炭/炭复合材料表面SiC/ZrSiO_4-SiO_2复合涂层的抗氧化性能与红外发射特性研究

Anti-oxidation and Infrared Emissivity Property of SiC/ZrSiO_4-SiO_2 Composite Coatings on Carbon/Carbon Composites

为提高炭/炭(C/C)复合材料的高温抗氧化性能并降低其红外发射率,采用包埋–刷涂法在其表面制备了SiC/ZrSiO_4-SiO_2复合涂层。借助XRD、SEM等表征分析了涂层的成分与微观结构,并研究了SiC/ZrSiO_4-SiO_2复合涂层包覆C/C复合材料在1500℃动态空气条件下的抗氧化性能,以及在90和500℃下的红外发射率。结果表明:由疏松结构SiC内涂层和镶嵌结构ZrSiO_4-SiO_2外涂层组成的SiC/ZrSiO_4-SiO_2复合涂层具有优异的抗氧化性能,在1500℃流动空气(0.6 L/min)等温氧化条件下氧化50 h后试样的氧化失重率仅为0.03%。在C/C复合材料表面制备SiC/ZrSiO_4-SiO_2复合涂层后其红外发射率明显降低,并随温度升高而越低。复合涂层包覆试样在90℃时3~5μm和8~14μm波段的平均红外发射率分别为0.55和0.66;在500℃时3~5μm和8~14μm波段的平均红外发射率分别为0.48和0.62。SiC/ZrSiO_4-SiO_2复合涂层包覆C/C复合材料可作为优良的低红外发射率高温热结构材料应用于航空航天领域。

The SiC/ZrSiO_4-SiO_2 composite coatings were prepared on carbon/carbon（C/C） composites by combining pack cementation and slurry painting method to improve the oxidation resistance and decrease the infrared emissivity. The phase compositions and microstructures of the as-prepared coatings were characterized by XRD and SEM. The oxidation resistance of the SiC/ZrSiO_4-SiO_2 coatings was evaluated in dynamic air（air flow rate 0.6 L/min） at 1500 °C. The infrared emissivity of the SiC/ZrSiO_4-SiO_2 coatings coated C/C samples were also investigated at 90 and 500 °C. The results show that the composite coatings which are composed of SiC inner coating with loose structure and ZrSiO_4-SiO_2 outer coating with mosaic structure exhibit excellent oxidation resistance and can protect C/C matrix from oxidation for long time. The mass loss rate of the SiC/ZrSiO_4-SiO_2 coatings coated samples is only 0.03% in dynamic air at 1500 °C after 55 h oxidation. The infrared emissivity of C/C composites can be decreased by coated SiC/ZrSiO_4-SiO_2 composite coatings, and the infrared emissivity descends with the temperature increasing. The average infrared emissivity of the coated C/C samples in 3~5 μm and 8~14 μm at 90 °C are 0.55 and 0.66, respectively. And the average infrared emissivity in 3~5 μm and 8~14 μm at 500 °C are 0.48 and 0.62, respectively. From the anti-oxidation and infrared emissivity property point of view, the C/C composites coated SiC/ZrSiO_4-SiO_2 coatings may be one of the most promising candidates as high-temperature structural materials applied in the field of aeronautics and astronautics.