| Due of its excellent physical and chemical properties,Nano-ZrO2 is widely used in power,heat,light,electricity,magnetism,sensing,catalysis,batteries and other fields.Since the surface atoms show active performance under the influence of intermolecular,hydrogen bonding and electrostatic interactions,Nano-ZrO2 is easy to stay in a thermodynamically unstable state and causes agglomeration problems.In order to solve these problems in the process of reunification, the researchers have introduced an organic surface modifier for powder surface modification modified. The experiments show that increasing the surface activity of nanoparticles,changing wettability and adhesion surface of the particles with a solvent interface material to achieve complete autonomy means,etc. are very effective means in the micro area.This paper has made use of the hydrotherma-homogeneous precipitation to produce highly dispersed of the nano-ZrO2 samples,as well as by means of the DLS, Zeta potential,DSC-TQXRD,TEM,IR and PL and other analytical testing,sample properties, morphology,dispersion and optical properties were studied. The main contents and conclusions of this paper are summarized as the following three parts:1. Research on Process of Nano-ZrO2 powders by means of hydrothermal-homogeneous precipitation methodTaking zirconium oxychloride (ZrOCl2·8H2O) as a reactant,urea (CO (NH2) 2) as a homogeneous precipitation agent,deionized water as a solvent,we use the hydrothermal-homogeneous precipitation method to produce nano-ZrO2 powders,Examines and summarizes the relationship between different process parameters and particle average particle size.The results show that there are optimal conditions for the hydrothermal temperature, hydrothermal time,precursor and the molar ratio of precipitating agent,under which the degree of particle agglomeration are weakest. Wherein hydrothermal temperature changing is more significant factor than the other three factors on the average particle size.Optimal conditions for the selected orthogonal experiment are:hydrothermal temperature is 130℃,hydrothermal reaction time is 5h,zirconium oxychloride molar concentration 0.05mol/L,zirconium oxychloride and urea molar ratio of 1:2.Under such conditions the average particle size of Nano-zirconia is 62.6nm.2. Research on the impact of negative and positive, neutral surfactants on the preparation of Nano-zirconia.Based on the previous method, we select the negative, positive and neutral surfactants to modify and further improve the dispersion of the particles. With PEG 2000, PVP, CTAB, SDBS as surfactants, we use the hydrothermal-homogeneous precipitation method to produce Nano-ZrO2 powders and test the influence of types of surfactants and moral concentration on average particle size,dispersion,morphology of the particles. Studies have shown that:Nano-ZrO2 powders at low concentration of surfactant CTAB modified distribution is relatively uniform, relatively small on average particle size,and with good dispersion and stability. When the concentration of CTAB reaches 9×10-4 mol/L, the sample dispersion is improved.and the average particle size is 54.6nm.3. Research on the effect of citric acid as a dispersant on the preparation of nano-zirconiaOn the basis of homogeneous-precipitation method,we further introduce the citric acid (CA) as an organic additive (surfactant) to prepare a highly dispersed Nano-ZrO2 particle with an average size less than 10nm. We examine the effect of different preparation conditions and the amount of CA add on its average particle size, Zeta potential,morphology,dispersion and optical properties,and make a brief analysis of mechanism of citric acid.The steric effects of CA’s spatial three-dimensional network structure ensures the effective dispersion of Nano-zirconia particles,improve the dispersion of Nano-zirconia powders and make sure that the particle size of Nano-zirconia under the critical dimensions exist in a stable tetragonal phase. TEM analysis adjusts the concentration of H+ solution to increase the particle agglomeration, improve the particle size.The exercise on exploring the critical size of Nano-zirconia powders show:the stable critical size of Nano-zirconia powders is about 10nm.The novelties of the work are mainly focused on the following aspects:(1) by conventional hydrothermal method, one-step synthesis of well crystallized tetragonal phase nanocrystalline zirconia powder. (2) the process optimization of surface modification, the Nano-zirconia powders synthesized with high dispersibility; (3) To overcome the current difficult to synthesize aqueous phase particle size controlled Nano-ZrO2 problems, and the controllable preparation process of nano ZrO2 powders size can be obtained under relatively simple experimental conditions. |
PDF Full Text Request