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Preparation and Characterization of Zirconia Ceramic Hollow Shells

Author: ZhouPeng
Tutor: ZhengYongTing
School: Harbin Institute of Technology
Course: Materials Science
Keywords: zirconia emulsion polymerization polystyrene microspheres core-shell microspheres hollow spheres
CLC: TQ174.6
Type: Master's thesis
Year: 2009
Downloads: 238
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Abstract


In this paper,monodisperse polystyrene microspheres in the size range of nano to sub-micron were prepared by emulsion polymerization method using styrene as monomer , potassium persulfate as initiator and sodium dodecyl sulfate as emulsifier.Then uniform coating ZrO2/PS core-shell microspheres were prepared using polystyrene microspheres as template and combining homogeneous precipitation method.The ZrO2 hollow spheres sample were obtained by calcining the ZrO2/PS core-shell microspheres.The main process conditions on the size of polystyrene microspheres and the situation of polystyrene microspheres coated with hydrated zirconia nanoparticles were studied,then reliable process parameters were obtained.Then the dispersion stability of polystyrene microspheres latex and formation mechanism of ZrO2/PS core-shell microspheres were analysised.The appearance,size,structure and component of the polystyrene microspheres, ZrO2/PS core-shell microspheres and ZrO2 hollow spheres sample were studied with SEM, laser particle size analysis,TG,FT-IR,XRD and XPS.The effects of the monomer consumption and initiator and emulsifier concentration on the size of polystyrene microspheres were studied. The results show that the size of polystyrene microspheres decreases with increase in concentration of initiator and emulsifier,and an increase in the monomer consumption will increase the particle size.The ZrO2/PS core-shell microspheres were prepared in water system using polystyrene microspheres about 350nm that have uniform particle size distribution prepared by ourselves as template,zirconium oxynitrate as zirconium source and urea as precipitant and regulator of PH,then the ZrO2 hollow spheres sample were obtained by calcining the ZrO2/PS core-shell microspheres at 600℃. The effects of the reactant concentration and dispersant on the situation of polystyrene microspheres coated with hydrated zirconia nanoparticles were studied.The results show that there haven’t hydrolyzate on the surface of the polystyrene microspheres with low zirconium oxynitrate and urea concentration,when increasing urea concentration the hydrolyzate will formate part-coating.The appropriate increase of concentration of urea and zirconium oxynitrate will be good for the formation of ZrO2/PS core-shell microspheres.When the concentration of zirconium oxynitrate is greater than 5.6×10-3mol/l and the concentration of urea is greater than 0.8mol/l,the polystyrene microspheres can be coated uniform by hydrated zirconia nanoparticles.However, too high concentration of urea will lead to hydrolysis of zirconium oxynitrate too fast and some small zirconia particles adsorped by the surface of polystyrene microspheres very slowly will grow up into big aggregates. The addition of dispersant is good for the dispersion of the zirconia nanoparticles and polystyrene microspheres latex and the formation of ZrO2/PS core-shell microspheres.The formation of characteristics of core-shell structure were confirmed by FT-IR,XPS and TG..The change in reaction process of PH value of the reaction system was investigated,and then we thought that PH value of the reaction system was the result of the combined effect of urea and zirconium oxynitrate and the control of PH value was very important for the formation ZrO2/PS core-shell microspheres.For the system of successful coating, generally the PH value of system goes through a process from strong acid to weak alkaline.

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