Byung Kyu Lim

Microstructure and mechanical properties of CNT/Ag nanocomposites fabricated by spark plasma sintering

Carbon nanotube/silver (CNT/Ag) nanocomposites include CNT volume fraction up to 10 vol.% were prepared by chemical reduction in solution followed by spark plasma sintering. Multiwalled CNTs underwent surface modifications by acid treatments, the Fourier transform infrared spectroscopy data indicated several functional groups loaded on the CNT surface by acid functionalisation. The acid-treated CNTs were sensitised and activated. Silver was deposited on the surface of the activated CNTs by chemical reduction of alkaline silver nitrate solution at room temperature. The microstructures of the prepared CNT/Ag nanocomposite powders were investigated by high-resolution scanning electron microscopy (HRSEM), transmission electron microscopy and X-ray powder diffraction analysis. The results indicated that the produced CNT/Ag nanocomposite powders have coated type morphology. The produced CNT/Ag nanocomposite powders were sintered by spark plasma sintering. It was observed from the microstructure investigations of the sintered materials by HRSEM that the CNTs were distributed in the silver matrix with good homogeneity. The hardness and the tensile properties of the produced CNT/Ag nanocomposites were measured. By increasing the volume fraction of CNTs in the silver matrix, the hardness values increased but the elongation values of the prepared CNT/Ag nanocomposites decreased. In addition, the tensile strength was increased by increasing the CNTs volume fraction up to 7.5 vol.%, but the sample composed of 10 vol.% CNT/Ag was fractured before yielding.

Fabrication processes and multi-functional applications of carbon nanotube nanocomposites

The microstructures and properties of carbon nanotube (CNT)/metal nanocomposites, which are fabricated by the molecular level mixing process, have been investigated for multifunctional applications as structural and functional materials. The molecular level mixing process provides a homogeneous dispersion of carbon nanotubes in metal matrices by inducing the ionic bonding between functionalized carbon nanotubes and metal ions. For the structural applications, CNT/Cu nanocomposites showed an outstanding enhancement in mechanical properties such as strength, modulus, and wear resistance. For the functional applications, CNT/Co nanocomposites showed excellent field emission behavior for possible applications on next generation field emission displays. SiC/W nanocomposites, fabricated by using CNT/W nanocomposite powders, showed good ablation properties for the applications as rocket propulsion materials.

Synthesis and characterization of CNT/LNMC nanocomposite electrode for Lithium Ion Battery

CNT/LiNi<inf>0.33</inf>Mn<inf>0.33</inf>Co<inf>0.33</inf>O<inf>2</inf> nanocomposite electrode material was fabricated for Lithium Ion Battery. Sol-Gel synthesis has been used to synthesize the nano-sized pristine LiNi<inf>0.33</inf>Mn<inf>0.33</inf>Co<inf>0.33</inf>O<inf>2</inf> (LNMC). CNT/LiNi<inf>0.33</inf>Mn<inf>0.33</inf>Co<inf>0.33</inf>O<inf>2</inf> nanocomposite has been synthesized by using low temperature dispersion method. Structural characterization of the material has been performed by using X-ray diffraction, which shows the formation of single phase LiNi<inf>0.33</inf>Mn<inf>0.33</inf>Co<inf>0.33</inf>O<inf>2</inf> with R-3m as space group. Morphological properties have been investigated by using characterization tool such as FESEM, which confirms the formation of composite material. Thermal properties have been characterized by DSC/TG measurements. Electrochemical performance of the material is under study. CNTs helped in increasing the cycle life of the material when cycled in the voltage range of 4.6-2.8V at a cycling rate of 0.2 mA/cm², however the impedance is found to be higher in case of the composite material compared to the pristine nano-sized LNMC.