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Corrosion Resistance of Selected Ceramic Materials to Nitric Acid.
MISSING :12 pages
The Bureau of Mines is investigating the acid resistance of ceramic materials to identify construction materials for emerging technology in chemical and metallurgical processes. Eight commercial ceramic materials, including two red shale, two fireclay, a silica, a silicon carbide, a carbon, and a high-alumina brick, were evaluated. Samples were exposed to 40 wt pct ho3 at 70 deg and 90 deg c and 60 wt pct hno3 at 50 deg, 70 deg, and 90 deg c for time periods of 110 days. Statistically significant changes in cold crushing strength were generally small or not detected, except for a strength drop in the high-alumina brick, which decreased in strength when exposed to the chosen acid concentrations at 90 deg c. Volume and weight changes were also measured. The leach rates of al, ca, fe, k, mg, na, si, and ti were monitored. Increasing temperature or a decrease in the acid concentration resulted in an increased ion leach rate. Of the conditions tested, the most severe corrosion occurred at 90 deg c for a 40-wt-pct hno3 solution. The silica brick had the best overall acid-resistant properties, followed by a red shale and a fireclay brick. The carbon and silicon carbide bricks are not recommended for service. Research at the Tuscaloosa Research Center is carried out under a memorandum of agreement between the Bureau of Mines, U.S. Department of the Interior, and the University of Alabama.
IH; Report of Investigations
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division