We present a novel composite material of nano-carbon with the highest value of thermal conductivity 2.6 W (m K)−1, by dispersing graphite powders and multi-walled carbon nanotubes (MWCNTs) in a polymer matrix of epoxy resin and the curing agent. Furthermore, this composite has been prepared as the heat dissipation system of high-brightness light emitting diodes (HB-LEDs), using a sandwich-structured thermal interface material (SSTIM) with metal for the inner layer and two composites for outer layers. The optimal for thermal conductivity of this thermal interface material (TIM) is 4.9 W (m K)−1, 58% higher than that of commercial products. This promising material can increase the cooling rate and lower the energy consumption of HB-LEDs.Highlights► We present a nanocarbon composite as thermal interface material(TIM) for LED. ► The composite includes graphite powders, multi-walled carbon nanotubes and polymer. ► We get the optimal ratio of these three materials from theoretical and experimental. ► We construct sandwich-structured to improve thermal conductivity. ► The paper shows how this TIM was incorporated into the LED package.

Large-area and homogeneous single-walled carbon nanotube (SWCNT) films have been deposited via arc discharge directly on glass substrate coated with a layer of indium tin oxide film. The characterization, by means of electron microscopy and Raman spectroscopy, shows that the as-grown films are uniformly woven and consist of SWCNT with diameters ranging from 0.82 to 1.15 nm. As a cathode material, the field emission test indicates the films have low turn-on field of ∼1.2 V/μm at 10 μA/cm2 emission current, and high emission intensity causing luminance of about 7000 cd/cm2 with fine uniformity. The best performing sample exhibits a constant degradation of less than 3% per hour at an emission current of around 1 mA. Measuring with the high voltage (2000 V) on the films for 2.0 h increased the field enhancement factor from 4500 to 5400 at the high field region. The results are of significance to the development of field emission display using nanoemitters.

Double-walled carbon nanotubes could be synthesized by arc-discharge method using ball-milling mixtures of iron, cobalt, nickel and sulfide as catalysts. Structures of these carbon nanotubes were characterized by TEM, HRTEM and Raman spectroscopy. Also the lithium insertion properties were examined. The results showed that the irreversible capacity of the double-walled carbon nanotube lithium ion batteries is high, which is considered to be related to the formation of SEI on the surface of the electrodes in the process of electrochemistry reaction.

The lithium-ion-conducting inorganic solid electrolytes in the oxide systems Li2O-SiO2-P2O5 and Li2O-TiO2-SiO2-P2O5 were prepared by the solid-state reaction, and the electrolyte pellet made by cold-pressing method had diameter of 13 mm and was about 1 mm thick. Phase identification and surface morphology of the products were carried out by X-ray diffraction and scanning electron microscopy. Ionic conductivity of the pellets was investigated through ac impedance. The results show that the adding of other cations can improve the ionic conductivity of the solid electrolyte, and the sintering temperature and duration can influence the ionic conductivity. The maximum ionic conductivity in the samples is 9.9 × 10−4 S/cm in the Li2O-TiO2-SiO2-P2O5 system.

A method to prepare the carbon nanotubes (CNTs)–Ni–P composite coating with different mass content of CNTs on the surface of 45# steel by electroless plating was proposed. The transmission electron microscopy (TEM) and the scanning electron microscopy (SEM) were used to observe the appearance of the as-prepared CNTs and the CNTs–Ni–P composite coating, and then the roughness of the coating surface was also analyzed by atomic force microscopy (AFM). Furthermore, the wear and friction behavior of the CNTs–Ni–P composite coating were investigated under oil-lubricated condition, Due to the self-lubrication property and the unique antifriction structure, CNTs can greatly improve the wear resistance of the CNTs–Ni–P composite coating, where the wear resistance of the CNTs–Ni–P composite coating is optimized with the intermediate mass content of 2 kg/m3 CNTs.

To estimate the apex field enhancement factor associated with carbon nanotubes (CNTs) array on a planar cathode surface, the image model of floated sphere between parallel anode and cathode plates was proposed. Firstly, the field enhancement factor of individual CNT was given as the following expression, β0=h/ρ+3.5β0=h/ρ+3.5, where h   is the height and ρρ is the radius of CNTs. Then the field enhancement factor of CNTs array was discussed and the above expression was modified to be β=h/ρ+3.5-Wβ=h/ρ+3.5-W, in which W is the function of the intertube distance R and represents the coulomb field interaction between the CNTs. All results show that the intertube distance of CNTs array critically affects the field emission. When the intertube distance is less than the height of tube, the field enhancement factor will decrease rapidly with decreasing the intertube distance. According to the calculated results and considering the field emission current density, the filed emission is optimal theoretically when the intertube distance is comparable with the height of CNTs.