Characterization of Ultrafine Glassy Powder for Al-Si-Ca-P-O-F Polynary System by Liquid Precipitation

Abstract

The ultrafine glassy powder of Al-Si-Ca-P-O-F polynary system was prepared by liquid precipitation method with several inorganic compounds as reactants containing the ions such as Al3+, SiO32-, P3O105-, Ca2+, F-, respectively. The powder was heat-treated in the range of temperature from 773 to 1173K and its crystallized processes were ascertained. The morphology, composition, bonding state and structure, crystallized behavior of the glassy powder were characterized by means of TEM, XRD, EDAX, IR, DSC etc methods. The results show that the powder containing Al, Si, Ca, P, O, F elements belongs to typical amorphous state, and the particles appeared hollow and near spherical morphology with the size from 30 to 70nm. The hollow particles collapsed as plate like conglutination state and a series of crystallized phases CaF2, Al2SiO5, Ca2SiO4, and Ca3(PO4)2 were separated sequentially during heat treatment in the range of temperature above. The characteristics of the glassy powder are similar to those of popular melting-quenched glass of the system. The network structure of the glass was mainly formed by the tetrahedrons of [SiO4], [AlO4] and [PO4], which were linked by the oxygen atoms of the angle in the tetrahedrons.

Characterization of Ultrafine Glassy Powder for Al-Si-Ca-P-O-F Polynary System by Sol-Gel Method

“…Crystal Ca 5 (PO 4 ) 2 SiO4 precipitated at 900°C. Compared to the LP and MQ powder [11], the crystallized temperature of SG powder is higher than that of LP powder and lower than that of MQ powder.…”

“…In recent years, the glassy nano powder by liquid precipitation (LP) method has been reported by present authors in an earlier paper [7]. However, the LP particles usually appeared hollow sphericity so that the concreted properties of powder maybe weaken [8,11]. Hence, the ultrafine glassy powder by sol-gel (SG) method is prepared, and further characterized and compared to MQ and LP powder in this paper.…”