Premium
Sialon Ceramics Prepared by Using CaH 2 as a Sintering Additive
Author(s) -
Cai Yanbing,
Shen Zhijian,
Grins Jekabs,
Esmaeilzadeh Saeid
Publication year - 2008
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.1551-2916.2008.02549.x
Subject(s) - sialon , sintering , materials science , microstructure , equiaxed crystals , ceramic , phase (matter) , composite material , metallurgy , mineralogy , chemistry , organic chemistry
In developing elongated α‐sialon grains, a nitrogen‐rich liquid phase sintering method was introduced by using CaH 2 as a sintering aid, so as to vary the N/O ratio of the liquid phase formed in the sintering process while keeping the Si/Al ratios constant. With increasing addition the phase contents changed from single β‐sialon to dual β/α‐sialons and to single Ca‐α‐sialon. At low N/O ratios the microstructures contained mainly equiaxed β‐sialon grains, and at high N/O ratios well faceted elongated Ca‐α‐sialon grains. The improved toughness ( K I C =7.8 MPa·m 1/2 ) and hardness ( H V10 =17.5 GPa) properties can be attributed to the formation of interlocked microstructures. High‐temperature compressive deformation tests indicated that the deformation onset temperature is determined mainly by the Si/Al and N/O ratios, whereas the deformation rate is affected by the microstructure, i.e., the morphology and amounts of elongated α‐sialon grains and residual glass phase, especially for the sialons with low N/O ratios.