F. Monteverde et A. Bellosi, High oxidation resistance of hot pressed silicon nitride containing yttriaand lanthania, J EUR CERAM, 18(16), 1998, pp. 2313-2321
Oxidation tests were carried out on Si3N4-La2O3-Y2O3 hot pressed ceramics u
p to 1500 degrees C. morphological and analytical characterizations were pe
rformed on surfaces and reaction scales after oxidation and correlated with
the oxidation kinetics. (Near)-parabolic behaviour was observed at tempera
tures <1450 degrees C for short periods, while for higher temperatures and
longer exposures rite kinetics shifted to a linear behaviour. Moreover the
excellent oxidation resistance (as demonstrated by extremely low weight gai
ns), particularly zip to 1450 degrees C, was related to the high refractori
ness of the grain boundary phases in this additive system. Strength degrada
tion after oxidation at several temperatures was also studied and discussed
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