Transition metals play an important role in the growth of carbon nanotubes (CNTs). Series of unsupported hybrid catalysts consisting of Ni:Cu, Ni:Cr, and Ni:Mn doped with Nd catalyst, respectively were synthesized by impregnation method. The catalytic performance of the catalyst for the production of CNTs was measured in the pyrolysis process of hydrocarbon source by catalytic chemical vapour deposition method. Acetylene gas was used as the source of carbon in the pyrolysis process. The decomposition of acetylene was carried out at 700ºC. The bulk properties of the catalysts were investigated by X-ray diffraction. Field emission scanning electron microscopy and thermal analysis were used to observe the morphology and thermal stability of the as-synthesized CNTs, respectively. Hybrid catalyst of Ni:Mn/Nd and Ni:Cr/Nd in 3:1 atomic ratio gave high percentage of carbon yield which was assigned for the high production of CNTs with the mass of yield 18 times greater than the initial mass of the catalyst used.
Glass-ceramics are a group of materials that takes advantage of the various glass-forming methods before they are subsequently heat-treated in a controlled manner to effect nucleation and crystallization to produce crystalline materials. The production of glassceramic materials is to overcome the low mechanical strength in pure glassy materials. In this work, a study on the crystallisation of a soda-lime-silica glass was undertaken to ascertain how the processing parameters affect the crystallization of such glasses, viz. either via a single or two-step heat-treatment procedure, as well as the effect of soaking duration at the heat-treatment temperature. A soda-lime-silica glass system was chosen because the raw materials for producing such glasses are readily available and can be considered to be the cheapest. The glass produced was examined by thermal analysis to determine the nucleation and crystallization temperatures before they were heat-treated using a single-step and a two-stage heat-treatment procedures. The resultant glassceramics produced were characterized using x-ray diffraction as well as by scanning electron microscopy. The results thus obtained showed that a two-stage heat-treatment procedure is more successful in producing a well-crystallized glass-ceramic product.