, and good chemical and thermal stability. Recently, the enhanced thermal conductivity enables Si₃N₄ to have potential application prospects in the electronic and orthopedic fields. Metal bonding with Si₃N₄ is often the key to these applications. Here we report a facile approach for the titanium-activated Cu bonding on Si₃N₄ substrates using an atmosphere plasma spray (APS) process. With X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) observation, it was shown that the interaction between the pre-bonded Ti (by APS) on Si₃N₄ promoted the adhesion and high bonding strength of APS Cu on Si₃N₄. The interfacial structure and phases were characterized, and tensile strength, electrical resistivity, thermal conductivity, and residual stress of Cu bonded Si₃N₄ were measured accordingly. The APS deposited Cu layer is dense, has a high purity, and is joined firmly with Ti pre-bonded Si₃N₄ substrate. The maximum tensile strength between Cu and Si₃N₄ is as high as 89.4 MPa. The Si₃N₄ substrate bonded with highly dense Cu demonstrates a low surface resistivity of 8.72 × 10⁻⁴ Ω∙mm, and high thermal conductivity of 98.12 W/m·K, which shows potential applications in electronic devices.     

Properties of CuMn1.5Ni0.5O4 spinel as high-performance cathode for solid oxide fuel cells

Spinel oxide cathode has made great progress in solid oxide fuel cells (SOFCs) because of its special characteristics different from perovskite. In this study, a spinel-structured SOFC cathode, CuMn_1.5Ni_0.5O₄ (CMN), is proposed. Rietveld refinement shows that CMN takes the cubic structure of the space group of P4₃32. CMN shows a high conductivity of about 70.0–91.2 S cm⁻¹ at 600–800 ºC in the air and exhibits good catalytic activity for oxygen. A symmetric cell with CMN-GDC composite cathode demonstrates a low Rp of 0.047 Ω cm² at 800 ºC. The charge transfer of oxygen is the rate-limiting process at lower temperatures. The performance test results of the button cell with CMN-GDC composite cathode are excellent, with high power densities of 1342.4 mW cm⁻² at 800 ºC. After a110h long-term test, the cell runs stably, and no microstructure damage is observed.