Preparation of New Inorganic Consolidated Materials Using Mechanochemical Phenomena and the Consolidation Mechanism

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New inorganic consolidated materials were synthesized by the reaction between potassium silicate solution (water glass), aluminum hydroxide and/or kaolinite, using mechanochemical phenomena. In order to prepare the consolidated materials, it was very important to enhance the mechanochemical phenomena of aluminum hydroxide and kaolinite by mechanical milling in a dry condition. Mechanical milling made their reactivity remarkably enhanced and they became approximately 1000 times as soluble as non-milled. Formation of low coordination number for Al played an important role in enhancement of the reactivity. Dissolution of Als+ ion of aluminum hydroxide into water glass contributed to formation of the consolidation mechanism. The dissolved ion promoted polymerization of water glass, resulting in synthesis of consolidated materials. To develop more practical materials and process, heat treatment before milling was proposed. The treatment accelerated dehydration of aluminum hydroxide and made the hydroxide porous, resulting in easy amorphization by milling in a short time. Accordingly, even milling with lower energy could activate the powder. The consolidated materials prepared with the activated powder exhibited higher bending and compressive strength and better water-resistance than conventional mortar. In case of using kaolinite as a starting material, moreover, the properties of the consolidated materials became much better. The consolidated material in the present project exhibited a potential of a practical material. Mechanochemical process was recognized as an important process not only for powder preparation but also for materials design.