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Cobalt manganese hydroxides with well-defined nanowire morphology (CoMn-HW) is scalable fabricated by adjusting solution contents, Mn/Co ratio and alkaline species. To further improve the conductivity of CoMn-HW, GO is introduced during fabrication process and reduced to rGO according to the high temperature and alkali atmosphere. By optimizing the adding mass of rGO, CoMn-HW/rGO with sandwiched like structure is successfully synthesized for supercapacitor electrode. The composite delivers a high specific capacitance of 784 F g−1 at current density of 0.5 A g−1, good rate capability (84.2% capacitance retention after current density increase 10 times). Moreover, an asymmetric supercapacitor with CoMn-HW/rGO10 as the positive electrode and active carbon as the negative electrode, is assembled and delivers a maximum energy density of 38.3 Wh kg−1 and power density of 8000 W kg−1, representing its potential in energy storage and conversion systems. • Co, Mn-hydroxides with nanowire morphology is scalable fabricated. • CoMn-HW/rGO with sandwiched like structure is synthesized under optimal synthesis condition. • An asymmetric supercapacitor based on CoMn-HW/rGO and AC is assembled with high energy and power densities. [ABSTRACT FROM AUTHOR]

In this article, ZnCo 2 O 4 nanowires deposited with two kinds of typical layered double hydroxides (Ni–Al,Co–Al LDH) are developed via scalable method. Two materials all display core–shell hierarchical structure. High specific capacitance of 2041 F g−1 and 1586 F g−1 are obtained for ZnCo 2 O 4 @Co–Al LDH and ZnCo 2 O 4 @Ni–Al LDH,respectively. Combining with active surface and synergistic effect, the role of hierarchical structure in enhancing performance is revealed. Moreover, two all solid state supercapacitors based on fabricated materials as positive electrodes, activated carbon as negative electrodes and PVA–KOH as polymer electrolyte are assembled. The maximum power and energy densities of ZnCo 2 O 4 @Co–Al LDH//AC are 6200 W kg−1 and 50.1 Wh kg−1, respectively. While the power and energy densities of ZnCo 2 O 4 @Ni–Al LDH//AC are 3400 W kg−1 and 27.8 Wh kg−1. At last, an energy storage–conversion system, based on solar cell as input device and assembled asymmetric supercapacitor ZnCo 2 O 4 @Co–Al LDH//AC as output device, is integrated as a self–sustaining power device, indicating its potential in practical applications. In this article, ZnCo 2 O 4 nanowires deposited with two kinds of typical layered double hydroxides (LDHs) are developed via scalable method. Combining with active surface and synergistic effect, the role of hierarchical structure of each material in enhancing performance is revealed. Moreover, an energy storage–conversion system, based on solar cell as input device and assembled asymmetric supercapacitor as output device, is integrated as a self–sustaining power device, further indicating its potential in practical applications. Image 1 [ABSTRACT FROM AUTHOR]

The room temperature abrasive wear behavior of three selected MAX phases, Ti 3 SiC 2 , solution strengthened Ti 2.7 Zr 0.3 SiC 2 and Cr 2 AlC, is investigated by low velocity scratch testing using a diamond conical indentor with a final radius of 100 μm and a cone angle of 120° and applied loads of up to 20 N. All three materials showed a relatively low wear resistance in comparison to most engineering ceramics such as Al 2 O 3, Si 3 N 4 and SiC. For all three materials, the wear rate scaled more or less linearly with the applied load. The softer Ti 3 SiC 2 with a hardness of 2.8 GPa showed the lowest wear resistance with extensive ploughing and grain breakout damage, both within and outside the direct wear track, in particular at the highest load. The hardest material, Ti 2.7 Zr 0.3 SiC 2 , with a hardness of 7.3 GPa, showed a 5 times better wear resistance. The Cr 2 AlC with a hardness of 4.8 GPa showed a wear resistance equal to or even better than that of the Ti 2.7 Zr 0.3 SiC 2. The wear mechanism depends on the applied load and the microstructure of the MAX phase materials tested. For the Ti 3 SiC 2 sample, a quasi-plastic deformation behavior occurs below a point load of 10 N, resulting in grain bending, kink band formation and delamination, grain de-cohesion, as well as trans-and intra-granular fracture near the scratch groove. At this load, the Ti 2.7 Zr 0.3 SiC 2 and Cr 2 AlC MAX samples display plastic ploughing, grain boundary cracks and material dislodgments. [ABSTRACT FROM AUTHOR]

Abstract Almost pure (Ti 1- x Zr x) 3 SiC 2 MAX phase solid solutions with x ranging up to 0.17 were synthesized at temperatures in the range of 1450–1750 °C with reactive Spark Plasma Sintering (SPS). The zirconium partially replaces the M-element titanium of the Ti 3 SiC 2 MAX phase up to x equals 0.17. The lattice parameters of the hexagonal (Ti 1- x Zr x) 3 SiC 2 MAX phase are determined with X-ray diffraction using Rietveld refinement and show an anisotropic lattice expansion upon Zr insertion into Ti 3 SiC 2. This observation is in very good agreement with density functional theory calculations where the deviation between the measured and calculated lattice parameter is less than 1%. The predicted elastic modulus reduction is only 4%. This behavior can be rationalized by considering the electronic structure, where only minute changes are observable as Zr is incorporated into Ti 3 SiC 2. The measured nanohardness of the synthesized (Ti 1- x Zr x) 3 SiC 2 MAX phase increases from 12.7 ± 1 GPa for Ti 3 SiC 2 to 16.3 ± 1.1 GPa when x is raised from 0 to 0.17 due to an increasing amount of accompanying Ti 1- y Zr y C. The elastic moduli of (Ti 1- x Zr x) 3 SiC 2 solid solutions measured by an ultrasonic pulse-echo method (325–354 GPa) are in good agreement with the predicted elastic moduli (357–342 GPa). [ABSTRACT FROM AUTHOR]