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

对由两种或三种矿物组成的混合物在不同类型的磨机中，在干燥常压和潮湿条件下进行磨矿。矿物为高岭石、三水铝石、滑石等无机材料，经混合，得到莫来石、堇青石、橄榄石等精细陶瓷的化学计量组成。随后，将地面混合物烧结形成陶瓷。采用XRD、TG-DTA、SEM-EDS、抗弯强度、热膨胀系数等测试手段表征了力学化学对微晶陶瓷微观结构、力学性能和热性能的影响。研究结果总结如下：(1)研磨过程使起始粉末由结晶状态转变为非晶状态。粉体的结构变化是由于粉体脱水引起的。(2)长时间研磨可以降低烧结温度，形成细陶瓷的单相。(3)烧结体的容重随磨矿时间和烧结温度的增加而增大。(4)烧结体的抗弯强度随磨削时间的增加而增大。(5)起始粉的研磨使烧结体的热膨胀系数相对较低。由此可见，启动粉的力学化学效应对提高微晶陶瓷的力学性能和热性能起着重要的作用。

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.