抄録
Mechanochemical behaviors of several hydrated crystals having such three types of crystallization water as H2O, OH radical and hydrogen bond were investigated.
Mechanochemical dehydration progressed in accordance with the order of thermal stability of the hydrates. Typical structural changes of the hydrates during grinding process were as follows; (1) CaSO4·2H2O→CaSO4·1/2H2O→IICaSO4, (2) Mg(OH)2→brucite gel (in the air), (3) Mg(OH)2→MgO(in vacuum), (4) Al(OH)3 gibbsite→κ-Al2O3→α-Al2O3, (5) CaHPO4·2H2O→CaHPO4→Ca2P2O7 (almost amorphous phase), (6) TiO2·nH2O gel→anatase→rutile.
It was found that most of the mechanochemical dehydrates except (5) existed as aggregation of fine crystals (1/100μ order) and did not transform into amorphous phase contrary to the phenomena observed in general products of grinding. Surface properties of the dehydrates, distorted by shear stress, were discussed in terms of their acidity and heat of wetting.
