Effect of Natural Flake Graphite and Carbon Fiber Additions on High-Temperature Properties of Dolmite-Carbon Refractories

摘要

The U.S. Bureau of Mines investigated the role of imported natural flake graphites in dolomite-carbon refractories used in steelmaking processes and evaluated carbon fibers as a potential substitute. Varying quantities (1.5-30%) of natural flake graphite and carbon fibers were added to test samples. The effect of the additions on modulus of rupture (75-2,750 F), deformation under load (2,750 F), and air-slag-metal resistance (3,000 F) was studied. When the quantity of 90%-carbon graphite addition varied between 0 and 30 wt pct, hot strength was highest, deformation under load lowest, and air-slag-metal wear the least at 10 wt pct. As test temperature increased from 500 to 2,750 F, the hot strength difference became less. Carbon fiber additions were limited to 1.5% in dolomite-carbon brick. At this level, physical properties were generally comparable to those obtained with natural flake graphite, but were below values obtained with 10%-flake-graphite additions. Carbon fibers are not considered a satisfactory substitute for natural flake graphite.