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Reaction of Vaporized Sodium Sulfate with Aluminous Refractories
Author(s) -
GOW KENELM V.
Publication year - 1951
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1951.tb13482.x
Subject(s) - mullite , sodium , sulfate , alkali metal , chemistry , materials science , mineralogy , sodium sulfate , inorganic chemistry , brick , metallurgy , composite material , ceramic , organic chemistry
A method was devised and tested whereby the action of an alkali salt, in the vapor or in the liquid state, on refractory materials may be studied under controlled conditions of temperature and pressure. Using Na 2 SO 4 , the progress of reaction was followed by (1) change of weight, (2) determination of SO 3 by precipitation, and (3) determination of Na 2 O by flame photometer. The materials studied were a commercial‐grade high‐alumina brick (88% Al 2 , 11 % SiO 2 ) * and fused crystalline alumina (99.5% Al 2 O 3 ). The dissociation of sodium sulfate, reacting in contact with high‐alumina refractory materials, is speeded more by the presence of SiO 2 , probably as the compound mullite, than by crystalline alpha‐alumina. The ultimate product in the commercial brick is probably nephelite, NaAl‐SiO 4 ; in the alumina, sodium alumina, NaAlO 4 . Exposure at 1200°C. in a vacuum of 150 μ of mercury approximately doubles the rate of deposition of sodium sulfate on the brick studied and adds one‐third to the rate on fused alumina, as compared with the rate in air at atmospheric pressure.