Effect of mechanical alloying time and rotation speed on evolution of CNTs/Al-2024 composite powders

Carbon nanotubes （CNTs） reinforced aluminum matrix composites were fabricated by mechanical milling followed by hot extrusion. The commercial Al-2024 alloy with 1% CNTs was milled under various ball milling conditions. Microstructure evolution and mechanical properties of the milled powder and consolidated bulk materials were examined by X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM） and mechanical test. The effect of CNTs concentration and milling time on the microstructure of the CNTs/Al-2024 composites was studied. Based on the structural observation, the formation behavior of nanostructure in ball milled powder was discussed. The results show that the increment in the milling time and ration speed, for a fixed amount of CNTs, causes a reduction of the particle size of powders resulting from MM. The finest particle size was obtained after 15 h of milling. Moreover, the composite had an increase in tensile strength due to the small amount of CNTs addition.

Effect of milling energy on preparation of Cu-Cr/CNT hybrid nano-composite by mechanical alloying

Production of Cu-Cr/carbon nanotube （CNT） hybrid nano-composite by wet and dry milling processes at three different levels of milling energy was investigated in order to study the effect of milling energy in two different media on dispersion of CNTs, and preparation of the nano-composite. The structural evolution and solid solution formation were evaluated by X-ray diffraction technique. The microstructure was characterized by scanning electron microscopy and transmission electron microscopy. Also, the mechanical properties were measured by microhardness test. The mean crystallite size was in the range of 20-63 nm depending on milling medium and energy. CNTs dispersion is a function of milling energy. According to FESEM images and microhardness results, it can be concluded that wet milling is more applicable in dispersing CNTs homogeneously in comparison to dry milling. It was also found that wet milling at higher milling energies can be a beneficial method of producing the homogeneous hybrid nano-composite with the least damages introducing on CNTs because of the higher microhardness which can be attributed to better dispersion of less damaged CNTs. Compared with crystallite size changes, CNTs dispersion and damages were considerably more effective on hardness.

Recent advances in flexible supercapacitors based on carbon nanotubes and graphene

Owing to the rapidly growing market for flexible electronics, there is an urgent demand to develop flexible energy storage devices. Flexible supercapacitors have received much attention due to their good flexibility, fast charge/discharge rate and long lifecycle times. Carbon nanotubes（CNTs） and graphene have good mechanical properties, which make them suitable for flexible supercapacitors. Based on different nanostructures of CNTs and graphene, we summarized the recent progress in CNTs-and graphene-based flexible supercapacitors with a brief description of the basic principles for evaluating their performance. Special emphasis was given to fabrication methods, capacitive performance and electrode configurations of different flexible supercapacitors.Furthermore, the remaining challenges and future research directions for CNTs-and graphene-based flexible supercapacitors have also been discussed.

Transparent flexible ZnO/MWCNTs/PBMA ternary nanocomposite film with enhanced mechanical properties

Functional organic-inorganic nanocomposites with high transparency show significant potential application in many fields. However, it is still a great challenge to prepare flexible transparent nanocomposites due to the intrinsic stiffness of the nanoparticles and the poor interaction between nanopartieles and organic matrices. In this work, a transparent ternary nanocomposite film with enhanced mechanical performance is fabricated by two-steps. First, the transparent ternary ZnO/MWCNTs/n-butyl methacrylate （BMA） nanodispersion is prepared by mixing the ZnO/BMA and MWCNTs/BMA dispersions directly. Then, the ternary nanocoposites film is fabricated via in-situ bulk polymerization of the above nanodispersions. As a result, the tensile strength of the ZnO/MWCNTs/poly-n-butyl methacrylate （PBMA） ternary film is enhanced by 42% and the elongation at break is three times that of ZnO/PBMA nanocomposite. The hardness of the film increases from 5B to 1H with 40 wt% ZnO. These results indicate that ZnO and MWCNTs can improve the mechanical properties of the composite significantly. Importantly, the ternary nanocomposite film still remains high transparency and exhibit excellent UV-shielding performance. The as-prepared transparent multifunctional nanocomposite films have promising applications in optical materials and devices, such as optical filters, contact lenses and protection packing.