FORMATIONOFMICRO_PORO_省略_ICHYDROTHERMALP.pdf

CHINA PARTICUOLOGY Vol. 2, No. 3, 124-127, 2004 l Research Note FORMATION OF MICRO-POROUS SPHERICAL PARTICLES OF CALCIUM SILICATE (XONOTLITE) IN DYNAMIC HYDROTHERMAL PROCESS Maoqiang Li1,* and Hongxun Liang2 1China Building Materials Academy, Beijing 100024, P. R. China 2Zhongbei Glass Technology Company, Beijing 100831, P. R. China *Author to whom correspondence should be addressed. Tel: 0086-10 E-mail: mql@public3.bta.net.cn Abstract Stirring during hydrothermal synthesis plays an important role in the formation of porous spher ical xonotlite particles. The size of spherical particles formed during dynamic hydrothermal process is related to the size of minimum vortices in the reaction slurry, which is determined by stirring speed. The kinetics of growth of xonotlite particles is de- termined by measuring the apparent viscosity of the reactant slurry at various reaction time and reaction temperatures. It is found that the growth of particles follows the contracting-volume equation, and the activation energies for nucleation -1 . and growth are 104 and 123 kJ mol , respectively. Keywords porous particle, xonotlite, dynamic hydrothermal synthesis Introduction Dynamic Hydrothermal Synthesis of Fig. 1 shows micro-porous spherical particles of calcium Xonotlite silicate, ranging in size from several microns to hundred Xonotlite particles are synthesized from amorphous sil- microns, and consisting