The Formation of Magnesium Oxychloride Phases in the Systems MgO‐MgCl₂‐H₂O and NaOH‐MgCl₂‐H₂O

Abstract

The reactions leading to the formation of crystalline Mg3(OH),CI*4H20 (phase S), Mg2(0H),CI .4Hz0 (phase 3), and Mg(OH)* are compared for the systems Mg0-MgCIZ-H20 and NaOH-MgCIZ-H20. The crystalline phases were determined by X-ray diffraction analysis. The concentration of the total magnesium and chloride in the solution and the pH of the solution determine the reaction product(s) in both systems. The influence of MgO reactivity and the molar ratio of reactants on the formation and stability of reaction products is discussed and the mechanism of the formation of phases 3 and 5 is explained. In the system Mg0-MgCI2-Hz0, MgO serves only to increase the concentration of total magnesium and the pH of the MgClz solution.

Effect of gauging solution densities on magnesia cement

“…As discussed earlier, the compressive strength for 1:1 molar ratio of dry mixes varied with the density of gauging solution. Consistent results are given in the literature (Ball, 1977;Bilinski et al, 1984;Dehua, 2003): crystalline phase development in neat magnesia cement pastes was generally needle-shaped. The needle-shaped crystals in this work were mostly visible in the 328Be sample, and were identified as magnesia cement F5 phase.…”

Hydrothermal formation and characterization of magnesium hydroxide chloride hydrate nanowires

“…In the ceramic field, the MgO-MgCl 2 -H 2 O system has been the subject for numerous investigations in the past few decades because several Mg x (OH) y Cl z Á mH 2 O have been shown as promising cements and building materials [18][19][20][21], and recently, some MHCH fibers, especially for the Mg 2 (OH) 3 Cl Á 4H 2 O, Mg 3 (OH) 5 Cl Á 4H 2 O, and Mg 10 (OH) 18 Cl 2 Á 5H 2 O phase, were proved to be well suited as an additive for resin, filler, filter medium, or reinforcements of polymers and plastics [22]. Depending on the conditions of preparation, many types of MHCH complexes, either stoichiometric or nonstoichiometric, can be prepared in the MgO-MgCl 2 -H 2 O system.…”

“…Although previous papers have emphasized the potential applications of this material [19][20][21][22], systematic information on its synthesis, and structure characterization of the material are lacking. Often, only some isolated data concerning preparation and structure of MHCHs were reported together with the description of their properties.…”

“…Magnesium hydroxide chloride hydrate (MHCH), with the general formula of Mg x (OH) y Cl z Á mH 2 O (2xÀyÀz ¼ 0, 0pmp6), can also be called basic magnesium chloride, or a solid solution in the Mg(OH) 2 -MgCl 2 -H 2 O system was first discovered by Sorel in 1867 [14][15][16][17][18][19][20][21]. In the ceramic field, the MHCH cement, also known as Sorel cement, has been the subject for numerous investigations in the past few decades because it possesses many superior to those of Portland cement.…”

Production of Waterproof Composite Magnesia Cement on the Basis of Local Mineral Resources

“…The complex salt crystallizes in the form of fibres and needles which play a role of a reinforcing component giving a high durability to the hardened stone (Sulimenko et al, 2001;http://www.premiercpg.com/PREMag_MOC.htm, 2014;Bilinski et al, 1984).…”