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Oxygen permeability of several ceramic oxides above 1200{degrees}C

Description: Oxygen permeability as a function of temperature was measured for several ceramic oxides over the range 1200 to 1700{degrees}C. Of the oxides testbed, alumina, beryllia, yttria, lanthanum halfnate, and calcium zironcate exhibited the lowest permeabilities in order of decreasing resistance to oxygen transport. None of the permeability constants were less than the 10{sup {minus}10} to 10{sup {minus}12} g O{sub 2}/cm {center_dot} s needed for a useful protective coating system above 1500{degrees}C. In some of the mixed oxide compounds, cation segregation was observed to occur with the more rapidly diffusing species segregating to the side of highest oxygen potential. Thus, segregation must be considered when selecting mixed oxides for high temperature applications.
Date: January 1, 1992
Creator: Courtright, E. L. & Prater, J. T.
Partner: UNT Libraries Government Documents Department

FAST BREEDER REACTOR THERMOCOUPLE DEVELOPMENT.

Description: Studies of very high-temperature thermocouple characteristics for instrumentation and electrical components used in fast breeder reactors showed that the thermoelectric emf produced along BeO, HfO{sub 2}, or ThO{sub 2} insulators can affect the output of the thermoelements. Bare-wire thermocouples are influenced by environment. Radiation effects on W versus W - Re thermocouples in the ORR after ~ 2 months in a 1.2 x 10{sup 14}n/cm{sup 2}-sec thermal and 2.1 x 10{sup 13}n/cm{sup 2}-sec fast flux indicate that W and W - Re thermoelements shift similarly in thermal emf, resulting in a positive error of 5 deg C. Hafnates such as CaHfO{sub 3}, SrHfO{sub 3}, and SrZrO{sub 3} were found to be inferior to BeO and HfO{sub 2} as thermocouple insulating materials. (F.S.)
Date: October 31, 1969
Creator: Funston, E.S. & Kuhlman, W.C.
Partner: UNT Libraries Government Documents Department

Oxygen permeability of several ceramic oxides above 1200 degrees C

Description: Oxygen permeability as a function of temperature was measured for several ceramic oxides over the range 1200 to 1700{degrees}C. Of the oxides testbed, alumina, beryllia, yttria, lanthanum halfnate, and calcium zironcate exhibited the lowest permeabilities in order of decreasing resistance to oxygen transport. None of the permeability constants were less than the 10{sup {minus}10} to 10{sup {minus}12} g O{sub 2}/cm {center dot} s needed for a useful protective coating system above 1500{degrees}C. In some of the mixed oxide compounds, cation segregation was observed to occur with the more rapidly diffusing species segregating to the side of highest oxygen potential. Thus, segregation must be considered when selecting mixed oxides for high temperature applications.
Date: January 1, 1992
Creator: Courtright, E.L. & Prater, J.T.
Partner: UNT Libraries Government Documents Department