Characteristic of Carbon Nanotubes Modified with Cobalt, Copper and Bromine

The paper presents results of studies on carbon nanotubes - as received, after cleaning and also after modification. Functional groups as well as metal nanoparticles have been attached, originating from cobalt sulphate, copper acetate and a mixture of hydrogen bromide and bromide. The surface studies on an atomic forces microscope (AFM), X-ray studies (phase composition analysis, crystallite sizes determination) as well as Raman spectroscopy studies were carried out on such nanotubes. The surface topography studies have shown that after the modification the diameter and length of nanotubes change. Also the surface development changes, which has been determined through roughness parameter measurements. The change of intensity, of crystallite size and of half-value width of main reflections originating from carbon for nanotubes modified in various ways have been determined using the X-ray analysis.

Reaction and Sintering Mechanism of Forsterite Lightweight Material in Sodium Carbonate Molten Salt

Using the natural forsterite and Na2CO3 as a raw material, the forsterite lightweight material was prepared in Na2CO3 molten salt. The reaction between forsterite and Na2CO3 and sintering mechanism of forsterite were studied in the paper. The sintering temperature was 1000 °C, 1100 °C, and the holding time was 1 h, 3 h, 5 h, 7 h, 10 h, respectively. The sintered samples were characterized by XRD and SEM for their microstructure and phase composition analysis which determined the mechanism of the chemical reaction and sintering in the sintering process. The product of Na2MgSiO4 phase in In earlier period of the reactions promoted the rearrangement of particles of forsterite in the initial stage of sintering process. The sintering mechanism was mainly controlled by the diffusion mechanism.

Influence of Pressure on the Crystallization in SiO2f/SiO2 Composites

The influence of pressure on the crystallization behavior in SiO2f/SiO2 composites hotpressed at 1350°C was studied. The crystalline phase composition analysis on SiO2f/SiO2 composites revealed that the formation of cristobalite was promoted when the hot-pressing pressure ≤ 12 MPa, however suppressed with higher pressure applied. It can be ascribed to the nucleation mechanism change from surface nucleation to bulk nucleation. Analysis on relative density as well as fracture microstructure of SiO2f/SiO2 composites confirmed the conclusion.