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Effect of Y‐α‐Sialon Seeding and Holding Time on the Formation of Elongated ( Ca , Dy )‐α‐Sialon Crystals Prepared via Carbothermal Reduction and Nitridation
Author(s) -
Huang Juntong,
Zhou Heping,
Huang Zhaohui,
Liu Guanghua,
Fang Minghao,
Liu Yan'gai
Publication year - 2012
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2012.05352.x
Subject(s) - sialon , nucleation , seeding , crystallization , seed crystal , phase (matter) , crystal (programming language) , materials science , crystal growth , crystallography , carbothermic reaction , chemical engineering , mineralogy , chemistry , single crystal , composite material , ceramic , organic chemistry , thermodynamics , programming language , physics , computer science , engineering
Single‐phase ( Ca , Dy )‐α‐Sialon with elongated crystals and high aspect ratios was prepared at 1700°C by carbothermal reduction and nitridation ( CRN ) with Y ‐α‐Sialon seed crystals. Effects of Y ‐α‐Sialon seeding and holding time on the phase assemblage and crystal morphology of CRN products were discussed. The results showed that adding seed crystals and prolonging holding time could facilitate not only phase transformation, but also crystal refinement. Moreover, they resulted in the increase of the aspect ratios of α‐Sialon crystals, due to the decreasing range in the crystal width exceeding that in the length. In addition, a highly unusual phenomenon of crystal size reduction during reaction was observed in the seeded samples with the holding time extending from 2 to 4 h. Crystallization from liquid phase and growth followed by nucleation based on the surface of existing large crystals were the growth modes of elongated α‐Sialon crystals.