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Sintering and Properties of Sialons without Externally Added Liquid Phase
Author(s) -
Bandyopadhyay Siddhartha,
Mckerji Joydhb
Publication year - 1987
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.1151-2916.1987.tb04898.x
Subject(s) - sialon , sintering , materials science , flexural strength , thermal expansion , phase (matter) , analytical chemistry (journal) , modulus , composite material , mineralogy , chemistry , organic chemistry , chromatography
β′‐Sialon has the general formula Si 6‐Z Al Z O Z N 8 ‐Z The synthesis of pure β′‐sialon with three different Z values of 0.5, 1.0, and 2.0 in the system Si 3 N 4 ‐AlN‐Al 2 O 3 ‐SiO 2 has been reported without the addition of a foreign sintering aid. A small shift in the composition toward the SiO 2 corner has been made in each case. The Z=1.0 and 2.0 sialon can be sintered almost to full density while that with Z=0.5 sialon is difficult even with a higher amount of excess oxide addition. A packing bed of Si 3 N 4 and SiO 2 in a weight ratio of 7:3 was found to be most useful. The coefficient of linear thermal expansion of Z=1.0 sialon is 2.2°10 ‐6 /°C (25° to 1000°C). The room‐temperature modulus of rupture value can be retained up to 90% of the value at 1400°C. A similar trend has also been observed in the K lC value with temperature. The steady‐state flexural creep rate varies from 0.5°10 ‐6 to 2.5°10 ‐6 h ‐1 in the temperature and load ranges of 1200° to 1300°C and 100 to 250 MPa.