Reactions and Equi ibria in Magnesium Oxych oride Cements |
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| Authors: | CHARLES A SORRE CHARLES R ARMSTRONG |
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| Affiliation: | Department of Ceramic Engineering, Schoo of Mines and Meta urgy, University of Missouri—Ro a, Ro a, Missouri 65401 |
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| Abstract: | Phase equi ibria in the system MgO-MgC 2-H2O at 2°±3°C were determined and the reactions by which the equi ibrium phases, 5Mg(OH)2 MgC 2 8H2O and 3Mg(OH)2 MgC 28H2O, deve op were studied by X-ray diffractometry. As reactive MgO is disso ved by magnesium ch oride so utions, a thixotropic suspension is converted to a ge, which then crysta izes to form the ternary oxych oride phases. Insufficient y active MgO disso ves more s ow y so that, in an open system, bu k composition can shift by evaporation of water, resu ting in crysta ization of a nonequi ibrium phase assemb age, with residua magnesium ch oride so ution and unreacted MgO. Imp ications of these nonequi ibrium reactions for the performance of magnesium oxych oride cements are discussed. |
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