共查询到20条相似文献,搜索用时 765 毫秒
2.
3.
Thermal expansion behaviors of some precursor-derived amorphous Si-C-N and Si-B-C-N ceramics, which were shaped by plastic forming after crosslink, were studied. To complete the shrinkage and densification, after thermolysis specimens were heat treated at a temperature of 1400℃ for 10 h in nitrogen atmosphere. The thermal expansion coefficient of VT50-derived amorphous Si-C-N ceramic increases from 1.98×10-6/K at 400℃ to 3.09×10-6/K at 1000℃, of NCP200-derived amorphous Si-C-N ceramic increases from 2.35×10-6/K at 400℃ to 3.45×10-6/K at 1000℃, and of T2-l-derived amorphous Si-B-C-N ceramic increases from 2.08×10-6/K at 400℃ to 3.18×10-6/K at 1000℃. No glass transition for these amorphous ceramic materials was detected, indicating that as-thermolyzed precursor-derived Si-(B-)C-N ceramic materials are amorphous solids, but not glasses. 相似文献
4.
5.
6.
聚苯乙烯—N—(4—羟基苯基)—马来酰亚胺合成的研究 总被引:1,自引:0,他引:1
为了比较合成方法,找到最佳的合成线路,本文从三条合成路线来探讨聚苯乙烯-N-(4-羟基苯基-马来酰亚胺的合成。元素分析表明共聚物组成为1:1;通过NMR、IR和UV,我们分析了共聚物的结构;通过DSC和TGA分析了共聚物的热性能;当_n=5.8×10~4时,玻璃化温度为257℃。 相似文献
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.