Journal of Materials Science

Pure Cu matrix composite reinforced by CrxOy-CNT hybrid was prepared via powder metallurgy in the present work. Microstructural analysis revealed that the formation of Cu2O nanoparticles at the interface is contributed to the interfacial bonding. The CrxOy-CNT/Cu composite of 1.0 vol% hybrid reinforcement exhibited excellent ultimate strength of 402.6 MPa, which was ~ 90.0% higher than that of unreinforced Cu (211.9 MPa). Meanwhile, the ultimate strength of the hybrid reinforcement was much higher than those of the separate components, which were 238.4 MPa of 1.0 vol% CNT/Cu composite and 339.1 MPa of 1.0 vol% CrxOy/Cu composite, respectively. Furthermore, the quantitative analysis indicated that Orowan looping system contributed the most to strength in CrxOy/Cu and CrxOy-CNT/Cu composites, whereas load transfer then contributed the most strength for CNT/Cu composite.

Molecular dynamics simulations are used to investigate the effect of graphene dispersion on the equilibrium structure and deformation of graphene/eicosane composites. Two graphene sheets with four different interlayer distances are incorporated, respectively, into a eicosane matrix to form graphene/eicosane composites representing different graphene dispersions. With greater graphene dispersion, the “adsorption solidification” of the eicosane increases, where eicosane molecular lamination, orientation, and extension become more uniform and stronger. In addition, eicosane molecular motion is inhibited more in the direction perpendicular to graphene surfaces. When these graphene/eicosane composites are deformed, the free volume initially increases slowly due to small, scattered voids. After reaching the yield strains, the free volume rises sharply as the structures of composites are damaged, and small voids merge into large voids. The damage always occurs in the region of the composite with the weakest “adsorption solidification.” Since this effect is stronger when the graphene sheets are more dispersed, more complete dispersion results in higher composite yield stresses. Lessons from these simulations may provide some insights into graphene/polyethylene composites, where suitable models would require very long equilibration times.

A direct observation of the grain growth and densification of BaTiO3 ceramics were made in a TEM equipped with an in-situ installed heating platform. Both real two-sphere and three-sphere models for BaTiO3 ceramics were found and parallel processes of the shrinkage between particles and the grain growth (coarsening) were observed during the heating process. Attempts of relating the grain growth and densification was made which reveals, though roughly, the close relation between the two competing process: they took place simultaneously and in parallel, therefore it is believed that the process took place via the same mass transport mechanism. Surface diffusion on the TiO2 particle surface was observed directly, which takes place with the co-motion of several lattice layers from a smaller grain onto the surface of an adjacent larger one. The surface diffusion was accompanied by the diminishing of a small grain, i.e., overall grain growth.

The UV–visible spectrophotometric method has been described the study of raw carbon nanotubes (R-MWCNTs) and functionalized multiwall carbon nanotubes (F-MWCNTs) for the control of bacterial growth by using validated analytical techniques. The absorption spectra of functionalized carbon nanotubes (F-MWCNTs) and raw carbon nanotubes (R-MWCNTs) show maximum absorbance at λ max 600 nm. The linear relationship was found between absorbance and concentration of R-MWCNTs and F-MWCNTs in the range of 0.25–2.0 μg mL−1. The linear regression equation was evaluated by statistical treatment of calibration data and gives the value of correlation coefficient for F-MWCNTs (0.9999) and R-MWCNTs (0.9993), which indicate excellent linearity. The Optical and regression characteristics of the proposed method were found apparent molar absorptivity, limits of detection (LOD), and limit of quantitation (LOQ) for R-MWCNTs and F-MWCNTs (5.75 × 102: 8.25 × 102 L mol−1 cm−1), (0.052: 0.018 μg mL−1), and (0.055: 0.158 μg mL−1), respectively. The validity of the proposed method was checked by precision, accuracy, linearity, limits of detection (LOD), and limit of quantitation (LOQ). The RSD (%) and quantitative recoveries (%) were obtained (0.026–0.0086) and (100.34 and 100.71) for R-MWCNTs: for F-MWCNTs by UV–visible spectrophotometric, respectively.

The synthesis of nickel aluminium hydroxypicrate, [Ni3Al(OH)8] (C6O7N3H2)·nH 2O, and lithium aluminium hydroxypicrate, [Al2Li(OH)6] (C6O7N3H2)·nH 2O by anion exchange is described. Picric acid and the corresponding hydroxycarbonates were used as starting materials. The new compounds were characterized by chemical analyses, electron microscopy, infrared spectroscopy and X-ray diffraction. The results obtained indicate that both are hydrotalcite-like compounds where the picrate anion lies between the basic layers. The thermal decomposition of the compounds was studied by differential thermal and thermogravimetric analysis.

A 36.8 wt% CaO-26.2wt% TiO2-37.0 wt % SiO2 glass (CTS) was employed as the ceramic brazer for the bonding of 3 mol% yttria stabilized zirconia (YSZ3). Sandwich-like YSZ3-CTS-YSZ3 specimens were fabricated and temperature dependence of the bonding strength was evaluated. An optimum bonding process was achieved at a bonding temperature of 1424 °C for 30min with CTS glass slurry having a glass/organic ratio of 1.82. The effects of processing parameters on the bending was investigated on the basis of the metallurgical evolution at the interface. In addition, predominating factors affecting the bonding strength were also explored.

Copper oxide (CuO) electrodes have outstanding potentials for supercapacitors in virtue of their low cost, environment friendly, especially, and the high theoretical specific capacitance (1800 F g−1). However, their poor electronic conductivity restricts the practical application. Doping appropriate transitional metal ions into host materials is an effective method to modulate the electronic structure and improve the conductivity, furthermore, enhancing the energy storage capacity. Herein, Mo-doped CuO nanosheets on Ni foams were obtained by combining a simple hydrothermal process and calcination treatment. Different doping concentrations of Mo were discussed, and the as-prepared 3 at.% Mo-doped CuO (Mo-CuO-2) exhibited the best electrical conductivity and the highest specific capacitance of 1392 F g−1 at 2 A g−1. In addition, an asymmetric supercapacitor device was assembled using Mo-CuO-2 and activated carbon as a positive electrode and a negative electrode, which exhibited a remarkable energy density of 36 Wh kg−1 at 810 W kg−1 and an excellent cycle life with 81% capacitance retention for over 5000 cycles. More significantly, Mo-CuO-2 is a promising material candidate for practical energy storage applications.