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SiAlON Composites Containing Rare‐Earth Melilite and Neighboring Phases
Author(s) -
Huang ZhenKun,
Liu ShihYu,
Rosenflanz Anatoly,
Chen IWei
Publication year - 1996
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.1151-2916.1996.tb08940.x
Subject(s) - melilite , sialon , sintering , materials science , phase (matter) , solubility , composite material , toughness , fracture toughness , ceramic , metallurgy , chemistry , organic chemistry , spinel
Sintering aids with a formulation of rare‐earth (R) melilite solid solution M'(R) have been introduced to several SiAlON composites to obtain high‐density bodies by pressureless and gas‐pressure sintering. These compositions include ones along the Si 3 N 4 –R 2 O 3 :9AlN line, which contain no Al 2 O 3 and are known to have excellent strength but very poor sinterability. Phase analysis and property (hardness, toughness, strength, and oxidation resistance) measurements reveal a complex set of structure–property–processing relationships that are composition‐dependent. Of the most importance is the Al—O content in various phases, which is dictated by the starting composition as well as Al—O solubility in M'(R). This influences the sinterability, strength, and phase assemblage through the compositions of the intermediate liquid and the final β'‐SiAlON. La 2 O 3 is further established as an effective sintering aid that does not affect the equilibrium phase assemblage. Overall, M'(R) and La 2 O 3 show promise as SiAlON sintering aids that allow high density to be achieved without compromising intrinsic mechanical and thermal properties.