A Study On Preparation Of Colloidal Silica Particles And Complex Core-shell Structures Of Nickel Hydroxide

Colloidal crystals are one of the systems constituted of meso or nano monodispersed colloidal which is ordered through a particular arrangement of the two or three dimensional. For the structural characteristics, it is used in many different areas. Monodispersed silica after self-assembled, with narrow size distribution,can be applied in paint, medicine and so on.Ultrafine nickel oxide powder, a nano-metallic material, has been used in many areas, such as catalysts, battery materials, adhesives and other hard alloy. Core-shell structural materials because of its composition, size, and different structures can be made into multi-functional materials. The cost of crystal can be reduced by coating nickel hydroxide onto silica. Also, the infrared absorption of the catalyst would be increased and the field of application. The coating of silica on nickel hydroxide can improve the toughness, wear resistance and corrosion resistance. Based on the plenty of the present literature, we mainly have carried out the following work.1. The monodispersed silicon dioxide colloidal particles were synthesized with TEOS of different purity.TEM, DLS were used to judge the size distribution of silicon dioxide and then explore the influence of the purity of raw materials on the particle size. It can be used to further the mechanism of silica nucleation and guide preparation on monodispersed silica. The silica then was assembled by the vertical deposition method. We can judge the quality of the colloidal crystal by observing the scanning electron microscope, after which we analyze the lacuna.2. The monodispersed nickel was prepared with micro-emulsion in solution of Triton X-100,n-heptane,n-hexyl alcohol. The effect of different conditions on the size of nano-particles:(1) The composition of micro emulsion affect the particle size, however, was not the main factor;(2) The size of particles gradually decreased with the increase of NaOH concentration;(3) The particle size keep unaltered while the concentration of the nickel sulfate is less than 0.05mol·L-1; The particle size increases with the concentration of the nickel sulfate. It showed that:the factors which influence the particle size included not only the concentration of sodium hydroxide and nickel sulfate but also the reaction rate of the reaction itself.3. Coordination precipitation was used to prepare two kinds of core-shell structure. Through TEM and XRD, we know that the silica coated on the nickel hydroxide was symmetrical and dissociative silica didn't appear; the effect of nickel hydroxide coated on silica was good, but with bad distribution. So the condition of reaction should be further explored.