TY - JOUR
T1 - Effect of preparation method on chemical; stability of sinterable calcium doped lanthanum chromites
AU - Sakai, Natsuko
AU - Kawada, Tatsuva
AU - Yokokawa, Harumi
AU - Dokiya, Masayuki
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1993
Y1 - 1993
N2 - The effect of preparation method on the chemical stability of sinterable (La, Ca) CrO3-δ powder was investigated. The ceramic method (powder mixing method) resulted in inhomogeneous distributions of the calcium content (x) in the perovskite phase (La1-xCaxCrO3-δ) after calcining at a temperature from 1223 to 1373 K. More homogeneous powder was obtained by the liquid mixing method. The distribution of calcium content caused a large amount of second phases such as calcium oxychromates (Cam(CrO4)n) in a powder prepared by the ceramic method, and an excess amount of the second phase remained as Ca5(CrO4)3OH on the surface of the ceramics after sintering at 1573 K. During a treatment in an H2+H2O gaseous mixture at 1273 K for 627 h, Cam(CrO4)n decomposed to CaO and A-CaCr2O4, and the decomposition was enhanced by the existence of silicon containing impurities. The liquid mixing method minimized the amount of Cam (CrO4)n and resulted in sufficient chemical stability in H2+H2O.
AB - The effect of preparation method on the chemical stability of sinterable (La, Ca) CrO3-δ powder was investigated. The ceramic method (powder mixing method) resulted in inhomogeneous distributions of the calcium content (x) in the perovskite phase (La1-xCaxCrO3-δ) after calcining at a temperature from 1223 to 1373 K. More homogeneous powder was obtained by the liquid mixing method. The distribution of calcium content caused a large amount of second phases such as calcium oxychromates (Cam(CrO4)n) in a powder prepared by the ceramic method, and an excess amount of the second phase remained as Ca5(CrO4)3OH on the surface of the ceramics after sintering at 1573 K. During a treatment in an H2+H2O gaseous mixture at 1273 K for 627 h, Cam(CrO4)n decomposed to CaO and A-CaCr2O4, and the decomposition was enhanced by the existence of silicon containing impurities. The liquid mixing method minimized the amount of Cam (CrO4)n and resulted in sufficient chemical stability in H2+H2O.
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U2 - 10.2109/jcersj.101.1195
DO - 10.2109/jcersj.101.1195
M3 - Article
AN - SCOPUS:0027699137
SN - 1882-0743
VL - 101
SP - 1195
EP - 1200
JO - Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan
JF - Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan
IS - 1179
ER -