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Influence of Chemical Reactions in Magnesia‐Graphite Refractories: II, Effects of Aluminum and Graphite Contents in Generic Products
Author(s) -
Baudín Carmen,
Alvarez Carlos,
Moore Robert E.
Publication year - 1999
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.1151-2916.1999.tb02277.x
Subject(s) - graphite , materials science , microstructure , aluminium , magnesium , young's modulus , modulus , chemical composition , metallurgy , oxygen , composite material , mineralogy , chemistry , organic chemistry
A group of magnesia‐graphite and magnesia‐graphite‐aluminum materials, the compositions of which represent a wide range of graphite contents (~10‐16.4 wt%), aluminum contents (0‐5.2 wt%), and MgO and graphite qualities, were fabricated, using standard commercial practices. Chemical analysis and determination of room‐temperature modulus of rupture (MOR) and Young's modulus, as well as a complete microstructural characterization of the as‐received materials, were performed. Mechanical characterization at high temperature (1000°, 1200°, and 1450°C) was done in terms of Young's modulus and MOR in an argon atmosphere (<1000 ppm oxygen at 1000°C). Modulus‐of‐elasticity values ranged from 4 to 16 GPa, and their evolution with temperature was determined by the evolution of the microstructure in the bulk of the specimens. A strong effect of aluminum‐metal concentration on Young's modulus overrode other microstructural differences among the materials. MOR values ranged from 6 to 20 MPa, and their evolution with temperature was determined by the evolution of the microstructure in the bulk of the specimens at the lower testing temperatures ( T lessthan equal to 1200°C) and by phase assemblages in the surface regions of the specimens‐essentially by the presence of the dense MgO zone‐at 1450°C. The thickness of the dense MgO zone in the aluminum‐containing materials was determined by the amount of aluminum and the MgO aggregate size.