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Effect of annealing on the fracture behavior of La 0.58 Sr 0.4 Co 0.8 Fe 0.2 O 3‐δ , a potential energy material for oxygen separation
Author(s) -
Sikder B.,
Pramanik R.,
Chanda A.
Publication year - 2017
Publication title -
materialwissenschaft und werkstofftechnik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.285
H-Index - 38
eISSN - 1521-4052
pISSN - 0933-5137
DOI - 10.1002/mawe.201600739
Subject(s) - indentation , annealing (glass) , fracture toughness , materials science , composite material , residual stress
The perovskite material La 0.58 Sr 0.4 Co 0.8 Fe 0.2 O 3‐δ , offers high oxygen permeability at elevated temperature and is considered as a potential material for oxygen separation membranes. It can enhance the efficiency of oxy‐fuel combustion at high temperatures (> 800 °C) and hence due to the high reliability demands, required by the long term operation at elevated temperatures, it requires a thorough investigation from the view point of structural stability. Aiming towards long term stability, the present work is a detailed and systematic study on the effect of annealing on the mechanical behavior of dense La 0.58 Sr 0.4 Co 0.8 Fe 0.2 O 3‐δ . The study reveals that the indentation fracture toughness of the material increases with increase in annealing temperature. In most of the indentation loads, the subsurface crack profile was Palmqvist in nature with low value of the ratio of crack length versus indentation size ( c / a ). A consistent pattern of variation of c / a and indentation fracture toughness ( K IC ) at all indentation loads was observed. Systematic drop in c / a and subsequent increase in fracture toughness in the as prepared test pieces has been attributed to residual stress accumulation during preparation.