现在测试真密度的常用方法为气体置换法,包括GB/T 5071-2013《耐火材料真密度测试方法》、ASTMD 2638-2002《用氦气体密度仪测定煅烧石油焦真密度的标准方法》和国际标准ISO/DIS 12154《Determination of density by volumetric displacement - Skeleton density by gas pycnometry》等。该方法是将小分子的氦气在一定的压力下通入仪器的样品仓,吸附在样品孔隙中的空气被氦气置换、填充,样品仓中的压力、温度等参数由高精度的传感器测定,利用波尔定律可精确测量被测样品的真实体积,从而测定材料真密度。氦气置换法与液体置换法相比,测试速度快,且减少了人为因素的影响,测试结果精密度较高。
The Controlled Pattern Growth of Aligned Carbon NanotubesAbstract Micropatterns of aligned carbon nanotubes (CNTs) have been prepared by chemical vapor deposition (CVD) method, and patterned structure of aligned CNTs was controlled through patterned formation of silicon oxide (SiO2) using lithographic technology. The simultaneous growth of carbon nanotubes in different directions could be realized. The building of nanotube-based micro-pattern is useful for fabricating electrical devices.(请下载全文欣赏)
Nanoscale Data Recording on an Organic Monolayer FilmWidely acknowledged as a critical technology in the development of information technology, nanometer-scale data recording has been thoroughly explored....(请下载全文欣赏)