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

在干燥、大气和潮湿条件下，在不同类型的磨机中对两种或三种矿物组成的混合物进行磨矿。矿物为高岭石、三水铝石、滑石等无机物，混合成莫来石、堇青石、镁橄榄石等精细陶瓷的化学计量比组成。随后，研磨的混合物被烧结以形成陶瓷。通过X射线衍射、热重-差热分析、扫描电子显微镜-能谱分析、抗弯强度、热膨胀系数等测试手段，表征了机械力化学作用对微细陶瓷微观结构和力学性能的影响。研究结果总结如下：(1)研磨操作使原始粉末由晶态向非晶态转变。粉料的结构变化是由于粉料的脱水所致。(2)长时间的研磨可以降低烧结温度，形成单相的细陶瓷。(3)烧结体的体积密度随着研磨时间和烧结温度的增加而增加。(4)烧结体的抗弯强度随着研磨时间的增加而增加。(5)起始粉料的研磨使烧结体的热膨胀系数相对较低。因此，起始粉料上出现的机械力化学效应对改善细粉陶瓷的力学性能和热性能起着重要作用。

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.