R&D of Highly Oriented Graphite Block made from Graphitization of Multi-Polyimide Films with Addition of Guest Element

在聚酰亚胺薄膜上添加和掺杂硼或稀土元素制备高取向石墨块，以获得高性能石墨单色计。从第一年的研究中发现，在1500 ~ 2500℃的温度下，加入硼或镧的聚酰亚胺薄膜的石墨化比未加入硼或镧的薄膜的石墨化更明显。但在添加物的情况下，膜的取向度略有下降。厚度为25 μ m的薄膜结晶度和取向性明显优于厚度为125 μ m的薄膜。在第二年的研究中，采用热压法制备了高取向石墨块。加入硼或镧的多层聚酰亚胺薄膜在石墨模具中凝固，在1500℃的真空条件下碳化，然后在2000℃的热压条件下热处理。硼和镧的加入也加速了石墨化程度。影片之间的衔接效果优于未添加嘉宾元素的影片。在热压条件下，硼或镧原子的扩散促进了膜间的连接。热压后的样品在2500℃的常压条件下再次热处理，获得较高的石墨化程度。然而，观察到膜之间有一些分离。通过本研究可以开发高性能石墨单色计的新工艺。获得完美的无缺陷高取向石墨块是今后的研究课题。

Fabrication of highly oriented graphite block was carried out from polyimide films with addition and doping of boron or rare earth elements for the purpose of obtaining a high performance graphite monochrometer. From the research of the first year it was found that graphitization of polyimide films with addition of boron or La proceeded more than the films with no addition by heat treatment at 1500ﾟC - 2500ﾟC.But degree of orientation was degraded slightly for the films with addition. Thinner film of 25 mum in thickness was much better for crystallinity and orientation than those film with thickness of 125mum. In the research of the second year fabrication of highly oriented graphite block was fabricated by hot-pressing method. Multi-layrs polyimide film with addition of boron or lanthanum was set in a graphite mold and carbonized at 1500ﾟC under vacuum condition, and then heat-treated at 2000ﾟC under hot-press coundition. Degree of graphitization was also accelerated by boron or lanthanum addition. Joining between films was better than the films without guest element addition. Joining between films was thought to be promoted by diffusion of boron or lanthanum atoms under hot-press condition. After hot pressing the sample was heat-treated again at 2500ﾟC under normal pressure condition for obtaining high degree of graphitization. However, some separation between films was observed. New processing for highly performance graphite monochrometer could be developed through this research. To obtain perfect highly oriented graphite block without any flaw is future research subject.