Study On The Preparation Of Transparent Alumina Hollow Ball By Template Method

In the research of ICF, the preparation of target material is one of the four pillars. During the ICF target fabrication techniques, how to get a high energy gain of the target is the key problem. Transparent Al2O3 hollow spheres have a good prospect of application as ICF target material because of its some unique advantages. This paper explored how to use polymethyl methacrylate(PMMA)microspheres as the template, and use chemical-coated method to prepare Al2O3 hollow spheres, but did not get the expected results. Then explored how to use micro emulsion encapsulation technology combined with sol-gel method to prepare Al2O3 hollow spheres and transparent Al2O3 hollow spheres.The as-prepared samples were charaeterized by fourier transform infrared spectroscopy(FTIR), X-ray diffraetion(XRD), scanning electron microscopy(SEM) and energy dispersive spectrum(EDX). The mechanisms of the formation of Al2O3 hollow spheres were also discussed.The sizes of PMMA in 0.5~3 mm have been prepared by the suspension polymerization method, and they have good mono-disperse. The core-shell structure( Al2O3/PMMA) are prepared by the combining chemically coated method, due to theirs thin coating layer and low density, Al2O3 hollow spheres can not be obtained after calcination. Al2O3 hollow spheres with diameters in500~2000um and wall thickness in 30~100um are prepared by micro emulsion encapsulation method and they have smooth surface. In addition, the concentric degree is above 98% and the nonconcentricity is about 3%. Diameters of hollow spheres are concentrated in 1100~1300μm by 40%, and 80% of them are concentrated in 900~1500μm. Transparent Al2O3 hollow spheres have been prepared after doping sintering aids and sintering in vacuum. The RMS surface roughness of transparent samples is about 3.13μm. In nitrogen atmosphere, the integrated heat transfer coefficient magnitude is at 103W·m- 2·K-1. It is found that doping of alumina with La2O3 and Mg O will restrain grain growth, promote sintering densification and improve light transmittance of transparent alumina ceramics. When La2O3 and Mg O content are 0.1% and 0.1%, respectively, the light transmittance of prepared transparent alumina hollow sphere are about42% and 45% respectively at the laser wavelength of 532 nm.