PbO-B_2O_3玻璃在不同重力条件下相组成和成分均匀性的研究

Phase and Homogenization of Lead Borate Glasses under Low,Normal,or High Gravity

以3.5PbO.96.5B2O3(m o l%)玻璃作为研究对象,着重研究其在不同重力条件下的分相现象。该部分讨论了2个落塔实验试样发生分相的重力条件,同时分析了试样的相组成和试样成分的不均匀性。结果发现,该成分玻璃发生分相后形成的富硼相和富铅相都是玻璃相。分相在高重力阶段发生的试样其成分均匀性最差,原因在于富硼相和富铅相间存在较大的密度差。

The drop shaft experiments reported in this paper were conducted at Japan Microgravity Center, whose experimental facility allowed us to study the phase separation of glass for a few seconds either under low or high gravity. In these few seconds, it also allowed us to record the actual temperatures of samples during the melting and solidifying of glasses; these temperatures are needed for the discussion of phase diagram. In the full paper, we describe and discuss in detail our research; here we give only a briefing. The glass with the composition of 3. 5PbO·96. 5B2O3 （mol%）was melted and solidified to explore the phase-separation of glass under low, normal or high gravity through drop shaft experiments. The homogenization of elements in different samples （one sample melted under low gravity and solidified under high gravity, another melted under low and high gravity and solidified under normal gravity, and a third melted and solidified both under normal gravity） was compared through EDS analysis and the phase of each sample was determined through XRD. Results show that the samples all phase-separated into two different glass phases： Pb-rich phase and B-rich phase no matter under what gravity condition the particular glass was melted and solidified. For all the samples, the elements along the horizontal direction are homogenous while those along the gravity direction are heterogeneous, and the homogeneity of the sample whose phaseseparation occurred under high gravity is the worst.