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Indexed by:期刊论文

Date of Publication:2018-03-01

Journal:CERAMICS INTERNATIONAL

Included Journals:SCIE、EI

Volume:44

Issue:4

Page Number:4176-4182

ISSN No.:0272-8842

Key Words:Nucleation mode selection; Molten removal particles; Free energies; Micro morphology; Growth mode; Laser cutting

Abstract:Because of the multiple selections on different crystalline faces in nucleation process of alpha-alumina, it is necessary to confirm the nucleation mode and growth mechanism of molten removal particles produced by alumina ceramics laser cutting. A model based on driving force of Helmholtz and Gibbs free energies is built to compare different critical nucleation sizes and corresponding nucleation barriers among several crystal planes. The calculation shows that when alumina ceramic is cooled and solidified from a molten state, the material is preferably nucleated in the parallelepiped model with extension and stack along the (11 (2) over bar0) plane. X-ray diffraction and scanning electron microscopy detections are taken to verify the nucleation mode that the morphologies thereof are shown as corners of an octahedron or edges of hexagons in different section directions. A pyramid stacking growth mode of spherical particles is proposed to coincide with the hollow micro morphology. The analysis concludes this model is feasible and it makes contribution to the potential application of removal particles for the field of ceramic powder metallurgy during laser processing.