C/C复合材料的光谱发射率研究

Study on Spectral Emissivity of C/C Composites

采用模压成型法制备了不同类型的C/C复合材料,测试了其法向光谱发射率的变化。结果表明,短切碳纤维增强的C/C复合材料,其法向光谱发射率在整个2500～13000nm的测试波段内普遍要高于碳布增强复合材料样品。短切碳纤维结构的相对松散,单位体积内物质的粒子数相对较少,这增加了电磁波的穿透深度,从而使得样品的法向光谱发射率较高,热辐射特性较好。纤维预制体和C/C复合材料样品的法向光谱发射率测试对比可知,两种不同碳材料的微结构差异使得树脂碳的法向光谱发射率优于纤维碳。利用Raman光谱对不同碳物质进行物相分析表明,树脂碳以sp3和sp2杂化态碳原子的混合结构使其内部产生的局域振动模式较多,这也是样品法向光谱发射率较高,热辐射特性较好的原因。

Different types of C/C composites were prepared by conventional molding,and the changes in normal spectral emissivity of samples were tested. The testing results show that spectral emissivity of C/C composite reinforced by short cut carbon fibers is generally higher than the sample reinforced by carbon cloth in the entire 2500-13000nm wavelength region. The structure of short cut carbon fibers is relatively loose and the number of material particles is less than other samples in unit volume,which increases the penetration depth of electromagnetic waves. This is the reason for higher normal spectral emissivity and better heat radiation property. Meanwhile,the test results of normal spectral emissivity for fiber perform and C/C composite samples show that the spectral emissivity of resin carbon is better than fiber carbon because of the difference in microstructure for the two kinds of carbon materials. Laser Raman spectroscopy was employed to analyze the microstructures of different carbon materials,and the results show that because sp^3 and sp^2 hybrid states of carbon atoms in resin carbon produced more vibration modes,the resin carbon also has higher normal spectral emissivity and better characteristics of heat radiation.