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Title: Analysis of refractory fiber insulations and hot-face coatings exposed to coal-oil mixture combustion products

Technical Report ·
OSTI ID:5270598

Refractory fibrous aluminosilicate insulations with and without hot face coatings were exposed to the combustion products of a coal-oil mixture (COM) (90% No. 6 residual oil and 10% coal) at about 1375/sup 0/C for 496 h. Samples of each insulation and coating were analyzed to study the effects of fuel impurities on the materials. Uncoated aluminosilicate insulations containing about 50% Al/sub 2/O/sub 3/ performed as well as those containing about 80%. In both types, fuel impurities reacted with fibers and resulted generally in lower Al/sub 2/O/sub 3/ and higher Fe/sub 2/O/sub 3/, SiO/sub 2/, and other impurities in the reaction layer on the surface of the specimens. The reaction layers, which were about 1 mm thick, consisted mostly of mullite and glass that contained Al, Ca, K, Si, and Ti. The glass in the reaction layers may have minimized penetration of fuel impurities. Most hot face coatings were restructured as a result of reaction with fuel impurities and exhibited increases in Fe/sub 2/O/sub 3/ and some other impurities. The Al/sub 2/O/sub 3/ content generally decreased, but the SiO/sub 2/ content increased or remained about the same. Alumina-based coatings mostly consisted of mullite and glass that contained fuel impurities. Three aluminosilicate coatings adhered to the insulations during the test, butthe phosphate-bonded high-alumina coatings spalled from some insulations. A zirconium silicate coating remained in place during the test but tended to separate from the insulation during sampling. Under the conditions of this test, the insulations and all except the phosphate-bonded hot face coatings satisfactorily resisted degradation by fuel impurities.

Research Organization:
Oak Ridge National Lab., TN (USA)
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
5270598
Report Number(s):
ORNL/TM-8243; ON: DE82018210
Country of Publication:
United States
Language:
English