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Phase Relations in the System Si 3 N 4 ‐SiO 2 ‐MgO and Their Interrelation with Strength and Oxidation
Author(s) -
LANGE F. F.
Publication year - 1978
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.1151-2916.1978.tb09229.x
Subject(s) - tie line , phase (matter) , silicon , analytical chemistry (journal) , materials science , fabrication , kinetics , mineralogy , line (geometry) , chemistry , metallurgy , thermodynamics , medicine , power (physics) , physics , electric power system , alternative medicine , organic chemistry , geometry , pathology , mathematics , chromatography , quantum mechanics
Phase relation studies of Si 3 N 1 , SiO 2 , and MgO have established three important subsolidus tie lines, viz. Si 3 N 4 ‐MgO, Si 3 N 4 ‐Mg 2 SiO 4 , and Si 2 N 2 O‐Mg 2 SiO 4 for nonoxidizing fabrication conditions. Strength measurements at 1400°C show that optimum strengths are obtained for compositions approaching the Si 3 N 4 ‐MgO and Si 3 N 4 ‐Si 2 N 2 O tie lines and that inferior strengths are obtained for compositions approaching the Si 3 N 4 ‐Mg 2 SiO 4 tie line. Oxidation measurements at 1375°C show that the oxidation kinetics depend on the content of MgO and Mg 2 SiO 4 phases. Optimum oxidation resistance is observed for compositions approaching the Si 3 N 4 ‐Si 2 N 2 O tie line. Strength and oxidation results are discussed with regard to phase equilibrium considerations.