聚氨酯表层涂覆制备掺铍碳化硅泡沫的研究

目的采用模板法通过先驱体涂覆裂解工艺获得性能优异的掺铍碳化硅泡沫陶瓷。方法以掺铍聚碳硅烷(PBe CS)、二甲苯作为先驱体配制浆料,采用聚氨酯泡沫为模板,表层挂浆并烧结预制件后获得碳化硅泡沫陶瓷。运用XRD、SEM、波导法、保护热板法等手段,研究了浸渍液配比、烧结温度与Be元素对泡沫陶瓷结构、电磁性能、热导率的影响。结果 PBe CS经过陶瓷裂解后转变为无定型Si C,组成泡沫陶瓷的骨架。泡沫的开孔率为70%~90%,网孔的孔径介于0.5~1.2 mm之间。随着温度、浸渍浓度的增加,骨架的表面越平滑,致密化提高。Be元素的添加提高了陶瓷产率,先驱体中Be含量过低及泡沫陶瓷孔隙率高,导致了Be元素的低介电损耗、高热导率等性能没能在材料的整体复合性能中得到体现。结论通过改变浸渍液配比、烧结温度可以获得所需结构性能的掺铍碳化硅泡沫陶瓷,Be元素对材料性能提升的证明还需进一步研究。

Silicon Carbide Doped Beryllium Foam Ceramic Preparation by the Sur-face of Polyurethane Coating

Objective To prepare silicon carbide ceramic with excellent properties by precursor infiltration pyrolysis. Methods Using polycarbosilane containing beryllium and xylene as the precursor mixed slurry, SiC foam ceramic was prepared through processes of sizing and sintering with the polyurethane foam as a template. The influence of the impregnation concentration, sintering temperature and Be elements on the structure, electromagnetic properties and thermal conductivity was studied by XRD, SEM, waveguide method and guarded hot plate method. Results The amorphous SiC foam ceramic was formed after pyrolysis of PbeCS with a porosity and pore size of 70%~90% and 0.5~1.2 mm respectively. With the increase of temperature and concentration of impregnation liquid, the surface smoothness and densification of SiC would increase. The Be elements improved the ceramic production. However, the lower content of Be in preceramic polymer and high porosity resulted in that performances like low dielectric loss and high thermal conductivity were not reflected in the overall composite performance. Conclusion The SiC foam ceramic with required structure and property can be obtained by changing the impregnation liquid concentration and sintering temperature. The performance improvement by Be elements needs to be further studied.