Mechanochemical Effects on Microstructure and Mechanical and Thermal Properties of Fine Ceramics

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Grinding of mixture composing of two or three kinds of minerals was conducted in different types of mill under dry atmospheric and wet conditions. The minerals were kaolinite, gibbsite, talc and other inorganic materials, and they were mixed so as to be stoichiometric compositions of mullite, cordierite, forsterite and other fine ceramics. Subsequently, the ground mixtures were sintered to form the ceramics. Mechanochemical effects on microstructure and mechanical and thermal properties of the fine ceramics were characterized by XRD,TG-DTA,SEM-EDS analyzes, and bending strength and thermal expansion, coefficient measurements. The research results are summarized as follows :(1)Grinding operation causes structural change of the starting powders from crystalline state into amorphous one. The structural change of the powders is attributed to the dehydration of the powders.(2)Prolonged grinding enables us to reduce the sintering tempera-ture to form monophase of the fine ceramics.(3)Bulk density of the sintered bodies increases with increasing the grinding time and the sintered temperature.(4)The bending strength of the sintered bodies increases with an increase in grinding time.(5)Grinding of the starting powders gives us relatively lower thermal expansion coefficient of the sintered bodies than usual.Thus, the mechanochemical effects appeared on the starting powders play a significant role to improve the mechanical and thermal properties of the fine ceramics.