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Title: High temperature alkali corrosion of ceramics in coal gas. Quarterly progress report No. 7, March 1, 1993--June 1, 1993

Abstract

Corrosion kinetics of SiC were investigated from 950 to 1100C at 0.63 vol% alkali vapor concentration. Corrosion rate in alkali is 10{sup 4} to 10{sup 5} times faster than oxidation rate of SiC in air. Activation energy of the alkali corrosion is 406 kj/mol, indicating a high sensitivity to temperature changes. Overall reaction appears to be controlled by the oxidation of SiC. The alkali corrosion kinetics of Si{sub 3}N{sub 4} from 950 to 1050{degrees}C were also examined in the same atmosphere (0.63 vol% alkali vapors). Reaction thickness of Si{sub 3}N{sub 4} appears to vary linearly with reaction time from 950 to 1050C, suggesting that the alkali corrosion process is controlled by the oxidation of Si{sub 3}N{sub 4}. At 1050{degrees}C, the alkali-enhanced oxidation of Si{sub 3}N{sub 4} is approximately 10{sup 7} times faster than the oxidation of Si{sub 3}N{sub 4} in dry oxygen. Compared to SiC corroded in the same alkali atmosphere, Si{sub 3}N{sub 4} seems to be less alkali-resistant than SiC. Phase relations of the Na{sub 2}O-Al{sub 2}TiO{sub 5} vertical section from 5--40 wt% Na{sub 2}O and 840-1100C were studied. Phase analysis indicates that this section is not a true binary system. A tentative phase diagram for the Na{sub 2}O-Al{submore » 2}O{sub 3}-TiO{sub 2} system was constructed.« less

Authors:
; ;
Publication Date:
Research Org.:
Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Center for Advanced Ceramic Materials
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10171441
Report Number(s):
DOE/PC/91309-T8
ON: DE93018889
DOE Contract Number:  
FG22-91PC91309
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 25 May 1993
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; SILICON NITRIDES; CORROSION; SILICON CARBIDES; SODIUM OXIDES; PHASE DIAGRAMS; ALUMINIUM OXIDES; TITANIUM OXIDES; PROGRESS REPORT; TEMPERATURE RANGE 1000-4000 K; CHEMICAL REACTION KINETICS; COAL GAS; VAPORS; ALKALI METALS; 360205; 360202; CORROSION AND EROSION; STRUCTURE AND PHASE STUDIES

Citation Formats

Pickrell, G R, Sun, T, and Brown, J J. High temperature alkali corrosion of ceramics in coal gas. Quarterly progress report No. 7, March 1, 1993--June 1, 1993. United States: N. p., 1993. Web. doi:10.2172/10171441.
Pickrell, G R, Sun, T, & Brown, J J. High temperature alkali corrosion of ceramics in coal gas. Quarterly progress report No. 7, March 1, 1993--June 1, 1993. United States. https://doi.org/10.2172/10171441
Pickrell, G R, Sun, T, and Brown, J J. 1993. "High temperature alkali corrosion of ceramics in coal gas. Quarterly progress report No. 7, March 1, 1993--June 1, 1993". United States. https://doi.org/10.2172/10171441. https://www.osti.gov/servlets/purl/10171441.
@article{osti_10171441,
title = {High temperature alkali corrosion of ceramics in coal gas. Quarterly progress report No. 7, March 1, 1993--June 1, 1993},
author = {Pickrell, G R and Sun, T and Brown, J J},
abstractNote = {Corrosion kinetics of SiC were investigated from 950 to 1100C at 0.63 vol% alkali vapor concentration. Corrosion rate in alkali is 10{sup 4} to 10{sup 5} times faster than oxidation rate of SiC in air. Activation energy of the alkali corrosion is 406 kj/mol, indicating a high sensitivity to temperature changes. Overall reaction appears to be controlled by the oxidation of SiC. The alkali corrosion kinetics of Si{sub 3}N{sub 4} from 950 to 1050{degrees}C were also examined in the same atmosphere (0.63 vol% alkali vapors). Reaction thickness of Si{sub 3}N{sub 4} appears to vary linearly with reaction time from 950 to 1050C, suggesting that the alkali corrosion process is controlled by the oxidation of Si{sub 3}N{sub 4}. At 1050{degrees}C, the alkali-enhanced oxidation of Si{sub 3}N{sub 4} is approximately 10{sup 7} times faster than the oxidation of Si{sub 3}N{sub 4} in dry oxygen. Compared to SiC corroded in the same alkali atmosphere, Si{sub 3}N{sub 4} seems to be less alkali-resistant than SiC. Phase relations of the Na{sub 2}O-Al{sub 2}TiO{sub 5} vertical section from 5--40 wt% Na{sub 2}O and 840-1100C were studied. Phase analysis indicates that this section is not a true binary system. A tentative phase diagram for the Na{sub 2}O-Al{sub 2}O{sub 3}-TiO{sub 2} system was constructed.},
doi = {10.2172/10171441},
url = {https://www.osti.gov/biblio/10171441}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 25 00:00:00 EDT 1993},
month = {Tue May 25 00:00:00 EDT 1993}
}