摘要:
研究了含氢聚硅氧烷(PSO)与二乙烯基苯(DVB)的交联与裂解。结果表明:只有在氯铂酸的催化作用下,PSO与DVB才能完全交联。DVB/PSO质量比对陶瓷产率的影响较大,DVB/PSO＝0.5时陶瓷产率最高,达到76%。裂解产物中Si,C,O的含量分别为38.3wt%,34.3wt%,27.4wt%。以质量比为0.5的DVB/PSO体系为先驱体,采用先驱体转化法制备出三维Cf/Si-O-C复合材料。研究发现:第一次裂解时采用热压辅助可以明显提高材料的力学性能。第一次在1600℃,10MPa的条件下热压裂解5min,后续真空浸渍-常压裂解处理六个周期所制得的材料具有较高的力学性能,其弯曲强度和断裂韧性分别为502MPa,23.7MPa·m 1/2。理想的界面结合状态是其具有高性能的主要原因。
Abstract:
The cross-linking and pyrolysis of hydrogen-containing polysiloxane(PSO) and divinylbenzene(DVB) were investigated in this paper. It was found that only catalyzed with H2PtCl6 could DVB/PSO cure completely. The mass ratio of DVB/PSO had a great effect on ceramic yield. The ceramic yield was the highest of 76 % when the mass ratio of DVB/PSO was 0.5. The content of Si, O, C in the product pyrolyzed at 1000 ℃ was 38.3 wt%, 27.4 wt%, and 34.3 wt%, respectively. Three-dimensional carbon fiber reinforced silicon oxycarbide composites (3D-B Cf/Si-O-C) were fabricated via precursor infiltration and pyrolysis using DVB/PSO as a precursor. The results indicated that the mechanical properties of 3D-B Cf/Si-O-C could be increased markedly if the first pyrolysis cycle was assisted by hot-pressing. The flexural strength and the fracture toughness of the composite, which was hot-pressed at 1600 ℃ for 5 min with a pressure of 10 MPa in the first pyrolysis cycle and treated subsequently with six cycles of vacuum infiltration and pyrolysis with a pressure of 1 atm, were 502 MPa and 23.7 MPa·m1/2, respectively. The high properties were mainly attributed to the ideal interface microstructures.
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