The influence of initial glass powder particle size on the level of crystalline phase formation in apatite (Ca-10(PO4)(6)(O,F-2))-wollastonite ((CaOSiO2)-Si-.) (A-W) glass-ceramic was investigated. Sample batches of A-W glass-ceramic were prepared with particle sizes ranging from 5 to 203microns. The initial glass and glass-ceramic materials were analysed using particle size analysis, differential thermal analysis (DTA) and X-ray diffractometry (XRD).
The DTA results demonstrated that the apatite peak remained constant whilst the smaller wollastonite phase peak gradually shifted towards the larger apatite peak. By 18microns the two crystalline peaks were indistinguishable. XRD analysis displayed an increase in apatite towards 18microns, decreasing thereafter with reduced particle size. Conversely, wollastonite was found to decrease towards 18microns. and then rapidly increase.
The DTA and XRD results suggest that at a particle size at or around 18microns, the mechanisms by which each of the two crystalline phases form may be altered, possibly by an interchange between surface and bulk nucleation.
|Number of pages||7|
|Journal||Glass science and technology-Glastechnische berichte|
|Publication status||Published - 2001|
- crystallization kinetics