Electrical stress and strain in lunar regolith simulants

Experiments to entrain dust with electrostatic and fluid-dynamic forces result in particulate clouds of aggregates rather than individual dust grains. This is explained within the framework of Griffith-flaw theory regarding the comminution/breakage of weak solids. Physical and electrical inhomogeneities in powders are equivalent to microcracks in solids insofar as they facilitate failure at stress risers. Electrical charging of powders induces bulk sample stresses similar to mechanical stresses experienced by strong solids, depending on the nature of the charging. A powder mass therefore “breaks” into clumps rather than separating into individual dust particles. This contrasts with the expectation that electrical forces on the Moon will eject a submicron population of dust from the regolith into the exosphere. A lunar regolith will contain physical and electrostatic inhomogeneities similar to those in most charged powders.     

钛酸锶陶瓷材料制备方法的进展

钛酸锶作为重要的、新兴的电子陶瓷材料 ,具有高的介电常数和高的折射常数 ,有显著的压电性能 ,是重要的铁电体 ,可作为介电材料和光电材料。随着钛酸锶电子陶瓷应用的日益广泛和对其性能要求的不断提高 ,其制备工艺已经越来越受到重视。为了制得质量更高的功能材料与器件 ,必须通过各种方法合成超细、高纯、无严重团聚、有特定形态的粉体及致密性强、耐高温的薄膜。综合叙述了钛酸锶电子陶瓷粉体及薄膜的制备方法 ,介绍了它们的优缺点 ,对各种方法进行了比较