相5和相3的形成机理研究

本文从结晶学、晶体化学和热力学的观点系统地研究了氯氧镁水泥硬化反应主要产物:相5[Mg_3Cl(OH)_5·4H_2O]和相3[Mg_2Cl(OH)_3·4H_2O]的形成与机制.相5和相3的形成主要取决于反应体系中初始反应物MgO,MgCl_2和H_2O的摩尔比.在MgO-MgCl_2-H_2O体系中,相5和相3都是不稳定的介稳相,在一定条件下,相5可以转变为相3和Mg(OH)_2,相3可转变为更稳定的Mg(OH)_2.     

FORMATION MECHANISM ON PHASE 5 AND PHASE 3

From the viewpoint of crystallography and thermodynamics the formation and phase-transformation reaction of phase 5[Mg,(OH)5Cl·4H2O] and phase 3[Mg2(OH)3Cl·4H2O] as a major resultant for the hardening reaction of magnesium oxychloride cement have been systematically investigated. It is recognized that the formation of phase 5 and phase 3 is mainly controlled by the molar ratio of MgO, MgCl2, and H2O in the initial reaction mixture. Phase 5 and phase 3 are formed by the reaction between MgO or Mg2+ dissolved out from MgO and the aqueous solution of MgCl2. In the system of MgO-MgCl2-H2O both phase 5 and phase 3 are metastable phases, and under given conditions phase 5 may transform into phase 3 and the latter also into Mg(OH)2.