Mechanochemical Synthesis of Tricalcium Aluminium Hydrate from Calcium Hydroxide-Boehmite Mixtures by Room Temperature Grinding

摘要

Tricalcium aluminium hydrate (3CaO centre dotAl_2O_3 centre dot 6H_2O is to C_3AH_6) is synthesizedmechanochemically from mixtures composed of calciumhydroxide (Ca(OH)_2) and pseudo-boehmite (#gamma#-AlO(OH))powders by room temperature grinding using a planetary ball mill.Use of the boehmite sample with inferior crystallinity is morefavorable for the mechanochemical synthesis rather than that withwell crystalline one. The time required to form C_3AH_6 from theCa(OH)_2-#gamma#-AlO(OH) mixtures ground for various timesexcess hydrated calcium aluminates such as C_2AH_8,C_3AH_(8-12) and C_2A_(0.5)H_(6.5) are formed in the startingand the short time ground mixtures, while a few amount of thesecompounds is formed in these hydrated mixtures after prolongedgrinding. Formation of these excess hydrated compounds, whichbelong to layered structural materials, is enhanced in the presenceof free Ca, Al compounds and water.